iknow-lab/mysql_manual_8_4_en · Datasets at Hugging Face

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https://dev.mysql.com/doc/refman/8.4/en/show-tables.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="show-tables"> </a> 15.7.7.39 SHOW TABLES Statement </h4> </div> </div> </div> <a class="indexterm" name="idm46045169128400"> </a> <a class="indexterm" name="idm46045169125632"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa14388240"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SHOW</span> <span class="token punctuation">[</span><span class="token keyword">EXTENDED</span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">FULL</span><span class="token punctuation">]</span> <span class="token keyword">TABLES</span> <span class="token punctuation">[</span>{<span class="token keyword">FROM</span> <span class="token operator">\|</span> <span class="token keyword">IN</span>} <em class="replaceable">db_name</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token operator">LIKE</span> <span class="token string">'<em class="replaceable">pattern</em>'</span> <span class="token operator">\|</span> <span class="token keyword">WHERE</span> <em class="replaceable">expr</em><span class="token punctuation">]</span></code></pre> </div> <p> <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> lists the non- <code class="literal"> TEMPORARY </code> tables in a given database. You can also get this list using the <a class="link" href="mysqlshow.html" title="6.5.6 mysqlshow — Display Database, Table, and Column Information"> <span class="command"> <strong> mysqlshow <em class="replaceable"> <code> db_name </code> </em> </strong> </span> </a> command. The <a class="link" href="string-comparison-functions.html#operator_like"> <code class="literal"> LIKE </code> </a> clause, if present, indicates which table names to match. The <code class="literal"> WHERE </code> clause can be given to select rows using more general conditions, as discussed in <a class="xref" href="extended-show.html" title="28.8 Extensions to SHOW Statements"> Section 28.8, “Extensions to SHOW Statements” </a> . </p> <p> Matching performed by the <code class="literal"> LIKE </code> clause is dependent on the setting of the <a class="link" href="server-system-variables.html#sysvar_lower_case_table_names"> <code class="literal"> lower_case_table_names </code> </a> system variable. </p> <p> The optional <code class="literal"> EXTENDED </code> modifier causes <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> to list hidden tables created by failed <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements. These temporary tables have names beginning with <code class="literal"> #sql </code> and can be dropped using <a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement"> <code class="literal"> DROP TABLE </code> </a> . </p> <p> This statement also lists any views in the database. The optional <code class="literal"> FULL </code> modifier causes <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> to display a second output column with values of <code class="literal"> BASE TABLE </code> for a table, <code class="literal"> VIEW </code> for a view, or <code class="literal"> SYSTEM VIEW </code> for an <code class="literal"> INFORMATION_SCHEMA </code> table. </p> <p> If you have no privileges for a base table or view, it does not show up in the output from <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> or <a class="link" href="mysqlshow.html" title="6.5.6 mysqlshow — Display Database, Table, and Column Information"> <span class="command"> <strong> mysqlshow db_name </strong> </span> </a> . </p> <p> Table information is also available from the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> table. See <a class="xref" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> Section 28.3.38, “The INFORMATION_SCHEMA TABLES Table” </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/sys-schema-prerequisites.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="sys-schema-prerequisites"> </a> 30.1 Prerequisites for Using the sys Schema </h2> </div> </div> </div> <p> Before using the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema, the prerequisites described in this section must be satisfied. </p> <p> Because the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema provides an alternative means of accessing the Performance Schema, the Performance Schema must be enabled for the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema to work. See <a class="xref" href="performance-schema-startup-configuration.html" title="29.3 Performance Schema Startup Configuration"> Section 29.3, “Performance Schema Startup Configuration” </a> . </p> <p> For full access to the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema, a user must have these privileges: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_select"> <code class="literal"> SELECT </code> </a> on all <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> tables and views </p> </li> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_execute"> <code class="literal"> EXECUTE </code> </a> on all <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> stored procedures and functions </p> </li> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_insert"> <code class="literal"> INSERT </code> </a> and <a class="link" href="privileges-provided.html#priv_update"> <code class="literal"> UPDATE </code> </a> for the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table, if changes are to be made to it </p> </li> <li class="listitem"> <p> Additional privileges for certain <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema stored procedures and functions, as noted in their descriptions (for example, the <a class="link" href="sys-ps-setup-save.html" title="30.4.4.14 The ps_setup_save() Procedure"> <code class="literal"> ps_setup_save() </code> </a> procedure) </p> </li> </ul> </div> <p> It is also necessary to have privileges for the objects underlying the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema objects: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_select"> <code class="literal"> SELECT </code> </a> on any Performance Schema tables accessed by <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema objects, and <a class="link" href="privileges-provided.html#priv_update"> <code class="literal"> UPDATE </code> </a> for any tables to be updated using <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema objects </p> </li> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> for the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table"> <code class="literal"> INNODB_BUFFER_PAGE </code> </a> table </p> </li> </ul> </div> <p> Certain Performance Schema instruments and consumers must be enabled and (for instruments) timed to take full advantage of <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema capabilities: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> All <code class="literal"> wait </code> instruments </p> </li> <li class="listitem"> <p> All <code class="literal"> stage </code> instruments </p> </li> <li class="listitem"> <p> All <code class="literal"> statement </code> instruments </p> </li> <li class="listitem"> <p> <code class="literal"> <em class="replaceable"> <code> xxx </code> </em> _current </code> and <code class="literal"> <em class="replaceable"> <code> xxx </code> </em> _history_long </code> consumers for all events </p> </li> </ul> </div> <p> You can use the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema itself to enable all of the additional instruments and consumers: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa93923863"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_instrument<span class="token punctuation">(</span><span class="token string">'wait'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_instrument<span class="token punctuation">(</span><span class="token string">'stage'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_instrument<span class="token punctuation">(</span><span class="token string">'statement'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_consumer<span class="token punctuation">(</span><span class="token string">'current'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_consumer<span class="token punctuation">(</span><span class="token string">'history_long'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> For many uses of the <code class="literal"> sys </code> schema, the default Performance Schema is sufficient for data collection. Enabling all the instruments and consumers just mentioned has a performance impact, so it is preferable to enable only the additional configuration you need. Also, remember that if you enable additional configuration, you can easily restore the default configuration like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa84602336"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_reset_to_default<span class="token punctuation">(</span><span class="token boolean">TRUE</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/clone-plugin-installation.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="clone-plugin-installation"> </a> 7.6.7.1 Installing the Clone Plugin </h4> </div> </div> </div> <a class="indexterm" name="idm46045255710528"> </a> <a class="indexterm" name="idm46045255709040"> </a> <p> This section describes how to install and configure the clone plugin. For remote cloning operations, the clone plugin must be installed on the donor and recipient MySQL server instances. </p> <p> For general information about installing or uninstalling plugins, see <a class="xref" href="plugin-loading.html" title="7.6.1 Installing and Uninstalling Plugins"> Section 7.6.1, “Installing and Uninstalling Plugins” </a> . </p> <p> To be usable by the server, the plugin library file must be located in the MySQL plugin directory (the directory named by the <a class="link" href="server-system-variables.html#sysvar_plugin_dir"> <code class="literal"> plugin_dir </code> </a> system variable). If necessary, set the value of <a class="link" href="server-system-variables.html#sysvar_plugin_dir"> <code class="literal"> plugin_dir </code> </a> at server startup to tell the server the plugin directory location. </p> <p> The plugin library file base name is <code class="literal"> mysql_clone.so </code> . The file name suffix differs by platform (for example, <code class="filename"> .so </code> for Unix and Unix-like systems, <code class="filename"> .dll </code> for Windows). </p> <p> To load the plugin at server startup, use the <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> --plugin-load-add </code> </a> option to name the library file that contains it. With this plugin-loading method, the option must be given each time the server starts. For example, put these lines in your <code class="filename"> my.cnf </code> file, adjusting the plugin library file name extension for your platform as necessary. (The plugin library file name extension depends on your platform. Common suffixes are <code class="filename"> .so </code> for Unix and Unix-like systems, <code class="filename"> .dll </code> for Windows.) </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa75520758"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">plugin-load-add</span><span class="token attr-value"><span class="token punctuation">=</span>mysql_clone.so</span></code></pre> </div> <p> After modifying <code class="filename"> my.cnf </code> , restart the server to cause the new settings to take effect. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> --plugin-load-add </code> </a> option cannot be used to load the clone plugin when restarting the server during an upgrade from a previous MySQL version. In such cases, attempting to restart the server with <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> plugin-load-add=mysql_clone.so </code> </a> raises the error <span class="errortext"> [ERROR] [MY-013238] [Server] Error installing plugin 'clone': Cannot install during upgrade. </span> To keep this from happening, upgrade the server before attempting to start the server with <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> plugin-load-add=mysql_clone.so </code> </a> . </p> </div> <p> Alternatively, to load the plugin at runtime, use this statement, adjusting the <code class="filename"> .so </code> suffix for your platform as necessary: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa45811432"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSTALL</span> <span class="token keyword">PLUGIN</span> <span class="token keyword">clone</span> <span class="token keyword">SONAME</span> <span class="token string">'mysql_clone.so'</span><span class="token punctuation">;</span></code></pre> </div> <p> <a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> <code class="literal"> INSTALL PLUGIN </code> </a> loads the plugin, and also registers it in the <code class="literal"> mysql.plugins </code> system table to cause the plugin to be loaded for each subsequent normal server startup without the need for <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> --plugin-load-add </code> </a> . </p> <p> To verify plugin installation, examine the Information Schema <a class="link" href="information-schema-plugins-table.html" title="28.3.22 The INFORMATION_SCHEMA PLUGINS Table"> <code class="literal"> PLUGINS </code> </a> table or use the <a class="link" href="show-plugins.html" title="15.7.7.27 SHOW PLUGINS Statement"> <code class="literal"> SHOW PLUGINS </code> </a> statement (see <a class="xref" href="obtaining-plugin-information.html" title="7.6.2 Obtaining Server Plugin Information"> Section 7.6.2, “Obtaining Server Plugin Information” </a> ). For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa7088920"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> PLUGIN_NAME<span class="token punctuation">,</span> PLUGIN_STATUS <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span><span class="token keyword">PLUGINS</span> <span class="token keyword">WHERE</span> PLUGIN_NAME <span class="token operator">=</span> <span class="token string">'clone'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> PLUGIN_NAME <span class="token punctuation">\|</span> PLUGIN_STATUS <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> clone <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> If the plugin fails to initialize, check the server error log for clone or plugin-related diagnostic messages. </p> <p> If the plugin has been previously registered with <a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> <code class="literal"> INSTALL PLUGIN </code> </a> or is loaded with <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> --plugin-load-add </code> </a> , you can use the <code class="option"> --clone </code> option at server startup to control the plugin activation state. For example, to load the plugin at startup and prevent it from being removed at runtime, use these options: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa61299599"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">plugin-load-add</span><span class="token attr-value"><span class="token punctuation">=</span>mysql_clone.so</span> <span class="token constant">clone</span><span class="token attr-value"><span class="token punctuation">=</span>FORCE_PLUS_PERMANENT</span></code></pre> </div> <p> If you want to prevent the server from running without the clone plugin, use <code class="option"> --clone </code> with a value of <code class="literal"> FORCE </code> or <code class="literal"> FORCE_PLUS_PERMANENT </code> to force server startup to fail if the plugin does not initialize successfully. </p> <p> For more information about plugin activation states, see <a class="xref" href="plugin-loading.html#server-plugin-activating" title="Controlling Plugin Activation State"> Controlling Plugin Activation State </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/replication-features-timeout.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-features-timeout"> </a> 19.5.1.32 Replication Retries and Timeouts </h4> </div> </div> </div> <a class="indexterm" name="idm46045135079808"> </a> <a class="indexterm" name="idm46045135078320"> </a> <a class="indexterm" name="idm46045135076832"> </a> <a class="indexterm" name="idm46045135075760"> </a> <p> The global value of the system variable <a class="link" href="replication-options-replica.html#sysvar_replica_transaction_retries"> <code class="literal"> replica_transaction_retries </code> </a> sets the maximum number of times for applier threads on a single-threaded or multithreaded replica to automatically retry failed transactions before stopping. Transactions are automatically retried when the SQL thread fails to execute them because of an <code class="literal"> InnoDB </code> deadlock, or when the transaction's execution time exceeds the <code class="literal"> InnoDB </code> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> value. If a transaction has a non-temporary error that prevents it from succeeding, it is not retried. </p> <p> The default setting for <a class="link" href="replication-options-replica.html#sysvar_replica_transaction_retries"> <code class="literal"> replica_transaction_retries </code> </a> is 10, meaning that a failing transaction with an apparently temporary error is retried 10 times before the applier thread stops. Setting the variable to 0 disables automatic retrying of transactions. On a multithreaded replica, the specified number of transaction retries can take place on all applier threads of all channels. The Performance Schema table <a class="link" href="performance-schema-replication-applier-status-table.html" title="29.12.11.5 The replication_applier_status Table"> <code class="literal"> replication_applier_status </code> </a> shows the total number of transaction retries that took place on each replication channel, in the <code class="literal"> COUNT_TRANSACTIONS_RETRIES </code> column. </p> <p> The process of retrying transactions can cause lag on a replica or on a Group Replication group member, which can be configured as a single-threaded or multithreaded replica. The Performance Schema table <a class="link" href="performance-schema-replication-applier-status-by-worker-table.html" title="29.12.11.7 The replication_applier_status_by_worker Table"> <code class="literal"> replication_applier_status_by_worker </code> </a> shows detailed information on transaction retries by the applier threads on a single-threaded or multithreaded replica. This data includes timestamps showing how long it took the applier thread to apply the last transaction from start to finish (and when the transaction currently in progress was started), and how long this was after the commit on the original source and the immediate source. The data also shows the number of retries for the last transaction and the transaction currently in progress, and enables you to identify the transient errors that caused the transactions to be retried. You can use this information to see whether transaction retries are the cause of replication lag, and investigate the root cause of the failures that led to the retries. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/information-schema-column-statistics-table.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-column-statistics-table"> </a> 28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045080067712"> </a> <p> The <a class="link" href="information-schema-column-statistics-table.html" title="28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table"> <code class="literal"> COLUMN_STATISTICS </code> </a> table provides access to histogram statistics for column values. </p> <p> For information about histogram statistics, see <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> , and <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> . </p> <p> You can see information only for columns for which you have some privilege. </p> <p> The <a class="link" href="information-schema-column-statistics-table.html" title="28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table"> <code class="literal"> COLUMN_STATISTICS </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> SCHEMA_NAME </code> </p> <p> The names of the schema for which the statistics apply. </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_NAME </code> </p> <p> The names of the column for which the statistics apply. </p> </li> <li class="listitem"> <p> <code class="literal"> COLUMN_NAME </code> </p> <p> The names of the column for which the statistics apply. </p> </li> <li class="listitem"> <p> <code class="literal"> HISTOGRAM </code> </p> <p> A <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> object describing the column statistics, stored as a histogram. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/partitioning-limitations-partitioning-keys-unique-keys.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="partitioning-limitations-partitioning-keys-unique-keys"> </a> 26.6.1 Partitioning Keys, Primary Keys, and Unique Keys </h3> </div> </div> </div> <a class="indexterm" name="idm46045082850928"> </a> <a class="indexterm" name="idm46045082849840"> </a> <a class="indexterm" name="idm46045082848352"> </a> <a class="indexterm" name="idm46045082847264"> </a> <a class="indexterm" name="idm46045082845776"> </a> <p> This section discusses the relationship of partitioning keys with primary keys and unique keys. The rule governing this relationship can be expressed as follows: All columns used in the partitioning expression for a partitioned table must be part of every unique key that the table may have. </p> <p> In other words, <span class="emphasis"> <em> every unique key on the table must use every column in the table's partitioning expression </em> </span> . (This also includes the table's primary key, since it is by definition a unique key. This particular case is discussed later in this section.) For example, each of the following table creation statements is invalid: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59193363"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span></code></pre> </div> <p> In each case, the proposed table would have at least one unique key that does not include all columns used in the partitioning expression. </p> <p> Each of the following statements is valid, and represents one way in which the corresponding invalid table creation statement could be made to work: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa6212186"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">,</span> col3<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col3<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span></code></pre> </div> <p> This example shows the error produced in such cases: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa54203607"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t3 <span class="token punctuation">(</span> <span class="token prompt"> -></span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> col3<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token output">ERROR 1491 (HY000)<span class="token punctuation">:</span> A PRIMARY KEY must include all columns in the table's partitioning function</span></code></pre> </div> <p> The <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> statement fails because both <code class="literal"> col1 </code> and <code class="literal"> col3 </code> are included in the proposed partitioning key, but neither of these columns is part of both of unique keys on the table. This shows one possible fix for the invalid table definition: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa83738260"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t3 <span class="token punctuation">(</span> <span class="token prompt"> -></span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">,</span> col3<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.05 sec)</span></code></pre> </div> <p> In this case, the proposed partitioning key <code class="literal"> col3 </code> is part of both unique keys, and the table creation statement succeeds. </p> <p> The following table cannot be partitioned at all, because there is no way to include in a partitioning key any columns that belong to both unique keys: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa37345684"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t4 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col3<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col2<span class="token punctuation">,</span> col4<span class="token punctuation">)</span> <span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> Since every primary key is by definition a unique key, this restriction also includes the table's primary key, if it has one. For example, the next two statements are invalid: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa37621533"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t5 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t6 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col3<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span> <span class="token function">YEAR</span><span class="token punctuation">(</span>col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span></code></pre> </div> <p> In both cases, the primary key does not include all columns referenced in the partitioning expression. However, both of the next two statements are valid: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa22763384"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t7 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> <span class="token function">YEAR</span><span class="token punctuation">(</span>col2<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t8 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">,</span> col4<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col2<span class="token punctuation">,</span> col1<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> <span class="token function">YEAR</span><span class="token punctuation">(</span>col2<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span></code></pre> </div> <p> If a table has no unique keys—this includes having no primary key—then this restriction does not apply, and you may use any column or columns in the partitioning expression as long as the column type is compatible with the partitioning type. </p> <p> For the same reason, you cannot later add a unique key to a partitioned table unless the key includes all columns used by the table's partitioning expression. Consider the partitioned table created as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78587086"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span><span class="token punctuation">,</span> c2 <span class="token datatype">INT</span><span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">RANGE</span><span class="token punctuation">(</span>c1<span class="token punctuation">)</span> <span class="token punctuation">(</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p0 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p1 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p2 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">30</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p3 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">40</span><span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.12 sec)</span></code></pre> </div> <p> It is possible to add a primary key to <code class="literal"> t_no_pk </code> using either of these <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE </code> </a> statements: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa45799369"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token comment" spellcheck="true"># possible PK</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">ADD</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>c1<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.13 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span> <span class="token comment" spellcheck="true"># drop this PK</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">DROP</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.10 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span> <span class="token comment" spellcheck="true"># use another possible PK</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">ADD</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>c1<span class="token punctuation">,</span> c2<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.12 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span> <span class="token comment" spellcheck="true"># drop this PK</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">DROP</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.09 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span></code></pre> </div> <p> However, the next statement fails, because <code class="literal"> c1 </code> is part of the partitioning key, but is not part of the proposed primary key: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa33913564"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token comment" spellcheck="true"># fails with error 1503</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">ADD</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>c2<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">ERROR 1503 (HY000)<span class="token punctuation">:</span> A PRIMARY KEY must include all columns in the table's partitioning function</span></code></pre> </div> <p> Since <code class="literal"> t_no_pk </code> has only <code class="literal"> c1 </code> in its partitioning expression, attempting to adding a unique key on <code class="literal"> c2 </code> alone fails. However, you can add a unique key that uses both <code class="literal"> c1 </code> and <code class="literal"> c2 </code> . </p> <p> These rules also apply to existing nonpartitioned tables that you wish to partition using <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE ... PARTITION BY </code> </a> . Consider a table <code class="literal"> np_pk </code> created as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa62477395"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> np_pk <span class="token punctuation">(</span> <span class="token prompt"> -></span> id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">name</span> <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">50</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> added <span class="token datatype">DATE</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>id<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.08 sec)</span></code></pre> </div> <p> The following <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE </code> </a> statement fails with an error, because the <code class="literal"> added </code> column is not part of any unique key in the table: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa63510578"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> np_pk <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span> <span class="token function">TO_DAYS</span><span class="token punctuation">(</span>added<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token output">ERROR 1503 (HY000)<span class="token punctuation">:</span> A PRIMARY KEY must include all columns in the table's partitioning function</span></code></pre> </div> <p> However, this statement using the <code class="literal"> id </code> column for the partitioning column is valid, as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa76626325"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> np_pk <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>id<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.11 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span></code></pre> </div> <p> In the case of <code class="literal"> np_pk </code> , the only column that may be used as part of a partitioning expression is <code class="literal"> id </code> ; if you wish to partition this table using any other column or columns in the partitioning expression, you must first modify the table, either by adding the desired column or columns to the primary key, or by dropping the primary key altogether. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-tablestats-table.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-innodb-tablestats-table"> </a> 28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View </h3> </div> </div> </div> <a class="indexterm" name="idm46045076337216"> </a> <p> The <a class="link" href="information-schema-innodb-tablestats-table.html" title="28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View"> <code class="literal"> INNODB_TABLESTATS </code> </a> table provides a view of low-level status information about <code class="literal"> InnoDB </code> tables. This data is used by the MySQL optimizer to calculate which index to use when querying an <code class="literal"> InnoDB </code> table. This information is derived from in-memory data structures rather than data stored on disk. There is no corresponding internal <code class="literal"> InnoDB </code> system table. </p> <p> <code class="literal"> InnoDB </code> tables are represented in this view if they have been opened since the last server restart and have not aged out of the table cache. Tables for which persistent stats are available are always represented in this view. </p> <p> Table statistics are updated only for <a class="link" href="delete.html" title="15.2.2 DELETE Statement"> <code class="literal"> DELETE </code> </a> or <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> operations that modify indexed columns. Statistics are not updated by operations that modify only nonindexed columns. </p> <p> <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> clears table statistics and sets the <code class="literal"> STATS_INITIALIZED </code> column to <code class="literal"> Uninitialized </code> . Statistics are collected again the next time the table is accessed. </p> <p> For related usage information and examples, see <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> . </p> <p> The <a class="link" href="information-schema-innodb-tablestats-table.html" title="28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View"> <code class="literal"> INNODB_TABLESTATS </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> TABLE_ID </code> </p> <p> An identifier representing the table for which statistics are available; the same value as <code class="literal"> INNODB_TABLES.TABLE_ID </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> NAME </code> </p> <p> The name of the table; the same value as <code class="literal"> INNODB_TABLES.NAME </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> STATS_INITIALIZED </code> </p> <p> The value is <code class="literal"> Initialized </code> if the statistics are already collected, <code class="literal"> Uninitialized </code> if not. </p> </li> <li class="listitem"> <p> <code class="literal"> NUM_ROWS </code> </p> <p> The current estimated number of rows in the table. Updated after each DML operation. The value could be imprecise if uncommitted transactions are inserting into or deleting from the table. </p> </li> <li class="listitem"> <p> <code class="literal"> CLUST_INDEX_SIZE </code> </p> <p> The number of pages on disk that store the clustered index, which holds the <code class="literal"> InnoDB </code> table data in primary key order. This value might be null if no statistics are collected yet for the table. </p> </li> <li class="listitem"> <p> <code class="literal"> OTHER_INDEX_SIZE </code> </p> <p> The number of pages on disk that store all secondary indexes for the table. This value might be null if no statistics are collected yet for the table. </p> </li> <li class="listitem"> <p> <code class="literal"> MODIFIED_COUNTER </code> </p> <p> The number of rows modified by DML operations, such as <code class="literal"> INSERT </code> , <code class="literal"> UPDATE </code> , <code class="literal"> DELETE </code> , and also cascade operations from foreign keys. This column is reset each time table statistics are recalculated </p> </li> <li class="listitem"> <p> <code class="literal"> AUTOINC </code> </p> <p> The next number to be issued for any auto-increment-based operation. The rate at which the <code class="literal"> AUTOINC </code> value changes depends on how many times auto-increment numbers have been requested and how many numbers are granted per request. </p> </li> <li class="listitem"> <p> <code class="literal"> REF_COUNT </code> </p> <p> When this counter reaches zero, the table metadata can be evicted from the table cache. </p> </li> </ul> </div> <h4> <a name="idm46045076296080"> </a> Example </h4> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa36130149"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_TABLESTATS <span class="token keyword">where</span> TABLE_ID <span class="token operator">=</span> <span class="token number">71</span>\G <span class="token output"><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> 1. row <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation">*</span> TABLE_ID<span class="token punctuation">:</span> 71 NAME<span class="token punctuation">:</span> test/t1 STATS_INITIALIZED<span class="token punctuation">:</span> Initialized NUM_ROWS<span class="token punctuation">:</span> 1 CLUST_INDEX_SIZE<span class="token punctuation">:</span> 1 OTHER_INDEX_SIZE<span class="token punctuation">:</span> 0 MODIFIED_COUNTER<span class="token punctuation">:</span> 1 AUTOINC<span class="token punctuation">:</span> 0 REF_COUNT<span class="token punctuation">:</span> 1</span></code></pre> </div> <h4> <a name="idm46045076293424"> </a> Notes </h4> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> This table is useful primarily for expert-level performance monitoring, or when developing performance-related extensions for MySQL. </p> </li> <li class="listitem"> <p> You must have the <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> privilege to query this table. </p> </li> <li class="listitem"> <p> Use the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> <code class="literal"> COLUMNS </code> </a> table or the <a class="link" href="show-columns.html" title="15.7.7.6 SHOW COLUMNS Statement"> <code class="literal"> SHOW COLUMNS </code> </a> statement to view additional information about the columns of this table, including data types and default values. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/myisamchk-other-options.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="myisamchk-other-options"> </a> 6.6.4.4 Other myisamchk Options </h4> </div> </div> </div> <p> <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> supports the following options for actions other than table checks and repairs: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_myisamchk_analyze"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_analyze"> <code class="option"> --analyze </code> </a> , <code class="option"> -a </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for analyze"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --analyze </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306872784"> </a> <a class="indexterm" name="idm46045306871296"> </a> <p> Analyze the distribution of key values. This improves join performance by enabling the join optimizer to better choose the order in which to join the tables and which indexes it should use. To obtain information about the key distribution, use a <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --description --verbose <em class="replaceable"> <code> tbl_name </code> </em> </strong> </span> </a> command or the <code class="literal"> SHOW INDEX FROM <em class="replaceable"> <code> tbl_name </code> </em> </code> statement. </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_block-search"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_block-search"> <code class="option"> --block-search= <em class="replaceable"> <code> offset </code> </em> </code> </a> , <code class="option"> -b <em class="replaceable"> <code> offset </code> </em> </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for block-search"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --block-search=offset </code> </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306855760"> </a> <a class="indexterm" name="idm46045306854272"> </a> <p> Find the record that a block at the given offset belongs to. </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_description"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_description"> <code class="option"> --description </code> </a> , <code class="option"> -d </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for description"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --description </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306844240"> </a> <a class="indexterm" name="idm46045306842752"> </a> <p> Print some descriptive information about the table. Specifying the <a class="link" href="myisamchk-general-options.html#option_myisamchk_verbose"> <code class="option"> --verbose </code> </a> option once or twice produces additional information. See <a class="xref" href="myisamchk-table-info.html" title="6.6.4.5 Obtaining Table Information with myisamchk"> Section 6.6.4.5, “Obtaining Table Information with myisamchk” </a> . </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_set-auto-increment"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_set-auto-increment"> <code class="option"> --set-auto-increment[= <em class="replaceable"> <code> value </code> </em> ] </code> </a> , <code class="option"> -A[ <em class="replaceable"> <code> value </code> </em> ] </code> </p> <a class="indexterm" name="idm46045306835552"> </a> <a class="indexterm" name="idm46045306834096"> </a> <p> Force <code class="literal"> AUTO_INCREMENT </code> numbering for new records to start at the given value (or higher, if there are existing records with <code class="literal"> AUTO_INCREMENT </code> values this large). If <em class="replaceable"> <code> value </code> </em> is not specified, <code class="literal"> AUTO_INCREMENT </code> numbers for new records begin with the largest value currently in the table, plus one. </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_sort-index"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_sort-index"> <code class="option"> --sort-index </code> </a> , <code class="option"> -S </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for sort-index"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --sort-index </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306821248"> </a> <a class="indexterm" name="idm46045306819760"> </a> <p> Sort the index tree blocks in high-low order. This optimizes seeks and makes table scans that use indexes faster. </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_sort-records"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_sort-records"> <code class="option"> --sort-records= <em class="replaceable"> <code> N </code> </em> </code> </a> , <code class="option"> -R <em class="replaceable"> <code> N </code> </em> </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for sort-records"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --sort-records=# </code> </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306806992"> </a> <a class="indexterm" name="idm46045306805504"> </a> <p> Sort records according to a particular index. This makes your data much more localized and may speed up range-based <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> and <code class="literal"> ORDER BY </code> operations that use this index. (The first time you use this option to sort a table, it may be very slow.) To determine a table's index numbers, use <a class="link" href="show-index.html" title="15.7.7.23 SHOW INDEX Statement"> <code class="literal"> SHOW INDEX </code> </a> , which displays a table's indexes in the same order that <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> sees them. Indexes are numbered beginning with 1. </p> <p> If keys are not packed ( <code class="literal"> PACK_KEYS=0 </code> ), they have the same length, so when <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> sorts and moves records, it just overwrites record offsets in the index. If keys are packed ( <code class="literal"> PACK_KEYS=1 </code> ), <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> must unpack key blocks first, then re-create indexes and pack the key blocks again. (In this case, re-creating indexes is faster than updating offsets for each index.) </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/ipv6-local-connections.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="ipv6-local-connections"> </a> 7.1.13.3 Connecting Using the IPv6 Local Host Address </h4> </div> </div> </div> <p> The following procedure shows how to configure MySQL to permit IPv6 connections by clients that connect to the local server using the <code class="literal"> ::1 </code> local host address. The instructions given here assume that your system supports IPv6. </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Start the MySQL server with an appropriate <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> setting to permit it to accept IPv6 connections. For example, put the following lines in the server option file and restart the server: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa17973723"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> </span></code></pre> </div> <p> Specifying (or <code class="literal"> :: </code> ) as the value for <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> permits both IPv4 and IPv6 connections on all server host IPv4 and IPv6 interfaces. If you want to bind the server to a specific list of addresses, you can do this by specifying a comma-separated list of values for <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> . This example specifies the local host addresses for both IPv4 and IPv6: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa78913468"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 127.0.0.1,::1</span></code></pre> </div> <p> For more information, see the <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> description in <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> . </p> </li> <li class="listitem"> <p> As an administrator, connect to the server and create an account for a local user who can connect from the <code class="literal"> ::1 </code> local IPv6 host address: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa21333848"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'ipv6user'</span>@<span class="token string">'::1'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'ipv6pass'</span><span class="token punctuation">;</span></code></pre> </div> <p> For the permitted syntax of IPv6 addresses in account names, see <a class="xref" href="account-names.html" title="8.2.4 Specifying Account Names"> Section 8.2.4, “Specifying Account Names” </a> . In addition to the <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> statement, you can issue <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> statements that give specific privileges to the account, although that is not necessary for the remaining steps in this procedure. </p> </li> <li class="listitem"> <p> Invoke the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client to connect to the server using the new account: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa73409060"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-h</span> <span class="token punctuation">:</span><span class="token punctuation">:</span>1 <span class="token property">-u</span> ipv6user <span class="token property">-pipv6pass</span></code></pre> </div> </li> <li class="listitem"> <p> Try some simple statements that show connection information: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa32741677"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">STATUS</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">Connection</span>: ::<span class="token number">1</span> via TCP<span class="token operator">/</span>IP <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">CURRENT_USER</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token variable">@@bind_address</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> CURRENT_USER() <span class="token punctuation">\|</span> @@bind_address <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> ipv6user@::1 <span class="token punctuation">\|</span> :: <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </li> </ol> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/controlling-query-plan-evaluation.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="controlling-query-plan-evaluation"> </a> 10.9.1 Controlling Query Plan Evaluation </h3> </div> </div> </div> <a class="indexterm" name="idm46045224538752"> </a> <p> The task of the query optimizer is to find an optimal plan for executing an SQL query. Because the difference in performance between <span class="quote"> “ <span class="quote"> good </span> ” </span> and <span class="quote"> “ <span class="quote"> bad </span> ” </span> plans can be orders of magnitude (that is, seconds versus hours or even days), most query optimizers, including that of MySQL, perform a more or less exhaustive search for an optimal plan among all possible query evaluation plans. For join queries, the number of possible plans investigated by the MySQL optimizer grows exponentially with the number of tables referenced in a query. For small numbers of tables (typically less than 7 to 10) this is not a problem. However, when larger queries are submitted, the time spent in query optimization may easily become the major bottleneck in the server's performance. </p> <p> A more flexible method for query optimization enables the user to control how exhaustive the optimizer is in its search for an optimal query evaluation plan. The general idea is that the fewer plans that are investigated by the optimizer, the less time it spends in compiling a query. On the other hand, because the optimizer skips some plans, it may miss finding an optimal plan. </p> <p> The behavior of the optimizer with respect to the number of plans it evaluates can be controlled using two system variables: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The <a class="link" href="server-system-variables.html#sysvar_optimizer_prune_level"> <code class="literal"> optimizer_prune_level </code> </a> variable tells the optimizer to skip certain plans based on estimates of the number of rows accessed for each table. Our experience shows that this kind of <span class="quote"> “ <span class="quote"> educated guess </span> ” </span> rarely misses optimal plans, and may dramatically reduce query compilation times. That is why this option is on ( <code class="literal"> optimizer_prune_level=1 </code> ) by default. However, if you believe that the optimizer missed a better query plan, this option can be switched off ( <code class="literal"> optimizer_prune_level=0 </code> ) with the risk that query compilation may take much longer. Note that, even with the use of this heuristic, the optimizer still explores a roughly exponential number of plans. </p> </li> <li class="listitem"> <p> The <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> variable tells how far into the <span class="quote"> “ <span class="quote"> future </span> ” </span> of each incomplete plan the optimizer should look to evaluate whether it should be expanded further. Smaller values of <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> may result in orders of magnitude smaller query compilation times. For example, queries with 12, 13, or more tables may easily require hours and even days to compile if <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> is close to the number of tables in the query. At the same time, if compiled with <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> equal to 3 or 4, the optimizer may compile in less than a minute for the same query. If you are unsure of what a reasonable value is for <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> , this variable can be set to 0 to tell the optimizer to determine the value automatically. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/replication-threads-monitor-worker.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-threads-monitor-worker"> </a> 19.2.3.2 Monitoring Replication Applier Worker Threads </h4> </div> </div> </div> <p> On a multithreaded replica, the Performance Schema tables <a class="link" href="performance-schema-replication-applier-status-by-coordinator-table.html" title="29.12.11.6 The replication_applier_status_by_coordinator Table"> <code class="literal"> replication_applier_status_by_coordinator </code> </a> and <a class="link" href="performance-schema-replication-applier-status-by-worker-table.html" title="29.12.11.7 The replication_applier_status_by_worker Table"> <code class="literal"> replication_applier_status_by_worker </code> </a> show status information for the replica's coordinator thread and applier worker threads respectively. For a replica with multiple channels, the threads for each channel are identified. </p> <p> A multithreaded replica's coordinator thread also prints statistics to the replica's error log on a regular basis if the verbosity setting is set to display informational messages. The statistics are printed depending on the volume of events that the coordinator thread has assigned to applier worker threads, with a maximum frequency of once every 120 seconds. The message lists the following statistics for the relevant replication channel, or the default replication channel (which is not named): </p> <div class="variablelist"> <dl class="variablelist"> <dt> <span class="term"> Seconds elapsed </span> </dt> <dd> <p> The difference in seconds between the current time and the last time this information was printed to the error log. </p> </dd> <dt> <span class="term"> Events assigned </span> </dt> <dd> <p> The total number of events that the coordinator thread has queued to all applier worker threads since the coordinator thread was started. </p> </dd> <dt> <span class="term"> Worker queues filled over overrun level </span> </dt> <dd> <p> The current number of events that are queued to any of the applier worker threads in excess of the overrun level, which is set at 90% of the maximum queue length of 16384 events. If this value is zero, no applier worker threads are operating at the upper limit of their capacity. </p> </dd> <dt> <span class="term"> Waited due to worker queue full </span> </dt> <dd> <p> The number of times that the coordinator thread had to wait to schedule an event because an applier worker thread's queue was full. If this value is zero, no applier worker threads exhausted their capacity. </p> </dd> <dt> <span class="term"> Waited due to the total size </span> </dt> <dd> <p> The number of times that the coordinator thread had to wait to schedule an event because the <a class="link" href="replication-options-replica.html#sysvar_replica_pending_jobs_size_max"> <code class="literal"> replica_pending_jobs_size_max </code> </a> limit had been reached. This system variable sets the maximum amount of memory (in bytes) available to applier worker thread queues holding events not yet applied. If an unusually large event exceeds this size, the transaction is held until all the applier worker threads have empty queues, and then processed. All subsequent transactions are held until the large transaction has been completed. </p> </dd> <dt> <span class="term"> Waited at clock conflicts </span> </dt> <dd> <p> The number of nanoseconds that the coordinator thread had to wait to schedule an event because a transaction that the event depended on had not yet been committed. If <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_type"> <code class="literal"> replica_parallel_type </code> </a> is set to <code class="literal"> DATABASE </code> (rather than <code class="literal"> LOGICAL_CLOCK </code> ), this value is always zero. </p> </dd> <dt> <span class="term"> Waited (count) when workers occupied </span> </dt> <dd> <p> The number of times that the coordinator thread slept for a short period, which it might do in two situations. The first situation is where the coordinator thread assigns an event and finds the applier worker thread's queue is filled beyond the underrun level of 10% of the maximum queue length, in which case it sleeps for a maximum of 1 millisecond. The second situation is where <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_type"> <code class="literal"> replica_parallel_type </code> </a> is set to <code class="literal"> LOGICAL_CLOCK </code> and the coordinator thread needs to assign the first event of a transaction to an applier worker thread's queue, it only does this to a worker with an empty queue, so if no queues are empty, the coordinator thread sleeps until one becomes empty. </p> </dd> <dt> <span class="term"> Waited when workers occupied </span> </dt> <dd> <p> The number of nanoseconds that the coordinator thread slept while waiting for an empty applier worker thread queue (that is, in the second situation described above, where <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_type"> <code class="literal"> replica_parallel_type </code> </a> is set to <code class="literal"> LOGICAL_CLOCK </code> and the first event of a transaction needs to be assigned). </p> </dd> </dl> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/encrypted-connection-protocols-ciphers.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="encrypted-connection-protocols-ciphers"> </a> 8.3.2 Encrypted Connection TLS Protocols and Ciphers </h3> </div> </div> </div> <p> MySQL supports multiple TLS protocols and ciphers, and enables configuring which protocols and ciphers to permit for encrypted connections. It is also possible to determine which protocol and cipher the current session uses. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-supported-protocols" title="Supported TLS Protocols"> Supported TLS Protocols </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-deprecated-protocols" title="Removal of Support for the TLSv1 and TLSv1.1 Protocols"> Removal of Support for the TLSv1 and TLSv1.1 Protocols </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-configuration" title="Connection TLS Protocol Configuration"> Connection TLS Protocol Configuration </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-cipher-configuration" title="Connection Cipher Configuration"> Connection Cipher Configuration </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-negotiation" title="Connection TLS Protocol Negotiation"> Connection TLS Protocol Negotiation </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-monitoring" title="Monitoring Current Client Session TLS Protocol and Cipher"> Monitoring Current Client Session TLS Protocol and Cipher </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-supported-protocols"> </a> Supported TLS Protocols </h4> </div> </div> </div> <p> MySQL 8.4 supports the TLSv1.2 and TLSv1.3 protocols for connections. To use TLSv1.3, both the MySQL server and the client application must be compiled using OpenSSL 1.1.1 or higher. The Group Replication component supports TLSv1.3 from MySQL 8.0.18 (for details, see <a class="xref" href="group-replication-secure-socket-layer-support-ssl.html" title="20.6.2 Securing Group Communication Connections with Secure Socket Layer (SSL)"> Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” </a> ). </p> <p> MySQL 8.4 does not support the old TLSv1 and TLSv1.1 protocols. </p> <p> Permitted TLS protocols can be configured on both the server side and client side to include only a subset of the supported TLS protocols. The configuration on both sides must include at least one protocol in common or connection attempts cannot negotiate a protocol to use. For details, see <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-negotiation" title="Connection TLS Protocol Negotiation"> Connection TLS Protocol Negotiation </a> . </p> <p> The host system may permit only certain TLS protocols, which means that MySQL connections cannot use protocols not allowed by the host even if MySQL itself permits them. Possible workarounds for this issue include the following: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Change the system-wide host configuration to permit additional TLS protocols. Consult your operating system documentation for instructions. For example, your system may have an <code class="literal"> /etc/ssl/openssl.cnf </code> file that contains these lines to restrict TLS protocols to TLSv1.3 or higher: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa45481712"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[system_default_sect]</span> <span class="token constant">MinProtocol</span> <span class="token attr-value"><span class="token punctuation">=</span> TLSv1.3</span></code></pre> </div> <p> Changing the value to a lower protocol version or <code class="literal"> None </code> makes the system more permissive. This workaround has the disadvantage that permitting lower (less secure) protocols may have adverse security consequences. </p> </li> <li class="listitem"> <p> If you cannot or prefer not to change the host system TLS configuration, change MySQL applications to use higher (more secure) TLS protocols that are permitted by the host system. This may not be possible for older versions of MySQL that support only lower protocol versions. For example, TLSv1 is the only supported protocol prior to MySQL 5.6.46, so attempts to connect to a pre-5.6.46 server fail even if the client is from a newer MySQL version that supports higher protocol versions. In such cases, an upgrade to a version of MySQL that supports additional TLS versions may be required. </p> </li> </ul> </div> <div class="variablelist"> <dl class="variablelist"> <dt> <span class="term"> System-wide host configuration </span> </dt> <dd> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If the MySQL configuration permits TLSv1.2, and your host system configuration permits only connections that use TLSv1.2 or higher, you can establish MySQL connections using TLSv1.2 only. </p> </li> <li class="listitem"> <p> Suppose the MySQL configuration permits TLSv1.2, but your host system configuration permits only connections that use TLSv1.3 or higher. If this is the case, you cannot establish MySQL connections at all, because no protocol permitted by MySQL is permitted by the host system. </p> </li> </ul> </div> </dd> </dl> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-deprecated-protocols"> </a> Removal of Support for the TLSv1 and TLSv1.1 Protocols </h4> </div> </div> </div> <p> Support for the TLSv1 and TLSv1.1 connection protocols was deprecated and removed in MySQL 8.0. For background, refer to the IETF memo <a class="ulink" href="https://tools.ietf.org/id/draft-ietf-tls-oldversions-deprecate-02.html" target="_blank"> Deprecating TLSv1.0 and TLSv1.1 </a> . In MySQL 8.4, connections can be made using only the more secure TLSv1.2 and TLSv1.3 protocols. TLSv1.3 requires that both the MySQL server and the client application are compiled with OpenSSL 1.1.1. </p> <p> For more information, see <a class="link" href="faqs-security.html#faq-mysql-tls-versions" title="A.9.7."> Does MySQL 8.4 support TLS 1.0 and 1.1? </a> </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-protocol-configuration"> </a> Connection TLS Protocol Configuration </h4> </div> </div> </div> <p> On the server side, the value of the <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> system variable determines which TLS protocols a MySQL server permits for encrypted connections. The <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> value applies to connections from clients, regular source/replica replication connections where this server instance is the source, Group Replication group communication connections, and Group Replication distributed recovery connections where this server instance is the donor. The administrative connection interface is configured similarly, but uses the <a class="link" href="server-system-variables.html#sysvar_admin_tls_version"> <code class="literal"> admin_tls_version </code> </a> system variable (see <a class="xref" href="administrative-connection-interface.html" title="7.1.12.2 Administrative Connection Management"> Section 7.1.12.2, “Administrative Connection Management” </a> ). This discussion applies to <a class="link" href="server-system-variables.html#sysvar_admin_tls_version"> <code class="literal"> admin_tls_version </code> </a> as well. </p> <p> The <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> value is a list of one or more comma-separated TLS protocol versions, which is not case-sensitive. By default, this variable lists all protocols that are supported by the SSL library used to compile MySQL and by the MySQL Server release. The default settings are therefore as shown in <a class="ulink" href="/doc/refman/8.0/en/encrypted-connection-protocols-ciphers.html#tls-support-defaults" target="_top"> MySQL Server TLS Protocol Default Settings </a> . </p> <p> To determine the value of <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> at runtime, use this statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa76162695"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">GLOBAL</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'tls_version'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Variable_name <span class="token punctuation">\|</span> Value <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> tls_version <span class="token punctuation">\|</span> TLSv1.2,TLSv1.3 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> To change the value of <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> , set it at server startup. For example, to permit connections that use the TLSv1.2 or TLSv1.3 protocol, but prohibit connections that use any other protocol, use these lines in the server <code class="filename"> my.cnf </code> file: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa50920394"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">tls_version</span><span class="token attr-value"><span class="token punctuation">=</span>TLSv1.2,TLSv1.3</span></code></pre> </div> <p> To be even more restrictive and permit only TLSv1.3 connections, set <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa59766875"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">tls_version</span><span class="token attr-value"><span class="token punctuation">=</span>TLSv1.3</span></code></pre> </div> <p> <code class="literal"> tls_version </code> can be changed at runtime. See <a class="xref" href="using-encrypted-connections.html#using-encrypted-connections-server-side-runtime-configuration" title="Server-Side Runtime Configuration and Monitoring for Encrypted Connections"> Server-Side Runtime Configuration and Monitoring for Encrypted Connections </a> . </p> <p> On the client side, the <a class="link" href="connection-options.html#option_general_tls-version"> <code class="option"> --tls-version </code> </a> option specifies which TLS protocols a client program permits for connections to the server. The format of the option value is the same as for the <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> system variable described previously (a list of one or more comma-separated protocol versions). </p> <p> For source/replica replication connections where this server instance is the replica, the <code class="literal"> SOURCE_TLS_VERSION </code> option for the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement specifies which TLS protocols the replica permits for connections to the source. The format of the option value is the same as for the <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> system variable described previously. See <a class="xref" href="replication-encrypted-connections.html" title="19.3.1 Setting Up Replication to Use Encrypted Connections"> Section 19.3.1, “Setting Up Replication to Use Encrypted Connections” </a> . </p> <p> The protocols that can be specified for <code class="literal"> SOURCE_TLS_VERSION </code> depend on the SSL library. This option is independent of and not affected by the server <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> value. For example, a server that acts as a replica can be configured with <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> set to TLSv1.3 to permit only incoming connections that use TLSv1.3, but also configured with <code class="literal"> SOURCE_TLS_VERSION </code> set to TLSv1.2 to permit only TLSv1.2 for outgoing replica connections to the source. </p> <p> For Group Replication distributed recovery connections where this server instance is the joining member that initiates distributed recovery (that is, the client), the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_version"> <code class="literal"> group_replication_recovery_tls_version </code> </a> system variable specifies which protocols are permitted by the client. Again, this option is independent of and not affected by the server <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> value, which applies when this server instance is the donor. A Group Replication server generally participates in distributed recovery both as a donor and as a joining member over the course of its group membership, so both these system variables should be set. See <a class="xref" href="group-replication-secure-socket-layer-support-ssl.html" title="20.6.2 Securing Group Communication Connections with Secure Socket Layer (SSL)"> Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” </a> . </p> <p> TLS protocol configuration affects which protocol a given connection uses, as described in <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-negotiation" title="Connection TLS Protocol Negotiation"> Connection TLS Protocol Negotiation </a> . </p> <p> Permitted protocols should be chosen such as not to leave <span class="quote"> “ <span class="quote"> holes </span> ” </span> in the list. For example, these server configuration values do not have holes: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa14697150"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">tls_version<span class="token attr-value"><span class="token punctuation">=</span>TLSv1.2,TLSv1.3</span> tls_version<span class="token attr-value"><span class="token punctuation">=</span>TLSv1.3</span></code></pre> </div> <p> The prohibition on holes also applies in other configuration contexts, such as for clients or replicas. </p> <p> Unless you intend to disable encrypted connections, the list of permitted protocols should not be empty. If you set a TLS version parameter to the empty string, encrypted connections cannot be established: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> : The server does not permit encrypted incoming connections. </p> </li> <li class="listitem"> <p> <a class="link" href="connection-options.html#option_general_tls-version"> <code class="option"> --tls-version </code> </a> : The client does not permit encrypted outgoing connections to the server. </p> </li> <li class="listitem"> <p> <code class="literal"> SOURCE_TLS_VERSION </code> : The replica does not permit encrypted outgoing connections to the source. </p> </li> <li class="listitem"> <p> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_version"> <code class="literal"> group_replication_recovery_tls_version </code> </a> : The joining member does not permit encrypted connections to the distributed recovery connection. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-cipher-configuration"> </a> Connection Cipher Configuration </h4> </div> </div> </div> <p> A default set of ciphers applies to encrypted connections, which can be overridden by explicitly configuring the permitted ciphers. During connection establishment, both sides of a connection must permit some cipher in common or the connection fails. Of the permitted ciphers common to both sides, the SSL library chooses the one supported by the provided certificate that has the highest priority. </p> <p> To specify a cipher or ciphers applicable for encrypted connections that use TLSv1.2: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Set the <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> ssl_cipher </code> </a> system variable on the server side, and use the <a class="link" href="connection-options.html#option_general_ssl-cipher"> <code class="option"> --ssl-cipher </code> </a> option for client programs. </p> </li> <li class="listitem"> <p> For regular source/replica replication connections, where this server instance is the source, set the <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> ssl_cipher </code> </a> system variable. Where this server instance is the replica, use the <code class="literal"> SOURCE_SSL_CIPHER </code> option for the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement. See <a class="xref" href="replication-encrypted-connections.html" title="19.3.1 Setting Up Replication to Use Encrypted Connections"> Section 19.3.1, “Setting Up Replication to Use Encrypted Connections” </a> . </p> </li> <li class="listitem"> <p> For a Group Replication group member, for Group Replication group communication connections and also for Group Replication distributed recovery connections where this server instance is the donor, set the <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> ssl_cipher </code> </a> system variable. For Group Replication distributed recovery connections where this server instance is the joining member, use the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_cipher"> <code class="literal"> group_replication_recovery_ssl_cipher </code> </a> system variable. See <a class="xref" href="group-replication-secure-socket-layer-support-ssl.html" title="20.6.2 Securing Group Communication Connections with Secure Socket Layer (SSL)"> Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” </a> . </p> </li> </ul> </div> <p> For encrypted connections that use TLSv1.3, OpenSSL 1.1.1 and higher supports the following ciphersuites, all of which are enabled by default for use with server system variables <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> --tls-ciphersuites </code> </a> or <a class="link" href="server-system-variables.html#sysvar_admin_tls_ciphersuites"> <code class="literal"> --admin-tls-ciphersuites </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa65442314"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">TLS_AES_128_GCM_SHA256 TLS_AES_256_GCM_SHA384 TLS_CHACHA20_POLY1305_SHA256 TLS_AES_128_CCM_SHA256</code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> In MySQL 8.4, use of <code class="literal"> TLS_AES_128_CCM_8_SHA256 </code> with server system variables <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> --tls-ciphersuites </code> </a> or <a class="link" href="server-system-variables.html#sysvar_admin_tls_ciphersuites"> <code class="literal"> --admin-tls-ciphersuites </code> </a> generates a deprecation warning. </p> </div> <p> To configure the permitted TLSv1.3 ciphersuites explicitly, set the following parameters. In each case, the configuration value is a list of zero or more colon-separated ciphersuite names. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> On the server side, use the <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> tls_ciphersuites </code> </a> system variable. If this variable is not set, its default value is <code class="literal"> NULL </code> , which means that the server permits the default set of ciphersuites. If the variable is set to the empty string, no ciphersuites are enabled and encrypted connections cannot be established. </p> </li> <li class="listitem"> <p> On the client side, use the <a class="link" href="connection-options.html#option_general_tls-ciphersuites"> <code class="option"> --tls-ciphersuites </code> </a> option. If this option is not set, the client permits the default set of ciphersuites. If the option is set to the empty string, no ciphersuites are enabled and encrypted connections cannot be established. </p> </li> <li class="listitem"> <p> For regular source/replica replication connections, where this server instance is the source, use the <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> tls_ciphersuites </code> </a> system variable. Where this server instance is the replica, use the <code class="literal"> SOURCE_TLS_CIPHERSUITES </code> option for the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement. See <a class="xref" href="replication-encrypted-connections.html" title="19.3.1 Setting Up Replication to Use Encrypted Connections"> Section 19.3.1, “Setting Up Replication to Use Encrypted Connections” </a> . </p> </li> <li class="listitem"> <p> For a Group Replication group member, for Group Replication group communication connections and also for Group Replication distributed recovery connections where this server instance is the donor, use the <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> tls_ciphersuites </code> </a> system variable. For Group Replication distributed recovery connections where this server instance is the joining member, use the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_ciphersuites"> <code class="literal"> group_replication_recovery_tls_ciphersuites </code> </a> system variable. See <a class="xref" href="group-replication-secure-socket-layer-support-ssl.html" title="20.6.2 Securing Group Communication Connections with Secure Socket Layer (SSL)"> Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” </a> . </p> </li> </ul> </div> <p> Ciphersuite support requires that both the MySQL server and the client application be compiled using OpenSSL 1.1.1 or higher. </p> <p> A given cipher may work only with particular TLS protocols, which affects the TLS protocol negotiation process. See <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-negotiation" title="Connection TLS Protocol Negotiation"> Connection TLS Protocol Negotiation </a> . </p> <p> To determine which ciphers a given server supports, check the session value of the <a class="link" href="server-status-variables.html#statvar_Ssl_cipher_list"> <code class="literal"> Ssl_cipher_list </code> </a> status variable: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa66789796"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SHOW</span> <span class="token keyword">SESSION</span> <span class="token keyword">STATUS</span> <span class="token operator">LIKE</span> <span class="token string">'Ssl_cipher_list'</span><span class="token punctuation">;</span></code></pre> </div> <p> The <a class="link" href="server-status-variables.html#statvar_Ssl_cipher_list"> <code class="literal"> Ssl_cipher_list </code> </a> status variable lists the possible SSL ciphers (empty for non-SSL connections). If MySQL supports TLSv1.3, the value includes the possible TLSv1.3 ciphersuites. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> ECDSA ciphers only work in combination with an SSL certificate that uses ECDSA for the digital signature, and they do not work with certificates that use RSA. MySQL Server’s automatic generation process for SSL certificates does not generate ECDSA signed certificates, it generates only RSA signed certificates. Do not select ECDSA ciphers unless you have an ECDSA certificate available to you. </p> </div> <p> For encrypted connections that use TLS.v1.3, MySQL uses the SSL library default ciphersuite list. </p> <p> For encrypted connections that use TLSv1.2, MySQL passes the following default cipher list to the SSL library when used with the server system variables <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> --ssl-cipher </code> </a> and <a class="link" href="server-system-variables.html#sysvar_admin_ssl_cipher"> <code class="literal"> --admin-ssl-cipher </code> </a> . </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa41336208"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ECDHE-ECDSA-AES128-GCM-SHA256 ECDHE-ECDSA-AES256-GCM-SHA384 ECDHE-RSA-AES128-GCM-SHA256 ECDHE-RSA-AES256-GCM-SHA384 ECDHE-ECDSA-CHACHA20-POLY1305 ECDHE-RSA-CHACHA20-POLY1305 ECDHE-ECDSA-AES256-CCM ECDHE-ECDSA-AES128-CCM DHE-RSA-AES128-GCM-SHA256 DHE-RSA-AES256-GCM-SHA384 DHE-RSA-AES256-CCM DHE-RSA-AES128-CCM DHE-RSA-CHACHA20-POLY1305</code></pre> </div> <p> These cipher restrictions are in place: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The following ciphers are deprecated and produce a warning when used with the server system variables <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> --ssl-cipher </code> </a> and <a class="link" href="server-system-variables.html#sysvar_admin_ssl_cipher"> <code class="literal"> --admin-ssl-cipher </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa53845696"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ECDHE-ECDSA-AES128-SHA256 ECDHE-RSA-AES128-SHA256 ECDHE-ECDSA-AES256-SHA384 ECDHE-RSA-AES256-SHA384 DHE-DSS-AES128-GCM-SHA256 DHE-RSA-AES128-SHA256 DHE-DSS-AES128-SHA256 DHE-DSS-AES256-GCM-SHA384 DHE-RSA-AES256-SHA256 DHE-DSS-AES256-SHA256 ECDHE-RSA-AES128-SHA ECDHE-ECDSA-AES128-SHA ECDHE-RSA-AES256-SHA ECDHE-ECDSA-AES256-SHA DHE-DSS-AES128-SHA DHE-RSA-AES128-SHA TLS_DHE_DSS_WITH_AES_256_CBC_SHA DHE-RSA-AES256-SHA AES128-GCM-SHA256 DH-DSS-AES128-GCM-SHA256 ECDH-ECDSA-AES128-GCM-SHA256 AES256-GCM-SHA384 DH-DSS-AES256-GCM-SHA384 ECDH-ECDSA-AES256-GCM-SHA384 AES128-SHA256 DH-DSS-AES128-SHA256 ECDH-ECDSA-AES128-SHA256 AES256-SHA256 DH-DSS-AES256-SHA256 ECDH-ECDSA-AES256-SHA384 AES128-SHA DH-DSS-AES128-SHA ECDH-ECDSA-AES128-SHA AES256-SHA DH-DSS-AES256-SHA ECDH-ECDSA-AES256-SHA DH-RSA-AES128-GCM-SHA256 ECDH-RSA-AES128-GCM-SHA256 DH-RSA-AES256-GCM-SHA384 ECDH-RSA-AES256-GCM-SHA384 DH-RSA-AES128-SHA256 ECDH-RSA-AES128-SHA256 DH-RSA-AES256-SHA256 ECDH-RSA-AES256-SHA384 ECDHE-RSA-AES128-SHA ECDHE-ECDSA-AES128-SHA ECDHE-RSA-AES256-SHA ECDHE-ECDSA-AES256-SHA DHE-DSS-AES128-SHA DHE-RSA-AES128-SHA TLS_DHE_DSS_WITH_AES_256_CBC_SHA DHE-RSA-AES256-SHA AES128-SHA DH-DSS-AES128-SHA ECDH-ECDSA-AES128-SHA AES256-SHA DH-DSS-AES256-SHA ECDH-ECDSA-AES256-SHA DH-RSA-AES128-SHA ECDH-RSA-AES128-SHA DH-RSA-AES256-SHA ECDH-RSA-AES256-SHA DES-CBC3-SHA</code></pre> </div> </li> <li class="listitem"> <p> The following ciphers are permanently restricted: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa44880851"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">!DHE-DSS-DES-CBC3-SHA !DHE-RSA-DES-CBC3-SHA !ECDH-RSA-DES-CBC3-SHA !ECDH-ECDSA-DES-CBC3-SHA !ECDHE-RSA-DES-CBC3-SHA !ECDHE-ECDSA-DES-CBC3-SHA</code></pre> </div> </li> <li class="listitem"> <p> The following categories of ciphers are permanently restricted: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa11359119"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">!aNULL !eNULL !EXPORT !LOW !MD5 !DES !RC2 !RC4 !PSK !SSLv3</code></pre> </div> </li> </ul> </div> <p> If the server is started with the <a class="link" href="server-system-variables.html#sysvar_ssl_cert"> <code class="literal"> ssl_cert </code> </a> system variable set to a certificate that uses any of the preceding restricted ciphers or cipher categories, the server starts with support for encrypted connections disabled. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-protocol-negotiation"> </a> Connection TLS Protocol Negotiation </h4> </div> </div> </div> <p> Connection attempts in MySQL negotiate use of the highest TLS protocol version available on both sides for which a protocol-compatible encryption cipher is available on both sides. The negotiation process depends on factors such as the SSL library used to compile the server and client, the TLS protocol and encryption cipher configuration, and which key size is used: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For a connection attempt to succeed, the server and client TLS protocol configuration must permit some protocol in common. </p> </li> <li class="listitem"> <p> Similarly, the server and client encryption cipher configuration must permit some cipher in common. A given cipher may work only with particular TLS protocols, so a protocol available to the negotiation process is not chosen unless there is also a compatible cipher. </p> </li> <li class="listitem"> <p> If TLSv1.3 is available, it is used if possible. (This means that server and client configuration both must permit TLSv1.3, and both must also permit some TLSv1.3-compatible encryption cipher.) Otherwise, MySQL continues through the list of available protocols, using TLSv1.2 if possible, and so forth. Negotiation proceeds from more secure protocols to less secure. Negotiation order is independent of the order in which protocols are configured. For example, negotiation order is the same regardless of whether <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> has a value of <code class="literal"> TLSv1.2,TLSv1.3 </code> or <code class="literal"> TLSv1.3,TLSv1.2 </code> . </p> </li> <li class="listitem"> <p> For better security, use a certificate with an RSA key size of at least 2048 bits. </p> </li> </ul> </div> <p> If the server and client do not have a permitted protocol in common, and a protocol-compatible cipher in common, the server terminates the connection request. </p> <p> MySQL permits specifying a list of protocols to support. This list is passed directly down to the underlying SSL library and is ultimately up to that library what protocols it actually enables from the supplied list. Please refer to the MySQL source code and the OpenSSL <a class="ulink" href="https://www.openssl.org/docs/man1.1.0/ssl/SSL_CTX_new.html" target="_blank"> <code class="literal"> SSL_CTX_new() </code> </a> documentation for information about how the SSL library handles this. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-protocol-monitoring"> </a> Monitoring Current Client Session TLS Protocol and Cipher </h4> </div> </div> </div> <p> To determine which encryption TLS protocol and cipher the current client session uses, check the session values of the <a class="link" href="server-status-variables.html#statvar_Ssl_version"> <code class="literal"> Ssl_version </code> </a> and <a class="link" href="server-status-variables.html#statvar_Ssl_cipher"> <code class="literal"> Ssl_cipher </code> </a> status variables: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa52834629"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>session_status <span class="token keyword">WHERE</span> VARIABLE_NAME <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token string">'Ssl_version'</span><span class="token punctuation">,</span><span class="token string">'Ssl_cipher'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> VARIABLE_NAME <span class="token punctuation">\|</span> VARIABLE_VALUE <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Ssl_cipher <span class="token punctuation">\|</span> DHE<span class="token punctuation">-</span>RSA<span class="token punctuation">-</span>AES128<span class="token punctuation">-</span>GCM<span class="token punctuation">-</span>SHA256 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> Ssl_version <span class="token punctuation">\|</span> TLSv1.2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> If the connection is not encrypted, both variables have an empty value. </p> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/table.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="table"> </a> 15.2.16 TABLE Statement </h3> </div> </div> </div> <a class="indexterm" name="idm46045179562896"> </a> <a class="indexterm" name="idm46045179561824"> </a> <a class="indexterm" name="idm46045179560368"> </a> <p> <code class="literal"> TABLE </code> is a DML statement which returns rows and columns of the named table. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa74040423"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">TABLE</span> <span class="token keyword"><em class="replaceable">table_name</em></span> <span class="token punctuation">[</span><span class="token keyword">ORDER</span> <span class="token keyword">BY</span> <span class="token keyword"><em class="replaceable">column_name</em></span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">LIMIT</span> <span class="token keyword"><em class="replaceable">number</em></span> <span class="token punctuation">[</span><span class="token keyword">OFFSET</span> <span class="token keyword"><em class="replaceable">number</em></span><span class="token punctuation">]</span><span class="token punctuation">]</span></code></pre> </div> <p> The <code class="literal"> TABLE </code> statement in some ways acts like <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> . Given the existence of a table named <code class="literal"> t </code> , the following two statements produce identical output: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa28115064"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">TABLE</span> t<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> t<span class="token punctuation">;</span></code></pre> </div> <p> You can order and limit the number of rows produced by <code class="literal"> TABLE </code> using <code class="literal"> ORDER BY </code> and <code class="literal"> LIMIT </code> clauses, respectively. These function identically to the same clauses when used with <code class="literal"> SELECT </code> (including an optional <code class="literal"> OFFSET </code> clause with <code class="literal"> LIMIT </code> ), as you can see here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa8192908"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> a <span class="token punctuation">\|</span> b <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 6 <span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 9 <span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 10 <span class="token punctuation">\|</span> <span class="token punctuation">-</span>4 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 11 <span class="token punctuation">\|</span> <span class="token punctuation">-</span>1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 13 <span class="token punctuation">\|</span> 3 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 14 <span class="token punctuation">\|</span> 6 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">7 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> b<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> a <span class="token punctuation">\|</span> b <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 10 <span class="token punctuation">\|</span> <span class="token punctuation">-</span>4 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 11 <span class="token punctuation">\|</span> <span class="token punctuation">-</span>1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 13 <span class="token punctuation">\|</span> 3 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 9 <span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 14 <span class="token punctuation">\|</span> 6 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 6 <span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">7 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t <span class="token keyword">LIMIT</span> <span class="token number">3</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> a <span class="token punctuation">\|</span> b <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 6 <span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 9 <span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> b <span class="token keyword">LIMIT</span> <span class="token number">3</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> a <span class="token punctuation">\|</span> b <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 10 <span class="token punctuation">\|</span> <span class="token punctuation">-</span>4 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 11 <span class="token punctuation">\|</span> <span class="token punctuation">-</span>1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> b <span class="token keyword">LIMIT</span> <span class="token number">3</span> <span class="token keyword">OFFSET</span> <span class="token number">2</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> a <span class="token punctuation">\|</span> b <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 13 <span class="token punctuation">\|</span> 3 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 9 <span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span></code></pre> </div> <p> <code class="literal"> TABLE </code> differs from <code class="literal"> SELECT </code> in two key respects: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> TABLE </code> always displays all columns of the table. </p> <p> <span class="emphasis"> <em> Exception </em> </span> : The output of <code class="literal"> TABLE </code> does <span class="emphasis"> <em> not </em> </span> include invisible columns. See <a class="xref" href="invisible-columns.html" title="15.1.20.10 Invisible Columns"> Section 15.1.20.10, “Invisible Columns” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE </code> does not allow for any arbitrary filtering of rows; that is, <code class="literal"> TABLE </code> does not support any <code class="literal"> WHERE </code> clause. </p> </li> </ul> </div> <p> For limiting which table columns are returned, filtering rows beyond what can be accomplished using <code class="literal"> ORDER BY </code> and <code class="literal"> LIMIT </code> , or both, use <code class="literal"> SELECT </code> . </p> <p> <code class="literal"> TABLE </code> can be used with temporary tables. </p> <p> <code class="literal"> TABLE </code> can also be used in place of <code class="literal"> SELECT </code> in a number of other constructs, including those listed here: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> With set operators such as <a class="link" href="union.html" title="15.2.18 UNION Clause"> <code class="literal"> UNION </code> </a> , as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa74014246"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t1<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> a <span class="token punctuation">\|</span> b <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span> 10 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span> 3 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span> 8 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t2<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> a <span class="token punctuation">\|</span> b <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 3 <span class="token punctuation">\|</span> 4 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 6 <span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">UNION</span> <span class="token keyword">TABLE</span> t2<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> a <span class="token punctuation">\|</span> b <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span> 10 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span> 3 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span> 8 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 3 <span class="token punctuation">\|</span> 4 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 6 <span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">6 rows in set (0.00 sec)</span></code></pre> </div> <p> The <a class="link" href="union.html" title="15.2.18 UNION Clause"> <code class="literal"> UNION </code> </a> just shown is equivalent to the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa90121703"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> t1 <span class="token keyword">UNION</span> <span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> t2<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> a <span class="token punctuation">\|</span> b <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span> 10 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span> 3 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span> 8 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span> 2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 3 <span class="token punctuation">\|</span> 4 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 6 <span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">6 rows in set (0.00 sec)</span></code></pre> </div> <p> <code class="literal"> TABLE </code> can also be used together in set operations with <code class="literal"> SELECT </code> statements, <a class="link" href="values.html" title="15.2.19 VALUES Statement"> <code class="literal"> VALUES </code> </a> statements, or both. See <a class="xref" href="union.html" title="15.2.18 UNION Clause"> Section 15.2.18, “UNION Clause” </a> , <a class="xref" href="except.html" title="15.2.4 EXCEPT Clause"> Section 15.2.4, “EXCEPT Clause” </a> , and <a class="xref" href="intersect.html" title="15.2.8 INTERSECT Clause"> Section 15.2.8, “INTERSECT Clause” </a> , for more information and examples. See also <a class="xref" href="set-operations.html" title="15.2.14 Set Operations with UNION, INTERSECT, and EXCEPT"> Section 15.2.14, “Set Operations with UNION, INTERSECT, and EXCEPT” </a> . </p> </li> <li class="listitem"> <p> With <code class="literal"> INTO </code> to populate user variables, and with <code class="literal"> INTO OUTFILE </code> or <code class="literal"> INTO DUMPFILE </code> to write table data to a file. See <a class="xref" href="select-into.html" title="15.2.13.1 SELECT ... INTO Statement"> Section 15.2.13.1, “SELECT ... INTO Statement” </a> , for more specific information and examples. </p> </li> <li class="listitem"> <p> In many cases where you can employ subqueries. Given any table <code class="literal"> t1 </code> with a column named <code class="literal"> a </code> , and a second table <code class="literal"> t2 </code> having a single column, statements such as the following are possible: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa54037426"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> a <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">TABLE</span> t2<span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> Assuming that the single column of table <code class="literal"> t1 </code> is named <code class="literal"> x </code> , the preceding is equivalent to each of the statements shown here (and produces exactly the same result in either case): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa75553223"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> a <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> x <span class="token keyword">FROM</span> t2<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> a <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> t2<span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> See <a class="xref" href="subqueries.html" title="15.2.15 Subqueries"> Section 15.2.15, “Subqueries” </a> , for more information. </p> </li> <li class="listitem"> <p> With <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> and <a class="link" href="replace.html" title="15.2.12 REPLACE Statement"> <code class="literal"> REPLACE </code> </a> statements, where you would otherwise use <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> . See <a class="xref" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement"> Section 15.2.7.1, “INSERT ... SELECT Statement” </a> , for more information and examples. </p> </li> <li class="listitem"> <p> <a class="link" href="table.html" title="15.2.16 TABLE Statement"> <code class="literal"> TABLE </code> </a> can also be used in many cases in place of the <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> in <a class="link" href="create-table-select.html" title="15.1.20.4 CREATE TABLE ... SELECT Statement"> <code class="literal"> CREATE TABLE ... SELECT </code> </a> or <a class="link" href="create-view.html" title="15.1.23 CREATE VIEW Statement"> <code class="literal"> CREATE VIEW ... SELECT </code> </a> . See the descriptions of these statements for more information and examples. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-configurator.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysql-configurator"> </a> 2.3.2 Configuration: Using MySQL Configurator </h3> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="mysql-configurator-workflow-server.html"> 2.3.2.1 MySQL Server Configuration with MySQL Configurator </a> </span> </dt> </dl> </div> <a class="indexterm" name="idm46045332375040"> </a> <p> MySQL Configurator is a standalone application designed to ease the complexity of configuring a MySQL server to run MySQL on Microsoft Windows. It is bundled with the MySQL server, in both the MSI and standalone Zip archive. </p> <h4> <a name="mysql-configurator-starting"> </a> Methods to Start MySQL Configurator </h4> <p> MySQL Configurator can both configure and reconfigure MySQL server; and the methods to start MySQL Configurator are: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The MySQL server MSI prompts to execute MySQL Configurator immediately after it installs the MySQL server. </p> </li> <li class="listitem"> <p> From the Start Menu: the MSI creates a MySQL Configurator start menu item. </p> </li> <li class="listitem"> <p> From the command line: the <code class="filename"> mysql-configurator.exe </code> executable is located in the same directory as <code class="filename"> mysqld.exe </code> and other MySQL binaries installed with the MySQL server. </p> <p> Typically this location is in <code class="filename"> C:\Program Files\MySQL\MySQL Server <em class="replaceable"> <code> X.Y </code> </em> \bin </code> if installed via the MSI, or a custom directory for the Zip archive. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-programs-ndbd.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysql-cluster-programs-ndbd"> </a> 25.5.1 ndbd — The NDB Cluster Data Node Daemon </h3> </div> </div> </div> <a class="indexterm" name="idm46045108436576"> </a> <a class="indexterm" name="idm46045108435632"> </a> <a class="indexterm" name="idm46045108434272"> </a> <a class="indexterm" name="idm46045108432912"> </a> <a class="indexterm" name="idm46045108432000"> </a> <p> The <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> binary provides the single-threaded version of the process that is used to handle all the data in tables employing the <code class="literal"> NDBCLUSTER </code> storage engine. This data node process enables a data node to accomplish distributed transaction handling, node recovery, checkpointing to disk, online backup, and related tasks. In NDB 8.4.1 and later, when started, <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> logs a warning similar to that shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa64625762"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">2024-05-28 13<span class="token punctuation">:</span>32<span class="token punctuation">:</span>16 <span class="token punctuation">[</span>ndbd<span class="token punctuation">]</span> WARNING <span class="token property">--</span> Running ndbd with a single thread of signal execution<span class="token punctuation">.</span> For multi-threaded signal execution run the ndbmtd binary<span class="token punctuation">.</span></code></pre> </div> <p> <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> is the multi-threaded version of this binary. </p> <p> In an NDB Cluster, a set of <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> processes cooperate in handling data. These processes can execute on the same computer (host) or on different computers. The correspondences between data nodes and Cluster hosts is completely configurable. </p> <a class="indexterm" name="idm46045108421648"> </a> <a class="indexterm" name="idm46045108420160"> </a> <a class="indexterm" name="idm46045108418672"> </a> <a class="indexterm" name="idm46045108417216"> </a> <p> Options that can be used with <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> are shown in the following table. Additional descriptions follow the table. </p> <p> </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> All of these options also apply to the multithreaded version of this program ( <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> ) and you may substitute <span class="quote"> “ <span class="quote"> <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> </span> ” </span> for <span class="quote"> “ <span class="quote"> <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> </span> ” </span> wherever the latter occurs in this section. </p> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_ndbd_bind-address"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_bind-address"> <code class="option"> --bind-address </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for bind-address"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --bind-address=name </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> </code> </td> </tr> </tbody> </table> </div> <p> Causes <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> to bind to a specific network interface (host name or IP address). This option has no default value. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_character-sets-dir"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_character-sets-dir"> <code class="option"> --character-sets-dir </code> </a> </p> <a class="indexterm" name="idm46045108392032"> </a> <a class="indexterm" name="idm46045108390576"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for character-sets-dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --character-sets-dir=path </code> </td> </tr> </tbody> </table> </div> <p> Directory containing character sets. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_connect-delay"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-delay"> <code class="option"> --connect-delay= <em class="replaceable"> <code> # </code> </em> </code> </a> </p> <a class="indexterm" name="idm46045108380464"> </a> <a class="indexterm" name="idm46045108378976"> </a> <a class="indexterm" name="idm46045108377488"> </a> <a class="indexterm" name="idm46045108376000"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-delay=# </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 3600 </code> </td> </tr> </tbody> </table> </div> <p> Determines the time to wait between attempts to contact a management server when starting (the number of attempts is controlled by the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retries"> <code class="option"> --connect-retries </code> </a> option). The default is 5 seconds. </p> <p> This option is deprecated, and is subject to removal in a future release of NDB Cluster. Use <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retry-delay"> <code class="option"> --connect-retry-delay </code> </a> instead. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_connect-retries"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retries"> <code class="option"> --connect-retries= <em class="replaceable"> <code> # </code> </em> </code> </a> </p> <a class="indexterm" name="idm46045108351696"> </a> <a class="indexterm" name="idm46045108350208"> </a> <a class="indexterm" name="idm46045108348720"> </a> <a class="indexterm" name="idm46045108347232"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-retries"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-retries=# </code> </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 12 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> -1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> Set the number of times to retry a connection before giving up; 0 means 1 attempt only (and no retries). The default is 12 attempts. The time to wait between attempts is controlled by the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retry-delay"> <code class="option"> --connect-retry-delay </code> </a> option. </p> <p> It is also possible to set this option to -1, in which case, the data node process continues indefinitely to try to connect. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_connect-retry-delay"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retry-delay"> <code class="option"> --connect-retry-delay= <em class="replaceable"> <code> # </code> </em> </code> </a> </p> <a class="indexterm" name="idm46045108326288"> </a> <a class="indexterm" name="idm46045108324832"> </a> <a class="indexterm" name="idm46045108323328"> </a> <a class="indexterm" name="idm46045108321824"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-retry-delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-retry-delay=# </code> </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Determines the time to wait between attempts to contact a management server when starting (the time between attempts is controlled by the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retries"> <code class="option"> --connect-retries </code> </a> option). The default is 5 seconds. </p> <p> This option takes the place of the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-delay"> <code class="option"> --connect-delay </code> </a> option, which is now deprecated and subject to removal in a future release of NDB Cluster. </p> <p> The short form <code class="option"> -r </code> for this option is also deprecated, and thus subject to removal. Use the long form instead. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_connect-string"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-string"> <code class="option"> --connect-string </code> </a> </p> <a class="indexterm" name="idm46045108298896"> </a> <a class="indexterm" name="idm46045108297408"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-string"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-string=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Same as <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_core-file"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_core-file"> <code class="option"> --core-file </code> </a> </p> <a class="indexterm" name="idm46045108282048"> </a> <a class="indexterm" name="idm46045108280560"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for core-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --core-file </code> </td> </tr> </tbody> </table> </div> <p> Write core file on error; used in debugging. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_daemon"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_daemon"> <code class="option"> --daemon </code> </a> , <code class="option"> -d </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for daemon"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --daemon </code> </td> </tr> </tbody> </table> </div> <p> Instructs <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> to execute as a daemon process. This is the default behavior. <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nodaemon"> <code class="option"> --nodaemon </code> </a> can be used to prevent the process from running as a daemon. </p> <p> This option has no effect when running <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> on Windows platforms. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_defaults-extra-file"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_defaults-extra-file"> <code class="option"> --defaults-extra-file </code> </a> </p> <a class="indexterm" name="idm46045108255440"> </a> <a class="indexterm" name="idm46045108253984"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-extra-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-extra-file=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read given file after global files are read. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_defaults-file"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_defaults-file"> <code class="option"> --defaults-file </code> </a> </p> <a class="indexterm" name="idm46045108239568"> </a> <a class="indexterm" name="idm46045108238080"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-file=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read default options from given file only. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_defaults-group-suffix"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_defaults-group-suffix"> <code class="option"> --defaults-group-suffix </code> </a> </p> <a class="indexterm" name="idm46045108223808"> </a> <a class="indexterm" name="idm46045108222352"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-group-suffix"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-group-suffix=string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Also read groups with concat(group, suffix). </p> </li> <li class="listitem"> <p> <a name="option_ndbd_filesystem-password"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_filesystem-password"> <code class="option"> --filesystem-password </code> </a> </p> <a class="indexterm" name="idm46045108208112"> </a> <a class="indexterm" name="idm46045108206656"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for filesystem-password"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --filesystem-password=password </code> </td> </tr> </tbody> </table> </div> <p> Pass the filesystem encryption and decryption password to the data node process using <code class="literal"> stdin </code> , <code class="literal"> tty </code> , or the <code class="filename"> my.cnf </code> file. </p> <p> Requires <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-encryptedfilesystem"> <code class="literal"> EncryptedFileSystem = 1 </code> </a> . </p> <p> For more information, see <a class="xref" href="mysql-cluster-tde.html" title="25.6.14 File System Encryption for NDB Cluster"> Section 25.6.14, “File System Encryption for NDB Cluster” </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_filesystem-password-from-stdin"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_filesystem-password-from-stdin"> <code class="option"> --filesystem-password-from-stdin </code> </a> </p> <a class="indexterm" name="idm46045108191824"> </a> <a class="indexterm" name="idm46045108190320"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for filesystem-password-from-stdin"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --filesystem-password-from-stdin={TRUE\|FALSE} </code> </td> </tr> </tbody> </table> </div> <p> Pass the filesystem encryption and decryption password to the data node process from <code class="literal"> stdin </code> (only). </p> <p> Requires <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-encryptedfilesystem"> <code class="literal"> EncryptedFileSystem = 1 </code> </a> . </p> <p> For more information, see <a class="xref" href="mysql-cluster-tde.html" title="25.6.14 File System Encryption for NDB Cluster"> Section 25.6.14, “File System Encryption for NDB Cluster” </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_foreground"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_foreground"> <code class="option"> --foreground </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for foreground"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --foreground </code> </td> </tr> </tbody> </table> </div> <p> Causes <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> to execute as a foreground process, primarily for debugging purposes. This option implies the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nodaemon"> <code class="option"> --nodaemon </code> </a> option. </p> <p> This option has no effect when running <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> on Windows platforms. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_help"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_help"> <code class="option"> --help </code> </a> </p> <a class="indexterm" name="idm46045108162224"> </a> <a class="indexterm" name="idm46045108160736"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for help"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --help </code> </td> </tr> </tbody> </table> </div> <p> Display help text and exit. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_initial"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial"> <code class="option"> --initial </code> </a> </p> <a class="indexterm" name="idm46045108151168"> </a> <a class="indexterm" name="idm46045108149680"> </a> <a class="indexterm" name="idm46045108148192"> </a> <a class="indexterm" name="idm46045108146704"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for initial"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --initial </code> </td> </tr> </tbody> </table> </div> <p> Instructs <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> to perform an initial start. An initial start erases any files created for recovery purposes by earlier instances of <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> . It also re-creates recovery log files. On some operating systems, this process can take a substantial amount of time. </p> <p> The option also causes the removal of all data files associated with Disk Data tablespaces and undo log files associated with log file groups that existed previously on this data node (see <a class="xref" href="mysql-cluster-disk-data.html" title="25.6.11 NDB Cluster Disk Data Tables"> Section 25.6.11, “NDB Cluster Disk Data Tables” </a> ). </p> <p> An <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial"> <code class="option"> --initial </code> </a> start is to be used <span class="emphasis"> <em> only </em> </span> when starting the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process under very special circumstances; this is because this option causes all files to be removed from the NDB Cluster file system and all redo log files to be re-created. These circumstances are listed here: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> When performing a software upgrade which has changed the contents of any files. </p> </li> <li class="listitem"> <p> When restarting the node with a new version of <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> . </p> </li> <li class="listitem"> <p> As a measure of last resort when for some reason the node restart or system restart repeatedly fails. In this case, be aware that this node can no longer be used to restore data due to the destruction of the data files. </p> </li> </ul> </div> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> To avoid the possibility of eventual data loss, it is recommended that you <span class="emphasis"> <em> not </em> </span> use the <code class="option"> --initial </code> option together with <code class="literal"> StopOnError = 0 </code> . Instead, set <code class="literal"> StopOnError </code> to 0 in <code class="filename"> config.ini </code> only after the cluster has been started, then restart the data nodes normally—that is, without the <code class="option"> --initial </code> option. See the description of the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-stoponerror"> <code class="literal"> StopOnError </code> </a> parameter for a detailed explanation of this issue. (Bug #24945638) </p> </div> <p> Use of this option prevents the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-startpartialtimeout"> <code class="literal"> StartPartialTimeout </code> </a> and <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-startpartitionedtimeout"> <code class="literal"> StartPartitionedTimeout </code> </a> configuration parameters from having any effect. </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> This option does <span class="emphasis"> <em> not </em> </span> affect backup files that have already been created by the affected node. </p> <p> This option also has no effect on recovery of data by a data node that is just starting (or restarting) from data nodes that are already running (unless they also were started with <code class="option"> --initial </code> , as part of an initial restart). This recovery of data occurs automatically, and requires no user intervention in an NDB Cluster that is running normally. </p> </div> <p> It is permissible to use this option when starting the cluster for the very first time (that is, before any data node files have been created); however, it is <span class="emphasis"> <em> not </em> </span> necessary to do so. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_initial-start"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial-start"> <code class="option"> --initial-start </code> </a> </p> <a class="indexterm" name="idm46045108111280"> </a> <a class="indexterm" name="idm46045108109792"> </a> <a class="indexterm" name="idm46045108108304"> </a> <a class="indexterm" name="idm46045108106816"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for initial-start"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --initial-start </code> </td> </tr> </tbody> </table> </div> <p> This option is used when performing a partial initial start of the cluster. Each node should be started with this option, as well as <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nowait-nodes"> <code class="option"> --nowait-nodes </code> </a> . </p> <p> Suppose that you have a 4-node cluster whose data nodes have the IDs 2, 3, 4, and 5, and you wish to perform a partial initial start using only nodes 2, 4, and 5—that is, omitting node 3: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa53739334"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">ndbd</span> <span class="token constant">--ndb-nodeid</span><span class="token attr-value"><span class="token punctuation">=</span>2</span> <span class="token constant">--nowait-nodes</span><span class="token attr-value"><span class="token punctuation">=</span>3</span> <span class="token property">--initial-start</span> <span class="token prompt">$> </span><span class="token command">ndbd</span> <span class="token constant">--ndb-nodeid</span><span class="token attr-value"><span class="token punctuation">=</span>4</span> <span class="token constant">--nowait-nodes</span><span class="token attr-value"><span class="token punctuation">=</span>3</span> <span class="token property">--initial-start</span> <span class="token prompt">$> </span><span class="token command">ndbd</span> <span class="token constant">--ndb-nodeid</span><span class="token attr-value"><span class="token punctuation">=</span>5</span> <span class="token constant">--nowait-nodes</span><span class="token attr-value"><span class="token punctuation">=</span>3</span> <span class="token property">--initial-start</span></code></pre> </div> <p> When using this option, you must also specify the node ID for the data node being started with the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-nodeid"> <code class="option"> --ndb-nodeid </code> </a> option. </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> Do not confuse this option with the <a class="link" href="mysql-cluster-programs-ndb-mgmd.html#option_ndb_mgmd_nowait-nodes"> <code class="option"> --nowait-nodes </code> </a> option for <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> , which can be used to enable a cluster configured with multiple management servers to be started without all management servers being online. </p> </div> </li> <li class="listitem"> <p> <a name="option_ndbd_install"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_install"> <code class="option"> --install[= <em class="replaceable"> <code> name </code> </em> ] </code> </a> </p> <a class="indexterm" name="idm46045108086592"> </a> <a class="indexterm" name="idm46045108085104"> </a> <a class="indexterm" name="idm46045108083616"> </a> <a class="indexterm" name="idm46045108082128"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for install"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --install[=name] </code> </td> </tr> <tr> <th> Platform Specific </th> <td> Windows </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ndbd </code> </td> </tr> </tbody> </table> </div> <p> Causes <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> to be installed as a Windows service. Optionally, you can specify a name for the service; if not set, the service name defaults to <code class="literal"> ndbd </code> . Although it is preferable to specify other <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> program options in a <code class="filename"> my.ini </code> or <code class="filename"> my.cnf </code> configuration file, it is possible to use together with <code class="option"> --install </code> . However, in such cases, the <code class="option"> --install </code> option must be specified first, before any other options are given, for the Windows service installation to succeed. </p> <p> It is generally not advisable to use this option together with the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial"> <code class="option"> --initial </code> </a> option, since this causes the data node file system to be wiped and rebuilt every time the service is stopped and started. Extreme care should also be taken if you intend to use any of the other <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> options that affect the starting of data nodes—including <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial-start"> <code class="option"> --initial-start </code> </a> , <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nostart"> <code class="option"> --nostart </code> </a> , and <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nowait-nodes"> <code class="option"> --nowait-nodes </code> </a> —together with <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_install"> <code class="option"> --install </code> </a> , and you should make absolutely certain you fully understand and allow for any possible consequences of doing so. </p> <p> The <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_install"> <code class="option"> --install </code> </a> option has no effect on non-Windows platforms. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_logbuffer-size"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_logbuffer-size"> <code class="option"> --logbuffer-size= <em class="replaceable"> <code> # </code> </em> </code> </a> </p> <a class="indexterm" name="idm46045108050864"> </a> <a class="indexterm" name="idm46045108049376"> </a> <a class="indexterm" name="idm46045108047888"> </a> <a class="indexterm" name="idm46045108046400"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for logbuffer-size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --logbuffer-size=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 32768 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 2048 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Sets the size of the data node log buffer. When debugging with high amounts of extra logging, it is possible for the log buffer to run out of space if there are too many log messages, in which case some log messages can be lost. This should not occur during normal operations. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_login-path"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_login-path"> <code class="option"> --login-path </code> </a> </p> <a class="indexterm" name="idm46045108027056"> </a> <a class="indexterm" name="idm46045108025568"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for login-path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --login-path=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read given path from login file. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_no-login-paths"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_no-login-paths"> <code class="option"> --no-login-paths </code> </a> </p> <a class="indexterm" name="idm46045108011248"> </a> <a class="indexterm" name="idm46045108009760"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-login-paths"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-login-paths </code> </td> </tr> </tbody> </table> </div> <p> Skips reading options from the login path file. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-connectstring"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> </p> <a class="indexterm" name="idm46045108000160"> </a> <a class="indexterm" name="idm46045107998704"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-connectstring"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-connectstring=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Set connection string for connecting to <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> . Syntax: <code class="literal"> [nodeid= <em class="replaceable"> <code> id </code> </em> ;][host=] <em class="replaceable"> <code> hostname </code> </em> [: <em class="replaceable"> <code> port </code> </em> ] </code> . Overrides entries in <code class="literal"> NDB_CONNECTSTRING </code> and <code class="filename"> my.cnf </code> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-mgmd-host"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-mgmd-host"> <code class="option"> --ndb-mgmd-host </code> </a> </p> <a class="indexterm" name="idm46045107979664"> </a> <a class="indexterm" name="idm46045107978176"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-mgmd-host"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-mgmd-host=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Same as <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-mgm-tls"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-mgm-tls"> <code class="option"> --ndb-mgm-tls </code> </a> </p> <a class="indexterm" name="idm46045107963056"> </a> <a class="indexterm" name="idm46045107961568"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-mgm-tls"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-mgm-tls=level </code> </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> relaxed </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> relaxed </code> </p> <p class="valid-value"> <code class="literal"> strict </code> </p> </td> </tr> </tbody> </table> </div> <p> Sets the level of TLS support required to connect to the management server; one of <code class="literal"> relaxed </code> or <code class="literal"> strict </code> . <code class="literal"> relaxed </code> (the default) means that a TLS connection is attempted, but success is not required; <code class="literal"> strict </code> means that TLS is required to connect. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-nodeid"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-nodeid"> <code class="option"> --ndb-nodeid </code> </a> </p> <a class="indexterm" name="idm46045107940688"> </a> <a class="indexterm" name="idm46045107939200"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-nodeid"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-nodeid=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Set node ID for this node, overriding any ID set by --ndb-connectstring. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-optimized-node-selection"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-optimized-node-selection"> <code class="option"> --ndb-optimized-node-selection </code> </a> </p> <a class="indexterm" name="idm46045107924800"> </a> <a class="indexterm" name="idm46045107923296"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-optimized-node-selection"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-optimized-node-selection </code> </td> </tr> </tbody> </table> </div> <p> Enable optimizations for selection of nodes for transactions. Enabled by default; use <code class="option"> --skip-ndb-optimized-node-selection </code> to disable. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-tls-search-path"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-tls-search-path"> <code class="option"> --ndb-tls-search-path </code> </a> </p> <a class="indexterm" name="idm46045107913008"> </a> <a class="indexterm" name="idm46045107911552"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-tls-search-path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-tls-search-path=list </code> </td> </tr> <tr> <th> Type </th> <td> Path name </td> </tr> <tr> <th> Default Value (Unix) </th> <td> <code class="literal"> $HOME/ndb-tls </code> </td> </tr> <tr> <th> Default Value (Windows) </th> <td> <code class="literal"> $HOMEDIR/ndb-tls </code> </td> </tr> </tbody> </table> </div> <p> Specify a list of directories to search for a CA file. On Unix platforms, the directory names are separated by colons ( <code class="literal"> : </code> ); on Windows systems, the semicolon character ( <code class="literal"> ; </code> ) is used as the separator. A directory reference may be relative or absolute; it may contain one or more environment variables, each denoted by a prefixed dollar sign ( <code class="literal"> $ </code> ), and expanded prior to use. </p> <p> Searching begins with the leftmost named directory and proceeds from left to right until a file is found. An empty string denotes an empty search path, which causes all searches to fail. A string consisting of a single dot ( <code class="literal"> . </code> ) indicates that the search path limited to the current working directory. </p> <p> If no search path is supplied, the compiled-in default value is used. This value depends on the platform used: On Windows, this is <code class="literal"> \ndb-tls </code> ; on other platforms (including Linux), it is <code class="literal"> $HOME/ndb-tls </code> . This can be overridden by compiling NDB Cluster using <a class="link" href="source-configuration-options.html#option_cmake_with_ndb_tls_search_path"> <code class="option"> -DWITH_NDB_TLS_SEARCH_PATH </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_nodaemon"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nodaemon"> <code class="option"> --nodaemon </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for nodaemon"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --nodaemon </code> </td> </tr> </tbody> </table> </div> <p> Prevents <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> from executing as a daemon process. This option overrides the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_daemon"> <code class="option"> --daemon </code> </a> option. This is useful for redirecting output to the screen when debugging the binary. </p> <p> The default behavior for <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> and <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> on Windows is to run in the foreground, making this option unnecessary on Windows platforms, where it has no effect. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_no-defaults"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_no-defaults"> <code class="option"> --no-defaults </code> </a> </p> <a class="indexterm" name="idm46045107872960"> </a> <a class="indexterm" name="idm46045107871472"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-defaults </code> </td> </tr> </tbody> </table> </div> <p> Do not read default options from any option file other than login file. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_nostart"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nostart"> <code class="option"> --nostart </code> </a> , <code class="option"> -n </code> </p> <a class="indexterm" name="idm46045107861504"> </a> <a class="indexterm" name="idm46045107860016"> </a> <a class="indexterm" name="idm46045107858528"> </a> <a class="indexterm" name="idm46045107857040"> </a> <a class="indexterm" name="idm46045107855552"> </a> <a class="indexterm" name="idm46045107854064"> </a> <a class="indexterm" name="idm46045107852576"> </a> <a class="indexterm" name="idm46045107851088"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for nostart"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --nostart </code> </td> </tr> </tbody> </table> </div> <p> Instructs <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> not to start automatically. When this option is used, <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> connects to the management server, obtains configuration data from it, and initializes communication objects. However, it does not actually start the execution engine until specifically requested to do so by the management server. This can be accomplished by issuing the proper <a class="link" href="mysql-cluster-mgm-client-commands.html#ndbclient-start"> <code class="literal"> START </code> </a> command in the management client (see <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> ). </p> </li> <li class="listitem"> <p> <a name="option_ndbd_nowait-nodes"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nowait-nodes"> <code class="option"> --nowait-nodes= <em class="replaceable"> <code> node_id_1 </code> </em> [, <em class="replaceable"> <code> node_id_2 </code> </em> [, ...]] </code> </a> </p> <a class="indexterm" name="idm46045107835600"> </a> <a class="indexterm" name="idm46045107834112"> </a> <a class="indexterm" name="idm46045107832624"> </a> <a class="indexterm" name="idm46045107831136"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for nowait-nodes"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --nowait-nodes=list </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> </code> </td> </tr> </tbody> </table> </div> <p> This option takes a list of data nodes for which the cluster does not wait, prior to starting. </p> <p> This can be used to start the cluster in a partitioned state. For example, to start the cluster with only half of the data nodes (nodes 2, 3, 4, and 5) running in a 4-node cluster, you can start each <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process with <code class="option"> --nowait-nodes=3,5 </code> . In this case, the cluster starts as soon as nodes 2 and 4 connect, and does <span class="emphasis"> <em> not </em> </span> wait <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-startpartitionedtimeout"> <code class="literal"> StartPartitionedTimeout </code> </a> milliseconds for nodes 3 and 5 to connect as it would otherwise. </p> <p> If you wanted to start up the same cluster as in the previous example without one <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> (say, for example, that the host machine for node 3 has suffered a hardware failure) then start nodes 2, 4, and 5 with <code class="option"> --nowait-nodes=3 </code> . Then the cluster starts as soon as nodes 2, 4, and 5 connect, and does not wait for node 3 to start. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_print-defaults"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_print-defaults"> <code class="option"> --print-defaults </code> </a> </p> <a class="indexterm" name="idm46045107810304"> </a> <a class="indexterm" name="idm46045107808816"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for print-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --print-defaults </code> </td> </tr> </tbody> </table> </div> <p> Print program argument list and exit. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_remove"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_remove"> <code class="option"> --remove[= <em class="replaceable"> <code> name </code> </em> ] </code> </a> </p> <a class="indexterm" name="idm46045107798912"> </a> <a class="indexterm" name="idm46045107797424"> </a> <a class="indexterm" name="idm46045107795936"> </a> <a class="indexterm" name="idm46045107794448"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for remove"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --remove[=name] </code> </td> </tr> <tr> <th> Platform Specific </th> <td> Windows </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ndbd </code> </td> </tr> </tbody> </table> </div> <p> Causes an <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process that was previously installed as a Windows service to be removed. Optionally, you can specify a name for the service to be uninstalled; if not set, the service name defaults to <code class="literal"> ndbd </code> . </p> <p> The <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_remove"> <code class="option"> --remove </code> </a> option has no effect on non-Windows platforms. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_usage"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_usage"> <code class="option"> --usage </code> </a> </p> <a class="indexterm" name="idm46045107774624"> </a> <a class="indexterm" name="idm46045107773136"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for usage"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --usage </code> </td> </tr> </tbody> </table> </div> <p> Display help text and exit; same as --help. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_verbose"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_verbose"> <code class="option"> --verbose </code> </a> , <code class="option"> -v </code> </p> <a class="indexterm" name="idm46045107763120"> </a> <a class="indexterm" name="idm46045107761632"> </a> <a class="indexterm" name="idm46045107760144"> </a> <a class="indexterm" name="idm46045107758656"> </a> <p> Causes extra debug output to be written to the node log. </p> <p> You can also use <a class="link" href="mysql-cluster-mgm-client-commands.html#ndbclient-nodelog-debug"> <code class="literal"> NODELOG DEBUG ON </code> </a> and <a class="link" href="mysql-cluster-mgm-client-commands.html#ndbclient-nodelog-debug"> <code class="literal"> NODELOG DEBUG OFF </code> </a> to enable and disable this extra logging while the data node is running. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_version"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_version"> <code class="option"> --version </code> </a> </p> <a class="indexterm" name="idm46045107751328"> </a> <a class="indexterm" name="idm46045107749840"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --version </code> </td> </tr> </tbody> </table> </div> <p> Display version information and exit. </p> </li> </ul> </div> <a class="indexterm" name="idm46045107742128"> </a> <a class="indexterm" name="idm46045107740640"> </a> <p> <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> generates a set of log files which are placed in the directory specified by <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datadir"> <code class="literal"> DataDir </code> </a> in the <code class="filename"> config.ini </code> configuration file. </p> <p> These log files are listed below. <em class="replaceable"> <code> node_id </code> </em> is and represents the node's unique identifier. For example, <code class="filename"> ndb_2_error.log </code> is the error log generated by the data node whose node ID is <code class="literal"> 2 </code> . </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045107732688"> </a> <a class="indexterm" name="idm46045107731200"> </a> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _error.log </code> is a file containing records of all crashes which the referenced <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process has encountered. Each record in this file contains a brief error string and a reference to a trace file for this crash. A typical entry in this file might appear as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa79311823"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">Date<span class="token operator">/</span>Time<span class="token operator">:</span> Saturday 30 July 2004 <span class="token operator">-</span> 00<span class="token operator">:</span>20<span class="token operator">:</span>01 Type of error<span class="token operator">:</span> error Message<span class="token operator">:</span> Internal program error <span class="token punctuation">(</span>failed ndbrequire<span class="token punctuation">)</span> Fault ID<span class="token operator">:</span> 2341 Problem data<span class="token operator">:</span> DbtupFixAlloc<span class="token punctuation">.</span>cpp Object of reference<span class="token operator">:</span> DBTUP <span class="token punctuation">(</span>Line<span class="token operator">:</span> 173<span class="token punctuation">)</span> ProgramName<span class="token operator">:</span> NDB Kernel ProcessID<span class="token operator">:</span> 14909 TraceFile<span class="token operator">:</span> ndb_2_trace<span class="token punctuation">.</span>log<span class="token punctuation">.</span>2 <span class="token operator">*</span><span class="token operator"></span>EOM<span class="token operator">*</span><span class="token operator"></span></code></pre> </div> <p> Listings of possible <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> exit codes and messages generated when a data node process shuts down prematurely can be found in <a class="ulink" href="/doc/ndb-internals/en/ndb-node-error-messages.html" target="_top"> Data Node Error Messages </a> . </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> <span class="emphasis"> <em> The last entry in the error log file is not necessarily the newest one </em> </span> (nor is it likely to be). Entries in the error log are <span class="emphasis"> <em> not </em> </span> listed in chronological order; rather, they correspond to the order of the trace files as determined in the <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _trace.log.next </code> file (see below). Error log entries are thus overwritten in a cyclical and not sequential fashion. </p> </div> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045107719616"> </a> <a class="indexterm" name="idm46045107718128"> </a> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _trace.log. <em class="replaceable"> <code> trace_id </code> </em> </code> is a trace file describing exactly what happened just before the error occurred. This information is useful for analysis by the NDB Cluster development team. </p> <p> It is possible to configure the number of these trace files that are created before old files are overwritten. <em class="replaceable"> <code> trace_id </code> </em> is a number which is incremented for each successive trace file. </p> </li> <li class="listitem"> <p> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _trace.log.next </code> is the file that keeps track of the next trace file number to be assigned. </p> </li> <li class="listitem"> <p> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _out.log </code> is a file containing any data output by the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process. This file is created only if <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> is started as a daemon, which is the default behavior. </p> </li> <li class="listitem"> <p> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> .pid </code> is a file containing the process ID of the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process when started as a daemon. It also functions as a lock file to avoid the starting of nodes with the same identifier. </p> </li> <li class="listitem"> <p> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _signal.log </code> is a file used only in debug versions of <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> , where it is possible to trace all incoming, outgoing, and internal messages with their data in the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process. </p> </li> </ul> </div> <p> It is recommended not to use a directory mounted through NFS because in some environments this can cause problems whereby the lock on the <code class="filename"> .pid </code> file remains in effect even after the process has terminated. </p> <p> To start <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> , it may also be necessary to specify the host name of the management server and the port on which it is listening. Optionally, one may also specify the node ID that the process is to use. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa14028626"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">ndbd</span> <span class="token constant">--connect-string</span>=<span class="token atrule">"nodeid=2;host=ndb_mgmd.mysql.com:1186"</span></code></pre> </div> <p> See <a class="xref" href="mysql-cluster-connection-strings.html" title="25.4.3.3 NDB Cluster Connection Strings"> Section 25.4.3.3, “NDB Cluster Connection Strings” </a> , for additional information about this issue. For more information about data node configuration parameters, see <a class="xref" href="mysql-cluster-ndbd-definition.html" title="25.4.3.6 Defining NDB Cluster Data Nodes"> Section 25.4.3.6, “Defining NDB Cluster Data Nodes” </a> . </p> <p> When <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> starts, it actually initiates two processes. The first of these is called the <span class="quote"> “ <span class="quote"> angel process </span> ” </span> ; its only job is to discover when the execution process has been completed, and then to restart the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process if it is configured to do so. Thus, if you attempt to kill <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> using the Unix <a class="link" href="kill.html" title="15.7.8.4 KILL Statement"> <span class="command"> <strong> kill </strong> </span> </a> command, it is necessary to kill both processes, beginning with the angel process. The preferred method of terminating an <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process is to use the management client and stop the process from there. </p> <p> The execution process uses one thread for reading, writing, and scanning data, as well as all other activities. This thread is implemented asynchronously so that it can easily handle thousands of concurrent actions. In addition, a watch-dog thread supervises the execution thread to make sure that it does not hang in an endless loop. A pool of threads handles file I/O, with each thread able to handle one open file. Threads can also be used for transporter connections by the transporters in the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process. In a multi-processor system performing a large number of operations (including updates), the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process can consume up to 2 CPUs if permitted to do so. </p> <p> For a machine with many CPUs it is possible to use several <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> processes which belong to different node groups; however, such a configuration is still considered experimental and is not supported for MySQL 8.4 in a production setting. See <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-tablespaces-brief-table.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-innodb-tablespaces-brief-table"> </a> 28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045076375216"> </a> <p> The <a class="link" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> <code class="literal"> INNODB_TABLESPACES_BRIEF </code> </a> table provides space ID, name, path, flag, and space type metadata for file-per-table, general, undo, and system tablespaces. </p> <p> <a class="link" href="information-schema-innodb-tablespaces-table.html" title="28.4.24 The INFORMATION_SCHEMA INNODB_TABLESPACES Table"> <code class="literal"> INNODB_TABLESPACES </code> </a> provides the same metadata but loads more slowly because other metadata provided by the table, such as <code class="literal"> FS_BLOCK_SIZE </code> , <code class="literal"> FILE_SIZE </code> , and <code class="literal"> ALLOCATED_SIZE </code> , must be loaded dynamically. </p> <p> Space and path metadata is also provided by the <a class="link" href="information-schema-innodb-datafiles-table.html" title="28.4.10 The INFORMATION_SCHEMA INNODB_DATAFILES Table"> <code class="literal"> INNODB_DATAFILES </code> </a> table. </p> <p> The <a class="link" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> <code class="literal"> INNODB_TABLESPACES_BRIEF </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> SPACE </code> </p> <p> The tablespace ID. </p> </li> <li class="listitem"> <p> <code class="literal"> NAME </code> </p> <p> The tablespace name. For file-per-table tablespaces, the name is in the form of <em class="replaceable"> <code> schema/table_name </code> </em> . </p> </li> <li class="listitem"> <p> <code class="literal"> PATH </code> </p> <p> The tablespace data file path. If a <a class="link" href="glossary.html#glos_file_per_table" title="file-per-table"> file-per-table </a> tablespace is created in a location outside the MySQL data directory, the path value is a fully qualified directory path. Otherwise, the path is relative to the data directory. </p> </li> <li class="listitem"> <p> <code class="literal"> FLAG </code> </p> <p> A numeric value that represents bit-level information about tablespace format and storage characteristics. </p> </li> <li class="listitem"> <p> <code class="literal"> SPACE_TYPE </code> </p> <p> The type of tablespace. Possible values include <code class="literal"> General </code> for <code class="literal"> InnoDB </code> general tablespaces, <code class="literal"> Single </code> for <code class="literal"> InnoDB </code> file-per-table tablespaces, and <code class="literal"> System </code> for the <code class="literal"> InnoDB </code> system tablespace. </p> </li> </ul> </div> <h4> <a name="idm46045076348432"> </a> Example </h4> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa49506278"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_TABLESPACES_BRIEF <span class="token keyword">WHERE</span> SPACE <span class="token operator">=</span> <span class="token number">7</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> SPACE <span class="token punctuation">\|</span> NAME <span class="token punctuation">\|</span> PATH <span class="token punctuation">\|</span> FLAG <span class="token punctuation">\|</span> SPACE_TYPE <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 7 <span class="token punctuation">\|</span> test/t1 <span class="token punctuation">\|</span> ./test/t1.ibd <span class="token punctuation">\|</span> 16417 <span class="token punctuation">\|</span> Single <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <h4> <a name="idm46045076345760"> </a> Notes </h4> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> You must have the <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> privilege to query this table. </p> </li> <li class="listitem"> <p> Use the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> <code class="literal"> COLUMNS </code> </a> table or the <a class="link" href="show-columns.html" title="15.7.7.6 SHOW COLUMNS Statement"> <code class="literal"> SHOW COLUMNS </code> </a> statement to view additional information about the columns of this table, including data types and default values. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/sys-memory-by-thread-by-current-bytes.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-memory-by-thread-by-current-bytes"> </a> 30.4.3.17 The memory_by_thread_by_current_bytes and x$memory_by_thread_by_current_bytes Views </h4> </div> </div> </div> <a class="indexterm" name="idm46045062847808"> </a> <a class="indexterm" name="idm46045062846352"> </a> <a class="indexterm" name="idm46045062844848"> </a> <a class="indexterm" name="idm46045062843328"> </a> <p> These views summarize memory use, grouped by thread. By default, rows are sorted by descending amount of memory used. </p> <p> The <a class="link" href="sys-memory-by-thread-by-current-bytes.html" title="30.4.3.17 The memory_by_thread_by_current_bytes and x$memory_by_thread_by_current_bytes Views"> <code class="literal"> memory_by_thread_by_current_bytes </code> </a> and <a class="link" href="sys-memory-by-thread-by-current-bytes.html" title="30.4.3.17 The memory_by_thread_by_current_bytes and x$memory_by_thread_by_current_bytes Views"> <code class="literal"> x$memory_by_thread_by_current_bytes </code> </a> views have these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> thread_id </code> </p> <p> The thread ID. </p> </li> <li class="listitem"> <p> <code class="literal"> user </code> </p> <p> The thread user or thread name. </p> </li> <li class="listitem"> <p> <code class="literal"> current_count_used </code> </p> <p> The current number of allocated memory blocks that have not been freed yet for the thread. </p> </li> <li class="listitem"> <p> <code class="literal"> current_allocated </code> </p> <p> The current number of allocated bytes that have not been freed yet for the thread. </p> </li> <li class="listitem"> <p> <code class="literal"> current_avg_alloc </code> </p> <p> The current number of allocated bytes per memory block for the thread. </p> </li> <li class="listitem"> <p> <code class="literal"> current_max_alloc </code> </p> <p> The largest single current memory allocation in bytes for the thread. </p> </li> <li class="listitem"> <p> <code class="literal"> total_allocated </code> </p> <p> The total memory allocation in bytes for the thread. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/privilege-checking.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="privilege-checking"> </a> 10.15.6 Privilege Checking </h3> </div> </div> </div> <p> In complex scenarios where the query uses SQL SECURITY DEFINER views or stored routines, it may be that a user is denied from seeing the trace of its query because it lacks some extra privileges on those objects. In that case, the trace will be shown as empty and the INSUFFICIENT_PRIVILEGES column will show "1". </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/stored-routines-syntax.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="stored-routines-syntax"> </a> 27.2.1 Stored Routine Syntax </h3> </div> </div> </div> <p> A stored routine is either a procedure or a function. Stored routines are created with the <a class="link" href="create-procedure.html" title="15.1.17 CREATE PROCEDURE and CREATE FUNCTION Statements"> <code class="literal"> CREATE PROCEDURE </code> </a> and <a class="link" href="create-function.html" title="15.1.14 CREATE FUNCTION Statement"> <code class="literal"> CREATE FUNCTION </code> </a> statements (see <a class="xref" href="create-procedure.html" title="15.1.17 CREATE PROCEDURE and CREATE FUNCTION Statements"> Section 15.1.17, “CREATE PROCEDURE and CREATE FUNCTION Statements” </a> ). A procedure is invoked using a <a class="link" href="call.html" title="15.2.1 CALL Statement"> <code class="literal"> CALL </code> </a> statement (see <a class="xref" href="call.html" title="15.2.1 CALL Statement"> Section 15.2.1, “CALL Statement” </a> ), and can only pass back values using output variables. A function can be called from inside a statement just like any other function (that is, by invoking the function's name), and can return a scalar value. The body of a stored routine can use compound statements (see <a class="xref" href="sql-compound-statements.html" title="15.6 Compound Statement Syntax"> Section 15.6, “Compound Statement Syntax” </a> ). </p> <p> Stored routines can be dropped with the <a class="link" href="drop-procedure.html" title="15.1.29 DROP PROCEDURE and DROP FUNCTION Statements"> <code class="literal"> DROP PROCEDURE </code> </a> and <a class="link" href="drop-function.html" title="15.1.26 DROP FUNCTION Statement"> <code class="literal"> DROP FUNCTION </code> </a> statements (see <a class="xref" href="drop-procedure.html" title="15.1.29 DROP PROCEDURE and DROP FUNCTION Statements"> Section 15.1.29, “DROP PROCEDURE and DROP FUNCTION Statements” </a> ), and altered with the <a class="link" href="alter-procedure.html" title="15.1.7 ALTER PROCEDURE Statement"> <code class="literal"> ALTER PROCEDURE </code> </a> and <a class="link" href="alter-function.html" title="15.1.4 ALTER FUNCTION Statement"> <code class="literal"> ALTER FUNCTION </code> </a> statements (see <a class="xref" href="alter-procedure.html" title="15.1.7 ALTER PROCEDURE Statement"> Section 15.1.7, “ALTER PROCEDURE Statement” </a> ). </p> <p> A stored procedure or function is associated with a particular database. This has several implications: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> When the routine is invoked, an implicit <code class="literal"> USE <em class="replaceable"> <code> db_name </code> </em> </code> is performed (and undone when the routine terminates). <a class="link" href="use.html" title="15.8.4 USE Statement"> <code class="literal"> USE </code> </a> statements within stored routines are not permitted. </p> </li> <li class="listitem"> <p> You can qualify routine names with the database name. This can be used to refer to a routine that is not in the current database. For example, to invoke a stored procedure <code class="literal"> p </code> or function <code class="literal"> f </code> that is associated with the <code class="literal"> test </code> database, you can say <code class="literal"> CALL test.p() </code> or <code class="literal"> test.f() </code> . </p> </li> <li class="listitem"> <p> When a database is dropped, all stored routines associated with it are dropped as well. </p> </li> </ul> </div> <p> Stored functions cannot be recursive. </p> <p> Recursion in stored procedures is permitted but disabled by default. To enable recursion, set the <a class="link" href="server-system-variables.html#sysvar_max_sp_recursion_depth"> <code class="literal"> max_sp_recursion_depth </code> </a> server system variable to a value greater than zero. Stored procedure recursion increases the demand on thread stack space. If you increase the value of <a class="link" href="server-system-variables.html#sysvar_max_sp_recursion_depth"> <code class="literal"> max_sp_recursion_depth </code> </a> , it may be necessary to increase thread stack size by increasing the value of <a class="link" href="server-system-variables.html#sysvar_thread_stack"> <code class="literal"> thread_stack </code> </a> at server startup. See <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> , for more information. </p> <p> MySQL supports a very useful extension that enables the use of regular <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> statements (that is, without using cursors or local variables) inside a stored procedure. The result set of such a query is simply sent directly to the client. Multiple <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> statements generate multiple result sets, so the client must use a MySQL client library that supports multiple result sets. This means the client must use a client library from a version of MySQL at least as recent as 4.1. The client should also specify the <code class="literal"> CLIENT_MULTI_RESULTS </code> option when it connects. For C programs, this can be done with the <a class="ulink" href="/doc/c-api/8.4/en/mysql-real-connect.html" target="_top"> <code class="literal"> mysql_real_connect() </code> </a> C API function. See <a class="ulink" href="/doc/c-api/8.4/en/mysql-real-connect.html" target="_top"> mysql_real_connect() </a> , and <a class="ulink" href="/doc/c-api/8.4/en/c-api-multiple-queries.html" target="_top"> Multiple Statement Execution Support </a> . </p> <p> A user variable referenced by a statement in a stored procedure has its type determined the first time the procedure is invoked, and retains this type each time the procedure is invoked thereafter. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/example-maximum-column-group.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="example-maximum-column-group"> </a> 5.6.3 Maximum of Column per Group </h3> </div> </div> </div> <p> <span class="emphasis"> <em> Task: Find the highest price per article. </em> </span> </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa87041549"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> article<span class="token punctuation">,</span> <span class="token function">MAX</span><span class="token punctuation">(</span>price<span class="token punctuation">)</span> <span class="token keyword">AS</span> price <span class="token keyword">FROM</span> shop <span class="token keyword">GROUP</span> <span class="token keyword">BY</span> article <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> article<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> article <span class="token punctuation">\|</span> price <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 0001 <span class="token punctuation">\|</span> 3.99 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 0002 <span class="token punctuation">\|</span> 10.99 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 0003 <span class="token punctuation">\|</span> 1.69 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 0004 <span class="token punctuation">\|</span> 19.95 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/replication-mode-change-online-disable-gtids.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-mode-change-online-disable-gtids"> </a> 19.1.4.3 Disabling GTID Transactions Online </h4> </div> </div> </div> <a class="indexterm" name="idm46045145395808"> </a> <p> This section describes how to disable GTID transactions on servers that are already online. This procedure does not require taking the server offline and is suited to use in production. However, if you have the possibility to take the servers offline when disabling GTIDs mode that process is easier. </p> <p> The process is similar to enabling GTID transactions while the server is online, but reversing the steps. The only thing that differs is the point at which you wait for logged transactions to replicate. </p> <p> Before starting, all servers must meet the following conditions: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> All servers have <a class="link" href="replication-options-gtids.html#sysvar_gtid_mode"> <code class="literal"> gtid_mode </code> </a> set to <code class="literal"> ON </code> . </p> </li> <li class="listitem"> <p> The <a class="link" href="replication-options-replica.html#option_mysqld_replicate-same-server-id"> <code class="option"> --replicate-same-server-id </code> </a> option is not set on any server. You cannot disable GTID transactions if this option is set together with the <a class="link" href="replication-options-binary-log.html#sysvar_log_replica_updates"> <code class="option"> --log-replica-updates </code> </a> option (default) and binary logging is enabled (also the default). Without GTIDs, this combination of options causes infinite loops in circular replication. </p> </li> </ul> </div> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Execute the following statements on each replica, and if you are using multi-source replication, do so for each channel, including the <code class="literal"> FOR CHANNEL </code> clause when using multi-source replication: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa63905681"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">STOP</span> <span class="token keyword">REPLICA</span> <span class="token punctuation">[</span><span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'<em class="replaceable">channel</em>'</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token keyword">CHANGE</span> <span class="token keyword">REPLICATION</span> <span class="token keyword">SOURCE</span> <span class="token keyword">TO</span> <span class="token keyword">SOURCE_AUTO_POSITION</span> <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token keyword">SOURCE_LOG_FILE</span> <span class="token operator">=</span> <span class="token string">'<em class="replaceable">file</em>'</span><span class="token punctuation">,</span> <span class="token keyword">SOURCE_LOG_POS</span> <span class="token operator">=</span> <em class="replaceable">position</em> <span class="token punctuation">[</span><span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'<em class="replaceable">channel</em>'</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token keyword">START</span> <span class="token keyword">REPLICA</span> <span class="token punctuation">[</span><span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'<em class="replaceable">channel</em>'</span><span class="token punctuation">]</span><span class="token punctuation">;</span></code></pre> </div> <p> You can obtain the values for <em class="replaceable"> <code> file </code> </em> and <em class="replaceable"> <code> position </code> </em> from the <code class="literal"> relay_source_log_file </code> and <code class="literal"> exec_source_log_position </code> columns in the output of <a class="link" href="show-replica-status.html" title="15.7.7.35 SHOW REPLICA STATUS Statement"> <code class="literal"> SHOW REPLICA STATUS </code> </a> . The <em class="replaceable"> <code> file </code> </em> and <em class="replaceable"> <code> channel </code> </em> names are strings; both of these must be quoted when used in the <a class="link" href="stop-replica.html" title="15.4.2.5 STOP REPLICA Statement"> <code class="literal"> STOP REPLICA </code> </a> , <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> , and <a class="link" href="start-replica.html" title="15.4.2.4 START REPLICA Statement"> <code class="literal"> START REPLICA </code> </a> statements. </p> </li> <li class="listitem"> <p> On each server, execute the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa54749112"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@@global.gtid_mode</span> <span class="token operator">=</span> ON_PERMISSIVE<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> On each server, execute the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa22579326"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@@global.gtid_mode</span> <span class="token operator">=</span> OFF_PERMISSIVE<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> On each server, wait until the global value of <a class="link" href="replication-options-gtids.html#sysvar_gtid_owned"> <code class="literal"> gtid_owned </code> </a> is equal to the empty string. This can be checked using the statement shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa30474902"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token variable">@@global.gtid_owned</span><span class="token punctuation">;</span></code></pre> </div> <p> On a replica, it is theoretically possible that this is empty and then becomes nonempty again. This is not a problem; it suffices that the value is empty at least once. </p> </li> <li class="listitem"> <p> Wait for all transactions that currently exist in any binary log to be committed on all replicas. See <a class="xref" href="replication-mode-change-online-verify-transactions.html" title="19.1.4.4 Verifying Replication of Anonymous Transactions"> Section 19.1.4.4, “Verifying Replication of Anonymous Transactions” </a> , for one method of checking that all anonymous transactions have replicated to all servers. </p> </li> <li class="listitem"> <p> If you use binary logs for anything other than replication—for example, to perform point-in-time backup or restore—wait until you no longer need any old binary logs containing GTID transactions. </p> <p> For instance, after the previous step has completed, you can execute <a class="link" href="flush.html#flush-logs"> <code class="literal"> FLUSH LOGS </code> </a> on the server where you are taking the backup. Then, either take a backup manually, or wait for the next iteration of any periodic backup routine you may have set up. </p> <p> Ideally, you should wait for the server to purge all binary logs that existed when step 5 was completed, and for any backup taken before then to expire. </p> <p> You should keep in mind that logs containing GTID transactions cannot be used after the next step. For this reason, before proceeding further, you must be sure that no uncommitted GTID transactions exist anywhere in the topology. </p> </li> <li class="listitem"> <p> On each server, execute the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa92523296"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@@global.gtid_mode</span> <span class="token operator">=</span> <span class="token keyword">OFF</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> On each server, set <a class="link" href="replication-options-gtids.html#sysvar_gtid_mode"> <code class="literal"> gtid_mode=OFF </code> </a> in <code class="filename"> my.cnf </code> . </p> <p> Optionally, you can also set <a class="link" href="replication-options-gtids.html#sysvar_enforce_gtid_consistency"> <code class="literal"> enforce_gtid_consistency=OFF </code> </a> . After doing so, you should add <a class="link" href="replication-options-gtids.html#sysvar_enforce_gtid_consistency"> <code class="literal"> enforce_gtid_consistency=OFF </code> </a> to your configuration file. </p> </li> </ol> </div> <p> If you want to downgrade to an earlier version of MySQL, you can do so now, using the normal downgrade procedure. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/replication-features-current-user.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-features-current-user"> </a> 19.5.1.8 Replication of CURRENT_USER() </h4> </div> </div> </div> <p> The following statements support use of the <a class="link" href="information-functions.html#function_current-user"> <code class="literal"> CURRENT_USER() </code> </a> function to take the place of the name of, and possibly the host for, an affected user or a definer: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="drop-user.html" title="15.7.1.5 DROP USER Statement"> <code class="literal"> DROP USER </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="rename-user.html" title="15.7.1.7 RENAME USER Statement"> <code class="literal"> RENAME USER </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="revoke.html" title="15.7.1.8 REVOKE Statement"> <code class="literal"> REVOKE </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-function.html" title="15.1.14 CREATE FUNCTION Statement"> <code class="literal"> CREATE FUNCTION </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-procedure.html" title="15.1.17 CREATE PROCEDURE and CREATE FUNCTION Statements"> <code class="literal"> CREATE PROCEDURE </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-trigger.html" title="15.1.22 CREATE TRIGGER Statement"> <code class="literal"> CREATE TRIGGER </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-event.html" title="15.1.13 CREATE EVENT Statement"> <code class="literal"> CREATE EVENT </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-view.html" title="15.1.23 CREATE VIEW Statement"> <code class="literal"> CREATE VIEW </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="alter-event.html" title="15.1.3 ALTER EVENT Statement"> <code class="literal"> ALTER EVENT </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="alter-view.html" title="15.1.11 ALTER VIEW Statement"> <code class="literal"> ALTER VIEW </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="set-password.html" title="15.7.1.10 SET PASSWORD Statement"> <code class="literal"> SET PASSWORD </code> </a> </p> </li> </ul> </div> <p> When binary logging is enabled and <a class="link" href="information-functions.html#function_current-user"> <code class="literal"> CURRENT_USER() </code> </a> or <a class="link" href="information-functions.html#function_current-user"> <code class="literal"> CURRENT_USER </code> </a> is used as the definer in any of these statements, MySQL Server ensures that the statement is applied to the same user on both the source and the replica when the statement is replicated. In some cases, such as statements that change passwords, the function reference is expanded before it is written to the binary log, so that the statement includes the user name. For all other cases, the name of the current user on the source is replicated to the replica as metadata, and the replica applies the statement to the current user named in the metadata, rather than to the current user on the replica. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/error-log-rule-based-filtering.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="error-log-rule-based-filtering"> </a> 7.4.2.6 Rule-Based Error Log Filtering (log_filter_dragnet) </h4> </div> </div> </div> <p> The <code class="literal"> log_filter_dragnet </code> log filter component enables log filtering based on user-defined rules. </p> <p> To enable the <code class="literal"> log_filter_dragnet </code> filter, first load the filter component, then modify the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value. The following example enables <code class="literal"> log_filter_dragnet </code> in combination with the built-in log sink: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa4617011"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSTALL</span> <span class="token keyword">COMPONENT</span> <span class="token string">'file://component_log_filter_dragnet'</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> log_error_services <span class="token operator">=</span> <span class="token string">'log_filter_dragnet; log_sink_internal'</span><span class="token punctuation">;</span></code></pre> </div> <p> To set <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> to take effect at server startup, use the instructions at <a class="xref" href="error-log-configuration.html" title="7.4.2.1 Error Log Configuration"> Section 7.4.2.1, “Error Log Configuration” </a> . Those instructions apply to other error-logging system variables as well. </p> <p> With <code class="literal"> log_filter_dragnet </code> enabled, define its filter rules by setting the <a class="link" href="server-system-variables.html#sysvar_dragnet.log_error_filter_rules"> <code class="literal"> dragnet.log_error_filter_rules </code> </a> system variable. A rule set consists of zero or more rules, where each rule is an <code class="literal"> IF </code> statement terminated by a period ( <code class="literal"> . </code> ) character. If the variable value is empty (zero rules), no filtering occurs. </p> <p> Example 1. This rule set drops information events, and, for other events, removes the <code class="literal"> source_line </code> field: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59750531"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> dragnet<span class="token punctuation">.</span>log_error_filter_rules <span class="token operator">=</span> <span class="token string">'IF prio>=INFORMATION THEN drop. IF EXISTS source_line THEN unset source_line.'</span><span class="token punctuation">;</span></code></pre> </div> <p> The effect is similar to the filtering performed by the <code class="literal"> log_sink_internal </code> filter with a setting of <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> <code class="literal"> log_error_verbosity=2 </code> </a> . </p> <p> For readability, you might find it preferable to list the rules on separate lines. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa65232995"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> dragnet<span class="token punctuation">.</span>log_error_filter_rules <span class="token operator">=</span> <span class="token string">' IF prio>=INFORMATION THEN drop. IF EXISTS source_line THEN unset source_line. '</span><span class="token punctuation">;</span></code></pre> </div> <p> Example 2: This rule limits information events to no more than one per 60 seconds: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa92804478"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> dragnet<span class="token punctuation">.</span>log_error_filter_rules <span class="token operator">=</span> <span class="token string">'IF prio>=INFORMATION THEN throttle 1/60.'</span><span class="token punctuation">;</span></code></pre> </div> <p> Once you have the filtering configuration set up as you desire, consider assigning <a class="link" href="server-system-variables.html#sysvar_dragnet.log_error_filter_rules"> <code class="literal"> dragnet.log_error_filter_rules </code> </a> using <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET PERSIST </code> </a> rather than <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET GLOBAL </code> </a> to make the setting persist across server restarts. Alternatively, add the setting to the server option file. </p> <p> When using <code class="literal"> log_filter_dragnet </code> , <a class="link" href="server-system-variables.html#sysvar_log_error_suppression_list"> <code class="literal"> log_error_suppression_list </code> </a> is ignored. </p> <p> To stop using the filtering language, first remove it from the set of error logging components. Usually this means using a different filter component rather than no filter component. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa17077236"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> log_error_services <span class="token operator">=</span> <span class="token string">'log_filter_internal; log_sink_internal'</span><span class="token punctuation">;</span></code></pre> </div> <p> Again, consider using <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET PERSIST </code> </a> rather than <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET GLOBAL </code> </a> to make the setting persist across server restarts. </p> <p> Then uninstall the filter <code class="literal"> log_filter_dragnet </code> component: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa38590988"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UNINSTALL</span> <span class="token keyword">COMPONENT</span> <span class="token string">'file://component_log_filter_dragnet'</span><span class="token punctuation">;</span></code></pre> </div> <p> The following sections describe aspects of <code class="literal"> log_filter_dragnet </code> operation in more detail: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-language" title="Grammar for log_filter_dragnet Rule Language"> Grammar for log_filter_dragnet Rule Language </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-actions" title="Actions for log_filter_dragnet Rules"> Actions for log_filter_dragnet Rules </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-fields" title="Field References in log_filter_dragnet Rules"> Field References in log_filter_dragnet Rules </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="error-log-dragnet-filtering-language"> </a> Grammar for log_filter_dragnet Rule Language </h5> </div> </div> </div> <p> The following grammar defines the language for <code class="literal"> log_filter_dragnet </code> filter rules. Each rule is an <code class="literal"> IF </code> statement terminated by a period ( <code class="literal"> . </code> ) character. The language is not case-sensitive. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa11116140"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple"><em class="replaceable">rule</em><span class="token operator">:</span> IF <em class="replaceable">condition</em> THEN <em class="replaceable">action</em> <span class="token punctuation">[</span>ELSEIF <em class="replaceable">condition</em> THEN <em class="replaceable">action</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token punctuation">[</span>ELSE <em class="replaceable">action</em><span class="token punctuation">]</span> <span class="token punctuation">.</span> <em class="replaceable">condition</em><span class="token operator">:</span> <span class="token punctuation">{</span> <em class="replaceable">field</em> <em class="replaceable">comparator</em> <em class="replaceable">value</em> <span class="token operator">\|</span> <span class="token punctuation">[</span>NOT<span class="token punctuation">]</span> EXISTS <em class="replaceable">field</em> <span class="token operator">\|</span> <em class="replaceable">condition</em> <span class="token punctuation">{</span>AND <span class="token operator">\|</span> OR<span class="token punctuation">}</span> <em class="replaceable">condition</em> <span class="token punctuation">}</span> <em class="replaceable">action</em><span class="token operator">:</span> <span class="token punctuation">{</span> drop <span class="token operator">\|</span> throttle <span class="token punctuation">{</span><em class="replaceable">count</em> <span class="token operator">\|</span> <em class="replaceable">count</em> <span class="token operator">/</span> <em class="replaceable">window_size</em><span class="token punctuation">}</span> <span class="token operator">\|</span> set <em class="replaceable">field</em> <span class="token punctuation">[</span><span class="token operator">:</span><span class="token operator">=</span> <span class="token operator">\|</span> <span class="token operator">=</span><span class="token punctuation">]</span> <em class="replaceable">value</em> <span class="token operator">\|</span> unset <span class="token punctuation">[</span><em class="replaceable">field</em><span class="token punctuation">]</span> <span class="token punctuation">}</span> <em class="replaceable">field</em><span class="token operator">:</span> <span class="token punctuation">{</span> <em class="replaceable">core_field</em> <span class="token operator">\|</span> <em class="replaceable">optional_field</em> <span class="token operator">\|</span> <em class="replaceable">user_defined_field</em> <span class="token punctuation">}</span> <em class="replaceable">core_field</em><span class="token operator">:</span> <span class="token punctuation">{</span> time <span class="token operator">\|</span> msg <span class="token operator">\|</span> prio <span class="token operator">\|</span> err_code <span class="token operator">\|</span> err_symbol <span class="token operator">\|</span> SQL_state <span class="token operator">\|</span> subsystem <span class="token punctuation">}</span> <em class="replaceable">optional_field</em><span class="token operator">:</span> <span class="token punctuation">{</span> OS_errno <span class="token operator">\|</span> OS_errmsg <span class="token operator">\|</span> label <span class="token operator">\|</span> user <span class="token operator">\|</span> host <span class="token operator">\|</span> thread <span class="token operator">\|</span> query_id <span class="token operator">\|</span> source_file <span class="token operator">\|</span> source_line <span class="token operator">\|</span> function <span class="token operator">\|</span> component <span class="token punctuation">}</span> <em class="replaceable">user_defined_field</em><span class="token operator">:</span> <em class="replaceable">sequence of characters in <span class="token punctuation">[</span>a<span class="token operator">-</span>zA<span class="token operator">-</span>Z0<span class="token operator">-</span>9_<span class="token punctuation">]</span> class</em> <em class="replaceable">comparator</em><span class="token operator">:</span> <span class="token punctuation">{</span><span class="token operator">==</span> <span class="token operator">\|</span> <span class="token operator">!=</span> <span class="token operator">\|</span> <span class="token operator"><</span><span class="token operator">></span> <span class="token operator">\|</span> <span class="token operator">>=</span> <span class="token operator">\|</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token operator">\|</span> <span class="token operator"><=</span> <span class="token operator">\|</span> <span class="token operator">=</span><span class="token operator"><</span> <span class="token operator">\|</span> <span class="token operator"><</span> <span class="token operator">\|</span> <span class="token operator">></span><span class="token punctuation">}</span> <em class="replaceable">value</em><span class="token operator">:</span> <span class="token punctuation">{</span> <em class="replaceable">string_literal</em> <span class="token operator">\|</span> <em class="replaceable">integer_literal</em> <span class="token operator">\|</span> <em class="replaceable">float_literal</em> <span class="token operator">\|</span> <em class="replaceable">error_symbol</em> <span class="token operator">\|</span> <em class="replaceable">priority</em> <span class="token punctuation">}</span> <em class="replaceable">count</em><span class="token operator">:</span> <em class="replaceable">integer_literal</em> <em class="replaceable">window_size</em><span class="token operator">:</span> <em class="replaceable">integer_literal</em> <em class="replaceable">string_literal</em><span class="token operator">:</span> <em class="replaceable">sequence of characters quoted as '<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>' or "<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>"</em> <em class="replaceable">integer_literal</em><span class="token operator">:</span> <em class="replaceable">sequence of characters in <span class="token punctuation">[</span>0<span class="token operator">-</span>9<span class="token punctuation">]</span> class</em> <em class="replaceable">float_literal</em><span class="token operator">:</span> <em class="replaceable">integer_literal</em><span class="token punctuation">[</span><span class="token punctuation">.</span><em class="replaceable">integer_literal</em><span class="token punctuation">]</span> <em class="replaceable">error_symbol</em><span class="token operator">:</span> <em class="replaceable">valid MySQL error symbol such as ER_ACCESS_DENIED_ERROR or ER_STARTUP</em> <em class="replaceable">priority</em><span class="token operator">:</span> <span class="token punctuation">{</span> ERROR <span class="token operator">\|</span> WARNING <span class="token operator">\|</span> INFORMATION <span class="token punctuation">}</span></code></pre> </div> <p> Simple conditions compare a field to a value or test field existence. To construct more complex conditions, use the <code class="literal"> AND </code> and <code class="literal"> OR </code> operators. Both operators have the same precedence and evaluate left to right. </p> <p> To escape a character within a string, precede it by a backslash ( <code class="literal"> \ </code> ). A backslash is required to include backslash itself or the string-quoting character, optional for other characters. </p> <p> For convenience, <code class="literal"> log_filter_dragnet </code> supports symbolic names for comparisons to certain fields. For readability and portability, symbolic values are preferable (where applicable) to numeric values. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Event priority values 1, 2, and 3 can be specified as <code class="literal"> ERROR </code> , <code class="literal"> WARNING </code> , and <code class="literal"> INFORMATION </code> . Priority symbols are recognized only in comparisons with the <code class="literal"> prio </code> field. These comparisons are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa21641723"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">=</span><span class="token operator">=</span> INFORMATION <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> prio <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">3</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> Error codes can be specified in numeric form or as the corresponding error symbol. For example, <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_startup" target="_top"> <code class="literal"> ER_STARTUP </code> </a> is the symbolic name for error <code class="literal"> 1408 </code> , so these comparisons are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa39210395"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_STARTUP <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">1408</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> Error symbols are recognized only in comparisons with the <code class="literal"> err_code </code> field and user-defined fields. </p> <p> To find the error symbol corresponding to a given error code number, use one of these methods: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Check the list of server errors at <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html" target="_top"> Server Error Message Reference </a> . </p> </li> <li class="listitem"> <p> Use the <a class="link" href="perror.html" title="6.8.1 perror — Display MySQL Error Message Information"> <span class="command"> <strong> perror </strong> </span> </a> command. Given an error number argument, <a class="link" href="perror.html" title="6.8.1 perror — Display MySQL Error Message Information"> <span class="command"> <strong> perror </strong> </span> </a> displays information about the error, including its symbol. </p> </li> </ul> </div> <p> Suppose that a rule set with error numbers looks like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa12698513"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">10927</span> <span class="token operator">OR</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">10914</span> <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">1131</span> <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> <p> Using <a class="link" href="perror.html" title="6.8.1 perror — Display MySQL Error Message Information"> <span class="command"> <strong> perror </strong> </span> </a> , determine the error symbols: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa96826383"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">perror</span> 10927 10914 1131 MySQL error code MY-010927 <span class="token punctuation">(</span>ER_ACCESS_DENIED_FOR_USER_ACCOUNT_LOCKED<span class="token punctuation">)</span><span class="token punctuation">:</span> Access denied for user <span class="token atrule">'%-.48s'</span>@<span class="token atrule">'%-.64s'</span><span class="token punctuation">.</span> Account is locked<span class="token punctuation">.</span> MySQL error code MY-010914 <span class="token punctuation">(</span>ER_ABORTING_USER_CONNECTION<span class="token punctuation">)</span><span class="token punctuation">:</span> Aborted connection %u to db<span class="token punctuation">:</span> <span class="token atrule">'%-.192s'</span> user<span class="token punctuation">:</span> <span class="token atrule">'%-.48s'</span> host<span class="token punctuation">:</span> <span class="token atrule">'%-.64s'</span> <span class="token punctuation">(</span>%-<span class="token punctuation">.</span>64s<span class="token punctuation">)</span><span class="token punctuation">.</span> MySQL error code MY-001131 <span class="token punctuation">(</span>ER_PASSWORD_ANONYMOUS_USER<span class="token punctuation">)</span><span class="token punctuation">:</span> You are using MySQL as an anonymous user and anonymous users are not allowed to change passwords</code></pre> </div> <p> Substituting error symbols for numbers, the rule set becomes: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa34039885"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_ACCESS_DENIED_FOR_USER_ACCOUNT_LOCKED <span class="token operator">OR</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_ABORTING_USER_CONNECTION <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_PASSWORD_ANONYMOUS_USER <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> </li> </ul> </div> <p> Symbolic names can be specified as quoted strings for comparison with string fields, but in such cases the names are strings that have no special meaning and <code class="literal"> log_filter_dragnet </code> does not resolve them to the corresponding numeric value. Also, typos may go undetected, whereas an error occurs immediately on <code class="literal"> SET </code> for attempts to use an unquoted symbol unknown to the server. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="error-log-dragnet-filtering-actions"> </a> Actions for log_filter_dragnet Rules </h5> </div> </div> </div> <p> <code class="literal"> log_filter_dragnet </code> supports these actions in filter rules: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> drop </code> : Drop the current log event (do not log it). </p> </li> <li class="listitem"> <p> <code class="literal"> throttle </code> : Apply rate limiting to reduce log verbosity for events matching particular conditions. The argument indicates a rate, in the form <em class="replaceable"> <code> count </code> </em> or <em class="replaceable"> <code> count </code> </em> / <em class="replaceable"> <code> window_size </code> </em> . The <em class="replaceable"> <code> count </code> </em> value indicates the permitted number of event occurrences to log per time window. The <em class="replaceable"> <code> window_size </code> </em> value is the time window in seconds; if omitted, the default window is 60 seconds. Both values must be integer literals. </p> <p> This rule throttles plugin-shutdown messages to 5 occurrences per 60 seconds: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa64309872"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_PLUGIN_SHUTTING_DOWN_PLUGIN <span class="token keyword">THEN</span> throttle <span class="token number">5</span><span class="token punctuation">.</span></code></pre> </div> <p> This rule throttles errors and warnings to 1000 occurrences per hour and information messages to 100 occurrences per hour: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa64509969"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator"><=</span> INFORMATION <span class="token keyword">THEN</span> throttle <span class="token number">1000</span><span class="token operator">/</span><span class="token number">3600</span> <span class="token keyword">ELSE</span> throttle <span class="token number">100</span><span class="token operator">/</span><span class="token number">3600</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> <code class="literal"> set </code> : Assign a value to a field (and cause the field to exist if it did not already). In subsequent rules, <code class="literal"> EXISTS </code> tests against the field name are true, and the new value can be tested by comparison conditions. </p> </li> <li class="listitem"> <p> <code class="literal"> unset </code> : Discard a field. In subsequent rules, <code class="literal"> EXISTS </code> tests against the field name are false, and comparisons of the field against any value are false. </p> <p> In the special case that the condition refers to exactly one field name, the field name following <code class="literal"> unset </code> is optional and <code class="literal"> unset </code> discards the named field. These rules are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa91475582"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> myfield <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">2</span> <span class="token keyword">THEN</span> unset myfield<span class="token punctuation">.</span> <span class="token keyword">IF</span> myfield <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">2</span> <span class="token keyword">THEN</span> unset<span class="token punctuation">.</span></code></pre> </div> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="error-log-dragnet-filtering-fields"> </a> Field References in log_filter_dragnet Rules </h5> </div> </div> </div> <p> <code class="literal"> log_filter_dragnet </code> rules support references to core, optional, and user-defined fields in error events. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-core-field-references" title="Core Field References"> Core Field References </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-optional-field-references" title="Optional Field References"> Optional Field References </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-user-defined-field-references" title="User-Defined Field References"> User-Defined Field References </a> </p> </li> </ul> </div> <h6> <a name="error-log-dragnet-core-field-references"> </a> Core Field References </h6> <p> The <code class="literal"> log_filter_dragnet </code> grammar at <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-language" title="Grammar for log_filter_dragnet Rule Language"> Grammar for log_filter_dragnet Rule Language </a> names the core fields that filter rules recognize. For general descriptions of these fields, see <a class="xref" href="error-log-event-fields.html" title="7.4.2.3 Error Event Fields"> Section 7.4.2.3, “Error Event Fields” </a> , with which you are assumed to be familiar. The following remarks provide additional information only as it pertains specifically to core field references as used within <code class="literal"> log_filter_dragnet </code> rules. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> prio </code> </p> <p> The event priority, to indicate an error, warning, or note/information event. In comparisons, each priority can be specified as a symbolic priority name or an integer literal. Priority symbols are recognized only in comparisons with the <code class="literal"> prio </code> field. These comparisons are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa65630554"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">=</span><span class="token operator">=</span> INFORMATION <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> prio <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">3</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> The following table shows the permitted priority levels. </p> <div class="informaltable"> <table summary="Error event priority levels."> <colgroup> <col style="width: 25%"/> <col style="width: 25%"/> <col style="width: 25%"/> </colgroup> <thead> <tr> <th scope="col"> Event Type </th> <th scope="col"> Priority Symbol </th> <th scope="col"> Numeric Priority </th> </tr> </thead> <tbody> <tr> <th align="left" scope="row"> Error event </th> <td> <code class="literal"> ERROR </code> </td> <td> 1 </td> </tr> <tr> <th align="left" scope="row"> Warning event </th> <td> <code class="literal"> WARNING </code> </td> <td> 2 </td> </tr> <tr> <th align="left" scope="row"> Note/information event </th> <td> <code class="literal"> INFORMATION </code> </td> <td> 3 </td> </tr> </tbody> </table> </div> <p> There is also a message priority of <code class="literal"> SYSTEM </code> , but system messages cannot be filtered and are always written to the error log. </p> <p> Priority values follow the principle that higher priorities have lower values, and vice versa. Priority values begin at 1 for the most severe events (errors) and increase for events with decreasing priority. For example, to discard events with priority lower than warnings, test for priority values higher than <code class="literal"> WARNING </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa13729542"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">></span> WARNING <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> <p> The following examples show the <code class="literal"> log_filter_dragnet </code> rules to achieve an effect similar to each <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> <code class="literal"> log_error_verbosity </code> </a> value permitted by the <code class="literal"> log_filter_internal </code> filter: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Errors only ( <code class="literal"> log_error_verbosity=1 </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa88074856"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">></span> <span class="token keyword">ERROR</span> <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> Errors and warnings ( <code class="literal"> log_error_verbosity=2 </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa32155938"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">></span> WARNING <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> Errors, warnings, and notes ( <code class="literal"> log_error_verbosity=3 </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa35059797"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">></span> INFORMATION <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> <p> This rule can actually be omitted because there are no <code class="literal"> prio </code> values greater than <code class="literal"> INFORMATION </code> , so effectively it drops nothing. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> err_code </code> </p> <p> The numeric event error code. In comparisons, the value to test can be specified as a symbolic error name or an integer literal. Error symbols are recognized only in comparisons with the <code class="literal"> err_code </code> field and user-defined fields. These comparisons are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa30834351"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_ACCESS_DENIED_ERROR <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">1045</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> <code class="literal"> err_symbol </code> </p> <p> The event error symbol, as a string (for example, <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_dup_key" target="_top"> <code class="literal"> 'ER_DUP_KEY' </code> </a> ). <code class="literal"> err_symbol </code> values are intended more for identifying particular lines in log output than for use in filter rule comparisons because <code class="literal"> log_filter_dragnet </code> does not resolve comparison values specified as strings to the equivalent numeric error code. (For that to occur, an error must be specified using its unquoted symbol.) </p> </li> </ul> </div> <h6> <a name="error-log-dragnet-optional-field-references"> </a> Optional Field References </h6> <p> The <code class="literal"> log_filter_dragnet </code> grammar at <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-language" title="Grammar for log_filter_dragnet Rule Language"> Grammar for log_filter_dragnet Rule Language </a> names the optional fields that filter rules recognize. For general descriptions of these fields, see <a class="xref" href="error-log-event-fields.html" title="7.4.2.3 Error Event Fields"> Section 7.4.2.3, “Error Event Fields” </a> , with which you are assumed to be familiar. The following remarks provide additional information only as it pertains specifically to optional field references as used within <code class="literal"> log_filter_dragnet </code> rules. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> label </code> </p> <p> The label corresponding to the <code class="literal"> prio </code> value, as a string. Filter rules can change the label for log sinks that support custom labels. <code class="literal"> label </code> values are intended more for identifying particular lines in log output than for use in filter rule comparisons because <code class="literal"> log_filter_dragnet </code> does not resolve comparison values specified as strings to the equivalent numeric priority. </p> </li> <li class="listitem"> <p> <code class="literal"> source_file </code> </p> <p> The source file in which the event occurred, without any leading path. For example, to test for the <code class="filename"> sql/gis/distance.cc </code> file, write the comparison like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa97396776"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> source_file <span class="token operator">=</span><span class="token operator">=</span> <span class="token string">"distance.cc"</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> </li> </ul> </div> <h6> <a name="error-log-dragnet-user-defined-field-references"> </a> User-Defined Field References </h6> <p> Any field name in a <code class="literal"> log_filter_dragnet </code> filter rule not recognized as a core or optional field name is taken to refer to a user-defined field. </p> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-disk-write-speed-base.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-ndbinfo-disk-write-speed-base"> </a> 25.6.17.28 The ndbinfo disk_write_speed_base Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045089525856"> </a> <p> The <code class="literal"> disk_write_speed_base </code> table provides base information about the speed of disk writes during LCP, backup, and restore operations. </p> <p> The <code class="literal"> disk_write_speed_base </code> table contains the following columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> node_id </code> </p> <p> Node ID of this node </p> </li> <li class="listitem"> <p> <code class="literal"> thr_no </code> </p> <p> Thread ID of this LDM thread </p> </li> <li class="listitem"> <p> <code class="literal"> millis_ago </code> </p> <p> Milliseconds since this reporting period ended </p> </li> <li class="listitem"> <p> <code class="literal"> millis_passed </code> </p> <p> Milliseconds elapsed in this reporting period </p> </li> <li class="listitem"> <p> <code class="literal"> backup_lcp_bytes_written </code> </p> <p> Number of bytes written to disk by local checkpoints and backup processes during this period </p> </li> <li class="listitem"> <p> <code class="literal"> redo_bytes_written </code> </p> <p> Number of bytes written to REDO log during this period </p> </li> <li class="listitem"> <p> <code class="literal"> target_disk_write_speed </code> </p> <p> Actual speed of disk writes per LDM thread (base data) </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/optimizing-innodb-many-tables.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="optimizing-innodb-many-tables"> </a> 10.5.10 Optimizing InnoDB for Systems with Many Tables </h3> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If you have configured <a class="link" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> non-persistent optimizer statistics </a> (a non-default configuration), <code class="literal"> InnoDB </code> computes index <a class="link" href="glossary.html#glos_cardinality" title="cardinality"> cardinality </a> values for a table the first time that table is accessed after startup, instead of storing such values in the table. This step can take significant time on systems that partition the data into many tables. Since this overhead only applies to the initial table open operation, to <span class="quote"> “ <span class="quote"> warm up </span> ” </span> a table for later use, access it immediately after startup by issuing a statement such as <code class="literal"> SELECT 1 FROM <em class="replaceable"> <code> tbl_name </code> </em> LIMIT 1 </code> . </p> <p> Optimizer statistics are persisted to disk by default, enabled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> configuration option. For information about persistent optimizer statistics, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/sys-sys-config.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-sys-config"> </a> 30.4.2.1 The sys_config Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045063503696"> </a> <a class="indexterm" name="idm46045063502208"> </a> <p> This table contains <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema configuration options, one row per option. Configuration changes made by updating this table persist across client sessions and server restarts. </p> <p> The <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> variable </code> </p> <p> The configuration option name. </p> </li> <li class="listitem"> <p> <code class="literal"> value </code> </p> <p> The configuration option value. </p> </li> <li class="listitem"> <p> <code class="literal"> set_time </code> </p> <p> The timestamp of the most recent modification to the row. </p> </li> <li class="listitem"> <p> <code class="literal"> set_by </code> </p> <p> The account that made the most recent modification to the row. The value is <code class="literal"> NULL </code> if the row has not been changed since the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema was installed. </p> </li> </ul> </div> <p> As an efficiency measure to minimize the number of direct reads from the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table, <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema functions that use a value from this table check for a user-defined variable with a corresponding name, which is the user-defined variable having the same name plus a <code class="literal"> @sys. </code> prefix. (For example, the variable corresponding to the <code class="literal"> diagnostics.include_raw </code> option is <code class="literal"> @sys.diagnostics.include_raw </code> .) If the user-defined variable exists in the current session and is non- <code class="literal"> NULL </code> , the function uses its value in preference to the value in the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table. Otherwise, the function reads and uses the value from the table. In the latter case, the calling function conventionally also sets the corresponding user-defined variable to the table value so that further references to the configuration option within the same session use the variable and need not read the table again. </p> <p> For example, the <code class="literal"> statement_truncate_len </code> option controls the maximum length of statements returned by the <a class="link" href="sys-format-statement.html" title="30.4.5.5 The format_statement() Function"> <code class="literal"> format_statement() </code> </a> function. The default is 64. To temporarily change the value to 32 for your current session, set the corresponding <code class="literal"> @sys.statement_truncate_len </code> user-defined variable: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59966965"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@stmt</span> <span class="token operator">=</span> <span class="token string">'SELECT variable, value, set_time, set_by FROM sys_config'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> sys<span class="token punctuation">.</span>format_statement<span class="token punctuation">(</span><span class="token variable">@stmt</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> sys.format_statement(@stmt) <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> SELECT variable, value, set_time, set_by FROM sys_config <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@sys.statement_truncate_len</span> <span class="token operator">=</span> <span class="token number">32</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> sys<span class="token punctuation">.</span>format_statement<span class="token punctuation">(</span><span class="token variable">@stmt</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> sys.format_statement(@stmt) <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> SELECT variabl ... ROM sys_config <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> Subsequent invocations of <a class="link" href="sys-format-statement.html" title="30.4.5.5 The format_statement() Function"> <code class="literal"> format_statement() </code> </a> within the session continue to use the user-defined variable value (32), rather than the value stored in the table (64). </p> <p> To stop using the user-defined variable and revert to using the value in the table, set the variable to <code class="literal"> NULL </code> within your session: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa4167757"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@sys.statement_truncate_len</span> <span class="token operator">=</span> <span class="token boolean">NULL</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> sys<span class="token punctuation">.</span>format_statement<span class="token punctuation">(</span><span class="token variable">@stmt</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> sys.format_statement(@stmt) <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> SELECT variable, value, set_time, set_by FROM sys_config <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> Alternatively, end your current session (causing the user-defined variable to no longer exist) and begin a new session. </p> <p> The conventional relationship just described between options in the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table and user-defined variables can be exploited to make temporary configuration changes that end when your session ends. However, if you set a user-defined variable and then subsequently change the corresponding table value within the same session, the changed table value is not used in that session as long as the user-defined variable exists with a non- <code class="literal"> NULL </code> value. (The changed table value <span class="emphasis"> <em> is </em> </span> used in other sessions in which the user-defined variable is not assigned.) </p> <p> The following list describes the options in the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table and the corresponding user-defined variables: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> diagnostics.allow_i_s_tables </code> , <code class="literal"> @sys.diagnostics.allow_i_s_tables </code> </p> <p> If this option is <code class="literal"> ON </code> , the <a class="link" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> <code class="literal"> diagnostics() </code> </a> procedure is permitted to perform table scans on the Information Schema <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> table. This can be expensive if there are many tables. The default is <code class="literal"> OFF </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> diagnostics.include_raw </code> , <code class="literal"> @sys.diagnostics.include_raw </code> </p> <p> If this option is <code class="literal"> ON </code> , the <a class="link" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> <code class="literal"> diagnostics() </code> </a> procedure includes the raw output from querying the <a class="link" href="sys-metrics.html" title="30.4.3.21 The metrics View"> <code class="literal"> metrics </code> </a> view. The default is <code class="literal"> OFF </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> ps_thread_trx_info.max_length </code> , <code class="literal"> @sys.ps_thread_trx_info.max_length </code> </p> <p> The maximum length for JSON output produced by the <a class="link" href="sys-ps-thread-trx-info.html" title="30.4.5.17 The ps_thread_trx_info() Function"> <code class="literal"> ps_thread_trx_info() </code> </a> function. The default is 65535. </p> </li> <li class="listitem"> <p> <code class="literal"> statement_performance_analyzer.limit </code> , <code class="literal"> @sys.statement_performance_analyzer.limit </code> </p> <p> The maximum number of rows to return for views that have no built-in limit. (For example, the <a class="link" href="sys-statements-with-runtimes-in-95th-percentile.html" title="30.4.3.38 The statements_with_runtimes_in_95th_percentile and x$statements_with_runtimes_in_95th_percentile Views"> <code class="literal"> statements_with_runtimes_in_95th_percentile </code> </a> view has a built-in limit in the sense that it returns only statements with average execution time in the 95th percentile.) The default is 100. </p> </li> <li class="listitem"> <p> <code class="literal"> statement_performance_analyzer.view </code> , <code class="literal"> @sys.statement_performance_analyzer.view </code> </p> <p> The custom query or view to be used by the <a class="link" href="sys-statement-performance-analyzer.html" title="30.4.4.25 The statement_performance_analyzer() Procedure"> <code class="literal"> statement_performance_analyzer() </code> </a> procedure (which is itself invoked by the <a class="link" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> <code class="literal"> diagnostics() </code> </a> procedure). If the option value contains a space, it is interpreted as a query. Otherwise, it must be the name of an existing view that queries the Performance Schema <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> table. There cannot be any <code class="literal"> LIMIT </code> clause in the query or view definition if the <code class="literal"> statement_performance_analyzer.limit </code> configuration option is greater than 0. The default is <code class="literal"> NULL </code> (no custom view defined). </p> </li> <li class="listitem"> <p> <code class="literal"> statement_truncate_len </code> , <code class="literal"> @sys.statement_truncate_len </code> </p> <p> The maximum length of statements returned by the <a class="link" href="sys-format-statement.html" title="30.4.5.5 The format_statement() Function"> <code class="literal"> format_statement() </code> </a> function. Longer statements are truncated to this length. The default is 64. </p> </li> </ul> </div> <p> Other options can be added to the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table. For example, the <a class="link" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> <code class="literal"> diagnostics() </code> </a> and <a class="link" href="sys-execute-prepared-stmt.html" title="30.4.4.3 The execute_prepared_stmt() Procedure"> <code class="literal"> execute_prepared_stmt() </code> </a> procedures use the <code class="literal"> debug </code> option if it exists, but this option is not part of the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table by default because debug output normally is enabled only temporarily, by setting the corresponding <code class="literal"> @sys.debug </code> user-defined variable. To enable debug output without having to set that variable in individual sessions, add the option to the table: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa59684147"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> sys<span class="token punctuation">.</span>sys_config <span class="token punctuation">(</span>variable<span class="token punctuation">,</span> <span class="token keyword">value</span><span class="token punctuation">)</span> <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token string">'debug'</span><span class="token punctuation">,</span> <span class="token string">'ON'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> To change the debug setting in the table, do two things. First, modify the value in the table itself: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa73381260"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">UPDATE</span> sys<span class="token punctuation">.</span>sys_config <span class="token keyword">SET</span> <span class="token keyword">value</span> <span class="token operator">=</span> <span class="token string">'OFF'</span> <span class="token keyword">WHERE</span> variable <span class="token operator">=</span> <span class="token string">'debug'</span><span class="token punctuation">;</span></code></pre> </div> <p> Second, to also ensure that procedure invocations within the current session use the changed value from the table, set the corresponding user-defined variable to <code class="literal"> NULL </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa13522173"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@sys.debug</span> <span class="token operator">=</span> <span class="token boolean">NULL</span><span class="token punctuation">;</span></code></pre> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-instrument-naming.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="performance-schema-instrument-naming"> </a> 29.6 Performance Schema Instrument Naming Conventions </h2> </div> </div> </div> <p> An instrument name consists of a sequence of elements separated by <code class="literal"> '/' </code> characters. Example names: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa75729489"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">wait/io/file/myisam/log wait/io/file/mysys/charset wait/lock/table/sql/handler wait/synch/cond/mysys/COND_alarm wait/synch/cond/sql/BINLOG::update_cond wait/synch/mutex/mysys/BITMAP_mutex wait/synch/mutex/sql/LOCK_delete wait/synch/rwlock/sql/Query_cache_query::lock stage/sql/closing tables stage/sql/Sorting result statement/com/Execute statement/com/Query statement/sql/create_table statement/sql/lock_tables errors</code></pre> </div> <p> The instrument name space has a tree-like structure. The elements of an instrument name from left to right provide a progression from more general to more specific. The number of elements a name has depends on the type of instrument. </p> <p> The interpretation of a given element in a name depends on the elements to the left of it. For example, <code class="literal"> myisam </code> appears in both of the following names, but <code class="literal"> myisam </code> in the first name is related to file I/O, whereas in the second it is related to a synchronization instrument: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa43228060"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">wait/io/file/myisam/log wait/synch/cond/myisam/MI_SORT_INFO::cond</code></pre> </div> <p> Instrument names consist of a prefix with a structure defined by the Performance Schema implementation and a suffix defined by the developer implementing the instrument code. The top-level element of an instrument prefix indicates the type of instrument. This element also determines which event timer in the <a class="link" href="performance-schema-performance-timers-table.html" title="29.12.22.6 The performance_timers Table"> <code class="literal"> performance_timers </code> </a> table applies to the instrument. For the prefix part of instrument names, the top level indicates the type of instrument. </p> <p> The suffix part of instrument names comes from the code for the instruments themselves. Suffixes may include levels such as these: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A name for the major element (a server module such as <code class="literal"> myisam </code> , <code class="literal"> innodb </code> , <code class="literal"> mysys </code> , or <code class="literal"> sql </code> ) or a plugin name. </p> </li> <li class="listitem"> <p> The name of a variable in the code, in the form <em class="replaceable"> <code> XXX </code> </em> (a global variable) or <code class="literal"> <em class="replaceable"> <code> CCC </code> </em> :: <em class="replaceable"> <code> MMM </code> </em> </code> (a member <em class="replaceable"> <code> MMM </code> </em> in class <em class="replaceable"> <code> CCC </code> </em> ). Examples: <code class="literal"> COND_thread_cache </code> , <code class="literal"> THR_LOCK_myisam </code> , <code class="literal"> BINLOG::LOCK_index </code> . </p> </li> </ul> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-top-level-instrument-elements" title="Top-Level Instrument Elements"> Top-Level Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-idle-instrument-elements" title="Idle Instrument Elements"> Idle Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-error-instrument-elements" title="Error Instrument Elements"> Error Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-memory-instrument-elements" title="Memory Instrument Elements"> Memory Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-stage-instrument-elements" title="Stage Instrument Elements"> Stage Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-statement-instrument-elements" title="Statement Instrument Elements"> Statement Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-thread-instrument-elements" title="Thread Instrument Elements"> Thread Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-wait-instrument-elements" title="Wait Instrument Elements"> Wait Instrument Elements </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-top-level-instrument-elements"> </a> Top-Level Instrument Elements </h3> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> idle </code> : An instrumented idle event. This instrument has no further elements. </p> </li> <li class="listitem"> <p> <code class="literal"> error </code> : An instrumented error event. This instrument has no further elements. </p> </li> <li class="listitem"> <p> <code class="literal"> memory </code> : An instrumented memory event. </p> </li> <li class="listitem"> <p> <code class="literal"> stage </code> : An instrumented stage event. </p> </li> <li class="listitem"> <p> <code class="literal"> statement </code> : An instrumented statement event. </p> </li> <li class="listitem"> <p> <code class="literal"> transaction </code> : An instrumented transaction event. This instrument has no further elements. </p> </li> <li class="listitem"> <p> <code class="literal"> wait </code> : An instrumented wait event. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-idle-instrument-elements"> </a> Idle Instrument Elements </h3> </div> </div> </div> <p> The <code class="literal"> idle </code> instrument is used for idle events, which The Performance Schema generates as discussed in the description of the <code class="literal"> socket_instances.STATE </code> column in <a class="xref" href="performance-schema-socket-instances-table.html" title="29.12.3.5 The socket_instances Table"> Section 29.12.3.5, “The socket_instances Table” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-error-instrument-elements"> </a> Error Instrument Elements </h3> </div> </div> </div> <p> The <code class="literal"> error </code> instrument indicates whether to collect information for server errors and warnings. This instrument is enabled by default. The <code class="literal"> TIMED </code> column for the <code class="literal"> error </code> row in the <a class="link" href="performance-schema-setup-instruments-table.html" title="29.12.2.3 The setup_instruments Table"> <code class="literal"> setup_instruments </code> </a> table is inapplicable because timing information is not collected. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-memory-instrument-elements"> </a> Memory Instrument Elements </h3> </div> </div> </div> <p> Memory instrumentation is enabled by default. Memory instrumentation can be enabled or disabled at startup, or dynamically at runtime by updating the <code class="literal"> ENABLED </code> column of the relevant instruments in the <a class="link" href="performance-schema-setup-instruments-table.html" title="29.12.2.3 The setup_instruments Table"> <code class="literal"> setup_instruments </code> </a> table. Memory instruments have names of the form <code class="literal"> memory/ <em class="replaceable"> <code> code_area </code> </em> / <em class="replaceable"> <code> instrument_name </code> </em> </code> where <em class="replaceable"> <code> code_area </code> </em> is a value such as <code class="literal"> sql </code> or <code class="literal"> myisam </code> , and <em class="replaceable"> <code> instrument_name </code> </em> is the instrument detail. </p> <p> Instruments named with the prefix <code class="literal"> memory/performance_schema/ </code> expose how much memory is allocated for internal buffers in the Performance Schema. The <code class="literal"> memory/performance_schema/ </code> instruments are built in, always enabled, and cannot be disabled at startup or runtime. Built-in memory instruments are displayed only in the <a class="link" href="performance-schema-memory-summary-tables.html" title="29.12.20.10 Memory Summary Tables"> <code class="literal"> memory_summary_global_by_event_name </code> </a> table. For more information, see <a class="xref" href="performance-schema-memory-model.html" title="29.17 The Performance Schema Memory-Allocation Model"> Section 29.17, “The Performance Schema Memory-Allocation Model” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-stage-instrument-elements"> </a> Stage Instrument Elements </h3> </div> </div> </div> <p> Stage instruments have names of the form <code class="literal"> stage/ <em class="replaceable"> <code> code_area </code> </em> / <em class="replaceable"> <code> stage_name </code> </em> </code> , where <em class="replaceable"> <code> code_area </code> </em> is a value such as <code class="literal"> sql </code> or <code class="literal"> myisam </code> , and <em class="replaceable"> <code> stage_name </code> </em> indicates the stage of statement processing, such as <code class="literal"> Sorting result </code> or <code class="literal"> Sending data </code> . Stages correspond to the thread states displayed by <a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement"> <code class="literal"> SHOW PROCESSLIST </code> </a> or that are visible in the Information Schema <a class="link" href="information-schema-processlist-table.html" title="28.3.23 The INFORMATION_SCHEMA PROCESSLIST Table"> <code class="literal"> PROCESSLIST </code> </a> table. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-statement-instrument-elements"> </a> Statement Instrument Elements </h3> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> statement/abstract/* </code> : An abstract instrument for statement operations. Abstract instruments are used during the early stages of statement classification before the exact statement type is known, then changed to a more specific statement instrument when the type is known. For a description of this process, see <a class="xref" href="performance-schema-statement-tables.html" title="29.12.6 Performance Schema Statement Event Tables"> Section 29.12.6, “Performance Schema Statement Event Tables” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> statement/com </code> : An instrumented command operation. These have names corresponding to <code class="literal"> COM_ <em class="replaceable"> <code> xxx </code> </em> </code> operations (see the <code class="filename"> mysql_com.h </code> header file and <code class="filename"> sql/sql_parse.cc </code> . For example, the <code class="literal"> statement/com/Connect </code> and <code class="literal"> statement/com/Init DB </code> instruments correspond to the <code class="literal"> COM_CONNECT </code> and <code class="literal"> COM_INIT_DB </code> commands. </p> </li> <li class="listitem"> <p> <code class="literal"> statement/scheduler/event </code> : A single instrument to track all events executed by the Event Scheduler. This instrument comes into play when a scheduled event begins executing. </p> </li> <li class="listitem"> <p> <code class="literal"> statement/sp </code> : An instrumented internal instruction executed by a stored program. For example, the <code class="literal"> statement/sp/cfetch </code> and <code class="literal"> statement/sp/freturn </code> instruments are used cursor fetch and function return instructions. </p> </li> <li class="listitem"> <p> <code class="literal"> statement/sql </code> : An instrumented SQL statement operation. For example, the <code class="literal"> statement/sql/create_db </code> and <code class="literal"> statement/sql/select </code> instruments are used for <a class="link" href="create-database.html" title="15.1.12 CREATE DATABASE Statement"> <code class="literal"> CREATE DATABASE </code> </a> and <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> statements. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-thread-instrument-elements"> </a> Thread Instrument Elements </h3> </div> </div> </div> <p> Instrumented threads are displayed in the <a class="link" href="performance-schema-setup-threads-table.html" title="29.12.2.5 The setup_threads Table"> <code class="literal"> setup_threads </code> </a> table, which exposes thread class names and attributes. </p> <p> Thread instruments begin with <code class="literal"> thread </code> (for example, <code class="literal"> thread/sql/parser_service </code> or <code class="literal"> thread/performance_schema/setup </code> ). </p> <p> The names of thread instruments for <code class="literal"> ndbcluster </code> plugin threads begin with <code class="literal"> thread/ndbcluster/ </code> ; for more information about these, see <a class="xref" href="mysql-cluster-ps-tables.html#mysql-cluster-plugin-threads" title="ndbcluster Plugin Threads"> ndbcluster Plugin Threads </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-wait-instrument-elements"> </a> Wait Instrument Elements </h3> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> wait/io </code> </p> <p> An instrumented I/O operation. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> wait/io/file </code> </p> <p> An instrumented file I/O operation. For files, the wait is the time waiting for the file operation to complete (for example, a call to <code class="literal"> fwrite() </code> ). Due to caching, the physical file I/O on the disk might not happen within this call. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/io/socket </code> </p> <p> An instrumented socket operation. Socket instruments have names of the form <code class="literal"> wait/io/socket/sql/ <em class="replaceable"> <code> socket_type </code> </em> </code> . The server has a listening socket for each network protocol that it supports. The instruments associated with listening sockets for TCP/IP or Unix socket file connections have a <em class="replaceable"> <code> socket_type </code> </em> value of <code class="literal"> server_tcpip_socket </code> or <code class="literal"> server_unix_socket </code> , respectively. When a listening socket detects a connection, the server transfers the connection to a new socket managed by a separate thread. The instrument for the new connection thread has a <em class="replaceable"> <code> socket_type </code> </em> value of <code class="literal"> client_connection </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> wait/io/table </code> </p> <p> An instrumented table I/O operation. These include row-level accesses to persistent base tables or temporary tables. Operations that affect rows are fetch, insert, update, and delete. For a view, waits are associated with base tables referenced by the view. </p> <p> Unlike most waits, a table I/O wait can include other waits. For example, table I/O might include file I/O or memory operations. Thus, <a class="link" href="performance-schema-events-waits-current-table.html" title="29.12.4.1 The events_waits_current Table"> <code class="literal"> events_waits_current </code> </a> for a table I/O wait usually has two rows. For more information, see <a class="xref" href="performance-schema-atom-molecule-events.html" title="29.8 Performance Schema Atom and Molecule Events"> Section 29.8, “Performance Schema Atom and Molecule Events” </a> . </p> <p> Some row operations might cause multiple table I/O waits. For example, an insert might activate a trigger that causes an update. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> wait/lock </code> </p> <p> An instrumented lock operation. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> wait/lock/table </code> </p> <p> An instrumented table lock operation. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/lock/metadata/sql/mdl </code> </p> <p> An instrumented metadata lock operation. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> wait/synch </code> </p> <p> An instrumented synchronization object. For synchronization objects, the <code class="literal"> TIMER_WAIT </code> time includes the amount of time blocked while attempting to acquire a lock on the object, if any. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> wait/synch/cond </code> </p> <p> A condition is used by one thread to signal to other threads that something they were waiting for has happened. If a single thread was waiting for a condition, it can wake up and proceed with its execution. If several threads were waiting, they can all wake up and compete for the resource for which they were waiting. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/synch/mutex </code> </p> <p> A mutual exclusion object used to permit access to a resource (such as a section of executable code) while preventing other threads from accessing the resource. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/synch/prlock </code> </p> <p> A priority <a class="link" href="glossary.html#glos_rw_lock" title="rw-lock"> rwlock </a> lock object. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/synch/rwlock </code> </p> <p> A plain <a class="link" href="glossary.html#glos_rw_lock" title="rw-lock"> read/write lock </a> object used to lock a specific variable for access while preventing its use by other threads. A shared read lock can be acquired simultaneously by multiple threads. An exclusive write lock can be acquired by only one thread at a time. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/synch/sxlock </code> </p> <p> A shared-exclusive (SX) lock is a type of <a class="link" href="glossary.html#glos_rw_lock" title="rw-lock"> rwlock </a> lock object that provides write access to a common resource while permitting inconsistent reads by other threads. <code class="literal"> sxlocks </code> optimize concurrency and improve scalability for read-write workloads. </p> </li> </ul> </div> </li> </ul> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/source-ssl-library-configuration.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="source-ssl-library-configuration"> </a> 2.8.6 Configuring SSL Library Support </h3> </div> </div> </div> <a class="indexterm" name="idm46045329404896"> </a> <a class="indexterm" name="idm46045329403408"> </a> <p> An SSL library is required for support of encrypted connections, entropy for random number generation, and other encryption-related operations. </p> <p> If you compile MySQL from a source distribution, <span class="command"> <strong> CMake </strong> </span> configures the distribution to use the installed OpenSSL library by default. </p> <p> To compile using OpenSSL, use this procedure: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Ensure that OpenSSL 1.0.1 or newer is installed on your system. If the installed OpenSSL version is older than 1.0.1, <span class="command"> <strong> CMake </strong> </span> produces an error at MySQL configuration time. If it is necessary to obtain OpenSSL, visit <a class="ulink" href="http://www.openssl.org" target="_blank"> http://www.openssl.org </a> . </p> </li> <li class="listitem"> <p> The <a class="link" href="source-configuration-options.html#option_cmake_with_ssl"> <code class="option"> WITH_SSL </code> </a> <span class="command"> <strong> CMake </strong> </span> option determines which SSL library to use for compiling MySQL (see <a class="xref" href="source-configuration-options.html" title="2.8.7 MySQL Source-Configuration Options"> Section 2.8.7, “MySQL Source-Configuration Options” </a> ). The default is <a class="link" href="source-configuration-options.html#option_cmake_with_ssl"> <code class="option"> -DWITH_SSL=system </code> </a> , which uses OpenSSL. To make this explicit, specify that option. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa1980377"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cmake <span class="token punctuation">.</span> <span class="token constant">-DWITH_SSL</span><span class="token attr-value"><span class="token punctuation">=</span>system</span></code></pre> </div> <p> That command configures the distribution to use the installed OpenSSL library. Alternatively, to explicitly specify the path name to the OpenSSL installation, use the following syntax. This can be useful if you have multiple versions of OpenSSL installed, to prevent <span class="command"> <strong> CMake </strong> </span> from choosing the wrong one: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa66585106"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cmake <span class="token punctuation">.</span> <span class="token constant">-DWITH_SSL</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">path_name</em></span></code></pre> </div> <p> Alternative OpenSSL system packages are supported by using <code class="option"> WITH_SSL=openssl11 </code> on EL7 or <code class="option"> WITH_SSL=openssl3 </code> on EL8. Authentication plugins, such as LDAP and Kerberos, are disabled since they do not support these alternative versions of OpenSSL. </p> </li> <li class="listitem"> <p> Compile and install the distribution. </p> </li> </ol> </div> <p> To check whether a <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> server supports encrypted connections, examine the value of the <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> system variable: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa39730916"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'tls_version'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Variable_name <span class="token punctuation">\|</span> Value <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> tls_version <span class="token punctuation">\|</span> TLSv1.2,TLSv1.3 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> If the value contains TLS versions then the server supports encrypted connections, otherwise it does not. </p> <p> For additional information, see <a class="xref" href="using-encrypted-connections.html" title="8.3.1 Configuring MySQL to Use Encrypted Connections"> Section 8.3.1, “Configuring MySQL to Use Encrypted Connections” </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/telemetry-metrics-meter-metrics.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="telemetry-metrics-meter-metrics"> </a> 35.4.3 Server Metrics </h3> </div> </div> </div> <p> The following server metrics are registered by default: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats" title="mysql.stats Metrics"> mysql.stats Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-com" title="mysql.stats.com Metrics"> mysql.stats.com Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-connection" title="mysql.stats.connection Metrics"> mysql.stats.connection Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-perf-schema" title="mysql.perf_schema Metrics"> mysql.perf_schema Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-handler" title="mysql.stats.handler Metrics"> mysql.stats.handler Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-myisam" title="mysql.stats.myisam Metrics"> mysql.stats.myisam Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-ssl" title="mysql.stats.ssl Metrics"> mysql.stats.ssl Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-inno" title="mysql.inno Metrics"> mysql.inno Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-inno-bufferpool" title="mysql.inno.buffer_pool Metrics"> mysql.inno.buffer_pool Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-inno-data" title="mysql.inno.data Metrics"> mysql.inno.data Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-x" title="mysql.x Metrics"> mysql.x Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-x-stmt" title="mysql.x.stmt Metrics"> mysql.x.stmt Metrics </a> </p> </li> </ul> </div> <p> The maximum number of metric instruments which can be created is set by <a class="link" href="performance-schema-system-variables.html#sysvar_performance_schema_max_metric_classes"> <code class="literal"> performance_schema_max_metric_classes </code> </a> . </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats"> </a> mysql.stats Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045058440592"> </a> <p class="title"> <b> Table 35.3 mysql.stats Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> aborted_clients </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Aborted_clients"> <code class="literal"> Aborted_clients </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections that were aborted because the client died without closing the connection properly </p> </td> </tr> <tr> <td> <p> <code class="literal"> aborted_connects </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Aborted_connects"> <code class="literal"> Aborted_connects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of failed attempts to connect to the MySQL server </p> </td> </tr> <tr> <td> <p> <code class="literal"> acl_cache_items_count </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Acl_cache_items_count"> <code class="literal"> Acl_cache_items_count </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of cached privilege objects </p> </td> </tr> <tr> <td> <p> <code class="literal"> binlog_cache.disk_use </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Binlog_cache_disk_use"> <code class="literal"> Binlog_cache_disk_use </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of transactions that used the temporary binary log cache but that exceeded the value of binlog_cache_size and used a temporary file to store statements from the transaction </p> </td> </tr> <tr> <td> <p> <code class="literal"> binlog_cache.use </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Binlog_cache_use"> <code class="literal"> Binlog_cache_use </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of transactions that used the binary log cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> binlog_stmt_cache_disk_use </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Binlog_stmt_cache_disk_use"> <code class="literal"> Binlog_stmt_cache_disk_use </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of nontransaction statements that used the binary log statement cache but that exceeded the value of binlog_stmt_cache_size and used a temporary file to store those statements. </p> </td> </tr> <tr> <td> <p> <code class="literal"> binlog_stmt_cache_use </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Binlog_stmt_cache_use"> <code class="literal"> Binlog_stmt_cache_use </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of nontransactional statements that used the binary log statement cache </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_received </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Bytes_received"> <code class="literal"> Bytes_received </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes received from all clients </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_sent </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Bytes_sent"> <code class="literal"> Bytes_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes sent to all clients </p> </td> </tr> <tr> <td> <p> <code class="literal"> created.tmp_disk_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Created_tmp_disk_tables"> <code class="literal"> Created_tmp_disk_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of internal on-disk temporary tables created by the server while executing statements </p> </td> </tr> <tr> <td> <p> <code class="literal"> created.tmp_files </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Created_tmp_files"> <code class="literal"> Created_tmp_files </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many temporary files mysqld has created </p> </td> </tr> <tr> <td> <p> <code class="literal"> created.tmp_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Created_tmp_tables"> <code class="literal"> Created_tmp_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of internal temporary tables created by the server while executing statements </p> </td> </tr> <tr> <td> <p> <code class="literal"> error_log.buffered_bytes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Error_log_buffered_bytes"> <code class="literal"> Error_log_buffered_bytes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of bytes currently used in the Performance Schema error_log table </p> </td> </tr> <tr> <td> <p> <code class="literal"> error_log.buffered_events </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Error_log_buffered_events"> <code class="literal"> Error_log_buffered_events </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of events currently present in the Performance Schema error_log table </p> </td> </tr> <tr> <td> <p> <code class="literal"> error_log.expired_events </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Error_log_expired_events"> <code class="literal"> Error_log_expired_events </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of events discarded from the Performance Schema error_log table to make room for new events </p> </td> </tr> <tr> <td> <p> <code class="literal"> flush_commands </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Flush_commands"> <code class="literal"> Flush_commands </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times the server flushes tables </p> </td> </tr> <tr> <td> <p> <code class="literal"> global_connection_memory </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Global_connection_memory"> <code class="literal"> Global_connection_memory </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The memory used by all user connections to the server </p> </td> </tr> <tr> <td> <p> <code class="literal"> locked_connects </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Locked_connects"> <code class="literal"> Locked_connects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of attempts to connect to locked user accounts </p> </td> </tr> <tr> <td> <p> <code class="literal"> max_execution_time_exceeded </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_exceeded"> <code class="literal"> Max_execution_time_exceeded </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SELECT statements for which the execution timeout was exceeded </p> </td> </tr> <tr> <td> <p> <code class="literal"> max_execution_time_set </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_set"> <code class="literal"> Max_execution_time_set </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SELECT statements for which a nonzero execution timeout was set </p> </td> </tr> <tr> <td> <p> <code class="literal"> max_execution_time_set_failed </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_set_failed"> <code class="literal"> Max_execution_time_set_failed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of <code class="literal"> SELECT </code> statements for which the attempt to set an execution timeout failed </p> </td> </tr> <tr> <td> <p> <code class="literal"> max_used_connections </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Max_used_connections"> <code class="literal"> Max_used_connections </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The maximum number of connections that have been in use simultaneously since the server started </p> </td> </tr> <tr> <td> <p> <code class="literal"> ongoing_anonymous_transaction_count </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ongoing_anonymous_transaction_count"> <code class="literal"> Ongoing_anonymous_transaction_count </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Shows the number of ongoing transactions which have been marked as anonymous </p> </td> </tr> <tr> <td> <p> <code class="literal"> open_files </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Open_files"> <code class="literal"> Open_files </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of files that are open. This count includes regular files opened by the server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> open_streams </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Open_streams"> <code class="literal"> Open_streams </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of streams that are open, used mainly for logging </p> </td> </tr> <tr> <td> <p> <code class="literal"> open_table_definitions </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Open_table_definitions"> <code class="literal"> Open_table_definitions </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of cached table definitions </p> </td> </tr> <tr> <td> <p> <code class="literal"> open_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Open_tables"> <code class="literal"> Open_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of tables that are open. </p> </td> </tr> <tr> <td> <p> <code class="literal"> opened_files </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Opened_files"> <code class="literal"> Opened_files </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of files that have been opened with <code class="literal"> my_open() </code> . </p> </td> </tr> <tr> <td> <p> <code class="literal"> opened_table_definitions </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Opened_table_definitions"> <code class="literal"> Opened_table_definitions </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of table definitions that have been cached. </p> </td> </tr> <tr> <td> <p> <code class="literal"> opened_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Opened_tables"> <code class="literal"> Opened_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of tables that have been opened </p> </td> </tr> <tr> <td> <p> <code class="literal"> prepared_stmt_count </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Prepared_stmt_count"> <code class="literal"> Prepared_stmt_count </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The current number of prepared statements </p> </td> </tr> <tr> <td> <p> <code class="literal"> queries </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Queries"> <code class="literal"> Queries </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of statements executed by the server, including ones executed within stored programs. It does not count <code class="literal"> COM_PING </code> or <code class="literal"> COM_STATISTICS </code> commands. </p> </td> </tr> <tr> <td> <p> <code class="literal"> questions </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Questions"> <code class="literal"> Questions </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of statements executed by the server. This includes only statements sent to the server by clients and not statements executed within stored programs. </p> </td> </tr> <tr> <td> <p> <code class="literal"> replica_open_temp_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Replica_open_temp_tables"> <code class="literal"> Replica_open_temp_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of temporary tables that the replication SQL thread currently has open. </p> </td> </tr> <tr> <td> <p> <code class="literal"> secondary_engine_execution_count </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Secondary_engine_execution_count"> <code class="literal"> Secondary_engine_execution_count </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of queries offloaded to a secondary engine </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_full_join </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_full_join"> <code class="literal"> Select_full_join </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins that perform table scans because they do not use indexes </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_full_range_join </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_full_range_join"> <code class="literal"> Select_full_range_join </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins that used a range search on a reference table </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_range </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_range"> <code class="literal"> Select_range </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins that used ranges on the first table </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_range_check </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_range_check"> <code class="literal"> Select_range_check </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins without keys that check for key usage after each row </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_scan </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_scan"> <code class="literal"> Select_scan </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins that did a full scan of the first table </p> </td> </tr> <tr> <td> <p> <code class="literal"> slow_launch_threads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Slow_launch_threads"> <code class="literal"> Slow_launch_threads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of threads that have taken more than slow_launch_time seconds to create. </p> </td> </tr> <tr> <td> <p> <code class="literal"> slow_queries </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Slow_queries"> <code class="literal"> Slow_queries </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of queries that have taken more than long_query_time seconds </p> </td> </tr> <tr> <td> <p> <code class="literal"> sort_merge_passes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Sort_merge_passes"> <code class="literal"> Sort_merge_passes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of merge passes that the sort algorithm has had to do </p> </td> </tr> <tr> <td> <p> <code class="literal"> sort_range </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Sort_range"> <code class="literal"> Sort_range </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sorts that were done using ranges </p> </td> </tr> <tr> <td> <p> <code class="literal"> sort_rows </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Sort_rows"> <code class="literal"> Sort_rows </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sorted rows. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sort_scan </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Sort_scan"> <code class="literal"> Sort_scan </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sorts that were done by scanning the table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_locks_immediate </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_locks_immediate"> <code class="literal"> Table_locks_immediate </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times that a request for a table lock could be granted immediately </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_locks_waited </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_locks_waited"> <code class="literal"> Table_locks_waited </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times that a request for a table lock could not be granted immediately and a wait was needed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_open_cache_hits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_hits"> <code class="literal"> Table_open_cache_hits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of hits for open tables cache lookups. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_open_cache_misses </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_misses"> <code class="literal"> Table_open_cache_misses </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of misses for open tables cache lookups. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_open_cache_overflows </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_overflows"> <code class="literal"> Table_open_cache_overflows </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of overflows for the open tables cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> tc_log_page_waits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Tc_log_page_waits"> <code class="literal"> Tc_log_page_waits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> For the memory-mapped implementation of the recovery log, this variable increments each time the server was not able to commit a transaction and had to wait for a free page in the log. </p> </td> </tr> <tr> <td> <p> <code class="literal"> threads_cached </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Threads_cached"> <code class="literal"> Threads_cached </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of threads in the thread cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> threads_connected </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Threads_connected"> <code class="literal"> Threads_connected </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of currently open connections </p> </td> </tr> <tr> <td> <p> <code class="literal"> threads_created </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Threads_created"> <code class="literal"> Threads_created </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of threads created to handle connections. </p> </td> </tr> <tr> <td> <p> <code class="literal"> threads_running </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Threads_running"> <code class="literal"> Threads_running </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of threads that are not sleeping. </p> </td> </tr> <tr> <td> <p> <code class="literal"> uptime </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Uptime"> <code class="literal"> Uptime </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of seconds that the server has been up. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 801px;"> <thead> <tr> <th style="width: 291.391px;"> Name </th> <th style="width: 291.391px;"> Source Variable </th> <th style="width: 63.875px;"> OTEL Type </th> <th style="width: 153.016px;"> Description </th> </tr> </thead> </table> </div> </div> <p> <br class="table-break"/> </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-com"> </a> mysql.stats.com Metrics </h4> </div> </div> </div> <p> The <code class="literal"> mysql.stats.com </code> metrics correspond to the <code class="literal"> Com_ <em class="replaceable"> <code> xxx </code> </em> </code> statement counter variables. See <a class="xref" href="server-status-variables.html" title="7.1.10 Server Status Variables"> Section 7.1.10, “Server Status Variables” </a> and <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xxx </a> for more information. </p> <p> The <code class="literal"> mysql.stats.com </code> metrics are named for those variables, without the <code class="literal"> Com_ </code> prefix. For example, the <code class="literal"> select </code> metric corresponds to the <code class="literal"> Com_select </code> statement counter variable. </p> <p> These metrics are of OTEL Type <code class="literal"> ASYNC COUNTER </code> and record the number of times (INTEGER) the corresponding command statement has been executed. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-connection"> </a> mysql.stats.connection Metrics </h4> </div> </div> </div> <p> The <code class="literal"> mysql.stats.connection </code> metrics correspond to the <code class="literal"> Connections </code> and <code class="literal"> Connection_ <em class="replaceable"> <code> XXX </code> </em> </code> status variables. </p> <div class="table"> <a name="idm46045058010112"> </a> <p class="title"> <b> Table 35.4 mysql.stats.connection Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> total </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connections"> <code class="literal"> Connections </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Cumulative count of total connections created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_accept </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_accept"> <code class="literal"> Connection_errors_accept </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors that occurred during calls to <code class="literal"> accept() </code> on the listening port. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_internal </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_internal"> <code class="literal"> Connection_errors_internal </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections refused due to internal errors in the server, such as failure to start a new thread or an out-of-memory condition. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_max_connections </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_max_connections"> <code class="literal"> Connection_errors_max_connections </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections refused because the server max_connections limit was reached. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_peer_address </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_peer_address"> <code class="literal"> Connection_errors_peer_address </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors that occurred while searching for connecting client IP addresses. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_select </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_select"> <code class="literal"> Connection_errors_select </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors that occurred during calls to select() or poll() on the listening port. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_tcpwrap </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_tcpwrap"> <code class="literal"> Connection_errors_tcpwrap </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections refused by the <code class="literal"> libwrap </code> library. </p> </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-perf-schema"> </a> mysql.perf_schema Metrics </h4> </div> </div> </div> <p> The <code class="literal"> mysql.perf_schema </code> correspond to the <code class="literal"> Performance_schema_ <em class="replaceable"> <code> XXX </code> </em> </code> status variables. See <a class="xref" href="performance-schema-status-monitoring.html" title="29.7 Performance Schema Status Monitoring"> Section 29.7, “Performance Schema Status Monitoring” </a> . </p> <div class="table"> <a name="idm46045057945936"> </a> <p class="title"> <b> Table 35.5 mysql.perf_schema Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> accounts_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_accounts_lost"> <code class="literal"> Performance_schema_accounts_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times a row could not be added to the accounts table because it was full. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cond_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_cond_classes_lost"> <code class="literal"> Performance_schema_cond_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many condition instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cond_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_cond_instances_lost"> <code class="literal"> Performance_schema_cond_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many condition instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> digest_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_digest_lost"> <code class="literal"> Performance_schema_digest_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of digest instances that could not be instrumented in the <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> file_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_classes_lost"> <code class="literal"> Performance_schema_file_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many file instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> file_handles_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_handles_lost"> <code class="literal"> Performance_schema_file_handles_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many file instrument instances could not be opened. </p> </td> </tr> <tr> <td> <p> <code class="literal"> file_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_instances_lost"> <code class="literal"> Performance_schema_file_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many file instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> hosts_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_hosts_lost"> <code class="literal"> Performance_schema_hosts_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times a row could not be added to the hosts table because it was full. </p> </td> </tr> <tr> <td> <p> <code class="literal"> index_stat_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_index_stat_lost"> <code class="literal"> Performance_schema_index_stat_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of indexes for which statistics were lost. </p> </td> </tr> <tr> <td> <p> <code class="literal"> locker_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_locker_lost"> <code class="literal"> Performance_schema_locker_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many events are lost or not recorded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> memory_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_memory_classes_lost"> <code class="literal"> Performance_schema_memory_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times a memory instrument could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> metadata_lock_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_metadata_lock_lost"> <code class="literal"> Performance_schema_metadata_lock_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of metadata locks that could not be instrumented in the <a class="link" href="performance-schema-metadata-locks-table.html" title="29.12.13.3 The metadata_locks Table"> <code class="literal"> metadata_locks </code> </a> table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> meter_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_meter_lost"> <code class="literal"> Performance_schema_meter_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many meter instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> metric_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_metric_lost"> <code class="literal"> Performance_schema_metric_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many metric instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> mutex_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_mutex_classes_lost"> <code class="literal"> Performance_schema_mutex_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many mutex instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> mutex_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_mutex_instances_lost"> <code class="literal"> Performance_schema_mutex_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many mutex instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> nested_statement_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_nested_statement_lost"> <code class="literal"> Performance_schema_nested_statement_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of stored program statements for which statistics were lost. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prepared_statements_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_prepared_statements_lost"> <code class="literal"> Performance_schema_prepared_statements_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of prepared statements that could not be instrumented in the <a class="link" href="performance-schema-prepared-statements-instances-table.html" title="29.12.6.4 The prepared_statements_instances Table"> <code class="literal"> prepared_statements_instances </code> </a> table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> program_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_program_lost"> <code class="literal"> Performance_schema_program_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of stored programs for which statistics were lost. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rwlock_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_rwlock_classes_lost"> <code class="literal"> Performance_schema_rwlock_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many rwlock instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rwlock_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_rwlock_instances_lost"> <code class="literal"> Performance_schema_rwlock_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many rwlock instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_connect_attrs_longest_seen </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_session_connect_attrs_longest_seen"> <code class="literal"> Performance_schema_session_connect_attrs_longest_seen </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Longest seen connection attribute received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_connect_attrs_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_session_connect_attrs_lost"> <code class="literal"> Performance_schema_session_connect_attrs_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections for which connection attribute truncation has occurred </p> </td> </tr> <tr> <td> <p> <code class="literal"> socket_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_socket_classes_lost"> <code class="literal"> Performance_schema_socket_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many socket instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> socket_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_socket_instances_lost"> <code class="literal"> Performance_schema_socket_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many socket instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> stage_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_stage_classes_lost"> <code class="literal"> Performance_schema_stage_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many stage instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> statement_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_statement_classes_lost"> <code class="literal"> Performance_schema_statement_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many statement instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_handles_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_handles_lost"> <code class="literal"> Performance_schema_table_handles_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many table instrument instances could not be opened. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_instances_lost"> <code class="literal"> Performance_schema_table_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many table instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_lock_stat_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_lock_stat_lost"> <code class="literal"> Performance_schema_table_lock_stat_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of tables for which lock statistics were lost. </p> </td> </tr> <tr> <td> <p> <code class="literal"> thread_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_thread_classes_lost"> <code class="literal"> Performance_schema_thread_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many thread instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> thread_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_thread_instances_lost"> <code class="literal"> Performance_schema_thread_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of thread instances that could not be instrumented in the <a class="link" href="performance-schema-threads-table.html" title="29.12.22.8 The threads Table"> <code class="literal"> threads </code> </a> table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> users_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_users_lost"> <code class="literal"> Performance_schema_users_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times a row could not be added to the <a class="link" href="performance-schema-users-table.html" title="29.12.8.3 The users Table"> <code class="literal"> users </code> </a> table because it was full. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 1077px;"> <thead> <tr> <th style="width: 283.266px;"> Name </th> <th style="width: 437.656px;"> Source Variable </th> <th style="width: 63.875px;"> OTEL Type </th> <th style="width: 291.391px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-handler"> </a> mysql.stats.handler Metrics </h4> </div> </div> </div> <p> The <code class="literal"> mysql.stats.handler </code> metrics correspond to the <code class="literal"> Handler_ <em class="replaceable"> <code> XXX </code> </em> </code> status variables. </p> <div class="table"> <a name="idm46045057692032"> </a> <p class="title"> <b> Table 35.6 mysql.perf_schema Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> commit </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_commit"> <code class="literal"> Handler_commit </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of internal COMMIT statements. </p> </td> </tr> <tr> <td> <p> <code class="literal"> delete </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_delete"> <code class="literal"> Handler_delete </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times that rows have been deleted from tables </p> </td> </tr> <tr> <td> <p> <code class="literal"> discover </code> </p> </td> <td> <p> <a class="link" href="mysql-cluster-options-variables.html#statvar_Handler_discover"> <code class="literal"> Handler_discover </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times that tables have been discovered. </p> </td> </tr> <tr> <td> <p> <code class="literal"> external_lock </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_external_lock"> <code class="literal"> Handler_external_lock </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The server increments this variable for each call to its external_lock() function, which generally occurs at the beginning and end of access to a table instance. </p> </td> </tr> <tr> <td> <p> <code class="literal"> mrr_init </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_mrr_init"> <code class="literal"> Handler_mrr_init </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times the server uses a storage engine's own Multi-Range Read implementation for table access. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prepare </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_prepare"> <code class="literal"> Handler_prepare </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> A counter for the prepare phase of two-phase commit operations. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_first </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_first"> <code class="literal"> Handler_read_first </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times the first entry in an index was read. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_key </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_key"> <code class="literal"> Handler_read_key </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read a row based on a key. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_last </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_last"> <code class="literal"> Handler_read_last </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read the last key in an index. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_next </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_next"> <code class="literal"> Handler_read_next </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read the next row in key order. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_prev </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_prev"> <code class="literal"> Handler_read_prev </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read the previous row in key order. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_rnd </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_rnd"> <code class="literal"> Handler_read_rnd </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read a row based on a fixed position. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_rnd_next </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_rnd_next"> <code class="literal"> Handler_read_rnd_next </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read the next row in the data file. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rollback </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_rollback"> <code class="literal"> Handler_rollback </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests for a storage engine to perform a rollback operation. </p> </td> </tr> <tr> <td> <p> <code class="literal"> savepoint </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_savepoint"> <code class="literal"> Handler_savepoint </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests for a storage engine to place a savepoint. </p> </td> </tr> <tr> <td> <p> <code class="literal"> savepoint_rollback </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_savepoint_rollback"> <code class="literal"> Handler_savepoint_rollback </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests for a storage engine to roll back to a savepoint. </p> </td> </tr> <tr> <td> <p> <code class="literal"> update </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_update"> <code class="literal"> Handler_update </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to update a row in a table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> write </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_write"> <code class="literal"> Handler_write </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to insert a row in a table. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 153.266px;"> Name </th> <th style="width: 218.266px;"> Source Variable </th> <th style="width: 124.016px;"> OTEL Type </th> <th style="width: 242.453px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-myisam"> </a> mysql.stats.myisam Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057554096"> </a> <p class="title"> <b> Table 35.7 mysql.perf_schema Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> key_blocks_not_flushed </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_blocks_not_flushed"> <code class="literal"> Key_blocks_not_flushed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of key blocks in the MyISAM key cache that have changed but have not yet been flushed to disk. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_blocks_unused </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_blocks_unused"> <code class="literal"> Key_blocks_unused </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of unused blocks in the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_blocks_used </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_blocks_used"> <code class="literal"> Key_blocks_used </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of used blocks in the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_read_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_read_requests"> <code class="literal"> Key_read_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read a key block from the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_reads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_reads"> <code class="literal"> Key_reads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of physical reads of a key block from disk into the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_write_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_write_requests"> <code class="literal"> Key_write_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to write a key block to the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_writes"> <code class="literal"> Key_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of physical writes of a key block from the MyISAM key cache to disk. </p> </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-ssl"> </a> mysql.stats.ssl Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057494256"> </a> <p class="title"> <b> Table 35.8 mysql.stats.ssl Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> client_connects </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_client_connects"> <code class="literal"> Ssl_client_connects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL connection attempts to an SSL-enabled replication source server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connect_renegotiates </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_connect_renegotiates"> <code class="literal"> Ssl_connect_renegotiates </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of negotiates needed to establish the connection to an SSL-enabled replication source server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> finished_accepts </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_finished_accepts"> <code class="literal"> Ssl_finished_accepts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of successful SSL connections to the server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> finished_connects </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_finished_connects"> <code class="literal"> Ssl_finished_connects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of successful replica connections to an SSL-enabled replication source server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_hits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_hits"> <code class="literal"> Ssl_session_cache_hits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL session cache hits. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_misses </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_misses"> <code class="literal"> Ssl_session_cache_misses </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL session cache misses. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_overflows </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_overflows"> <code class="literal"> Ssl_session_cache_overflows </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL session cache overflows. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_size </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_size"> <code class="literal"> Ssl_session_cache_size </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The SSL session cache size. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_timeouts </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_timeouts"> <code class="literal"> Ssl_session_cache_timeouts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL session cache timeouts. </p> </td> </tr> <tr> <td> <p> <code class="literal"> used_session_cache_entries </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_used_session_cache_entries"> <code class="literal"> Ssl_used_session_cache_entries </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many SSL session cache entries were used. </p> </td> </tr> <tr> <td> <p> <code class="literal"> accept_renegotiates </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_accept_renegotiates"> <code class="literal"> Ssl_accept_renegotiates </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of negotiates needed to establish the connection. </p> </td> </tr> <tr> <td> <p> <code class="literal"> accepts </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_accepts"> <code class="literal"> Ssl_accepts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of accepted SSL connections. </p> </td> </tr> <tr> <td> <p> <code class="literal"> callback_cache_hits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_callback_cache_hits"> <code class="literal"> Ssl_callback_cache_hits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of callback cache hits. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 218.266px;"> Name </th> <th style="width: 250.766px;"> Source Variable </th> <th style="width: 97.4062px;"> OTEL Type </th> <th style="width: 171.562px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-inno"> </a> mysql.inno Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057391856"> </a> <p class="title"> <b> Table 35.9 mysql.inno Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> dblwr_pages_written </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_pages_written"> <code class="literal"> Innodb_dblwr_pages_written </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages that have been written for doublewrite operations </p> </td> </tr> <tr> <td> <p> <code class="literal"> dblwr_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_writes"> <code class="literal"> Innodb_dblwr_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of doublewrite operations that have been performed </p> </td> </tr> <tr> <td> <p> <code class="literal"> redo_log_logical_size </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_logical_size"> <code class="literal"> Innodb_redo_log_logical_size </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> LSN range size in bytes containing in-use redo log data. </p> </td> </tr> <tr> <td> <p> <code class="literal"> redo_log_physical_size </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_physical_size"> <code class="literal"> Innodb_redo_log_physical_size </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Disk space in bytes currently consumed by all redo log files on disk, excluding spare redo log files </p> </td> </tr> <tr> <td> <p> <code class="literal"> redo_log_capacity_resized </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_capacity_resized"> <code class="literal"> Innodb_redo_log_capacity_resized </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Redo log capacity in bytes for all redo log files, after the last completed capacity resize operation </p> </td> </tr> <tr> <td> <p> <code class="literal"> log_waits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_log_waits"> <code class="literal"> Innodb_log_waits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of log waits due to small log buffer </p> </td> </tr> <tr> <td> <p> <code class="literal"> log_write_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_log_write_requests"> <code class="literal"> Innodb_log_write_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of log write requests </p> </td> </tr> <tr> <td> <p> <code class="literal"> log_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_log_writes"> <code class="literal"> Innodb_log_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of physical writes to the InnoDB redo log file </p> </td> </tr> <tr> <td> <p> <code class="literal"> os_log_fsyncs </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_fsyncs"> <code class="literal"> Innodb_os_log_fsyncs </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of fsync log writes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> os_log_pending_fsyncs </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_fsyncs"> <code class="literal"> Innodb_os_log_pending_fsyncs </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of pending fsync writes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> os_log_pending_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_writes"> <code class="literal"> Innodb_os_log_pending_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of pending log file writes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> os_log_written </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_written"> <code class="literal"> Innodb_os_log_written </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Bytes of log written. </p> </td> </tr> <tr> <td> <p> <code class="literal"> page_size </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_page_size"> <code class="literal"> Innodb_page_size </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> InnoDB page size in bytes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_created </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_created"> <code class="literal"> Innodb_pages_created </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages created </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_read </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_read"> <code class="literal"> Innodb_pages_read </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages read. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_written </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_written"> <code class="literal"> Innodb_pages_written </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages written. </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_current_waits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_current_waits"> <code class="literal"> Innodb_row_lock_current_waits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of row locks currently being waited for. </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_time </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time"> <code class="literal"> Innodb_row_lock_time </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Time spent in acquiring row locks, in milliseconds </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_time_avg </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_avg"> <code class="literal"> Innodb_row_lock_time_avg </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The average time to acquire a row lock, in milliseconds </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_time_max </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_max"> <code class="literal"> Innodb_row_lock_time_max </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The maximum time to acquire a row lock, in milliseconds. </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_waits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_waits"> <code class="literal"> Innodb_row_lock_waits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of times a row lock had to be waited for. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rows_deleted </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_deleted"> <code class="literal"> Innodb_rows_deleted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of rows inserted into InnoDB tables. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rows_read </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_read"> <code class="literal"> Innodb_rows_read </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of rows read from InnoDB tables </p> </td> </tr> <tr> <td> <p> <code class="literal"> rows_updated </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_updated"> <code class="literal"> Innodb_rows_updated </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of rows updated in InnoDB tables. </p> </td> </tr> <tr> <td> <p> <code class="literal"> system_rows_deleted </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_deleted"> <code class="literal"> Innodb_system_rows_deleted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of rows deleted from InnoDB tables belonging to system-created schemas. </p> </td> </tr> <tr> <td> <p> <code class="literal"> system_rows_inserted </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_inserted"> <code class="literal"> Innodb_system_rows_inserted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of rows inserted into InnoDB tables belonging to system-created schemas </p> </td> </tr> <tr> <td> <p> <code class="literal"> system_rows_read </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_read"> <code class="literal"> Innodb_system_rows_read </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of rows read from InnoDB tables belonging to system-created schemas. </p> </td> </tr> <tr> <td> <p> <code class="literal"> system_rows_updated </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_updated"> <code class="literal"> Innodb_system_rows_updated </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of rows updated in InnoDB tables belonging to system-created schemas. </p> </td> </tr> <tr> <td> <p> <code class="literal"> num_open_files </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_num_open_files"> <code class="literal"> Innodb_num_open_files </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of files currently open. </p> </td> </tr> <tr> <td> <p> <code class="literal"> truncated_status_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_truncated_status_writes"> <code class="literal"> Innodb_truncated_status_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of times output from the <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> statement has been truncated. </p> </td> </tr> <tr> <td> <p> <code class="literal"> undo_tablespaces_total </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_total"> <code class="literal"> Innodb_undo_tablespaces_total </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Total number of undo tablespaces. </p> </td> </tr> <tr> <td> <p> <code class="literal"> undo_tablespaces_explicit </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_explicit"> <code class="literal"> Innodb_undo_tablespaces_explicit </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of user-created undo tablespaces. </p> </td> </tr> <tr> <td> <p> <code class="literal"> undo_tablespaces_active </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_active"> <code class="literal"> Innodb_undo_tablespaces_active </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of active undo tablespaces, including implicit and explicit tablespaces </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 210.141px;"> Name </th> <th style="width: 267.016px;"> Source Variable </th> <th style="width: 95.0625px;"> OTEL Type </th> <th style="width: 165.781px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-inno-bufferpool"> </a> mysql.inno.buffer_pool Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057146720"> </a> <p class="title"> <b> Table 35.10 mysql.inno.buffer_pool Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> pages_data </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_data"> <code class="literal"> Innodb_buffer_pool_pages_data </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer pages containing data. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_data </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_data"> <code class="literal"> Innodb_buffer_pool_bytes_data </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer bytes containing data. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_dirty </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_dirty"> <code class="literal"> Innodb_buffer_pool_pages_dirty </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer pages currently dirty. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_dirty </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_dirty"> <code class="literal"> Innodb_buffer_pool_bytes_dirty </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer bytes currently dirty </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_flushed </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_flushed"> <code class="literal"> Innodb_buffer_pool_pages_flushed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to flush pages from the InnoDB buffer pool. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_free </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_free"> <code class="literal"> Innodb_buffer_pool_pages_free </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer pages currently free. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_misc </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_misc"> <code class="literal"> Innodb_buffer_pool_pages_misc </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer pages for misc use such as row locks or the adaptive hash index. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_total </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_total"> <code class="literal"> Innodb_buffer_pool_pages_total </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Total buffer pool size in pages. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_ahead_rnd </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_rnd"> <code class="literal"> Innodb_buffer_pool_read_ahead_rnd </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of 'random' read-aheads initiated by InnoDB. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_ahead </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead"> <code class="literal"> Innodb_buffer_pool_read_ahead </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages read as read ahead. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_ahead_evicted </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_evicted"> <code class="literal"> Innodb_buffer_pool_read_ahead_evicted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Read-ahead pages evicted without being accessed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_requests"> <code class="literal"> Innodb_buffer_pool_read_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of logical read requests. </p> </td> </tr> <tr> <td> <p> <code class="literal"> reads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_reads"> <code class="literal"> Innodb_buffer_pool_reads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of reads directly from disk. </p> </td> </tr> <tr> <td> <p> <code class="literal"> wait_free </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_wait_free"> <code class="literal"> Innodb_buffer_pool_wait_free </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of times waited for free buffer. </p> </td> </tr> <tr> <td> <p> <code class="literal"> write_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_write_requests"> <code class="literal"> Innodb_buffer_pool_write_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of write requests. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 153.266px;"> Name </th> <th style="width: 307.641px;"> Source Variable </th> <th style="width: 99.75px;"> OTEL Type </th> <th style="width: 177.344px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-inno-data"> </a> mysql.inno.data Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057030256"> </a> <p class="title"> <b> Table 35.11 mysql.inno.data Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> fsyncs </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_fsyncs"> <code class="literal"> Innodb_data_fsyncs </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of <code class="literal"> fsync() </code> calls. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pending_fsyncs </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_fsyncs"> <code class="literal"> Innodb_data_pending_fsyncs </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of pending fsync operations. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pending_reads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_reads"> <code class="literal"> Innodb_data_pending_reads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The current number of pending reads </p> </td> </tr> <tr> <td> <p> <code class="literal"> pending_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_writes"> <code class="literal"> Innodb_data_pending_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The current number of pending writes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_read"> <code class="literal"> Innodb_data_read </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Amount of data read in bytes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> reads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_reads"> <code class="literal"> Innodb_data_reads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of reads initiated. </p> </td> </tr> <tr> <td> <p> <code class="literal"> writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_writes"> <code class="literal"> Innodb_data_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of writes initiated. </p> </td> </tr> <tr> <td> <p> <code class="literal"> written </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_written"> <code class="literal"> Innodb_data_written </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Amount of data written in bytes. </p> </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-x"> </a> mysql.x Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045056962976"> </a> <p class="title"> <b> Table 35.12 mysql.x Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> aborted_clients </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_aborted_clients"> <code class="literal"> Mysqlx_aborted_clients </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of clients that were disconnected because of an input or output error. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_received </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received"> <code class="literal"> Mysqlx_bytes_received </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The total number of bytes received through the network, measured before decompression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_received_compressed_payload </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_compressed_payload"> <code class="literal"> Mysqlx_bytes_received_compressed_payload </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes received as compressed message payloads, measured before decompression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_received_uncompressed_frame </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_uncompressed_frame"> <code class="literal"> Mysqlx_bytes_received_uncompressed_frame </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes received as compressed message payloads, measured after decompression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent"> <code class="literal"> Mysqlx_bytes_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The total number of bytes sent through the network. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_sent_compressed_payload </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_compressed_payload"> <code class="literal"> Mysqlx_bytes_sent_compressed_payload </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes sent as compressed message payloads, measured after compression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_sent_uncompressed_frame </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_uncompressed_frame"> <code class="literal"> Mysqlx_bytes_sent_uncompressed_frame </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes sent as compressed message payloads, measured before compression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connection_accept_errors </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_accept_errors"> <code class="literal"> Mysqlx_connection_accept_errors </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have caused accept errors. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connection_errors </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_errors"> <code class="literal"> Mysqlx_connection_errors </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have caused errors. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connections_accepted </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_accepted"> <code class="literal"> Mysqlx_connections_accepted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have been accepted. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connections_closed </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_closed"> <code class="literal"> Mysqlx_connections_closed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have been closed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connections_rejected </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_rejected"> <code class="literal"> Mysqlx_connections_rejected </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have been rejected. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_create_view </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_create_view"> <code class="literal"> Mysqlx_crud_create_view </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of create view requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_delete </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_delete"> <code class="literal"> Mysqlx_crud_delete </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of delete requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_drop_view </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_drop_view"> <code class="literal"> Mysqlx_crud_drop_view </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of drop view requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_find </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_find"> <code class="literal"> Mysqlx_crud_find </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of find requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_insert </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_insert"> <code class="literal"> Mysqlx_crud_insert </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of insert requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_modify_view </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_modify_view"> <code class="literal"> Mysqlx_crud_modify_view </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of modify view requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_update </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_update"> <code class="literal"> Mysqlx_crud_update </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of update requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cursor_close </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_close"> <code class="literal"> Mysqlx_cursor_close </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of cursor-close messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cursor_fetch </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_fetch"> <code class="literal"> Mysqlx_cursor_fetch </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of cursor-fetch messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cursor_open </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_open"> <code class="literal"> Mysqlx_cursor_open </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of cursor-open messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_sent"> <code class="literal"> Mysqlx_errors_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors sent to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_unknown_message_type </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_unknown_message_type"> <code class="literal"> Mysqlx_errors_unknown_message_type </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of unknown message types that have been received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> expect_close </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_close"> <code class="literal"> Mysqlx_expect_close </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of expectation blocks closed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> expect_open </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_open"> <code class="literal"> Mysqlx_expect_open </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of expectation blocks opened. </p> </td> </tr> <tr> <td> <p> <code class="literal"> init_error </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_init_error"> <code class="literal"> Mysqlx_init_error </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors during initialisation. </p> </td> </tr> <tr> <td> <p> <code class="literal"> messages_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_messages_sent"> <code class="literal"> Mysqlx_messages_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The total number of messages of all types sent to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> notice_global_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_global_sent"> <code class="literal"> Mysqlx_notice_global_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of global notifications sent to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> notice_other_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_other_sent"> <code class="literal"> Mysqlx_notice_other_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of other types of notices sent back to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> notice_warning_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_warning_sent"> <code class="literal"> Mysqlx_notice_warning_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of warning notices sent back to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> notified_by_group_replication </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notified_by_group_replication"> <code class="literal"> Mysqlx_notified_by_group_replication </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of Group Replication notifications sent to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prep_deallocate </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_deallocate"> <code class="literal"> Mysqlx_prep_deallocate </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of prepared-statement-deallocate messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prep_execute </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_execute"> <code class="literal"> Mysqlx_prep_execute </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of prepared-statement-execute messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prep_prepare </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_prepare"> <code class="literal"> Mysqlx_prep_prepare </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of prepared-statement messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rows_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_rows_sent"> <code class="literal"> Mysqlx_rows_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of rows sent back to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions"> <code class="literal"> Mysqlx_sessions </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sessions that have been opened. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_accepted </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_accepted"> <code class="literal"> Mysqlx_sessions_accepted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of session attempts which have been accepted. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_closed </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_closed"> <code class="literal"> Mysqlx_sessions_closed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sessions that have been closed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_fatal_error </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_fatal_error"> <code class="literal"> Mysqlx_sessions_fatal_error </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sessions that have closed with a fatal error. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_killed </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_killed"> <code class="literal"> Mysqlx_sessions_killed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sessions which have been killed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_rejected </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_rejected"> <code class="literal"> Mysqlx_sessions_rejected </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of session attempts which have been rejected. </p> </td> </tr> <tr> <td> <p> <code class="literal"> ssl_accepts </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_accepts"> <code class="literal"> Mysqlx_ssl_accepts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of accepted SSL connections. </p> </td> </tr> <tr> <td> <p> <code class="literal"> ssl_finished_accepts </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_finished_accepts"> <code class="literal"> Mysqlx_ssl_finished_accepts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of successful SSL connections to the server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> worker_threads </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads"> <code class="literal"> Mysqlx_worker_threads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of worker threads available. </p> </td> </tr> <tr> <td> <p> <code class="literal"> worker_threads_active </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads_active"> <code class="literal"> Mysqlx_worker_threads_active </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of worker threads currently used. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 780px;"> <thead> <tr> <th style="width: 275.141px;"> Name </th> <th style="width: 332.016px;"> Source Variable </th> <th style="width: 63.875px;"> OTEL Type </th> <th style="width: 107.703px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-x-stmt"> </a> mysql.x.stmt Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045056626752"> </a> <p class="title"> <b> Table 35.13 mysql.x.stmt Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> create_collection </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection"> <code class="literal"> Mysqlx_stmt_create_collection </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of create collection statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> create_collection_index </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection_index"> <code class="literal"> Mysqlx_stmt_create_collection_index </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of create collection index statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> disable_notices </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_disable_notices"> <code class="literal"> Mysqlx_stmt_disable_notices </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of disable notice statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> drop_collection </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection"> <code class="literal"> Mysqlx_stmt_drop_collection </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of drop collection statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> drop_collection_index </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection_index"> <code class="literal"> Mysqlx_stmt_drop_collection_index </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of drop collection index statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> enable_notices </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_enable_notices"> <code class="literal"> Mysqlx_stmt_enable_notices </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of enable notice statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> ensure_collection </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ensure_collection"> <code class="literal"> Mysqlx_stmt_ensure_collection </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of ensure collection statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> execute_mysqlx </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_mysqlx"> <code class="literal"> Mysqlx_stmt_execute_mysqlx </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of StmtExecute messages received with namespace set to mysqlx. </p> </td> </tr> <tr> <td> <p> <code class="literal"> execute_sql </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_sql"> <code class="literal"> Mysqlx_stmt_execute_sql </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of StmtExecute requests received for the SQL namespace. </p> </td> </tr> <tr> <td> <p> <code class="literal"> get_collection_options </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_get_collection_options"> <code class="literal"> Mysqlx_stmt_get_collection_options </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of get collection object statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> kill_client </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_kill_client"> <code class="literal"> Mysqlx_stmt_kill_client </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of kill client statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> list_clients </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_clients"> <code class="literal"> Mysqlx_stmt_list_clients </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of list client statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> list_notices </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_notices"> <code class="literal"> Mysqlx_stmt_list_notices </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of list notice statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> list_objects </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_objects"> <code class="literal"> Mysqlx_stmt_list_objects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of list object statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> modify_collection_options </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_modify_collection_options"> <code class="literal"> Mysqlx_stmt_modify_collection_options </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of modify collection options statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> ping </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ping"> <code class="literal"> Mysqlx_stmt_ping </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of ping statements received. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 210.141px;"> Name </th> <th style="width: 307.641px;"> Source Variable </th> <th style="width: 83.3281px;"> OTEL Type </th> <th style="width: 136.891px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/group-replication-message-compression.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="group-replication-message-compression"> </a> 20.7.4 Message Compression </h3> </div> </div> </div> <a class="indexterm" name="idm46045132157984"> </a> <p> For messages sent between online group members, Group Replication enables message compression by default. Whether a specific message is compressed depends on the threshold that you configure using the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> system variable. Messages that have a payload larger than the specified number of bytes are compressed. </p> <p> The default compression threshold is 1000000 bytes. You could use the following statements to increase the compression threshold to 2MB, for example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa7024708"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">STOP</span> <span class="token keyword">GROUP_REPLICATION</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> group_replication_compression_threshold <span class="token operator">=</span> <span class="token number">2097152</span><span class="token punctuation">;</span> <span class="token keyword">START</span> <span class="token keyword">GROUP_REPLICATION</span><span class="token punctuation">;</span></code></pre> </div> <p> If you set <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> to zero, message compression is disabled. </p> <p> Group Replication uses the LZ4 compression algorithm to compress messages sent in the group. Note that the maximum supported input size for the LZ4 compression algorithm is 2113929216 bytes. This limit is lower than the maximum possible value for the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> system variable, which is matched to the maximum message size accepted by XCom. The LZ4 maximum input size is therefore a practical limit for message compression, and transactions above this size cannot be committed when message compression is enabled. With the LZ4 compression algorithm, do not set a value greater than 2113929216 bytes for <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> . </p> <p> The value of <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> is not required by Group Replication to be the same on all group members. However, it is advisable to set the same value on all group members in order to avoid unnecessary rollback of transactions, failure of message delivery, or failure of message recovery. </p> <p> You can also configure compression for messages sent for distributed recovery by the method of state transfer from a donor's binary log. Compression for these messages, which are sent from a donor already in the group to a joining member, is controlled separately using the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_compression_algorithms"> <code class="literal"> group_replication_recovery_compression_algorithms </code> </a> and <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_zstd_compression_level"> <code class="literal"> group_replication_recovery_zstd_compression_level </code> </a> system variables. For more information, see <a class="xref" href="connection-compression-control.html" title="6.2.8 Connection Compression Control"> Section 6.2.8, “Connection Compression Control” </a> . </p> <p> Binary log transaction compression, enabled by the <a class="link" href="replication-options-binary-log.html#sysvar_binlog_transaction_compression"> <code class="literal"> binlog_transaction_compression </code> </a> system variable, can also be used to save bandwidth. The transaction payloads remain compressed when they are transferred between group members. If you use binary log transaction compression in combination with Group Replication's message compression, message compression has less opportunity to act on the data, but can still compress headers and those events and transaction payloads that are uncompressed. For more information on binary log transaction compression, see <a class="xref" href="binary-log-transaction-compression.html" title="7.4.4.5 Binary Log Transaction Compression"> Section 7.4.4.5, “Binary Log Transaction Compression” </a> . </p> <p> Compression for messages sent in the group happens at the group communication engine level, before the data is handed over to the group communication thread, so it takes place within the context of the <code class="literal"> mysql </code> user session thread. If the message payload size exceeds the threshold set by <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> , the transaction payload is compressed before being sent out to the group, and decompressed when it is received. Upon receiving a message, the member checks the message envelope to verify whether it is compressed or not. If needed, then the member decompresses the transaction, before delivering it to the upper layer. This process is shown in the following figure. </p> <div class="figure"> <a name="idm46045132135168"> </a> <p class="title"> <b> Figure 20.13 Compression Support </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="The MySQL Group Replication plugin architecture is shown as described in an earlier topic, with the five layers of the plugin positioned between the MySQL server and the replication group. Compression and decompression are handled by the Group Communication System API, which is the fourth layer of the Group Replication plugin. The group communication engine (the fifth layer of the plugin) and the group members use the compressed transactions with the smaller data size. The MySQL Server core and the three higher layers of the Group Replication plugin (the APIs, the capture, applier, and recovery components, and the replication protocol module) use the original transactions with the larger data size." src="images/gr-compress-decompress.png" style="width: 100%; max-width: 588px;"/> </div> </div> </div> <br class="figure-break"/> <p> When network bandwidth is a bottleneck, message compression can provide up to 30-40% throughput improvement at the group communication level. This is especially important within the context of large groups of servers under load. The TCP peer-to-peer nature of the interconnections between <span class="emphasis"> <em> N </em> </span> participants in the group makes the sender send the same amount of data <span class="emphasis"> <em> N </em> </span> times. Furthermore, binary logs are likely to exhibit a high compression ratio. This makes compression a compelling feature for Group Replication workloads that contain large transactions. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/group-replication-view-changes.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="group-replication-view-changes"> </a> 20.5.4.5 How Distributed Recovery Works </h4> </div> </div> </div> <a class="indexterm" name="idm46045132932672"> </a> <a class="indexterm" name="idm46045132931184"> </a> <p> When Group Replication's distributed recovery process is carrying out state transfer from the binary log, to synchronize the joining member with the donor up to a specific point in time, the joining member and donor make use of GTIDs (see <a class="xref" href="replication-gtids.html" title="19.1.3 Replication with Global Transaction Identifiers"> Section 19.1.3, “Replication with Global Transaction Identifiers” </a> ). However, GTIDs only provide a means to realize which transactions the joining member is missing. They do not help marking a specific point in time to which the server joining the group must catch up, nor do they convey certification information. This is the job of binary log view markers, which mark view changes in the binary log stream, and also contain additional metadata information, supplying the joining member with missing certification-related data. </p> <p> This topic explains the role of view changes and the view change identifier, and the steps to carry out state transfer from the binary log. </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-view-and-view-changes"> </a> View and View Changes </h5> </div> </div> </div> <p> A <span class="emphasis"> <em> view </em> </span> corresponds to a group of members participating actively in the current configuration, in other words at a specific point in time. They are functioning correctly and online in the group. </p> <p> A <span class="emphasis"> <em> view change </em> </span> occurs when a modification to the group configuration happens, such as a member joining or leaving. Any group membership change results in an independent view change communicated to all members at the same logical point in time. </p> <p> A <span class="emphasis"> <em> view identifier </em> </span> uniquely identifies a view. It is generated whenever a view change happens. </p> <p> At the group communication layer, view changes with their associated view identifiers mark boundaries between the data exchanged before and after a member joins. This concept is implemented through a binary log event: the "view change log event" (VCLE). The view identifier is recorded to demarcate transactions transmitted before and after changes happen in the group membership. </p> <p> The view identifier itself is built from two parts: a randomly generated part, and a monotonically increasing integer. The randomly generated part is generated when the group is created, and remains unchanged while there is at least one member in the group. The integer is incremented every time a view change happens. Using these two different parts enables the view identifier to identify incremental group changes caused by members joining or leaving, and also to identify the situation where all members leave the group in a full group shutdown, so no information remains of what view the group was in. Randomly generating part of the identifier when the group is started from the beginning ensures that the data markers in the binary log remain unique, and an identical identifier is not reused after a full group shutdown, as this would cause issues with distributed recovery in the future. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-begin-stable-group"> </a> Begin: Stable Group </h5> </div> </div> </div> <p> All servers are online and processing incoming transactions from the group. Some servers may be a little behind in terms of transactions replicated, but eventually they converge. The group acts as one distributed and replicated database. </p> <div class="figure"> <a name="idm46045132918672"> </a> <p class="title"> <b> Figure 20.8 Stable Group </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Servers S1, S2, and S3 are members of the group. The most recent item in all of their binary logs is transaction T20." src="images/gr-recovery-1.png" style="width: 100%; max-width: 653px;"/> </div> </div> </div> <br class="figure-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-view-change-member-joins"> </a> View Change: a Member Joins </h5> </div> </div> </div> <p> Whenever a new member joins the group and therefore a view change is performed, every online server queues a view change log event for execution. This is queued because before the view change, several transactions can be queued on the server to be applied and as such, these belong to the old view. Queuing the view change event after them guarantees a correct marking of when this happened. </p> <p> Meanwhile, the joining member selects a suitable donor from the list of online servers as stated by the membership service through the view abstraction. A member joins on view 4 and the online members write a view change event to the binary log. </p> <div class="figure"> <a name="idm46045132909072"> </a> <p class="title"> <b> Figure 20.9 A Member Joins </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Server S4 joins the group and looks for a donor. Servers S1, S2, and S3 each queue the view change entry VC4 for their binary logs. Meanwhile, server S1 is receiving new transaction T21." src="images/gr-recovery-2.png" style="width: 100%; max-width: 606px;"/> </div> </div> </div> <br class="figure-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-state-transfer-catching-up"> </a> State Transfer: Catching Up </h5> </div> </div> </div> <p> If group members and the joining member are set up with the clone plugin (see <a class="xref" href="group-replication-cloning.html" title="20.5.4.2 Cloning for Distributed Recovery"> Section 20.5.4.2, “Cloning for Distributed Recovery” </a> ), and the difference in transactions between the joining member and the group exceeds the threshold set for a remote cloning operation ( <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_clone_threshold"> <code class="literal"> group_replication_clone_threshold </code> </a> ), Group Replication begins distributed recovery with a remote cloning operation. A remote cloning operation is also carried out if required transactions are no longer present in any group member's binary log files. During a remote cloning operation, the existing data on the joining member is removed, and replaced with a copy of the donor's data. When the remote cloning operation is complete and the joining member has restarted, state transfer from a donor's binary log is carried out to get the transactions that the group applied while the remote cloning operation was in progress. If there is not a large transaction gap, or if the clone plugin is not installed, Group Replication proceeds directly to state transfer from a donor's binary log. </p> <p> For state transfer from a donor's binary log, a connection is established between the joining member and the donor and state transfer begins. This interaction with the donor continues until the server joining the group's applier thread processes the view change log event that corresponds to the view change triggered when the server joining the group came into the group. In other words, the server joining the group replicates from the donor, until it gets to the marker with the view identifier which matches the view marker it is already in. </p> <div class="figure"> <a name="idm46045132896352"> </a> <p class="title"> <b> Figure 20.10 State Transfer: Catching Up </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Server S4 has chosen server S2 as the donor. State transfer is executed from server S2 to server S4 until the view change entry VC4 is reached (view_id = VC4). Server S4 uses a temporary applier buffer for state transfer, and its binary log is currently empty." src="images/gr-recovery-3.png" style="width: 100%; max-width: 620px;"/> </div> </div> </div> <br class="figure-break"/> <p> As view identifiers are transmitted to all members in the group at the same logical time, the server joining the group knows at which view identifier it should stop replicating. This avoids complex GTID set calculations because the view identifier clearly marks which data belongs to each group view. </p> <p> While the server joining the group is replicating from the donor, it is also caching incoming transactions from the group. Eventually, it stops replicating from the donor and switches to applying those that are cached. </p> <div class="figure"> <a name="idm46045132887984"> </a> <p class="title"> <b> Figure 20.11 Queued Transactions </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="State transfer is complete. Server S4 has applied the transactions up to T20 and written them to its binary log. Server S4 has cached transaction T21, which arrived after the view change, in a temporary applier buffer while recovering." src="images/gr-recovery-4.png" style="width: 100%; max-width: 555px;"/> </div> </div> </div> <br class="figure-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-finish-caught-up"> </a> Finish: Caught Up </h5> </div> </div> </div> <p> When the server joining the group recognizes a view change log event with the expected view identifier, the connection to the donor is terminated and it starts applying the cached transactions. Although it acts as a marker in the binary log, delimiting view changes, the view change log event also plays another role. It conveys the certification information as perceived by all servers when the server joining the group entered the group, in other words the last view change. Without it, the server joining the group would not have the necessary information to be able to certify (detect conflicts) subsequent transactions. </p> <p> The duration of the catch up is not deterministic, because it depends on the workload and the rate of incoming transactions to the group. This process is completely online and the server joining the group does not block any other server in the group while it is catching up. Therefore the number of transactions the server joining the group is behind when it moves to this stage can, for this reason, vary and thus increase or decrease according to the workload. </p> <p> When the server joining the group reaches zero queued transactions and its stored data is equal to the other members, its public state changes to online. </p> <div class="figure"> <a name="idm46045132877104"> </a> <p class="title"> <b> Figure 20.12 Instance Online </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Server S4 is now an online member of the group. It has applied cached transaction T21, so its binary log shows the same items as the binary logs of the other group members, and it no longer needs the temporary applier buffer. New incoming transaction T22 is now received and applied by all group members." src="images/gr-recovery-5.png" style="width: 100%; max-width: 652px;"/> </div> </div> </div> <br class="figure-break"/> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/gis-class-multicurve.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="gis-class-multicurve"> </a> 13.4.2.10 MultiCurve Class </h4> </div> </div> </div> <p> A <code class="literal"> MultiCurve </code> is a geometry collection composed of <code class="literal"> Curve </code> elements. <code class="literal"> MultiCurve </code> is a noninstantiable class. </p> <p> <span class="bold"> <strong> <code class="literal"> MultiCurve </code> Properties </strong> </span> </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A <code class="literal"> MultiCurve </code> is a one-dimensional geometry. </p> </li> <li class="listitem"> <p> A <code class="literal"> MultiCurve </code> is simple if and only if all of its elements are simple; the only intersections between any two elements occur at points that are on the boundaries of both elements. </p> </li> <li class="listitem"> <p> A <code class="literal"> MultiCurve </code> boundary is obtained by applying the <span class="quote"> “ <span class="quote"> mod 2 union rule </span> ” </span> (also known as the <span class="quote"> “ <span class="quote"> odd-even rule </span> ” </span> ): A point is in the boundary of a <code class="literal"> MultiCurve </code> if it is in the boundaries of an odd number of <code class="literal"> Curve </code> elements. </p> </li> <li class="listitem"> <p> A <code class="literal"> MultiCurve </code> is closed if all of its elements are closed. </p> </li> <li class="listitem"> <p> The boundary of a closed <code class="literal"> MultiCurve </code> is always empty. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/database-count-limit.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="database-count-limit"> </a> 10.4.5 Limits on Number of Databases and Tables </h3> </div> </div> </div> <a class="indexterm" name="idm46045226469792"> </a> <a class="indexterm" name="idm46045226468320"> </a> <a class="indexterm" name="idm46045226466816"> </a> <a class="indexterm" name="idm46045226465312"> </a> <p> MySQL has no limit on the number of databases. The underlying file system may have a limit on the number of directories. </p> <p> MySQL has no limit on the number of tables. The underlying file system may have a limit on the number of files that represent tables. Individual storage engines may impose engine-specific constraints. <code class="literal"> InnoDB </code> permits up to 4 billion tables. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-programs-ndb-drop-table.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysql-cluster-programs-ndb-drop-table"> </a> 25.5.11 ndb_drop_table — Drop an NDB Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045103509312"> </a> <p> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html" title="25.5.11 ndb_drop_table — Drop an NDB Table"> <span class="command"> <strong> ndb_drop_table </strong> </span> </a> drops the specified <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> table. (If you try to use this on a table created with a storage engine other than <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> , the attempt fails with the error <span class="errortext"> 723: No such table exists </span> .) This operation is extremely fast; in some cases, it can be an order of magnitude faster than using a MySQL <a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement"> <code class="literal"> DROP TABLE </code> </a> statement on an <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> table. </p> <h4> <a name="idm46045103501104"> </a> Usage </h4> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa5470933"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ndb_drop_table <span class="token property">-c</span> <em class="replaceable">connection_string</em> <em class="replaceable">tbl_name</em> <span class="token property">-d</span> <em class="replaceable">db_name</em></code></pre> </div> <p> Options that can be used with <a class="link" href="mysql-cluster-programs-ndb-drop-table.html" title="25.5.11 ndb_drop_table — Drop an NDB Table"> <span class="command"> <strong> ndb_drop_table </strong> </span> </a> are shown in the following table. Additional descriptions follow the table. </p> <p> </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_ndb_drop_table_character-sets-dir"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_character-sets-dir"> <code class="option"> --character-sets-dir </code> </a> </p> <a class="indexterm" name="idm46045103493280"> </a> <a class="indexterm" name="idm46045103491776"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for character-sets-dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --character-sets-dir=path </code> </td> </tr> </tbody> </table> </div> <p> Directory containing character sets. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_connect-retries"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_connect-retries"> <code class="option"> --connect-retries </code> </a> </p> <a class="indexterm" name="idm46045103481984"> </a> <a class="indexterm" name="idm46045103480496"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-retries"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-retries=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 12 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 12 </code> </td> </tr> </tbody> </table> </div> <p> Number of times to retry connection before giving up. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_connect-retry-delay"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_connect-retry-delay"> <code class="option"> --connect-retry-delay </code> </a> </p> <a class="indexterm" name="idm46045103461440"> </a> <a class="indexterm" name="idm46045103459936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-retry-delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-retry-delay=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 5 </code> </td> </tr> </tbody> </table> </div> <p> Number of seconds to wait between attempts to contact management server. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_connect-string"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_connect-string"> <code class="option"> --connect-string </code> </a> </p> <a class="indexterm" name="idm46045103440880"> </a> <a class="indexterm" name="idm46045103439392"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-string"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-string=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Same as <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_core-file"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_core-file"> <code class="option"> --core-file </code> </a> </p> <a class="indexterm" name="idm46045103423968"> </a> <a class="indexterm" name="idm46045103422480"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for core-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --core-file </code> </td> </tr> </tbody> </table> </div> <p> Write core file on error; used in debugging. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_database"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_database"> <code class="option"> --database </code> </a> , <code class="option"> -d </code> </p> <a class="indexterm" name="idm46045103412352"> </a> <a class="indexterm" name="idm46045103410864"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for database"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --database=name </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> TEST_DB </code> </td> </tr> </tbody> </table> </div> <p> Name of the database in which the table resides. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_defaults-extra-file"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_defaults-extra-file"> <code class="option"> --defaults-extra-file </code> </a> </p> <a class="indexterm" name="idm46045103396512"> </a> <a class="indexterm" name="idm46045103395008"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-extra-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-extra-file=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read given file after global files are read. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_defaults-file"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_defaults-file"> <code class="option"> --defaults-file </code> </a> </p> <a class="indexterm" name="idm46045103380720"> </a> <a class="indexterm" name="idm46045103379232"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-file=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read default options from given file only. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_defaults-group-suffix"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_defaults-group-suffix"> <code class="option"> --defaults-group-suffix </code> </a> </p> <a class="indexterm" name="idm46045103364880"> </a> <a class="indexterm" name="idm46045103363376"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-group-suffix"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-group-suffix=string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Also read groups with concat(group, suffix). </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_help"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_help"> <code class="option"> --help </code> </a> </p> <a class="indexterm" name="idm46045103349088"> </a> <a class="indexterm" name="idm46045103347600"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for help"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --help </code> </td> </tr> </tbody> </table> </div> <p> Display help text and exit. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_login-path"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_login-path"> <code class="option"> --login-path </code> </a> </p> <a class="indexterm" name="idm46045103337792"> </a> <a class="indexterm" name="idm46045103336304"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for login-path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --login-path=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read given path from login file. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_no-login-paths"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_no-login-paths"> <code class="option"> --no-login-paths </code> </a> </p> <a class="indexterm" name="idm46045103322096"> </a> <a class="indexterm" name="idm46045103320608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-login-paths"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-login-paths </code> </td> </tr> </tbody> </table> </div> <p> Skips reading options from the login path file. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-connectstring"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> </p> <a class="indexterm" name="idm46045103311008"> </a> <a class="indexterm" name="idm46045103309552"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-connectstring"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-connectstring=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Set connection string for connecting to <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> . Syntax: <code class="literal"> [nodeid= <em class="replaceable"> <code> id </code> </em> ;][host=] <em class="replaceable"> <code> hostname </code> </em> [: <em class="replaceable"> <code> port </code> </em> ] </code> . Overrides entries in <code class="literal"> NDB_CONNECTSTRING </code> and <code class="filename"> my.cnf </code> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-mgm-tls"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-mgm-tls"> <code class="option"> --ndb-mgm-tls </code> </a> </p> <a class="indexterm" name="idm46045103290576"> </a> <a class="indexterm" name="idm46045103289088"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-mgm-tls"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-mgm-tls=level </code> </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> relaxed </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> relaxed </code> </p> <p class="valid-value"> <code class="literal"> strict </code> </p> </td> </tr> </tbody> </table> </div> <p> Sets the level of TLS support required to connect to the management server; one of <code class="literal"> relaxed </code> or <code class="literal"> strict </code> . <code class="literal"> relaxed </code> (the default) means that a TLS connection is attempted, but success is not required; <code class="literal"> strict </code> means that TLS is required to connect. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-mgmd-host"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-mgmd-host"> <code class="option"> --ndb-mgmd-host </code> </a> </p> <a class="indexterm" name="idm46045103268080"> </a> <a class="indexterm" name="idm46045103266592"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-mgmd-host"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-mgmd-host=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Same as <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-nodeid"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-nodeid"> <code class="option"> --ndb-nodeid </code> </a> </p> <a class="indexterm" name="idm46045103251280"> </a> <a class="indexterm" name="idm46045103249792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-nodeid"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-nodeid=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Set node ID for this node, overriding any ID set by <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-optimized-node-selection"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-optimized-node-selection"> <code class="option"> --ndb-optimized-node-selection </code> </a> </p> <a class="indexterm" name="idm46045103234480"> </a> <a class="indexterm" name="idm46045103232976"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-optimized-node-selection"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-optimized-node-selection </code> </td> </tr> </tbody> </table> </div> <p> Enable optimizations for selection of nodes for transactions. Enabled by default; use <code class="option"> --skip-ndb-optimized-node-selection </code> to disable. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-tls-search-path"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-tls-search-path"> <code class="option"> --ndb-tls-search-path </code> </a> </p> <a class="indexterm" name="idm46045103222544"> </a> <a class="indexterm" name="idm46045103221040"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-tls-search-path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-tls-search-path=list </code> </td> </tr> <tr> <th> Type </th> <td> Path name </td> </tr> <tr> <th> Default Value (Unix) </th> <td> <code class="literal"> $HOME/ndb-tls </code> </td> </tr> <tr> <th> Default Value (Windows) </th> <td> <code class="literal"> $HOMEDIR/ndb-tls </code> </td> </tr> </tbody> </table> </div> <p> Specify a list of directories to search for a CA file. On Unix platforms, the directory names are separated by colons ( <code class="literal"> : </code> ); on Windows systems, the semicolon character ( <code class="literal"> ; </code> ) is used as the separator. A directory reference may be relative or absolute; it may contain one or more environment variables, each denoted by a prefixed dollar sign ( <code class="literal"> $ </code> ), and expanded prior to use. </p> <p> Searching begins with the leftmost named directory and proceeds from left to right until a file is found. An empty string denotes an empty search path, which causes all searches to fail. A string consisting of a single dot ( <code class="literal"> . </code> ) indicates that the search path limited to the current working directory. </p> <p> If no search path is supplied, the compiled-in default value is used. This value depends on the platform used: On Windows, this is <code class="literal"> \ndb-tls </code> ; on other platforms (including Linux), it is <code class="literal"> $HOME/ndb-tls </code> . This can be overridden by compiling NDB Cluster using <a class="link" href="source-configuration-options.html#option_cmake_with_ndb_tls_search_path"> <code class="option"> -DWITH_NDB_TLS_SEARCH_PATH </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_no-defaults"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_no-defaults"> <code class="option"> --no-defaults </code> </a> </p> <a class="indexterm" name="idm46045103197280"> </a> <a class="indexterm" name="idm46045103195792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-defaults </code> </td> </tr> </tbody> </table> </div> <p> Do not read default options from any option file other than login file. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_print-defaults"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_print-defaults"> <code class="option"> --print-defaults </code> </a> </p> <a class="indexterm" name="idm46045103186032"> </a> <a class="indexterm" name="idm46045103184544"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for print-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --print-defaults </code> </td> </tr> </tbody> </table> </div> <p> Print program argument list and exit. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_usage"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_usage"> <code class="option"> --usage </code> </a> </p> <a class="indexterm" name="idm46045103174832"> </a> <a class="indexterm" name="idm46045103173344"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for usage"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --usage </code> </td> </tr> </tbody> </table> </div> <p> Display help text and exit; same as <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_help"> <code class="option"> --help </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_version"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_version"> <code class="option"> --version </code> </a> </p> <a class="indexterm" name="idm46045103162592"> </a> <a class="indexterm" name="idm46045103161104"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --version </code> </td> </tr> </tbody> </table> </div> <p> Display version information and exit. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/system-schema.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="system-schema"> </a> 7.3 The mysql System Schema </h2> </div> </div> </div> <p> The <code class="literal"> mysql </code> schema is the system schema. It contains tables that store information required by the MySQL server as it runs. A broad categorization is that the <code class="literal"> mysql </code> schema contains data dictionary tables that store database object metadata, and system tables used for other operational purposes. The following discussion further subdivides the set of system tables into smaller categories. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-data-dictionary-tables" title="Data Dictionary Tables"> Data Dictionary Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-grant-tables" title="Grant System Tables"> Grant System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-object-tables" title="Object Information System Tables"> Object Information System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-log-tables" title="Log System Tables"> Log System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-help-tables" title="Server-Side Help System Tables"> Server-Side Help System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-time-zone-tables" title="Time Zone System Tables"> Time Zone System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-replication-tables" title="Replication System Tables"> Replication System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-optimizer-tables" title="Optimizer System Tables"> Optimizer System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-miscellaneous-tables" title="Miscellaneous System Tables"> Miscellaneous System Tables </a> </p> </li> </ul> </div> <p> The remainder of this section enumerates the tables in each category, with cross references for additional information. Data dictionary tables and system tables use the <code class="literal"> InnoDB </code> storage engine unless otherwise indicated. </p> <p> <code class="literal"> mysql </code> system tables and data dictionary tables reside in a single <code class="literal"> InnoDB </code> tablespace file named <code class="filename"> mysql.ibd </code> in the MySQL data directory. Previously, these tables were created in individual tablespace files in the <code class="literal"> mysql </code> database directory. </p> <p> Data-at-rest encryption can be enabled for the <code class="literal"> mysql </code> system schema tablespace. For more information, see <a class="xref" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> Section 17.13, “InnoDB Data-at-Rest Encryption” </a> . </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-data-dictionary-tables"> </a> Data Dictionary Tables </h3> </div> </div> </div> <p> These tables comprise the data dictionary, which contains metadata about database objects. For additional information, see <a class="xref" href="data-dictionary.html" title="Chapter 16 MySQL Data Dictionary"> Chapter 16, <i> MySQL Data Dictionary </i> </a> . </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> catalogs </code> : Catalog information. </p> <a class="indexterm" name="idm46045259885920"> </a> <a class="indexterm" name="idm46045259884432"> </a> </li> <li class="listitem"> <p> <code class="literal"> character_sets </code> : Information about available character sets. </p> <a class="indexterm" name="idm46045259881408"> </a> <a class="indexterm" name="idm46045259879920"> </a> </li> <li class="listitem"> <p> <code class="literal"> check_constraints </code> : Information about <code class="literal"> CHECK </code> constraints defined on tables. See <a class="xref" href="create-table-check-constraints.html" title="15.1.20.6 CHECK Constraints"> Section 15.1.20.6, “CHECK Constraints” </a> . </p> <a class="indexterm" name="idm46045259875312"> </a> <a class="indexterm" name="idm46045259873824"> </a> </li> <li class="listitem"> <p> <code class="literal"> collations </code> : Information about collations for each character set. </p> <a class="indexterm" name="idm46045259870784"> </a> <a class="indexterm" name="idm46045259869296"> </a> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259867168"> </a> <a class="indexterm" name="idm46045259865680"> </a> <code class="literal"> column_statistics </code> : Histogram statistics for column values. See <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> column_type_elements </code> : Information about types used by columns. </p> <a class="indexterm" name="idm46045259861136"> </a> <a class="indexterm" name="idm46045259859632"> </a> </li> <li class="listitem"> <p> <code class="literal"> columns </code> : Information about columns in tables. </p> <a class="indexterm" name="idm46045259856592"> </a> <a class="indexterm" name="idm46045259855104"> </a> </li> <li class="listitem"> <p> <code class="literal"> dd_properties </code> : A table that identifies data dictionary properties, such as its version. The server uses this to determine whether the data dictionary must be upgraded to a newer version. </p> <a class="indexterm" name="idm46045259851920"> </a> <a class="indexterm" name="idm46045259850432"> </a> </li> <li class="listitem"> <p> <code class="literal"> events </code> : Information about Event Scheduler events. See <a class="xref" href="event-scheduler.html" title="27.4 Using the Event Scheduler"> Section 27.4, “Using the Event Scheduler” </a> . If the server is started with the <a class="link" href="server-options.html#option_mysqld_skip-grant-tables"> <code class="option"> --skip-grant-tables </code> </a> option, the event scheduler is disabled and events registered in the table do not run. See <a class="xref" href="events-configuration.html" title="27.4.2 Event Scheduler Configuration"> Section 27.4.2, “Event Scheduler Configuration” </a> . </p> <a class="indexterm" name="idm46045259844736"> </a> <a class="indexterm" name="idm46045259843248"> </a> </li> <li class="listitem"> <p> <code class="literal"> foreign_keys </code> , <code class="literal"> foreign_key_column_usage </code> : Information about foreign keys. </p> <a class="indexterm" name="idm46045259839488"> </a> <a class="indexterm" name="idm46045259838000"> </a> <a class="indexterm" name="idm46045259836512"> </a> <a class="indexterm" name="idm46045259835008"> </a> </li> <li class="listitem"> <p> <code class="literal"> index_column_usage </code> : Information about columns used by indexes. </p> <a class="indexterm" name="idm46045259831968"> </a> <a class="indexterm" name="idm46045259830464"> </a> </li> <li class="listitem"> <p> <code class="literal"> index_partitions </code> : Information about partitions used by indexes. </p> <a class="indexterm" name="idm46045259827424"> </a> <a class="indexterm" name="idm46045259825936"> </a> </li> <li class="listitem"> <p> <code class="literal"> index_stats </code> : Used to store dynamic index statistics generated when <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> is executed. </p> <a class="indexterm" name="idm46045259821648"> </a> <a class="indexterm" name="idm46045259820160"> </a> </li> <li class="listitem"> <p> <code class="literal"> indexes </code> : Information about table indexes. </p> <a class="indexterm" name="idm46045259817152"> </a> <a class="indexterm" name="idm46045259815664"> </a> </li> <li class="listitem"> <p> <code class="literal"> innodb_ddl_log </code> : Stores DDL logs for crash-safe DDL operations. </p> <a class="indexterm" name="idm46045259812640"> </a> <a class="indexterm" name="idm46045259811152"> </a> </li> <li class="listitem"> <p> <code class="literal"> parameter_type_elements </code> : Information about stored procedure and function parameters, and about return values for stored functions. </p> <a class="indexterm" name="idm46045259808048"> </a> <a class="indexterm" name="idm46045259806544"> </a> </li> <li class="listitem"> <p> <code class="literal"> parameters </code> : Information about stored procedures and functions. See <a class="xref" href="stored-routines.html" title="27.2 Using Stored Routines"> Section 27.2, “Using Stored Routines” </a> . </p> <a class="indexterm" name="idm46045259802640"> </a> <a class="indexterm" name="idm46045259801152"> </a> </li> <li class="listitem"> <p> <code class="literal"> resource_groups </code> : Information about resource groups. See <a class="xref" href="resource-groups.html" title="7.1.16 Resource Groups"> Section 7.1.16, “Resource Groups” </a> . </p> <a class="indexterm" name="idm46045259797472"> </a> <a class="indexterm" name="idm46045259795984"> </a> </li> <li class="listitem"> <p> <code class="literal"> routines </code> : Information about stored procedures and functions. See <a class="xref" href="stored-routines.html" title="27.2 Using Stored Routines"> Section 27.2, “Using Stored Routines” </a> . </p> <a class="indexterm" name="idm46045259792272"> </a> <a class="indexterm" name="idm46045259790784"> </a> </li> <li class="listitem"> <p> <code class="literal"> schemata </code> : Information about schemata. In MySQL, a schema is a database, so this table provides information about databases. </p> <a class="indexterm" name="idm46045259787680"> </a> <a class="indexterm" name="idm46045259786192"> </a> </li> <li class="listitem"> <p> <code class="literal"> st_spatial_reference_systems </code> : Information about available spatial reference systems for spatial data. </p> <a class="indexterm" name="idm46045259783120"> </a> <a class="indexterm" name="idm46045259781616"> </a> </li> <li class="listitem"> <p> <code class="literal"> table_partition_values </code> : Information about values used by table partitions. </p> <a class="indexterm" name="idm46045259778560"> </a> <a class="indexterm" name="idm46045259777056"> </a> </li> <li class="listitem"> <p> <code class="literal"> table_partitions </code> : Information about partitions used by tables. </p> <a class="indexterm" name="idm46045259774016"> </a> <a class="indexterm" name="idm46045259772528"> </a> </li> <li class="listitem"> <p> <code class="literal"> table_stats </code> : Information about dynamic table statistics generated when <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> is executed. </p> <a class="indexterm" name="idm46045259768224"> </a> <a class="indexterm" name="idm46045259766736"> </a> </li> <li class="listitem"> <p> <code class="literal"> tables </code> : Information about tables in databases. </p> <a class="indexterm" name="idm46045259763712"> </a> <a class="indexterm" name="idm46045259762224"> </a> </li> <li class="listitem"> <p> <code class="literal"> tablespace_files </code> : Information about files used by tablespaces. </p> <a class="indexterm" name="idm46045259759200"> </a> <a class="indexterm" name="idm46045259757712"> </a> </li> <li class="listitem"> <p> <code class="literal"> tablespaces </code> : Information about active tablespaces. </p> <a class="indexterm" name="idm46045259754688"> </a> <a class="indexterm" name="idm46045259753200"> </a> </li> <li class="listitem"> <p> <code class="literal"> triggers </code> : Information about triggers. </p> <a class="indexterm" name="idm46045259750192"> </a> <a class="indexterm" name="idm46045259748704"> </a> </li> <li class="listitem"> <p> <code class="literal"> view_routine_usage </code> : Information about dependencies between views and stored functions used by them. </p> <a class="indexterm" name="idm46045259745632"> </a> <a class="indexterm" name="idm46045259744128"> </a> </li> <li class="listitem"> <p> <code class="literal"> view_table_usage </code> : Used to track dependencies between views and their underlying tables. </p> <a class="indexterm" name="idm46045259741056"> </a> <a class="indexterm" name="idm46045259739568"> </a> </li> </ul> </div> <p> Data dictionary tables are invisible. They cannot be read with <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> , do not appear in the output of <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> , are not listed in the <code class="literal"> INFORMATION_SCHEMA.TABLES </code> table, and so forth. However, in most cases there are corresponding <code class="literal"> INFORMATION_SCHEMA </code> tables that can be queried. Conceptually, the <code class="literal"> INFORMATION_SCHEMA </code> provides a view through which MySQL exposes data dictionary metadata. For example, you cannot select from the <code class="literal"> mysql.schemata </code> table directly: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa17852283"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> mysql<span class="token punctuation">.</span>schemata<span class="token punctuation">;</span> <span class="token output">ERROR 3554 (HY000)<span class="token punctuation">:</span> Access to data dictionary table 'mysql.schemata' is rejected.</span></code></pre> </div> <p> Instead, select that information from the corresponding <code class="literal"> INFORMATION_SCHEMA </code> table: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa53997455"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>SCHEMATA\G <span class="token output"><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> 1. row <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> CATALOG_NAME<span class="token punctuation">:</span> def SCHEMA_NAME<span class="token punctuation">:</span> mysql DEFAULT_CHARACTER_SET_NAME<span class="token punctuation">:</span> utf8mb4 DEFAULT_COLLATION_NAME<span class="token punctuation">:</span> utf8mb4_0900_ai_ci SQL_PATH<span class="token punctuation">:</span> NULL DEFAULT_ENCRYPTION<span class="token punctuation">:</span> NO <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> 2. row <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> CATALOG_NAME<span class="token punctuation">:</span> def SCHEMA_NAME<span class="token punctuation">:</span> information_schema DEFAULT_CHARACTER_SET_NAME<span class="token punctuation">:</span> utf8mb3 DEFAULT_COLLATION_NAME<span class="token punctuation">:</span> utf8mb3_general_ci SQL_PATH<span class="token punctuation">:</span> NULL DEFAULT_ENCRYPTION<span class="token punctuation">:</span> NO <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> 3. row <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> CATALOG_NAME<span class="token punctuation">:</span> def SCHEMA_NAME<span class="token punctuation">:</span> performance_schema DEFAULT_CHARACTER_SET_NAME<span class="token punctuation">:</span> utf8mb4 DEFAULT_COLLATION_NAME<span class="token punctuation">:</span> utf8mb4_0900_ai_ci SQL_PATH<span class="token punctuation">:</span> NULL DEFAULT_ENCRYPTION<span class="token punctuation">:</span> NO ...</span></code></pre> </div> <p> There is no Information Schema table that corresponds exactly to <code class="literal"> mysql.indexes </code> , but <a class="link" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table"> <code class="literal"> INFORMATION_SCHEMA.STATISTICS </code> </a> contains much of the same information. </p> <p> As of yet, there are no <code class="literal"> INFORMATION_SCHEMA </code> tables that correspond exactly to <code class="literal"> mysql.foreign_keys </code> , <code class="literal"> mysql.foreign_key_column_usage </code> . The standard SQL way to obtain foreign key information is by using the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-referential-constraints-table.html" title="28.3.25 The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table"> <code class="literal"> REFERENTIAL_CONSTRAINTS </code> </a> and <a class="link" href="information-schema-key-column-usage-table.html" title="28.3.16 The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table"> <code class="literal"> KEY_COLUMN_USAGE </code> </a> tables; these tables are now implemented as views on the <code class="literal"> foreign_keys </code> , <code class="literal"> foreign_key_column_usage </code> , and other data dictionary tables. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-grant-tables"> </a> Grant System Tables </h3> </div> </div> </div> <p> These system tables contain grant information about user accounts and the privileges held by them. For additional information about the structure, contents, and purpose of the these tables, see <a class="xref" href="grant-tables.html" title="8.2.3 Grant Tables"> Section 8.2.3, “Grant Tables” </a> . </p> <p> The MySQL 8.4 grant tables are <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> (transactional) tables. Account-management statements are transactional and either succeed for all named users or roll back and have no effect if any error occurs. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> user </code> : User accounts, global privileges, and other nonprivilege columns. </p> <a class="indexterm" name="idm46045259710416"> </a> <a class="indexterm" name="idm46045259708928"> </a> <a class="indexterm" name="idm46045259707440"> </a> </li> <li class="listitem"> <p> <code class="literal"> global_grants </code> : Assignments of dynamic global privileges to users; see <a class="xref" href="privileges-provided.html#static-dynamic-privileges" title="Static Versus Dynamic Privileges"> Static Versus Dynamic Privileges </a> . </p> <a class="indexterm" name="idm46045259703472"> </a> <a class="indexterm" name="idm46045259701984"> </a> <a class="indexterm" name="idm46045259700496"> </a> </li> <li class="listitem"> <p> <code class="literal"> db </code> : Database-level privileges. </p> <a class="indexterm" name="idm46045259697536"> </a> <a class="indexterm" name="idm46045259696048"> </a> <a class="indexterm" name="idm46045259694560"> </a> </li> <li class="listitem"> <p> <code class="literal"> tables_priv </code> : Table-level privileges. </p> <a class="indexterm" name="idm46045259691568"> </a> <a class="indexterm" name="idm46045259690080"> </a> <a class="indexterm" name="idm46045259688592"> </a> </li> <li class="listitem"> <p> <code class="literal"> columns_priv </code> : Column-level privileges. </p> <a class="indexterm" name="idm46045259685600"> </a> <a class="indexterm" name="idm46045259684112"> </a> <a class="indexterm" name="idm46045259682624"> </a> </li> <li class="listitem"> <p> <code class="literal"> procs_priv </code> : Stored procedure and function privileges. </p> <a class="indexterm" name="idm46045259679600"> </a> <a class="indexterm" name="idm46045259678112"> </a> <a class="indexterm" name="idm46045259676624"> </a> </li> <li class="listitem"> <p> <code class="literal"> proxies_priv </code> : Proxy-user privileges. </p> <a class="indexterm" name="idm46045259673632"> </a> <a class="indexterm" name="idm46045259672144"> </a> <a class="indexterm" name="idm46045259670656"> </a> </li> <li class="listitem"> <p> <code class="literal"> default_roles </code> : This table lists default roles to be activated after a user connects and authenticates, or executes <a class="link" href="set-role.html" title="15.7.1.11 SET ROLE Statement"> <code class="literal"> SET ROLE DEFAULT </code> </a> . </p> <a class="indexterm" name="idm46045259666304"> </a> <a class="indexterm" name="idm46045259664816"> </a> <a class="indexterm" name="idm46045259663328"> </a> </li> <li class="listitem"> <p> <code class="literal"> role_edges </code> : This table lists edges for role subgraphs. </p> <p> A given <code class="literal"> user </code> table row might refer to a user account or a role. The server can distinguish whether a row represents a user account, a role, or both by consulting the <code class="literal"> role_edges </code> table for information about relations between authentication IDs. </p> <a class="indexterm" name="idm46045259658192"> </a> <a class="indexterm" name="idm46045259656704"> </a> <a class="indexterm" name="idm46045259655216"> </a> </li> <li class="listitem"> <p> <code class="literal"> password_history </code> : Information about password changes. </p> <a class="indexterm" name="idm46045259652192"> </a> <a class="indexterm" name="idm46045259650704"> </a> <a class="indexterm" name="idm46045259649216"> </a> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-object-tables"> </a> Object Information System Tables </h3> </div> </div> </div> <p> These system tables contain information about components, loadable functions, and server-side plugins: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> component </code> : The registry for server components installed using <a class="link" href="install-component.html" title="15.7.4.3 INSTALL COMPONENT Statement"> <code class="literal"> INSTALL COMPONENT </code> </a> . Any components listed in this table are installed by a loader service during the server startup sequence. See <a class="xref" href="component-loading.html" title="7.5.1 Installing and Uninstalling Components"> Section 7.5.1, “Installing and Uninstalling Components” </a> . </p> <a class="indexterm" name="idm46045259641664"> </a> <a class="indexterm" name="idm46045259640176"> </a> </li> <li class="listitem"> <p> <code class="literal"> func </code> : The registry for loadable functions installed using <a class="link" href="create-function-loadable.html" title="15.7.4.1 CREATE FUNCTION Statement for Loadable Functions"> <code class="literal"> CREATE FUNCTION </code> </a> . During the normal startup sequence, the server loads functions registered in this table. If the server is started with the <a class="link" href="server-options.html#option_mysqld_skip-grant-tables"> <code class="option"> --skip-grant-tables </code> </a> option, functions registered in the table are not loaded and are unavailable. See <a class="xref" href="function-loading.html" title="7.7.1 Installing and Uninstalling Loadable Functions"> Section 7.7.1, “Installing and Uninstalling Loadable Functions” </a> . </p> <a class="indexterm" name="idm46045259633776"> </a> <a class="indexterm" name="idm46045259632288"> </a> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Like the <code class="literal"> mysql.func </code> system table, the Performance Schema <a class="link" href="performance-schema-user-defined-functions-table.html" title="29.12.22.10 The user_defined_functions Table"> <code class="literal"> user_defined_functions </code> </a> table lists loadable functions installed using <a class="link" href="create-function-loadable.html" title="15.7.4.1 CREATE FUNCTION Statement for Loadable Functions"> <code class="literal"> CREATE FUNCTION </code> </a> . Unlike the <code class="literal"> mysql.func </code> table, the <a class="link" href="performance-schema-user-defined-functions-table.html" title="29.12.22.10 The user_defined_functions Table"> <code class="literal"> user_defined_functions </code> </a> table also lists functions installed automatically by server components or plugins. This difference makes <a class="link" href="performance-schema-user-defined-functions-table.html" title="29.12.22.10 The user_defined_functions Table"> <code class="literal"> user_defined_functions </code> </a> preferable to <code class="literal"> mysql.func </code> for checking which functions are installed. See <a class="xref" href="performance-schema-user-defined-functions-table.html" title="29.12.22.10 The user_defined_functions Table"> Section 29.12.22.10, “The user_defined_functions Table” </a> . </p> </div> </li> <li class="listitem"> <p> <code class="literal"> plugin </code> : The registry for server-side plugins installed using <a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> <code class="literal"> INSTALL PLUGIN </code> </a> . During the normal startup sequence, the server loads plugins registered in this table. If the server is started with the <a class="link" href="server-options.html#option_mysqld_skip-grant-tables"> <code class="option"> --skip-grant-tables </code> </a> option, plugins registered in the table are not loaded and are unavailable. See <a class="xref" href="plugin-loading.html" title="7.6.1 Installing and Uninstalling Plugins"> Section 7.6.1, “Installing and Uninstalling Plugins” </a> . </p> <a class="indexterm" name="idm46045259616640"> </a> <a class="indexterm" name="idm46045259615152"> </a> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-log-tables"> </a> Log System Tables </h3> </div> </div> </div> <p> The server uses these system tables for logging: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259610928"> </a> <a class="indexterm" name="idm46045259609440"> </a> <code class="literal"> general_log </code> : The general query log table. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259606432"> </a> <a class="indexterm" name="idm46045259604944"> </a> <code class="literal"> slow_log </code> : The slow query log table. </p> </li> </ul> </div> <p> Log tables use the <code class="literal"> CSV </code> storage engine. </p> <p> For more information, see <a class="xref" href="server-logs.html" title="7.4 MySQL Server Logs"> Section 7.4, “MySQL Server Logs” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-help-tables"> </a> Server-Side Help System Tables </h3> </div> </div> </div> <a class="indexterm" name="idm46045259598944"> </a> <a class="indexterm" name="idm46045259597456"> </a> <p> These system tables contain server-side help information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259594720"> </a> <a class="indexterm" name="idm46045259593232"> </a> <code class="literal"> help_category </code> : Information about help categories. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259590208"> </a> <a class="indexterm" name="idm46045259588720"> </a> <code class="literal"> help_keyword </code> : Keywords associated with help topics. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259585696"> </a> <a class="indexterm" name="idm46045259584208"> </a> <code class="literal"> help_relation </code> : Mappings between help keywords and topics. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259581184"> </a> <a class="indexterm" name="idm46045259579696"> </a> <code class="literal"> help_topic </code> : Help topic contents. </p> </li> </ul> </div> <p> For more information, see <a class="xref" href="server-side-help-support.html" title="7.1.17 Server-Side Help Support"> Section 7.1.17, “Server-Side Help Support” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-time-zone-tables"> </a> Time Zone System Tables </h3> </div> </div> </div> <a class="indexterm" name="idm46045259574624"> </a> <a class="indexterm" name="idm46045259573136"> </a> <p> These system tables contain time zone information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259570416"> </a> <a class="indexterm" name="idm46045259568928"> </a> <code class="literal"> time_zone </code> : Time zone IDs and whether they use leap seconds. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259565888"> </a> <a class="indexterm" name="idm46045259564432"> </a> <code class="literal"> time_zone_leap_second </code> : When leap seconds occur. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259561408"> </a> <a class="indexterm" name="idm46045259559920"> </a> <code class="literal"> time_zone_name </code> : Mappings between time zone IDs and names. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259556896"> </a> <a class="indexterm" name="idm46045259555392"> </a> <a class="indexterm" name="idm46045259553888"> </a> <a class="indexterm" name="idm46045259552384"> </a> <code class="literal"> time_zone_transition </code> , <code class="literal"> time_zone_transition_type </code> : Time zone descriptions. </p> </li> </ul> </div> <p> For more information, see <a class="xref" href="time-zone-support.html" title="7.1.15 MySQL Server Time Zone Support"> Section 7.1.15, “MySQL Server Time Zone Support” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-replication-tables"> </a> Replication System Tables </h3> </div> </div> </div> <p> The server uses these system tables to support replication: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259545376"> </a> <a class="indexterm" name="idm46045259543888"> </a> <code class="literal"> gtid_executed </code> : Table for storing GTID values. See <a class="xref" href="replication-gtids-concepts.html#replication-gtids-gtid-executed-table" title="mysql.gtid_executed Table"> mysql.gtid_executed Table </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259539936"> </a> <a class="indexterm" name="idm46045259538448"> </a> <code class="literal"> ndb_binlog_index </code> : Binary log information for NDB Cluster replication. This table is created only if the server is built with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> support. See <a class="xref" href="mysql-cluster-replication-schema.html" title="25.7.4 NDB Cluster Replication Schema and Tables"> Section 25.7.4, “NDB Cluster Replication Schema and Tables” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259532432"> </a> <a class="indexterm" name="idm46045259530944"> </a> <a class="indexterm" name="idm46045259529456"> </a> <a class="indexterm" name="idm46045259528000"> </a> <a class="indexterm" name="idm46045259526496"> </a> <a class="indexterm" name="idm46045259525008"> </a> <code class="literal"> slave_master_info </code> , <code class="literal"> slave_relay_log_info </code> , <code class="literal"> slave_worker_info </code> : Used to store replication information on replica servers. See <a class="xref" href="replica-logs.html" title="19.2.4 Relay Log and Replication Metadata Repositories"> Section 19.2.4, “Relay Log and Replication Metadata Repositories” </a> . </p> </li> </ul> </div> <p> All of the tables just listed use the <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> storage engine. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-optimizer-tables"> </a> Optimizer System Tables </h3> </div> </div> </div> <p> These system tables are for use by the optimizer: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259516000"> </a> <a class="indexterm" name="idm46045259514544"> </a> <a class="indexterm" name="idm46045259513040"> </a> <a class="indexterm" name="idm46045259511536"> </a> <code class="literal"> innodb_index_stats </code> , <code class="literal"> innodb_table_stats </code> : Used for <code class="literal"> InnoDB </code> persistent optimizer statistics. See <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259506400"> </a> <a class="indexterm" name="idm46045259504912"> </a> <a class="indexterm" name="idm46045259503424"> </a> <a class="indexterm" name="idm46045259501936"> </a> <code class="literal"> server_cost </code> , <code class="literal"> engine_cost </code> : The optimizer cost model uses tables that contain cost estimate information about operations that occur during query execution. <code class="literal"> server_cost </code> contains optimizer cost estimates for general server operations. <code class="literal"> engine_cost </code> contains estimates for operations specific to particular storage engines. See <a class="xref" href="cost-model.html" title="10.9.5 The Optimizer Cost Model"> Section 10.9.5, “The Optimizer Cost Model” </a> . </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-miscellaneous-tables"> </a> Miscellaneous System Tables </h3> </div> </div> </div> <p> Other system tables do not fit the preceding categories: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259493504"> </a> <a class="indexterm" name="idm46045259492016"> </a> <a class="indexterm" name="idm46045259490528"> </a> <a class="indexterm" name="idm46045259489040"> </a> <code class="literal"> audit_log_filter </code> , <code class="literal"> audit_log_user </code> : If MySQL Enterprise Audit is installed, these tables provide persistent storage of audit log filter definitions and user accounts. See <a class="xref" href="audit-log-reference.html#audit-log-tables" title="Audit Log Tables"> Audit Log Tables </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259484400"> </a> <a class="indexterm" name="idm46045259482896"> </a> <a class="indexterm" name="idm46045259481392"> </a> <a class="indexterm" name="idm46045259479904"> </a> <a class="indexterm" name="idm46045259478416"> </a> <a class="indexterm" name="idm46045259476912"> </a> <a class="indexterm" name="idm46045259475408"> </a> <a class="indexterm" name="idm46045259473920"> </a> <a class="indexterm" name="idm46045259472432"> </a> <a class="indexterm" name="idm46045259470928"> </a> <code class="literal"> firewall_group_allowlist </code> , <code class="literal"> firewall_groups </code> , <code class="literal"> firewall_memebership </code> , <code class="literal"> firewall_users </code> , <code class="literal"> firewall_whitelist </code> : If MySQL Enterprise Firewall is installed, these tables provide persistent storage for information used by the firewall. See <a class="xref" href="firewall.html" title="8.4.7 MySQL Enterprise Firewall"> Section 8.4.7, “MySQL Enterprise Firewall” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259464224"> </a> <a class="indexterm" name="idm46045259462736"> </a> <code class="literal"> servers </code> : Used by the <code class="literal"> FEDERATED </code> storage engine. See <a class="xref" href="federated-create-server.html" title="18.8.2.2 Creating a FEDERATED Table Using CREATE SERVER"> Section 18.8.2.2, “Creating a FEDERATED Table Using CREATE SERVER” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259458160"> </a> <a class="indexterm" name="idm46045259456656"> </a> <code class="literal"> innodb_dynamic_metadata </code> : Used by the <code class="literal"> InnoDB </code> storage engine to store fast-changing table metadata such as auto-increment counter values and index tree corruption flags. Replaces the data dictionary buffer table that resided in the <code class="literal"> InnoDB </code> system tablespace. </p> </li> </ul> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/populating-spatial-columns.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="populating-spatial-columns"> </a> 13.4.7 Populating Spatial Columns </h3> </div> </div> </div> <p> After you have created spatial columns, you can populate them with spatial data. </p> <p> Values should be stored in internal geometry format, but you can convert them to that format from either Well-Known Text (WKT) or Well-Known Binary (WKB) format. The following examples demonstrate how to insert geometry values into a table by converting WKT values to internal geometry format: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Perform the conversion directly in the <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa40367248"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token string">'POINT(1 1)'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'POINT(1 1)'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> Perform the conversion prior to the <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa60588488"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token string">'POINT(1 1)'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> </ul> </div> <p> The following examples insert more complex geometries into the table: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa3958881"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'LINESTRING(0 0,1 1,2 2)'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'GEOMETRYCOLLECTION(POINT(1 1),LINESTRING(0 0,1 1,2 2,3 3,4 4))'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> The preceding examples use <a class="link" href="gis-wkt-functions.html#function_st-geomfromtext"> <code class="literal"> ST_GeomFromText() </code> </a> to create geometry values. You can also use type-specific functions: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa86706678"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'POINT(1 1)'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_PointFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'LINESTRING(0 0,1 1,2 2)'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_LineStringFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_PolygonFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'GEOMETRYCOLLECTION(POINT(1 1),LINESTRING(0 0,1 1,2 2,3 3,4 4))'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomCollFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> A client application program that wants to use WKB representations of geometry values is responsible for sending correctly formed WKB in queries to the server. There are several ways to satisfy this requirement. For example: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Inserting a <code class="literal"> POINT(1 1) </code> value with hex literal syntax: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa15629375"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromWKB</span><span class="token punctuation">(</span>X<span class="token string">'0101000000000000000000F03F000000000000F03F'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> An ODBC application can send a WKB representation, binding it to a placeholder using an argument of <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> type: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa24970565"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromWKB</span><span class="token punctuation">(</span>?<span class="token punctuation">)</span><span class="token punctuation">)</span></code></pre> </div> <p> Other programming interfaces may support a similar placeholder mechanism. </p> </li> <li class="listitem"> <p> In a C program, you can escape a binary value using <a class="ulink" href="/doc/c-api/8.4/en/mysql-real-escape-string-quote.html" target="_top"> <code class="literal"> mysql_real_escape_string_quote() </code> </a> and include the result in a query string that is sent to the server. See <a class="ulink" href="/doc/c-api/8.4/en/mysql-real-escape-string-quote.html" target="_top"> mysql_real_escape_string_quote() </a> . </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/sys-statement-performance-analyzer.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-statement-performance-analyzer"> </a> 30.4.4.25 The statement_performance_analyzer() Procedure </h4> </div> </div> </div> <a class="indexterm" name="idm46045061216480"> </a> <a class="indexterm" name="idm46045061214960"> </a> <p> Creates a report of the statements running on the server. The views are calculated based on the overall and/or delta activity. </p> <p> This procedure disables binary logging during its execution by manipulating the session value of the <a class="link" href="replication-options-binary-log.html#sysvar_sql_log_bin"> <code class="literal"> sql_log_bin </code> </a> system variable. That is a restricted operation, so the procedure requires privileges sufficient to set restricted session variables. See <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> . </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-statement-performance-analyzer-parameters"> </a> Parameters </h5> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> in_action ENUM('snapshot', 'overall', 'delta', 'create_tmp', 'create_table', 'save', 'cleanup') </code> : The action to take. These values are permitted: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> snapshot </code> : Store a snapshot. The default is to make a snapshot of the current content of the Performance Schema <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> table. By setting <code class="literal"> in_table </code> , this can be overwritten to copy the content of the specified table. The snapshot is stored in the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema <code class="literal"> tmp_digests </code> temporary table. </p> </li> <li class="listitem"> <p> <code class="literal"> overall </code> : Generate an analysis based on the content of the table specified by <code class="literal"> in_table </code> . For the overall analysis, <code class="literal"> in_table </code> can be <a class="link" href="date-and-time-functions.html#function_now"> <code class="literal"> NOW() </code> </a> to use a fresh snapshot. This overwrites an existing snapshot. Use <code class="literal"> NULL </code> for <code class="literal"> in_table </code> to use the existing snapshot. If <code class="literal"> in_table </code> is <code class="literal"> NULL </code> and no snapshot exists, a new snapshot is created. The <code class="literal"> in_views </code> parameter and the <code class="literal"> statement_performance_analyzer.limit </code> configuration option affect the operation of this procedure. </p> </li> <li class="listitem"> <p> <code class="literal"> delta </code> : Generate a delta analysis. The delta is calculated between the reference table specified by <code class="literal"> in_table </code> and the snapshot, which must exist. This action uses the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema <code class="literal"> tmp_digests_delta </code> temporary table. The <code class="literal"> in_views </code> parameter and the <code class="literal"> statement_performance_analyzer.limit </code> configuration option affect the operation of this procedure. </p> </li> <li class="listitem"> <p> <code class="literal"> create_table </code> : Create a regular table suitable for storing the snapshot for later use (for example, for calculating deltas). </p> </li> <li class="listitem"> <p> <code class="literal"> create_tmp </code> : Create a temporary table suitable for storing the snapshot for later use (for example, for calculating deltas). </p> </li> <li class="listitem"> <p> <code class="literal"> save </code> : Save the snapshot in the table specified by <code class="literal"> in_table </code> . The table must exist and have the correct structure. If no snapshot exists, a new snapshot is created. </p> </li> <li class="listitem"> <p> <code class="literal"> cleanup </code> : Remove the temporary tables used for the snapshot and delta. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> in_table VARCHAR(129) </code> : The table parameter used for some of the actions specified by the <code class="literal"> in_action </code> parameter. Use the format <em class="replaceable"> <code> db_name.tbl_name </code> </em> or <em class="replaceable"> <code> tbl_name </code> </em> without using any backtick ( <code class="literal"> ` </code> ) identifier-quoting characters. Periods ( <code class="literal"> . </code> ) are not supported in database and table names. </p> <p> The meaning of the <code class="literal"> in_table </code> value for each <code class="literal"> in_action </code> value is detailed in the individual <code class="literal"> in_action </code> value descriptions. </p> </li> <li class="listitem"> <p> <code class="literal"> in_views SET ('with_runtimes_in_95th_percentile', 'analysis', 'with_errors_or_warnings', 'with_full_table_scans', 'with_sorting', 'with_temp_tables', 'custom') </code> : Which views to include. This parameter is a <code class="literal"> SET </code> value, so it can contain multiple view names, separated by commas. The default is to include all views except <code class="literal"> custom </code> . The following values are permitted: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> with_runtimes_in_95th_percentile </code> : Use the <a class="link" href="sys-statements-with-runtimes-in-95th-percentile.html" title="30.4.3.38 The statements_with_runtimes_in_95th_percentile and x$statements_with_runtimes_in_95th_percentile Views"> <code class="literal"> statements_with_runtimes_in_95th_percentile </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> analysis </code> : Use the <a class="link" href="sys-statement-analysis.html" title="30.4.3.35 The statement_analysis and x$statement_analysis Views"> <code class="literal"> statement_analysis </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> with_errors_or_warnings </code> : Use the <a class="link" href="sys-statements-with-errors-or-warnings.html" title="30.4.3.36 The statements_with_errors_or_warnings and x$statements_with_errors_or_warnings Views"> <code class="literal"> statements_with_errors_or_warnings </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> with_full_table_scans </code> : Use the <a class="link" href="sys-statements-with-full-table-scans.html" title="30.4.3.37 The statements_with_full_table_scans and x$statements_with_full_table_scans Views"> <code class="literal"> statements_with_full_table_scans </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> with_sorting </code> : Use the <a class="link" href="sys-statements-with-sorting.html" title="30.4.3.39 The statements_with_sorting and x$statements_with_sorting Views"> <code class="literal"> statements_with_sorting </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> with_temp_tables </code> : Use the <a class="link" href="sys-statements-with-temp-tables.html" title="30.4.3.40 The statements_with_temp_tables and x$statements_with_temp_tables Views"> <code class="literal"> statements_with_temp_tables </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> custom </code> : Use a custom view. This view must be specified using the <code class="literal"> statement_performance_analyzer.view </code> configuration option to name a query or an existing view. </p> </li> </ul> </div> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-statement-performance-analyzer-configuration-options"> </a> Configuration Options </h5> </div> </div> </div> <p> <a class="link" href="sys-statement-performance-analyzer.html" title="30.4.4.25 The statement_performance_analyzer() Procedure"> <code class="literal"> statement_performance_analyzer() </code> </a> operation can be modified using the following configuration options or their corresponding user-defined variables (see <a class="xref" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> Section 30.4.2.1, “The sys_config Table” </a> ): </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> debug </code> , <code class="literal"> @sys.debug </code> </p> <p> If this option is <code class="literal"> ON </code> , produce debugging output. The default is <code class="literal"> OFF </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> statement_performance_analyzer.limit </code> , <code class="literal"> @sys.statement_performance_analyzer.limit </code> </p> <p> The maximum number of rows to return for views that have no built-in limit. The default is 100. </p> </li> <li class="listitem"> <p> <code class="literal"> statement_performance_analyzer.view </code> , <code class="literal"> @sys.statement_performance_analyzer.view </code> </p> <p> The custom query or view to be used. If the option value contains a space, it is interpreted as a query. Otherwise, it must be the name of an existing view that queries the Performance Schema <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> table. There cannot be any <code class="literal"> LIMIT </code> clause in the query or view definition if the <code class="literal"> statement_performance_analyzer.limit </code> configuration option is greater than 0. If specifying a view, use the same format as for the <code class="literal"> in_table </code> parameter. The default is <code class="literal"> NULL </code> (no custom view defined). </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-statement-performance-analyzer-example"> </a> Example </h5> </div> </div> </div> <p> To create a report with the queries in the 95th percentile since the last truncation of <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> and with a one-minute delta period: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Create a temporary table to store the initial snapshot. </p> </li> <li class="listitem"> <p> Create the initial snapshot. </p> </li> <li class="listitem"> <p> Save the initial snapshot in the temporary table. </p> </li> <li class="listitem"> <p> Wait one minute. </p> </li> <li class="listitem"> <p> Create a new snapshot. </p> </li> <li class="listitem"> <p> Perform analysis based on the new snapshot. </p> </li> <li class="listitem"> <p> Perform analysis based on the delta between the initial and new snapshots. </p> </li> </ol> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa93939511"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'create_tmp'</span><span class="token punctuation">,</span> <span class="token string">'mydb.tmp_digests_ini'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.08 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'snapshot'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.02 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'save'</span><span class="token punctuation">,</span> <span class="token string">'mydb.tmp_digests_ini'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">DO</span> <span class="token function">SLEEP</span><span class="token punctuation">(</span><span class="token number">60</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (1 min 0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'snapshot'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.02 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'overall'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token string">'with_runtimes_in_95th_percentile'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Next Output <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Queries with Runtime in 95th Percentile <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">1 row in set (0.05 sec)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'delta'</span><span class="token punctuation">,</span> <span class="token string">'mydb.tmp_digests_ini'</span><span class="token punctuation">,</span> <span class="token string">'with_runtimes_in_95th_percentile'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Next Output <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Queries with Runtime in 95th Percentile <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">1 row in set (0.03 sec)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> Create an overall report of the 95th percentile queries and the top 10 queries with full table scans: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa54901623"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'snapshot'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.01 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@sys.statement_performance_analyzer.limit</span> <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'overall'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token string">'with_runtimes_in_95th_percentile,with_full_table_scans'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Next Output <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Queries with Runtime in 95th Percentile <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">1 row in set (0.01 sec)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Next Output <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Top 10 Queries with Full Table Scan <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">1 row in set (0.09 sec)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> Use a custom view showing the top 10 queries sorted by total execution time, refreshing the view every minute using the <span class="command"> <strong> watch </strong> </span> command in Linux: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78470561"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token operator">OR</span> <span class="token keyword">REPLACE</span> <span class="token keyword">VIEW</span> mydb<span class="token punctuation">.</span>my_statements <span class="token keyword">AS</span> <span class="token keyword">SELECT</span> sys<span class="token punctuation">.</span>format_statement<span class="token punctuation">(</span>DIGEST_TEXT<span class="token punctuation">)</span> <span class="token keyword">AS</span> <span class="token keyword">query</span><span class="token punctuation">,</span> <span class="token keyword">SCHEMA_NAME</span> <span class="token keyword">AS</span> db<span class="token punctuation">,</span> COUNT_STAR <span class="token keyword">AS</span> exec_count<span class="token punctuation">,</span> sys<span class="token punctuation">.</span>format_time<span class="token punctuation">(</span>SUM_TIMER_WAIT<span class="token punctuation">)</span> <span class="token keyword">AS</span> total_latency<span class="token punctuation">,</span> sys<span class="token punctuation">.</span>format_time<span class="token punctuation">(</span>AVG_TIMER_WAIT<span class="token punctuation">)</span> <span class="token keyword">AS</span> avg_latency<span class="token punctuation">,</span> <span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token function">IFNULL</span><span class="token punctuation">(</span>SUM_ROWS_SENT <span class="token operator">/</span> <span class="token function">NULLIF</span><span class="token punctuation">(</span>COUNT_STAR<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> rows_sent_avg<span class="token punctuation">,</span> <span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token function">IFNULL</span><span class="token punctuation">(</span>SUM_ROWS_EXAMINED <span class="token operator">/</span> <span class="token function">NULLIF</span><span class="token punctuation">(</span>COUNT_STAR<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> rows_examined_avg<span class="token punctuation">,</span> <span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token function">IFNULL</span><span class="token punctuation">(</span>SUM_ROWS_AFFECTED <span class="token operator">/</span> <span class="token function">NULLIF</span><span class="token punctuation">(</span>COUNT_STAR<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> rows_affected_avg<span class="token punctuation">,</span> DIGEST <span class="token keyword">AS</span> digest <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>events_statements_summary_by_digest <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> SUM_TIMER_WAIT <span class="token keyword">DESC</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.10 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'create_table'</span><span class="token punctuation">,</span> <span class="token string">'mydb.digests_prev'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.10 sec)</span> $<span class="token operator">></span> watch <span class="token operator">-</span>n <span class="token number">60</span> <span class="token string">"mysql sys --table -e \" > SET @sys.statement_performance_analyzer.view = 'mydb.my_statements'; > SET @sys.statement_performance_analyzer.limit = 10; > CALL statement_performance_analyzer('snapshot', NULL, NULL); > CALL statement_performance_analyzer('delta', 'mydb.digests_prev', 'custom'); > CALL statement_performance_analyzer('save', 'mydb.digests_prev', NULL); > \""</span> <span class="token keyword">Every</span> <span class="token number">60</span><span class="token punctuation">.</span>0s: mysql sys <span class="token comment" spellcheck="true">--table -e " ... Mon Dec 22 10:58:51 2014</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Next Output <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Top 10 Queries Using Custom View <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token 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punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> query <span class="token punctuation">\|</span> db <span class="token punctuation">\|</span> exec_count <span class="token punctuation">\|</span> total_latency <span class="token punctuation">\|</span> avg_latency <span class="token punctuation">\|</span> rows_sent_avg <span class="token punctuation">\|</span> rows_examined_avg <span class="token punctuation">\|</span> rows_affected_avg <span class="token punctuation">\|</span> digest <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token 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punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/information-schema-view-routine-usage-table.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-view-routine-usage-table"> </a> 28.3.48 The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045077951552"> </a> <p> The <a class="link" href="information-schema-view-routine-usage-table.html" title="28.3.48 The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table"> <code class="literal"> VIEW_ROUTINE_USAGE </code> </a> table provides access to information about stored functions used in view definitions. The table does not list information about built-in (native) functions or loadable functions used in the definitions. </p> <p> You can see information only for views for which you have some privilege, and only for functions for which you have some privilege. </p> <p> The <a class="link" href="information-schema-view-routine-usage-table.html" title="28.3.48 The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table"> <code class="literal"> VIEW_ROUTINE_USAGE </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> TABLE_CATALOG </code> </p> <p> The name of the catalog to which the view belongs. This value is always <code class="literal"> def </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_SCHEMA </code> </p> <p> The name of the schema (database) to which the view belongs. </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_NAME </code> </p> <p> The name of the view. </p> </li> <li class="listitem"> <p> <code class="literal"> SPECIFIC_CATALOG </code> </p> <p> The name of the catalog to which the function used in the view definition belongs. This value is always <code class="literal"> def </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> SPECIFIC_SCHEMA </code> </p> <p> The name of the schema (database) to which the function used in the view definition belongs. </p> </li> <li class="listitem"> <p> <code class="literal"> SPECIFIC_NAME </code> </p> <p> The name of the function used in the view definition. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/network-namespace-support.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="network-namespace-support"> </a> 7.1.14 Network Namespace Support </h3> </div> </div> </div> <a class="indexterm" name="idm46045260630096"> </a> <a class="indexterm" name="idm46045260629024"> </a> <p> A network namespace is a logical copy of the network stack from the host system. Network namespaces are useful for setting up containers or virtual environments. Each namespace has its own IP addresses, network interfaces, routing tables, and so forth. The default or global namespace is the one in which the host system physical interfaces exist. </p> <p> Namespace-specific address spaces can lead to problems when MySQL connections cross namespaces. For example, the network address space for a MySQL instance running in a container or virtual network may differ from the address space of the host machine. This can produce phenomena such as a client connection from an address in one namespace appearing to the MySQL server to be coming from a different address, even for client and server running on the same machine. Suppose that both processes run on a host with IP address <code class="literal"> 203.0.113.10 </code> but use different namespaces. A connection may produce a result like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa99221306"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">$<span class="token operator">></span> mysql <span class="token operator">--</span>user<span class="token operator">=</span>admin <span class="token operator">--</span>host<span class="token operator">=</span>203<span class="token punctuation">.</span>0<span class="token punctuation">.</span>113<span class="token punctuation">.</span>10 <span class="token operator">--</span>protocol<span class="token operator">=</span>tcp mysql<span class="token operator">></span> SELECT USER<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token operator">+</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">+</span> <span class="token operator">\|</span> USER<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">\|</span> <span class="token operator">+</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">+</span> <span class="token operator">\|</span> admin@198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>2 <span class="token operator">\|</span> <span class="token operator">+</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">+</span></code></pre> </div> <p> In this case, the expected <a class="link" href="information-functions.html#function_user"> <code class="literal"> USER() </code> </a> value is <code class="literal"> [email protected] </code> . Such behavior can make it difficult to assign account permissions properly if the address from which an connection originates is not what it appears. </p> <p> To address this issue, MySQL enables specifying the network namespace to use for TCP/IP connections, so that both endpoints of connections use an agreed-upon common address space. </p> <p> MySQL supports network namespaces on platforms that implement them. Support within MySQL applies to: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The MySQL server, <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . </p> </li> <li class="listitem"> <p> X Plugin. </p> </li> <li class="listitem"> <p> The <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client and the <span class="command"> <strong> mysqlxtest </strong> </span> test suite client. (Other clients are not supported. They must be invoked from within the network namespace of the server to which they are to connect.) </p> </li> <li class="listitem"> <p> Regular replication. </p> </li> <li class="listitem"> <p> Group Replication, only when using the MySQL communication stack to establish group communication connections. </p> </li> </ul> </div> <p> The following sections describe how to use network namespaces in MySQL: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="network-namespace-support.html#network-namespaces-host-prerequisites" title="Host System Prerequisites"> Host System Prerequisites </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="network-namespace-support.html#network-namespaces-mysql-configuration" title="MySQL Configuration"> MySQL Configuration </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="network-namespace-support.html#network-namespaces-monitoring" title="Network Namespace Monitoring"> Network Namespace Monitoring </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="network-namespaces-host-prerequisites"> </a> Host System Prerequisites </h4> </div> </div> </div> <p> Prior to using network namespace support in MySQL, these host system prerequisites must be satisfied: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The host operating system must support network namespaces. (For example, Linux.) </p> </li> <li class="listitem"> <p> Any network namespace to be used by MySQL must first be created on the host system. </p> </li> <li class="listitem"> <p> Host name resolution must be configured by the system administrator to support network namespaces. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> A known limitation is that, within MySQL, host name resolution does not work for names specified in network namespace-specific host files. For example, if the address for a host name in the <code class="literal"> red </code> namespace is specified in the <code class="filename"> /etc/netns/red/hosts </code> file, binding to the name fails on both the server and client sides. The workaround is to use the IP address rather than the host name. </p> </div> </li> <li class="listitem"> <p> The system administrator must enable the <code class="literal"> CAP_SYS_ADMIN </code> operating system privilege for the MySQL binaries that support network namespaces ( <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> , <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> , <span class="command"> <strong> mysqlxtest </strong> </span> ). </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> Enabling <code class="literal"> CAP_SYS_ADMIN </code> is a security sensitive operation because it enables a process to perform other privileged actions in addition to setting namespaces. For a description of its effects, see <a class="ulink" href="https://man7.org/linux/man-pages/man7/capabilities.7.html" target="_blank"> https://man7.org/linux/man-pages/man7/capabilities.7.html </a> . </p> <p> Because <code class="literal"> CAP_SYS_ADMIN </code> must be enabled explicitly by the system administrator, MySQL binaries by default do not have network namespace support enabled. The system administrator should evaluate the security implications of running MySQL processes with <code class="literal"> CAP_SYS_ADMIN </code> before enabling it. </p> </div> </li> </ul> </div> <p> The instructions in the following example set up network namespaces named <code class="literal"> red </code> and <code class="literal"> blue </code> . The names you choose may differ, as may the network addresses and interfaces on your host system. </p> <p> Invoke the commands shown here either as the <code class="literal"> root </code> operating system user or by prefixing each command with <span class="command"> <strong> sudo </strong> </span> . For example, to invoke the <span class="command"> <strong> ip </strong> </span> or <span class="command"> <strong> setcap </strong> </span> command if you are not <code class="literal"> root </code> , use <span class="command"> <strong> sudo ip </strong> </span> or <span class="command"> <strong> sudo setcap </strong> </span> . </p> <p> To configure network namespaces, use the <span class="command"> <strong> ip </strong> </span> command. For some operations, the <span class="command"> <strong> ip </strong> </span> command must execute within a particular namespace (which must already exist). In such cases, begin the command like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa69926930"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip netns exec <em class="replaceable">namespace_name</em></code></pre> </div> <p> For example, this command executes within the <code class="literal"> red </code> namespace to bring up the loopback interface: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa92041966"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip netns exec red ip link set lo up</code></pre> </div> <p> To add namespaces named <code class="literal"> red </code> and <code class="literal"> blue </code> , each with its own virtual Ethernet device used as a link between namespaces and its own loopback interface: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa75626178"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip netns add red ip link add veth-red type veth peer name vpeer-red ip link set vpeer-red netns red ip addr add 192<span class="token punctuation">.</span>0<span class="token punctuation">.</span>2<span class="token punctuation">.</span>1/24 dev veth-red ip link set veth-red up ip netns exec red ip addr add 192<span class="token punctuation">.</span>0<span class="token punctuation">.</span>2<span class="token punctuation">.</span>2/24 dev vpeer-red ip netns exec red ip link set vpeer-red up ip netns exec red ip link set lo up ip netns add blue ip link add veth-blue type veth peer name vpeer-blue ip link set vpeer-blue netns blue ip addr add 198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>1/24 dev veth-blue ip link set veth-blue up ip netns exec blue ip addr add 198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>2/24 dev vpeer-blue ip netns exec blue ip link set vpeer-blue up ip netns exec blue ip link set lo up <span class="token comment" spellcheck="true"># if you want to enable inter-subnet routing...</span> sysctl net<span class="token punctuation">.</span>ipv4<span class="token punctuation">.</span>ip_forward<span class="token attr-value"><span class="token punctuation">=</span>1</span> ip netns exec red ip route add default via 192<span class="token punctuation">.</span>0<span class="token punctuation">.</span>2<span class="token punctuation">.</span>1 ip netns exec blue ip route add default via 198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>1</code></pre> </div> <p> A diagram of the links between namespaces looks like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa67975921"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">red global blue 192.0.2.2 <=> 192.0.2.1 (vpeer-red) (veth-red) 198.51.100.1 <=> 198.51.100.2 (veth-blue) (vpeer-blue)</code></pre> </div> <p> To check which namespaces and links exist: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa29643824"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip netns list ip link list</code></pre> </div> <p> To see the routing tables for the global and named namespaces: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa88437224"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip route show ip netns exec red ip route show ip netns exec blue ip route show</code></pre> </div> <p> To remove the <code class="literal"> red </code> and <code class="literal"> blue </code> links and namespaces: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa84054608"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip link del veth-red ip link del veth-blue ip netns del red ip netns del blue sysctl net<span class="token punctuation">.</span>ipv4<span class="token punctuation">.</span>ip_forward<span class="token attr-value"><span class="token punctuation">=</span>0</span></code></pre> </div> <p> So that the MySQL binaries that include network namespace support can actually use namespaces, you must grant them the <code class="literal"> CAP_SYS_ADMIN </code> capability. The following <span class="command"> <strong> setcap </strong> </span> commands assume that you have changed location to the directory containing your MySQL binaries (adjust the pathname for your system as necessary): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa92882441"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cd /usr/local/mysql/bin</code></pre> </div> <p> To grant <code class="literal"> CAP_SYS_ADMIN </code> capability to the appropriate binaries: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa47369150"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">setcap cap_sys_admin+ep <span class="token punctuation">.</span>/mysqld setcap cap_sys_admin+ep <span class="token punctuation">.</span>/mysql setcap cap_sys_admin+ep <span class="token punctuation">.</span>/mysqlxtest</code></pre> </div> <p> To check <code class="literal"> CAP_SYS_ADMIN </code> capability: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa30592321"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">getcap</span> <span class="token punctuation">.</span>/mysqld <span class="token punctuation">.</span>/mysql <span class="token punctuation">.</span>/mysqlxtest <span class="token punctuation">.</span>/mysqld = cap_sys_admin+ep <span class="token punctuation">.</span>/mysql = cap_sys_admin+ep <span class="token punctuation">.</span>/mysqlxtest = cap_sys_admin+ep</code></pre> </div> <p> To remove <code class="literal"> CAP_SYS_ADMIN </code> capability: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa91835259"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">setcap <span class="token property">-r</span> <span class="token punctuation">.</span>/mysqld setcap <span class="token property">-r</span> <span class="token punctuation">.</span>/mysql setcap <span class="token property">-r</span> <span class="token punctuation">.</span>/mysqlxtest</code></pre> </div> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> If you reinstall binaries to which you have previously applied <span class="command"> <strong> setcap </strong> </span> , you must use <span class="command"> <strong> setcap </strong> </span> again. For example, if you perform an in-place MySQL upgrade, failure to grant the <code class="literal"> CAP_SYS_ADMIN </code> capability again results in namespace-related failures. The server fails with this error for attempts to bind to an address with a named namespace: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa2792879"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[ERROR] [MY-013408] [Server] setns() failed with error 'Operation not permitted'</code></pre> </div> <p> A client invoked with the <a class="link" href="mysql-command-options.html#option_mysql_network-namespace"> <code class="option"> --network-namespace </code> </a> option fails like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa85496059"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ERROR: Network namespace error: Operation not permitted</code></pre> </div> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="network-namespaces-mysql-configuration"> </a> MySQL Configuration </h4> </div> </div> </div> <p> Assuming that the preceding host system prerequisites have been satisfied, MySQL enables configuring the server-side namespace for the listening (inbound) side of connections and the client-side namespace for the outbound side of connections. </p> <p> On the server side, the <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> , <a class="link" href="server-system-variables.html#sysvar_admin_address"> <code class="literal"> admin_address </code> </a> , and <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_bind_address"> <code class="literal"> mysqlx_bind_address </code> </a> system variables have extended syntax for specifying the network namespace to use for a given IP address or host name on which to listen for incoming connections. To specify a namespace for an address, add a slash and the namespace name. For example, a server <code class="filename"> my.cnf </code> file might contain these lines: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa85576297"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 127.0.1.1,192.0.2.2/red,198.51.100.2/blue</span> <span class="token constant">admin_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 102.0.2.2/red</span> <span class="token constant">mysqlx_bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 102.0.2.2/red</span></code></pre> </div> <p> These rules apply: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A network namespace can be specified for an IP address or a host name. </p> </li> <li class="listitem"> <p> A network namespace cannot be specified for a wildcard IP address. </p> </li> <li class="listitem"> <p> For a given address, the network namespace is optional. If given, it must be specified as a <code class="literal"> / <em class="replaceable"> <code> ns </code> </em> </code> suffix immediately following the address. </p> </li> <li class="listitem"> <p> An address with no <code class="literal"> / <em class="replaceable"> <code> ns </code> </em> </code> suffix uses the host system global namespace. The global namespace is therefore the default. </p> </li> <li class="listitem"> <p> An address with a <code class="literal"> / <em class="replaceable"> <code> ns </code> </em> </code> suffix uses the namespace named <em class="replaceable"> <code> ns </code> </em> . </p> </li> <li class="listitem"> <p> The host system must support network namespaces and each named namespace must previously have been set up. Naming a nonexistent namespace produces an error. </p> </li> <li class="listitem"> <p> <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> and <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_bind_address"> <code class="literal"> mysqlx_bind_address </code> </a> accept a list of multiple comma-separated addresses, the variable value can specify addresses in the global namespace, in named namespaces, or a mix. </p> </li> </ul> </div> <p> If an error occurs during server startup for attempts to use a namespace, the server does not start. If errors occur for X Plugin during plugin initialization such that it is unable to bind to any address, the plugin fails its initialization sequence and the server does not load it. </p> <p> On the client side, a network namespace can be specified in these contexts: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client and the <span class="command"> <strong> mysqlxtest </strong> </span> test suite client, use the <a class="link" href="mysql-command-options.html#option_mysql_network-namespace"> <code class="option"> --network-namespace </code> </a> option. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa42222649"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token constant">--host</span><span class="token attr-value"><span class="token punctuation">=</span>192.0.2.2</span> <span class="token constant">--network-namespace</span><span class="token attr-value"><span class="token punctuation">=</span>red</span></code></pre> </div> <p> If the <a class="link" href="mysql-command-options.html#option_mysql_network-namespace"> <code class="option"> --network-namespace </code> </a> option is omitted, the connection uses the default (global) namespace. </p> </li> <li class="listitem"> <p> For replication connections from replica servers to source servers, use the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement and specify the <code class="literal"> NETWORK_NAMESPACE </code> option. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa69766761"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CHANGE</span> <span class="token keyword">REPLICATION</span> <span class="token keyword">SOURCE</span> <span class="token keyword">TO</span> <span class="token keyword">SOURCE_HOST</span> <span class="token operator">=</span> <span class="token string">'192.0.2.2'</span><span class="token punctuation">,</span> <span class="token keyword">NETWORK_NAMESPACE</span> <span class="token operator">=</span> <span class="token string">'red'</span><span class="token punctuation">;</span></code></pre> </div> <p> If the <code class="literal"> NETWORK_NAMESPACE </code> option is omitted, replication connections use the default (global) namespace. </p> </li> </ul> </div> <p> The following example sets up a MySQL server that listens for connections in the global, <code class="literal"> red </code> , and <code class="literal"> blue </code> namespaces, and shows how to configure accounts that connect from the <code class="literal"> red </code> and <code class="literal"> blue </code> namespaces. It is assumed that the <code class="literal"> red </code> and <code class="literal"> blue </code> namespaces have already been created as shown in <a class="xref" href="network-namespace-support.html#network-namespaces-host-prerequisites" title="Host System Prerequisites"> Host System Prerequisites </a> . </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Configure the server to listen on addresses in multiple namespaces. Put these lines in the server <code class="filename"> my.cnf </code> file and start the server: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa25984069"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 127.0.1.1,192.0.2.2/red,198.51.100.2/blue</span></code></pre> </div> <p> The value tells the server to listen on the loopback address <code class="literal"> 127.0.0.1 </code> in the global namespace, the address <code class="literal"> 192.0.2.2 </code> in the <code class="literal"> red </code> namespace, and the address <code class="literal"> 198.51.100.2 </code> in the <code class="literal"> blue </code> namespace. </p> </li> <li class="listitem"> <p> Connect to the server in the global namespace and create accounts that have permission to connect from an address in the address space of each named namespace: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa67139881"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> root <span class="token property">-h</span> 127<span class="token punctuation">.</span>0<span class="token punctuation">.</span>0<span class="token punctuation">.</span>1 <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> <em class="replaceable">root_password</em> <span class="token prompt">mysql></span><span class="token command"> CREATE</span> USER <span class="token atrule">'red_user'</span>@<span class="token atrule">'192.0.2.2'</span> IDENTIFIED BY <span class="token atrule">'<em class="replaceable">red_user_password</em>'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span><span class="token command"> CREATE</span> USER <span class="token atrule">'blue_user'</span>@<span class="token atrule">'198.51.100.2'</span> IDENTIFIED BY <span class="token atrule">'<em class="replaceable">blue_user_password</em>'</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> Verify that you can connect to the server in each named namespace: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa63667850"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> red_user <span class="token property">-h</span> 192<span class="token punctuation">.</span>0<span class="token punctuation">.</span>2<span class="token punctuation">.</span>2 <span class="token constant">--network-namespace</span><span class="token attr-value"><span class="token punctuation">=</span>red</span> <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> <em class="replaceable">red_user_password</em> <span class="token prompt">mysql></span><span class="token command"> SELECT</span> USER<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> USER() <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> [email protected] <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa92628822"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> blue_user <span class="token property">-h</span> 198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>2 <span class="token constant">--network-namespace</span><span class="token attr-value"><span class="token punctuation">=</span>blue</span> <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> <em class="replaceable">blue_user_password</em> <span class="token prompt">mysql></span><span class="token command"> SELECT</span> USER<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> USER() <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> [email protected] <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> You might see different results from <a class="link" href="information-functions.html#function_user"> <code class="literal"> USER() </code> </a> , which can return a value that includes a host name rather than an IP address if your DNS is configured to be able to resolve the address to the corresponding host name and the server is not run with the <a class="link" href="server-system-variables.html#sysvar_skip_name_resolve"> <code class="literal"> skip_name_resolve </code> </a> system variable enabled. </p> </div> <p> You might also try invoking <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> without the <a class="link" href="mysql-command-options.html#option_mysql_network-namespace"> <code class="option"> --network-namespace </code> </a> option to see whether the connection attempt succeeds, and, if so, how the <a class="link" href="information-functions.html#function_user"> <code class="literal"> USER() </code> </a> value is affected. </p> </li> </ol> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="network-namespaces-monitoring"> </a> Network Namespace Monitoring </h4> </div> </div> </div> <p> For replication monitoring purposes, these information sources have a column that displays the applicable network namespace for connections: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The Performance Schema <code class="literal"> replication_connection_configuration </code> table. See <a class="xref" href="performance-schema-replication-connection-configuration-table.html" title="29.12.11.11 The replication_connection_configuration Table"> Section 29.12.11.11, “The replication_connection_configuration Table” </a> . </p> </li> <li class="listitem"> <p> The replica server connection metadata repository. See <a class="xref" href="replica-logs-status.html" title="19.2.4.2 Replication Metadata Repositories"> Section 19.2.4.2, “Replication Metadata Repositories” </a> . </p> </li> <li class="listitem"> <p> The <a class="link" href="show-replica-status.html" title="15.7.7.35 SHOW REPLICA STATUS Statement"> <code class="literal"> SHOW REPLICA STATUS </code> </a> statement. </p> </li> </ul> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/replication-privilege-checks.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="replication-privilege-checks"> </a> 19.3.3 Replication Privilege Checks </h3> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="replication-privilege-checks-account.html"> 19.3.3.1 Privileges For The Replication PRIVILEGE_CHECKS_USER Account </a> </span> </dt> <dt> <span class="section"> <a href="replication-privilege-checks-gr.html"> 19.3.3.2 Privilege Checks For Group Replication Channels </a> </span> </dt> <dt> <span class="section"> <a href="replication-privilege-checks-recover.html"> 19.3.3.3 Recovering From Failed Replication Privilege Checks </a> </span> </dt> </dl> </div> <p> By default, MySQL replication (including Group Replication) does not carry out privilege checks when transactions that were already accepted by another server are applied on a replica or group member. You can create a user account with the appropriate privileges to apply the transactions that are normally replicated on a channel, and specify this as the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account for the replication applier, using a <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement. MySQL then checks each transaction against the user account's privileges to verify that you have authorized the operation for that channel. The account can also be safely used by an administrator to apply or reapply transactions from <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> output, for example to recover from a replication error on the channel. </p> <p> The use of a <code class="literal"> PRIVILEGE_CHECKS_USER </code> account helps secure a replication channel against the unauthorized or accidental use of privileged or unwanted operations. The <code class="literal"> PRIVILEGE_CHECKS_USER </code> account provides an additional layer of security in situations such as these: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> You are replicating between a server instance on your organization's network, and a server instance on another network, such as an instance supplied by a cloud service provider. </p> </li> <li class="listitem"> <p> You want to have multiple on-premise or off-site deployments administered as separate units, without giving one administrator account privileges on all the deployments. </p> </li> <li class="listitem"> <p> You want to have an administrator account that enables an administrator to perform only operations that are directly relevant to the replication channel and the databases it replicates, rather than having wide privileges on the server instance. </p> </li> </ul> </div> <p> You can increase the security of a replication channel where privilege checks are applied by adding one or both of these options to the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement when you specify the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account for the channel: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The <code class="literal"> REQUIRE_ROW_FORMAT </code> option makes the replication channel accept only row-based replication events. When <code class="literal"> REQUIRE_ROW_FORMAT </code> is set, you must use row-based binary logging ( <a class="link" href="replication-options-binary-log.html#sysvar_binlog_format"> <code class="literal"> binlog_format=ROW </code> </a> ) on the source server. With statement-based binary logging, some administrator-level privileges might be required for the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account to execute transactions successfully. </p> </li> <li class="listitem"> <p> The <code class="literal"> REQUIRE_TABLE_PRIMARY_KEY_CHECK </code> option makes the replication channel use its own policy for primary key checks. Setting <code class="literal"> ON </code> means that primary keys are always required, and setting <code class="literal"> OFF </code> means that primary keys are never required. The default setting, <code class="literal"> STREAM </code> , sets the session value of the <a class="link" href="server-system-variables.html#sysvar_sql_require_primary_key"> <code class="literal"> sql_require_primary_key </code> </a> system variable using the value that is replicated from the source for each transaction. When <code class="literal"> PRIVILEGE_CHECKS_USER </code> is set, setting <code class="literal"> REQUIRE_TABLE_PRIMARY_KEY_CHECK </code> to either <code class="literal"> ON </code> or <code class="literal"> OFF </code> means that the user account does not need session administration level privileges to set restricted session variables, which are required to change the value of <a class="link" href="server-system-variables.html#sysvar_sql_require_primary_key"> <code class="literal"> sql_require_primary_key </code> </a> . It also normalizes the behavior across replication channels for different sources. </p> </li> </ul> </div> <p> You grant the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege to enable a user account to appear as the <code class="literal"> PRIVILEGE_CHECKS_USER </code> for a replication applier thread, and to execute the internal-use <a class="link" href="binlog.html" title="15.7.8.1 BINLOG Statement"> <code class="literal"> BINLOG </code> </a> statements used by mysqlbinlog. The user name and host name for the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account must follow the syntax described in <a class="xref" href="account-names.html" title="8.2.4 Specifying Account Names"> Section 8.2.4, “Specifying Account Names” </a> , and the user must not be an anonymous user (with a blank user name) or the <code class="literal"> CURRENT_USER </code> . To create a new account, use <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> . To grant this account the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege, use the <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> statement. For example, to create a user account <code class="literal"> priv_repl </code> , which can be used manually by an administrator from any host in the <code class="literal"> example.com </code> domain, and requires an encrypted connection, issue the following statements: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa21760136"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> sql_log_bin <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'priv_repl'</span>@<span class="token string">'%.example.com'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">password</em>'</span> <span class="token keyword">REQUIRE</span> <span class="token keyword">SSL</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> REPLICATION_APPLIER <span class="token keyword">ON</span> <span class="token operator"></span><span class="token punctuation">.</span><span class="token operator"></span> <span class="token keyword">TO</span> <span class="token string">'priv_repl'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> sql_log_bin <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span></code></pre> </div> <p> The <code class="literal"> SET sql_log_bin </code> statements are used so that the account management statements are not added to the binary log and sent to the replication channels (see <a class="xref" href="set-sql-log-bin.html" title="15.4.1.3 SET sql_log_bin Statement"> Section 15.4.1.3, “SET sql_log_bin Statement” </a> ). </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> The <code class="literal"> caching_sha2_password </code> authentication plugin is the default for new users (for details, see <a class="xref" href="caching-sha2-pluggable-authentication.html" title="8.4.1.2 Caching SHA-2 Pluggable Authentication"> Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication” </a> ). To connect to a server using a user account that authenticates with this plugin, you must either set up an encrypted connection as described in <a class="xref" href="replication-encrypted-connections.html" title="19.3.1 Setting Up Replication to Use Encrypted Connections"> Section 19.3.1, “Setting Up Replication to Use Encrypted Connections” </a> , or enable the unencrypted connection to support password exchange using an RSA key pair. </p> </div> <p> After setting up the user account, use the <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> statement to grant additional privileges to enable the user account to make the database changes that you expect the applier thread to carry out, such as updating specific tables held on the server. These same privileges enable an administrator to use the account if they need to execute any of those transactions manually on the replication channel. If an unexpected operation is attempted for which you did not grant the appropriate privileges, the operation is disallowed and the replication applier thread stops with an error. <a class="xref" href="replication-privilege-checks-account.html" title="19.3.3.1 Privileges For The Replication PRIVILEGE_CHECKS_USER Account"> Section 19.3.3.1, “Privileges For The Replication PRIVILEGE_CHECKS_USER Account” </a> explains what additional privileges the account needs. For example, to grant the <code class="literal"> priv_repl </code> user account the <a class="link" href="privileges-provided.html#priv_insert"> <code class="literal"> INSERT </code> </a> privilege to add rows to the <code class="literal"> cust </code> table in <code class="literal"> db1 </code> , issue the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa20609017"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> <span class="token keyword">INSERT</span> <span class="token keyword">ON</span> db1<span class="token punctuation">.</span>cust <span class="token keyword">TO</span> <span class="token string">'priv_repl'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">;</span></code></pre> </div> <p> You assign the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account for a replication channel using a <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement. If replication is running, issue <a class="link" href="stop-replica.html" title="15.4.2.5 STOP REPLICA Statement"> <code class="literal"> STOP REPLICA </code> </a> before the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement, and <a class="link" href="start-replica.html" title="15.4.2.4 START REPLICA Statement"> <code class="literal"> START REPLICA </code> </a> after it. The use of row-based binary logging is strongly recommended when <code class="literal"> PRIVILEGE_CHECKS_USER </code> is set; you can use the statement to set <code class="literal"> REQUIRE_ROW_FORMAT </code> to enforce this. </p> <p> When you restart the replication channel, checks on dynamic privileges are applied from that point on. However, static global privileges are not active in the applier's context until you reload the grant tables, because these privileges are not changed for a connected client. To activate static privileges, perform a flush-privileges operation. This can be done by issuing a <a class="link" href="flush.html#flush-privileges"> <code class="literal"> FLUSH PRIVILEGES </code> </a> statement or by executing a <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin flush-privileges </strong> </span> </a> or <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin reload </strong> </span> </a> command. </p> <p> For example, to start privilege checks on the channel <code class="literal"> channel_1 </code> on a running replica, issue the following statements: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa47531897"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">STOP</span> <span class="token keyword">REPLICA</span> <span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'channel_1'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CHANGE</span> <span class="token keyword">REPLICATION</span> <span class="token keyword">SOURCE</span> <span class="token keyword">TO</span> <span class="token operator">></span> <span class="token keyword">PRIVILEGE_CHECKS_USER</span> <span class="token operator">=</span> <span class="token string">'priv_repl'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">,</span> <span class="token operator">></span> <span class="token keyword">REQUIRE_ROW_FORMAT</span> <span class="token operator">=</span> <span class="token number">1</span> <span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'channel_1'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">FLUSH</span> <span class="token keyword">PRIVILEGES</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">START</span> <span class="token keyword">REPLICA</span> <span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'channel_1'</span><span class="token punctuation">;</span></code></pre> </div> <p> If you do not specify a channel and no other channels exist, the statement is applied to the default channel. The user name and host name for the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account for a channel are shown in the Performance Schema <a class="link" href="performance-schema-replication-applier-configuration-table.html" title="29.12.11.2 The replication_applier_configuration Table"> <code class="literal"> replication_applier_configuration </code> </a> table, where they are properly escaped so they can be copied directly into SQL statements to execute individual transactions. </p> <p> If you are using the <code class="literal"> Rewriter </code> plugin, you should grant the <code class="literal"> PRIVILEGE_CHECKS_USER </code> user account the <a class="link" href="privileges-provided.html#priv_skip-query-rewrite"> <code class="literal"> SKIP_QUERY_REWRITE </code> </a> privilege. This prevents statements issued by this user from being rewritten. See <a class="xref" href="rewriter-query-rewrite-plugin.html" title="7.6.4 The Rewriter Query Rewrite Plugin"> Section 7.6.4, “The Rewriter Query Rewrite Plugin” </a> , for more information. </p> <p> When <code class="literal"> REQUIRE_ROW_FORMAT </code> is set for a replication channel, the replication applier does not create or drop temporary tables, and so does not set the <a class="link" href="server-system-variables.html#sysvar_pseudo_thread_id"> <code class="literal"> pseudo_thread_id </code> </a> session system variable. It does not execute <code class="literal"> LOAD DATA INFILE </code> instructions, and so does not attempt file operations to access or delete the temporary files associated with data loads (logged as a <code class="literal"> Format_description_log_event </code> ). It does not execute <code class="literal"> INTVAR </code> , <code class="literal"> RAND </code> , and <code class="literal"> USER_VAR </code> events, which are used to reproduce the client's connection state for statement-based replication. (An exception is <code class="literal"> USER_VAR </code> events that are associated with DDL queries, which are executed.) It does not execute any statements that are logged within DML transactions. If the replication applier detects any of these types of event while attempting to queue or apply a transaction, the event is not applied, and replication stops with an error. </p> <p> You can set <code class="literal"> REQUIRE_ROW_FORMAT </code> for a replication channel whether or not you set a <code class="literal"> PRIVILEGE_CHECKS_USER </code> account. The restrictions implemented when you set this option increase the security of the replication channel even without privilege checks. You can also specify the <code class="option"> --require-row-format </code> option when you use <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> , to enforce row-based replication events in <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> output. </p> <p> <b> Security Context. </b> By default, when a replication applier thread is started with a user account specified as the <code class="literal"> PRIVILEGE_CHECKS_USER </code> , the security context is created using default roles, or with all roles if <a class="link" href="server-system-variables.html#sysvar_activate_all_roles_on_login"> <code class="literal"> activate_all_roles_on_login </code> </a> is set to <code class="literal"> ON </code> . </p> <p> You can use roles to supply a general privilege set to accounts that are used as <code class="literal"> PRIVILEGE_CHECKS_USER </code> accounts, as in the following example. Here, instead of granting the <a class="link" href="privileges-provided.html#priv_insert"> <code class="literal"> INSERT </code> </a> privilege for the <code class="literal"> db1.cust </code> table directly to a user account as in the earlier example, this privilege is granted to the role <code class="literal"> priv_repl_role </code> along with the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege. The role is then used to grant the privilege set to two user accounts, both of which can now be used as <code class="literal"> PRIVILEGE_CHECKS_USER </code> accounts: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa94585178"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> sql_log_bin <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'priv_repa'</span>@<span class="token string">'%.example.com'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">password</em>'</span> <span class="token keyword">REQUIRE</span> <span class="token keyword">SSL</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'priv_repb'</span>@<span class="token string">'%.example.com'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">password</em>'</span> <span class="token keyword">REQUIRE</span> <span class="token keyword">SSL</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">ROLE</span> <span class="token string">'priv_repl_role'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> REPLICATION_APPLIER <span class="token keyword">TO</span> <span class="token string">'priv_repl_role'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> <span class="token keyword">INSERT</span> <span class="token keyword">ON</span> db1<span class="token punctuation">.</span>cust <span class="token keyword">TO</span> <span class="token string">'priv_repl_role'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> <span class="token string">'priv_repl_role'</span> <span class="token keyword">TO</span> <span class="token string">'priv_repa'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">,</span> <span class="token string">'priv_repb'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token keyword">DEFAULT</span> <span class="token keyword">ROLE</span> <span class="token string">'priv_repl_role'</span> <span class="token keyword">TO</span> <span class="token string">'priv_repa'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">,</span> <span class="token string">'priv_repb'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> sql_log_bin <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span></code></pre> </div> <p> Be aware that when the replication applier thread creates the security context, it checks the privileges for the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account, but does not carry out password validation, and does not carry out checks relating to account management, such as checking whether the account is locked. The security context that is created remains unchanged for the lifetime of the replication applier thread. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replication.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="mysql-cluster-replication"> </a> 25.7 NDB Cluster Replication </h2> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="mysql-cluster-replication-abbreviations.html"> 25.7.1 NDB Cluster Replication: Abbreviations and Symbols </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-general.html"> 25.7.2 General Requirements for NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-issues.html"> 25.7.3 Known Issues in NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-schema.html"> 25.7.4 NDB Cluster Replication Schema and Tables </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-preparation.html"> 25.7.5 Preparing the NDB Cluster for Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-starting.html"> 25.7.6 Starting NDB Cluster Replication (Single Replication Channel) </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-two-channels.html"> 25.7.7 Using Two Replication Channels for NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-failover.html"> 25.7.8 Implementing Failover with NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-backups.html"> 25.7.9 NDB Cluster Backups With NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-multi-source.html"> 25.7.10 NDB Cluster Replication: Bidirectional and Circular Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-mta.html"> 25.7.11 NDB Cluster Replication Using the Multithreaded Applier </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-conflict-resolution.html"> 25.7.12 NDB Cluster Replication Conflict Resolution </a> </span> </dt> </dl> </div> <a class="indexterm" name="idm46045086859680"> </a> <a class="indexterm" name="idm46045086857776"> </a> <a class="indexterm" name="idm46045086855872"> </a> <a class="indexterm" name="idm46045086854800"> </a> <a class="indexterm" name="idm46045086853344"> </a> <p> NDB Cluster supports <span class="firstterm"> asynchronous replication </span> , more usually referred to simply as <span class="quote"> “ <span class="quote"> replication </span> ” </span> . This section explains how to set up and manage a configuration in which one group of computers operating as an NDB Cluster replicates to a second computer or group of computers. We assume some familiarity on the part of the reader with standard MySQL replication as discussed elsewhere in this Manual. (See <a class="xref" href="replication.html" title="Chapter 19 Replication"> Chapter 19, <i> Replication </i> </a> ). </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> NDB Cluster does not support replication using GTIDs; semisynchronous replication and group replication are also not supported by the <code class="literal"> NDB </code> storage engine. </p> </div> <p> Normal (non-clustered) replication involves a source server and a replica server, the source being so named because operations and data to be replicated originate with it, and the replica being the recipient of these. In NDB Cluster, replication is conceptually very similar but can be more complex in practice, as it may be extended to cover a number of different configurations including replicating between two complete clusters. Although an NDB Cluster itself depends on the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine for clustering functionality, it is not necessary to use <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> as the storage engine for the replica's copies of the replicated tables (see <a class="xref" href="mysql-cluster-replication-issues.html#mysql-cluster-replication-ndb-to-non-ndb" title="Replication from NDB to other storage engines"> Replication from NDB to other storage engines </a> ). However, for maximum availability, it is possible (and preferable) to replicate from one NDB Cluster to another, and it is this scenario that we discuss, as shown in the following figure: </p> <div class="figure"> <a name="fig-mysql-cluster-cluster-replication"> </a> <p class="title"> <b> Figure 25.10 NDB Cluster-to-Cluster Replication Layout </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Much of the content is described in the surrounding text. It visualizes how a MySQL source is replicated. The replica differs in that it shows an I/O (receiver) thread pointing to a relay binary log which points to an SQL (applier) thread. In addition, while the binary log points to and from the NDBCLUSTER engine on the source server, on the replica it points directly to an SQL node (MySQL server)." src="images/cluster-replication-overview.png" style="width: 100%; max-width: 716px;"/> </div> </div> </div> <br class="figure-break"/> <p> In this scenario, the replication process is one in which successive states of a source cluster are logged and saved to a replica cluster. This process is accomplished by a special thread known as the NDB binary log injector thread, which runs on each MySQL server and produces a binary log ( <code class="literal"> binlog </code> ). This thread ensures that all changes in the cluster producing the binary log—and not just those changes that are effected through the MySQL Server—are inserted into the binary log with the correct serialization order. We refer to the MySQL source and replica servers as replication servers or replication nodes, and the data flow or line of communication between them as a <span class="firstterm"> replication channel </span> . </p> <p> For information about performing point-in-time recovery with NDB Cluster and NDB Cluster Replication, see <a class="xref" href="mysql-cluster-replication-pitr.html" title="25.7.9.2 Point-In-Time Recovery Using NDB Cluster Replication"> Section 25.7.9.2, “Point-In-Time Recovery Using NDB Cluster Replication” </a> . </p> <a class="indexterm" name="idm46045086831712"> </a> <a class="indexterm" name="idm46045086830256"> </a> <p> <b> NDB API replica status variables. </b> NDB API counters can provide enhanced monitoring capabilities on replica clusters. These counters are implemented as NDB statistics <code class="literal"> _replica </code> status variables, as seen in the output of <a class="link" href="show-status.html" title="15.7.7.37 SHOW STATUS Statement"> <code class="literal"> SHOW STATUS </code> </a> , or in the results of queries against the Performance Schema <a class="link" href="performance-schema-status-variable-tables.html" title="29.12.15 Performance Schema Status Variable Tables"> <code class="literal"> session_status </code> </a> or <a class="link" href="performance-schema-status-variable-tables.html" title="29.12.15 Performance Schema Status Variable Tables"> <code class="literal"> global_status </code> </a> table in a <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client session connected to a MySQL Server that is acting as a replica in NDB Cluster Replication. By comparing the values of these status variables before and after the execution of statements affecting replicated <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables, you can observe the corresponding actions taken on the NDB API level by the replica, which can be useful when monitoring or troubleshooting NDB Cluster Replication. <a class="xref" href="mysql-cluster-ndb-api-statistics.html" title="25.6.16 NDB API Statistics Counters and Variables"> Section 25.6.16, “NDB API Statistics Counters and Variables” </a> , provides additional information. </p> <p> <b> Replication from NDB to non-NDB tables. </b> It is possible to replicate <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables from an NDB Cluster acting as the replication source to tables using other MySQL storage engines such as <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> or <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> on a replica <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . This is subject to a number of conditions; see <a class="xref" href="mysql-cluster-replication-issues.html#mysql-cluster-replication-ndb-to-non-ndb" title="Replication from NDB to other storage engines"> Replication from NDB to other storage engines </a> , and <a class="xref" href="mysql-cluster-replication-issues.html#mysql-cluster-replication-ndb-to-nontransactional" title="Replication from NDB to a nontransactional storage engine"> Replication from NDB to a nontransactional storage engine </a> , for more information. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/group-replication-performance-xcom-cache-reduce.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="group-replication-performance-xcom-cache-reduce"> </a> 20.7.6.2 Reducing the cache size </h4> </div> </div> </div> <p> The minimum setting for the XCom message cache size in MySQL 8.4 is 128 MB, which enables deployment on a host that has a restricted amount of available memory. Having a very low <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_message_cache_size"> <code class="literal"> group_replication_message_cache_size </code> </a> setting is not recommended if the host is on an unstable network, because a smaller message cache makes it harder for group members to reconnect after a transient loss of connectivity. </p> <p> If a reconnecting member cannot retrieve all the messages it needs from the XCom message cache, the member must leave the group and rejoin it, in order to retrieve the missing transactions from another member's binary log using distributed recovery. A member that has left a group makes three auto-rejoin attempts by default, so the process of rejoining the group can still take place without operator intervention. However, rejoining using distributed recovery is a significantly longer and more complex process than retrieving messages from an XCom message cache, so the member takes longer to become available and the performance of the group can be impacted. On a stable network, which minimizes the frequency and duration of transient losses of connectivity for members, the frequency of this occurrence should also be minimized, so the group might be able to tolerate a smaller XCom message cache size without a significant impact on its performance. </p> <p> If you are considering reducing the cache size limit, you can query the Performance Schema table <a class="link" href="performance-schema-memory-summary-tables.html" title="29.12.20.10 Memory Summary Tables"> <code class="literal"> memory_summary_global_by_event_name </code> </a> using the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa6704907"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>memory_summary_global_by_event_name <span class="token keyword">WHERE</span> EVENT_NAME <span class="token operator">LIKE</span> <span class="token string">'memory/group_rpl/GCS_XCom::xcom_cache'</span><span class="token punctuation">;</span></code></pre> </div> <p> This returns memory usage statistics for the message cache, including the current number of cached entries and current size of the cache. If you reduce the cache size limit, XCom removes the oldest entries that have been decided and delivered until the current size is below the limit. XCom might temporarily exceed the cache size limit while this removal process is ongoing. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/information-schema-tables-extensions-table.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-tables-extensions-table"> </a> 28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045078297552"> </a> <p> The <a class="link" href="information-schema-tables-extensions-table.html" title="28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table"> <code class="literal"> TABLES_EXTENSIONS </code> </a> table provides information about table attributes defined for primary and secondary storage engines. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The <a class="link" href="information-schema-tables-extensions-table.html" title="28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table"> <code class="literal"> TABLES_EXTENSIONS </code> </a> table is reserved for future use. </p> </div> <p> The <a class="link" href="information-schema-tables-extensions-table.html" title="28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table"> <code class="literal"> TABLES_EXTENSIONS </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> TABLE_CATALOG </code> </p> <p> The name of the catalog to which the table belongs. This value is always <code class="literal"> def </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_SCHEMA </code> </p> <p> The name of the schema (database) to which the table belongs. </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_NAME </code> </p> <p> The name of the table. </p> </li> <li class="listitem"> <p> <code class="literal"> ENGINE_ATTRIBUTE </code> </p> <p> Table attributes defined for the primary storage engine. Reserved for future use. </p> </li> <li class="listitem"> <p> <code class="literal"> SECONDARY_ENGINE_ATTRIBUTE </code> </p> <p> Table attributes defined for the secondary storage engine. Reserved for future use. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/information-schema-introduction.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="information-schema-introduction"> </a> 28.1 Introduction </h2> </div> </div> </div> <p> <code class="literal"> INFORMATION_SCHEMA </code> provides access to database <span class="firstterm"> metadata </span> , information about the MySQL server such as the name of a database or table, the data type of a column, or access privileges. Other terms that are sometimes used for this information are <span class="firstterm"> data dictionary </span> and <span class="firstterm"> system catalog </span> . </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-usage-notes" title="INFORMATION_SCHEMA Usage Notes"> INFORMATION_SCHEMA Usage Notes </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-character-set-considerations" title="Character Set Considerations"> Character Set Considerations </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-as-show-alternative" title="INFORMATION_SCHEMA as Alternative to SHOW Statements"> INFORMATION_SCHEMA as Alternative to SHOW Statements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-privileges" title="INFORMATION_SCHEMA and Privileges"> INFORMATION_SCHEMA and Privileges </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-performance-considerations" title="Performance Considerations"> Performance Considerations </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-standards-considerations" title="Standards Considerations"> Standards Considerations </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-conventions" title="Conventions in the INFORMATION_SCHEMA Reference Sections"> Conventions in the INFORMATION_SCHEMA Reference Sections </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-related-information" title="Related Information"> Related Information </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-usage-notes"> </a> INFORMATION_SCHEMA Usage Notes </h3> </div> </div> </div> <p> <code class="literal"> INFORMATION_SCHEMA </code> is a database within each MySQL instance, the place that stores information about all the other databases that the MySQL server maintains. The <code class="literal"> INFORMATION_SCHEMA </code> database contains several read-only tables. They are actually views, not base tables, so there are no files associated with them, and you cannot set triggers on them. Also, there is no database directory with that name. </p> <p> Although you can select <code class="literal"> INFORMATION_SCHEMA </code> as the default database with a <a class="link" href="use.html" title="15.8.4 USE Statement"> <code class="literal"> USE </code> </a> statement, you can only read the contents of tables, not perform <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , or <a class="link" href="delete.html" title="15.2.2 DELETE Statement"> <code class="literal"> DELETE </code> </a> operations on them. </p> <p> Here is an example of a statement that retrieves information from <code class="literal"> INFORMATION_SCHEMA </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa89260799"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token keyword">table_name</span><span class="token punctuation">,</span> table_type<span class="token punctuation">,</span> <span class="token keyword">engine</span> <span class="token keyword">FROM</span> information_schema<span class="token punctuation">.</span><span class="token keyword">tables</span> <span class="token keyword">WHERE</span> table_schema <span class="token operator">=</span> <span class="token string">'db5'</span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> <span class="token keyword">table_name</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> table_name <span class="token punctuation">\|</span> table_type <span class="token punctuation">\|</span> engine <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> fk <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> InnoDB <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> fk2 <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> InnoDB <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> goto <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> into <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> k <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> kurs <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> loop <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> pk <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> InnoDB <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> t <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> t2 <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> t3 <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> t7 <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> tables <span class="token punctuation">\|</span> BASE TABLE <span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> v <span class="token punctuation">\|</span> VIEW <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> v2 <span class="token punctuation">\|</span> VIEW <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> v3 <span class="token punctuation">\|</span> VIEW <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> v56 <span class="token punctuation">\|</span> VIEW <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">17 rows in set (0.01 sec)</span></code></pre> </div> <p> Explanation: The statement requests a list of all the tables in database <code class="literal"> db5 </code> , showing just three pieces of information: the name of the table, its type, and its storage engine. </p> <p> Information about generated invisible primary keys is visible by default in all <code class="literal"> INFORMATION_SCHEMA </code> tables describing table columns, keys, or both, such as the <a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> <code class="literal"> COLUMNS </code> </a> and <a class="link" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table"> <code class="literal"> STATISTICS </code> </a> tables. If you wish to make such information hidden from queries that select from these tables, you can do so by setting the value of the <a class="link" href="server-system-variables.html#sysvar_show_gipk_in_create_table_and_information_schema"> <code class="literal"> show_gipk_in_create_table_and_information_schema </code> </a> server system variable to <code class="literal"> OFF </code> . For more information, see <a class="xref" href="create-table-gipks.html" title="15.1.20.11 Generated Invisible Primary Keys"> Section 15.1.20.11, “Generated Invisible Primary Keys” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-character-set-considerations"> </a> Character Set Considerations </h3> </div> </div> </div> <p> The definition for character columns (for example, <code class="literal"> TABLES.TABLE_NAME </code> ) is generally <code class="literal"> VARCHAR( <em class="replaceable"> <code> N </code> </em> ) CHARACTER SET utf8mb3 </code> where <em class="replaceable"> <code> N </code> </em> is at least 64. MySQL uses the default collation for this character set ( <code class="literal"> utf8mb3_general_ci </code> ) for all searches, sorts, comparisons, and other string operations on such columns. </p> <p> Because some MySQL objects are represented as files, searches in <code class="literal"> INFORMATION_SCHEMA </code> string columns can be affected by file system case sensitivity. For more information, see <a class="xref" href="charset-collation-information-schema.html" title="12.8.7 Using Collation in INFORMATION_SCHEMA Searches"> Section 12.8.7, “Using Collation in INFORMATION_SCHEMA Searches” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-as-show-alternative"> </a> INFORMATION_SCHEMA as Alternative to SHOW Statements </h3> </div> </div> </div> <p> The <code class="literal"> SELECT ... FROM INFORMATION_SCHEMA </code> statement is intended as a more consistent way to provide access to the information provided by the various <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statements that MySQL supports ( <a class="link" href="show-databases.html" title="15.7.7.15 SHOW DATABASES Statement"> <code class="literal"> SHOW DATABASES </code> </a> , <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> , and so forth). Using <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> has these advantages, compared to <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> : </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> It conforms to Codd's rules, because all access is done on tables. </p> </li> <li class="listitem"> <p> You can use the familiar syntax of the <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> statement, and only need to learn some table and column names. </p> </li> <li class="listitem"> <p> The implementor need not worry about adding keywords. </p> </li> <li class="listitem"> <p> You can filter, sort, concatenate, and transform the results from <code class="literal"> INFORMATION_SCHEMA </code> queries into whatever format your application needs, such as a data structure or a text representation to parse. </p> </li> <li class="listitem"> <p> This technique is more interoperable with other database systems. For example, Oracle Database users are familiar with querying tables in the Oracle data dictionary. </p> </li> </ul> </div> <p> Because <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> is familiar and widely used, the <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statements remain as an alternative. In fact, along with the implementation of <code class="literal"> INFORMATION_SCHEMA </code> , there are enhancements to <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> as described in <a class="xref" href="extended-show.html" title="28.8 Extensions to SHOW Statements"> Section 28.8, “Extensions to SHOW Statements” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-privileges"> </a> INFORMATION_SCHEMA and Privileges </h3> </div> </div> </div> <p> For most <code class="literal"> INFORMATION_SCHEMA </code> tables, each MySQL user has the right to access them, but can see only the rows in the tables that correspond to objects for which the user has the proper access privileges. In some cases (for example, the <code class="literal"> ROUTINE_DEFINITION </code> column in the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-routines-table.html" title="28.3.30 The INFORMATION_SCHEMA ROUTINES Table"> <code class="literal"> ROUTINES </code> </a> table), users who have insufficient privileges see <code class="literal"> NULL </code> . Some tables have different privilege requirements; for these, the requirements are mentioned in the applicable table descriptions. For example, <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> tables (tables with names that begin with <code class="literal"> INNODB_ </code> ) require the <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> privilege. </p> <p> The same privileges apply to selecting information from <code class="literal"> INFORMATION_SCHEMA </code> and viewing the same information through <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statements. In either case, you must have some privilege on an object to see information about it. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-performance-considerations"> </a> Performance Considerations </h3> </div> </div> </div> <p> <code class="literal"> INFORMATION_SCHEMA </code> queries that search for information from more than one database might take a long time and impact performance. To check the efficiency of a query, you can use <a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement"> <code class="literal"> EXPLAIN </code> </a> . For information about using <a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement"> <code class="literal"> EXPLAIN </code> </a> output to tune <code class="literal"> INFORMATION_SCHEMA </code> queries, see <a class="xref" href="information-schema-optimization.html" title="10.2.3 Optimizing INFORMATION_SCHEMA Queries"> Section 10.2.3, “Optimizing INFORMATION_SCHEMA Queries” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-standards-considerations"> </a> Standards Considerations </h3> </div> </div> </div> <p> The implementation for the <code class="literal"> INFORMATION_SCHEMA </code> table structures in MySQL follows the ANSI/ISO SQL:2003 standard Part 11 <em class="citetitle"> Schemata </em> . Our intent is approximate compliance with SQL:2003 core feature F021 <em class="citetitle"> Basic information schema </em> . </p> <p> Users of SQL Server 2000 (which also follows the standard) may notice a strong similarity. However, MySQL has omitted many columns that are not relevant for our implementation, and added columns that are MySQL-specific. One such added column is the <code class="literal"> ENGINE </code> column in the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> table. </p> <p> Although other DBMSs use a variety of names, like <code class="literal"> syscat </code> or <code class="literal"> system </code> , the standard name is <code class="literal"> INFORMATION_SCHEMA </code> . </p> <p> To avoid using any name that is reserved in the standard or in DB2, SQL Server, or Oracle, we changed the names of some columns marked <span class="quote"> “ <span class="quote"> MySQL extension </span> ” </span> . (For example, we changed <code class="literal"> COLLATION </code> to <code class="literal"> TABLE_COLLATION </code> in the <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> table.) See the list of reserved words near the end of this article: <a class="ulink" href="https://web.archive.org/web/20070428032454/http://www.dbazine.com/db2/db2-disarticles/gulutzan5" target="_blank"> https://web.archive.org/web/20070428032454/http://www.dbazine.com/db2/db2-disarticles/gulutzan5 </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-conventions"> </a> Conventions in the INFORMATION_SCHEMA Reference Sections </h3> </div> </div> </div> <p> The following sections describe each of the tables and columns in <code class="literal"> INFORMATION_SCHEMA </code> . For each column, there are three pieces of information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <span class="quote"> “ <span class="quote"> <code class="literal"> INFORMATION_SCHEMA </code> Name </span> ” </span> indicates the name for the column in the <code class="literal"> INFORMATION_SCHEMA </code> table. This corresponds to the standard SQL name unless the <span class="quote"> “ <span class="quote"> Remarks </span> ” </span> field says <span class="quote"> “ <span class="quote"> MySQL extension. </span> ” </span> </p> </li> <li class="listitem"> <p> <span class="quote"> “ <span class="quote"> <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> Name </span> ” </span> indicates the equivalent field name in the closest <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statement, if there is one. </p> </li> <li class="listitem"> <p> <span class="quote"> “ <span class="quote"> Remarks </span> ” </span> provides additional information where applicable. If this field is <code class="literal"> NULL </code> , it means that the value of the column is always <code class="literal"> NULL </code> . If this field says <span class="quote"> “ <span class="quote"> MySQL extension, </span> ” </span> the column is a MySQL extension to standard SQL. </p> </li> </ul> </div> <p> Many sections indicate what <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statement is equivalent to a <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> that retrieves information from <code class="literal"> INFORMATION_SCHEMA </code> . For <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statements that display information for the default database if you omit a <code class="literal"> FROM <em class="replaceable"> <code> db_name </code> </em> </code> clause, you can often select information for the default database by adding an <code class="literal"> AND TABLE_SCHEMA = SCHEMA() </code> condition to the <code class="literal"> WHERE </code> clause of a query that retrieves information from an <code class="literal"> INFORMATION_SCHEMA </code> table. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-related-information"> </a> Related Information </h3> </div> </div> </div> <p> These sections discuss additional <code class="literal"> INFORMATION_SCHEMA </code> -related topics: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> information about <code class="literal"> INFORMATION_SCHEMA </code> tables specific to the <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> storage engine: <a class="xref" href="innodb-information-schema-tables.html" title="28.4 INFORMATION_SCHEMA InnoDB Tables"> Section 28.4, “INFORMATION_SCHEMA InnoDB Tables” </a> </p> </li> <li class="listitem"> <p> information about <code class="literal"> INFORMATION_SCHEMA </code> tables specific to the thread pool plugin: <a class="xref" href="thread-pool-information-schema-tables.html" title="28.5 INFORMATION_SCHEMA Thread Pool Tables"> Section 28.5, “INFORMATION_SCHEMA Thread Pool Tables” </a> </p> </li> <li class="listitem"> <p> information about <code class="literal"> INFORMATION_SCHEMA </code> tables specific to the <code class="literal"> CONNECTION_CONTROL </code> plugin: <a class="xref" href="connection-control-information-schema-tables.html" title="28.6 INFORMATION_SCHEMA Connection-Control Tables"> Section 28.6, “INFORMATION_SCHEMA Connection-Control Tables” </a> </p> </li> <li class="listitem"> <p> Answers to questions that are often asked concerning the <code class="literal"> INFORMATION_SCHEMA </code> database: <a class="xref" href="faqs-information-schema.html" title="A.7 MySQL 8.4 FAQ: INFORMATION_SCHEMA"> Section A.7, “MySQL 8.4 FAQ: INFORMATION_SCHEMA” </a> </p> </li> <li class="listitem"> <p> <code class="literal"> INFORMATION_SCHEMA </code> queries and the optimizer: <a class="xref" href="information-schema-optimization.html" title="10.2.3 Optimizing INFORMATION_SCHEMA Queries"> Section 10.2.3, “Optimizing INFORMATION_SCHEMA Queries” </a> </p> </li> <li class="listitem"> <p> The effect of collation on <code class="literal"> INFORMATION_SCHEMA </code> comparisons: <a class="xref" href="charset-collation-information-schema.html" title="12.8.7 Using Collation in INFORMATION_SCHEMA Searches"> Section 12.8.7, “Using Collation in INFORMATION_SCHEMA Searches” </a> </p> </li> </ul> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-data-node-memory-management.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-data-node-memory-management"> </a> 25.4.3.13 Data Node Memory Management </h4> </div> </div> </div> <p> All memory allocation for a data node is performed when the node is started. This ensures that the data node can run in a stable manner without using swap memory, so that <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> can be used for latency-sensitive (realtime) applications. The following types of memory are allocated on data node startup: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Data memory </p> </li> <li class="listitem"> <p> Shared global memory </p> </li> <li class="listitem"> <p> Redo log buffers </p> </li> <li class="listitem"> <p> Job buffers </p> </li> <li class="listitem"> <p> Send buffers </p> </li> <li class="listitem"> <p> Page cache for disk data records </p> </li> <li class="listitem"> <p> Schema transaction memory </p> </li> <li class="listitem"> <p> Transaction memory </p> </li> <li class="listitem"> <p> Undo log buffer </p> </li> <li class="listitem"> <p> Query memory </p> </li> <li class="listitem"> <p> Block objects </p> </li> <li class="listitem"> <p> Schema memory </p> </li> <li class="listitem"> <p> Block data structures </p> </li> <li class="listitem"> <p> Long signal memory </p> </li> <li class="listitem"> <p> Shared memory communication buffers </p> </li> </ul> </div> <p> The <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> memory manager, which regulates most data node memory, handles the following memory resources: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Data Memory ( <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> ) </p> </li> <li class="listitem"> <p> Redo log buffers ( <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redobuffer"> <code class="literal"> RedoBuffer </code> </a> ) </p> </li> <li class="listitem"> <p> Job buffers </p> </li> <li class="listitem"> <p> Send buffers ( <a class="link" href="mysql-cluster-tcp-definition.html#ndbparam-tcp-sendbuffermemory"> <code class="literal"> SendBufferMemory </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-totalsendbuffermemory"> <code class="literal"> TotalSendBufferMemory </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-extrasendbuffermemory"> <code class="literal"> ExtraSendBufferMemory </code> </a> ) </p> </li> <li class="listitem"> <p> Disk Data record page cache ( <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-diskpagebuffermemory"> <code class="literal"> DiskPageBufferMemory </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-diskpagebufferentries"> <code class="literal"> DiskPageBufferEntries </code> </a> ) </p> </li> <li class="listitem"> <p> Transaction memory ( <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> ) </p> </li> <li class="listitem"> <p> Query memory </p> </li> <li class="listitem"> <p> Disk access records </p> </li> <li class="listitem"> <p> File buffers </p> </li> </ul> </div> <p> Each of these resources is set up with a reserved memory area and a maximum memory area. The reserved memory area can be used only by the resource for which it is reserved and cannot be shared with other resources; a given resource can never allocate more than the maximum memory allowed for the resource. A resource that has no maximum memory can expand to use all the shared memory in the memory manager. </p> <p> The size of the global shared memory for these resources is controlled by the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-sharedglobalmemory"> <code class="literal"> SharedGlobalMemory </code> </a> configuration parameter (default: 128 MB). </p> <p> Data memory is always reserved and never acquires any memory from shared memory. It is controlled using the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> configuration parameter, whose maximum is 16384 GB. <code class="literal"> DataMemory </code> is where records are stored, including hash indexes (approximately 15 bytes per row), ordered indexes (10-12 bytes per row per index), and row headers (16-32 bytes per row). </p> <p> Redo log buffers also use reserved memory only; this is controlled by the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redobuffer"> <code class="literal"> RedoBuffer </code> </a> configuration parameter, which sets the size of the redo log buffer per LDM thread. This means that the actual amount of memory used is the value of this parameter multiplied by the number of LDM threads in the data node. </p> <p> Job buffers use reserved memory only; the size of this memory is calculated by <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> , based on the numbers of threads of various types. </p> <p> Send buffers have a reserved part but can also allocate an additional 25% of shared global memory. The send buffer reserved size is calculated in two steps: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Use the value of the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-totalsendbuffermemory"> <code class="literal"> TotalSendBufferMemory </code> </a> configuration parameter (no default value) or the sum of the individual send buffers used by all individual connections to the data node. A data node is connected to all other data nodes, to all API nodes, and to all management nodes. This means that, in a cluster with 2 data nodes, 2 management nodes, and 10 API nodes each data node has 13 node connections. Since the default value for <a class="link" href="mysql-cluster-tcp-definition.html#ndbparam-tcp-sendbuffermemory"> <code class="literal"> SendBufferMemory </code> </a> for a data node connection is 2 MByte, this works out to 26 MB total. </p> </li> <li class="listitem"> <p> To obtain the total reserved size for the send buffer, the value of the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-extrasendbuffermemory"> <code class="literal"> ExtraSendBufferMemory </code> </a> configuration parameter, if any (default value 0). is added to the value obtained in the previous step. </p> </li> </ol> </div> <p> In other words, if <code class="literal"> TotalSendBufferMemory </code> has been set, the send buffer size is <code class="literal"> TotalSendBufferMemory + ExtraSendBufferMemory </code> ; otherwise, the size of the send buffer is equal to <code class="literal"> ([ <em class="replaceable"> <code> number of node connections </code> </em> ] * SendBufferMemory) + ExtraSendBufferMemory </code> . </p> <p> The page cache for disk data records uses a reserved resource only; the size of this resource is controlled by the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-diskpagebuffermemory"> <code class="literal"> DiskPageBufferMemory </code> </a> configuration parameter (default 64 MB). Memory for 32 KB disk page entries is also allocated; the number of these is determined by the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-diskpagebufferentries"> <code class="literal"> DiskPageBufferEntries </code> </a> configuration parameter (default 10). </p> <p> Transaction memory has a reserved part that either is calculated by <code class="literal"> NDB </code> , or is set explicitly using the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> configuration parameter; transaction memory can also use an unlimited amount of shared global memory. Transaction memory is used for all operational resources handling transactions, scans, locks, scan buffers, and trigger operations. It also holds table rows as they are updated, before the next commit writes them to data memory. </p> <p> Resources are allocated from a common transaction memory resource and can also use resources from global shared memory. the size of this resource can be controlled using a single <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> configuration parameter. </p> <p> Reserved memory for undo log buffers can be set using the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-initiallogfilegroup"> <code class="literal"> InitialLogFileGroup </code> </a> configuration parameter. If an undo log buffer is created as part of a <a class="link" href="create-logfile-group.html" title="15.1.16 CREATE LOGFILE GROUP Statement"> <code class="literal"> CREATE LOGFILE GROUP </code> </a> SQL statement, the memory is taken from the transaction memory. </p> <p> A number of resources relating to metadata for Disk Data resources also have no reserved part, and use shared global memory only. Shared global shared memory is thus shared between send buffers, transaction memory, and Disk Data metadata. </p> <p> If <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> is not set, it is calculated based on the following parameters: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentoperations"> <code class="literal"> MaxNoOfConcurrentOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrenttransactions"> <code class="literal"> MaxNoOfConcurrentTransactions </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooffiredtriggers"> <code class="literal"> MaxNoOfFiredTriggers </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocaloperations"> <code class="literal"> MaxNoOfLocalOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentindexoperations"> <code class="literal"> MaxNoOfConcurrentIndexOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentscans"> <code class="literal"> MaxNoOfConcurrentScans </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocalscans"> <code class="literal"> MaxNoOfLocalScans </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-batchsizeperlocalscan"> <code class="literal"> BatchSizePerLocalScan </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionbuffermemory"> <code class="literal"> TransactionBufferMemory </code> </a> </p> </li> </ul> </div> <p> When <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> is set explicitly, none of the configuration parameters just listed are used to calculate memory size. In addition, the parameters <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentindexoperations"> <code class="literal"> MaxNoOfConcurrentIndexOperations </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooffiredtriggers"> <code class="literal"> MaxNoOfFiredTriggers </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocaloperations"> <code class="literal"> MaxNoOfLocalOperations </code> </a> , and <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocalscans"> <code class="literal"> MaxNoOfLocalScans </code> </a> are incompatible with <code class="literal"> TransactionMemory </code> and cannot be set concurrently with it; if <code class="literal"> TransactionMemory </code> is set and any of these four parameters are also set in the <code class="filename"> config.ini </code> configuration file, the management server cannot start. </p> <p> The <code class="literal"> MaxNoOfConcurrentIndexOperations </code> , <code class="literal"> MaxNoOfFiredTriggers </code> , <code class="literal"> MaxNoOfLocalOperations </code> , and <code class="literal"> MaxNoOfLocalScans </code> parameters are all deprecated; you should expect them to be removed from a future release of MySQL NDB Cluster. </p> <p> The transaction memory resource contains a large number of memory pools. Each memory pool represents an object type and contains a set of objects; each pool includes a reserved part allocated to the pool at startup; this reserved memory is never returned to shared global memory. Reserved records are found using a data structure having only a single level for fast retrieval, which means that a number of records in each pool should be reserved. The number of reserved records in each pool has some impact on performance and reserved memory allocation, but is generally necessary only in certain very advanced use cases to set the reserved sizes explicitly. </p> <p> The size of the reserved part of the pool can be controlled by setting the following configuration parameters: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedconcurrentindexoperations"> <code class="literal"> ReservedConcurrentIndexOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedfiredtriggers"> <code class="literal"> ReservedFiredTriggers </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedconcurrentoperations"> <code class="literal"> ReservedConcurrentOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedlocalscans"> <code class="literal"> ReservedLocalScans </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedconcurrenttransactions"> <code class="literal"> ReservedConcurrentTransactions </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedconcurrentscans"> <code class="literal"> ReservedConcurrentScans </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedtransactionbuffermemory"> <code class="literal"> ReservedTransactionBufferMemory </code> </a> </p> </li> </ul> </div> <p> For any of the parameters just listed that is not set explicitly in <code class="filename"> config.ini </code> , the reserved setting is calculated as 25% of the corresponding maximum setting. For example, if unset, <code class="literal"> ReservedConcurrentIndexOperations </code> is calculated as 25% of <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentindexoperations"> <code class="literal"> MaxNoOfConcurrentIndexOperations </code> </a> , and <code class="literal"> ReservedLocalScans </code> is calculated as 25% of <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocalscans"> <code class="literal"> MaxNoOfLocalScans </code> </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> If <code class="literal"> ReservedTransactionBufferMemory </code> is not set, it is calculated as 25% of <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionbuffermemory"> <code class="literal"> TransactionBufferMemory </code> </a> . </p> </div> <p> The number of reserved records is per data node; these records are split among the threads handling them (LDM and TC threads) on each node. In most cases, it is sufficient to set <code class="literal"> TransactionMemory </code> alone, and to allow the number of records in pools to be governed by its value. </p> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentscans"> <code class="literal"> MaxNoOfConcurrentScans </code> </a> limits the number of concurrent scans that can be active in each TC thread. This is important in guarding against cluster overload. </p> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentoperations"> <code class="literal"> MaxNoOfConcurrentOperations </code> </a> limits the number of operations that can be active at any one time in updating transactions. (Simple reads are not affected by this parameter.) This number needs to be limited because it is necessary to preallocate memory for node failure handling, and a resource must be available for handling the maximum number of active operations in one TC thread when contending with node failures. It is imperative that <code class="literal"> MaxNoOfConcurrentOperations </code> be set to the same number on all nodes (this can be done most easily by setting a value for it once, in the <code class="literal"> [ndbd default] </code> section of the <code class="filename"> config.ini </code> global configuration file). While its value can be increased using a rolling restart (see <a class="xref" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster"> Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster” </a> ), decreasing it in this way is not considered safe due to the possibility of a node failure occurring during the rolling restart. </p> <p> It is possible to limit the size of a single transaction in NDB Cluster through the <code class="filename"> MaxDMLOperationsPerTransaction </code> parameter. If this is not set, the size of one transaction is limited by <code class="literal"> MaxNoOfConcurrentOperations </code> since this parameter limits the total number of concurrent operations per TC thread. </p> <p> Schema memory size is controlled by the following set of configuration parameters: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofsubscriptions"> <code class="literal"> MaxNoOfSubscriptions </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofsubscribers"> <code class="literal"> MaxNoOfSubscribers </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentsuboperations"> <code class="literal"> MaxNoOfConcurrentSubOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofattributes"> <code class="literal"> MaxNoOfAttributes </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooftables"> <code class="literal"> MaxNoOfTables </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooforderedindexes"> <code class="literal"> MaxNoOfOrderedIndexes </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofuniquehashindexes"> <code class="literal"> MaxNoOfUniqueHashIndexes </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooftriggers"> <code class="literal"> MaxNoOfTriggers </code> </a> </p> </li> </ul> </div> <p> The number of nodes and the number of LDM threads also have a major impact on the size of schema memory since the number of partitions in each table and each partition (and its fragment replicas) have to be represented in schema memory. </p> <p> In addition, a number of other records are allocated during startup. These are relatively small. Each block in each thread contains block objects that use memory. This memory size is also normally quite small compared to the other data node memory structures. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/information-schema-ndb-transid-mysql-connection-map-table.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-ndb-transid-mysql-connection-map-table"> </a> 28.3.18 The INFORMATION_SCHEMA ndb_transid_mysql_connection_map Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045079514080"> </a> <p> The <code class="literal"> ndb_transid_mysql_connection_map </code> table provides a mapping between <code class="literal"> NDB </code> transactions, <code class="literal"> NDB </code> transaction coordinators, and MySQL Servers attached to an NDB Cluster as API nodes. This information is used when populating the <a class="link" href="mysql-cluster-ndbinfo-server-operations.html" title="25.6.17.55 The ndbinfo server_operations Table"> <code class="literal"> server_operations </code> </a> and <a class="link" href="mysql-cluster-ndbinfo-server-transactions.html" title="25.6.17.56 The ndbinfo server_transactions Table"> <code class="literal"> server_transactions </code> </a> tables of the <a class="link" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> <code class="literal"> ndbinfo </code> </a> NDB Cluster information database. </p> <div class="informaltable"> <table summary="Columns in the INFORMATION_SCHEMA ndb_transid_mysql_connection_map table. The table lists INFORMATION_SCHEMA names along with corresponding SHOW names (if applicable), and remarks."> <colgroup> <col style="width: 40%"/> <col style="width: 30%"/> <col style="width: 30%"/> </colgroup> <thead> <tr> <th scope="col"> <code class="literal"> INFORMATION_SCHEMA </code> Name </th> <th scope="col"> <code class="literal"> SHOW </code> Name </th> <th scope="col"> Remarks </th> </tr> </thead> <tbody> <tr> <th scope="row"> <code class="literal"> mysql_connection_id </code> </th> <td> </td> <td> MySQL Server connection ID </td> </tr> <tr> <th scope="row"> <code class="literal"> node_id </code> </th> <td> </td> <td> Transaction coordinator node ID </td> </tr> <tr> <th scope="row"> <code class="literal"> ndb_transid </code> </th> <td> </td> <td> <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> transaction ID </td> </tr> </tbody> </table> </div> <p> The <code class="literal"> mysql_connection_id </code> is the same as the connection or session ID shown in the output of <a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement"> <code class="literal"> SHOW PROCESSLIST </code> </a> . </p> <p> There are no <code class="literal"> SHOW </code> statements associated with this table. </p> <p> This is a nonstandard table, specific to NDB Cluster. It is implemented as an <code class="literal"> INFORMATION_SCHEMA </code> plugin; you can verify that it is supported by checking the output of <a class="link" href="show-plugins.html" title="15.7.7.27 SHOW PLUGINS Statement"> <code class="literal"> SHOW PLUGINS </code> </a> . If <code class="literal"> ndb_transid_mysql_connection_map </code> support is enabled, the output from this statement includes a plugin having this name, of type <code class="literal"> INFORMATION SCHEMA </code> , and having status <code class="literal"> ACTIVE </code> , as shown here (using emphasized text): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78673417"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">PLUGINS</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token 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punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> binlog <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> mysql_native_password <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> AUTHENTICATION <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> sha256_password <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> AUTHENTICATION <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> caching_sha2_password <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> AUTHENTICATION <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> sha2_cache_cleaner <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> AUDIT <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> daemon_keyring_proxy_plugin <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> DAEMON <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> CSV <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> MEMORY <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> InnoDB <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> INNODB_TRX <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> INFORMATION SCHEMA <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> INNODB_CMP <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> INFORMATION SCHEMA <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token output"><span class="token punctuation">\|</span> INNODB_SESSION_TEMP_TABLESPACES <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> INFORMATION SCHEMA <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> MyISAM <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> MRG_MYISAM <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> PERFORMANCE_SCHEMA <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> TempTable <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> ARCHIVE <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> BLACKHOLE <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> ndbcluster <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> ndbinfo <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> STORAGE ENGINE <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation"></span><em><span class="token punctuation">\|</span> ndb_transid_mysql_connection_map <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> INFORMATION SCHEMA <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></em><span class="token punctuation"></span></span> <span class="token output"><span class="token punctuation">\|</span> ngram <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> FTPARSER <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> mysqlx_cache_cleaner <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> AUDIT <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> mysqlx <span class="token punctuation">\|</span> ACTIVE <span class="token punctuation">\|</span> DAEMON <span class="token punctuation">\|</span> NULL <span class="token punctuation">\|</span> GPL <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">47 rows in set (0.01 sec)</span></code></pre> </div> <p> The plugin is enabled by default. You can disable it (or force the server not to run unless the plugin starts) by starting the server with the <a class="link" href="mysql-cluster-options-variables.html#option_mysqld_ndb-transid-mysql-connection-map"> <code class="option"> --ndb-transid-mysql-connection-map </code> </a> option. If the plugin is disabled, the status is shown by <a class="link" href="show-plugins.html" title="15.7.7.27 SHOW PLUGINS Statement"> <code class="literal"> SHOW PLUGINS </code> </a> as <code class="literal"> DISABLED </code> . The plugin cannot be enabled or disabled at runtime. </p> <p> Although the names of this table and its columns are displayed using lowercase, you can use uppercase or lowercase when referring to them in SQL statements. </p> <p> For this table to be created, the MySQL Server must be a binary supplied with the NDB Cluster distribution, or one built from the NDB Cluster sources with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine support enabled. It is not available in the standard MySQL 8.4 Server. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/partitioning-maintenance.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="partitioning-maintenance"> </a> 26.3.4 Maintenance of Partitions </h3> </div> </div> </div> <a class="indexterm" name="idm46045083488768"> </a> <a class="indexterm" name="idm46045083487280"> </a> <a class="indexterm" name="idm46045083485792"> </a> <a class="indexterm" name="idm46045083484304"> </a> <a class="indexterm" name="idm46045083482816"> </a> <a class="indexterm" name="idm46045083481328"> </a> <a class="indexterm" name="idm46045083479840"> </a> <a class="indexterm" name="idm46045083478352"> </a> <p> A number of table and partition maintenance tasks can be carried out on partitioned tables using SQL statements intended for such purposes. </p> <p> Table maintenance of partitioned tables can be accomplished using the statements <a class="link" href="check-table.html" title="15.7.3.2 CHECK TABLE Statement"> <code class="literal"> CHECK TABLE </code> </a> , <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> , <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> , and <a class="link" href="repair-table.html" title="15.7.3.5 REPAIR TABLE Statement"> <code class="literal"> REPAIR TABLE </code> </a> , which are supported for partitioned tables. </p> <p> You can use a number of extensions to <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE </code> </a> for performing operations of this type on one or more partitions directly, as described in the following list: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <b> Rebuilding partitions. </b> Rebuilds the partition; this has the same effect as dropping all records stored in the partition, then reinserting them. This can be useful for purposes of defragmentation. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa20479541"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">REBUILD</span> <span class="token keyword">PARTITION</span> p0<span class="token punctuation">,</span> p1<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> <b> Optimizing partitions. </b> If you have deleted a large number of rows from a partition or if you have made many changes to a partitioned table with variable-length rows (that is, having <a class="link" href="char.html" title="13.3.2 The CHAR and VARCHAR Types"> <code class="literal"> VARCHAR </code> </a> , <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> , or <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> TEXT </code> </a> columns), you can use <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE ... OPTIMIZE PARTITION </code> </a> to reclaim any unused space and to defragment the partition data file. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa66451909"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">OPTIMIZE</span> <span class="token keyword">PARTITION</span> p0<span class="token punctuation">,</span> p1<span class="token punctuation">;</span></code></pre> </div> <p> Using <code class="literal"> OPTIMIZE PARTITION </code> on a given partition is equivalent to running <code class="literal"> CHECK PARTITION </code> , <code class="literal"> ANALYZE PARTITION </code> , and <code class="literal"> REPAIR PARTITION </code> on that partition. </p> <p> Some MySQL storage engines, including <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> , do not support per-partition optimization; in these cases, <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE ... OPTIMIZE PARTITION </code> </a> analyzes and rebuilds the entire table, and causes an appropriate warning to be issued. (Bug #11751825, Bug #42822) Use <code class="literal"> ALTER TABLE ... REBUILD PARTITION </code> and <code class="literal"> ALTER TABLE ... ANALYZE PARTITION </code> instead, to avoid this issue. </p> </li> <li class="listitem"> <p> <b> Analyzing partitions. </b> This reads and stores the key distributions for partitions. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa78820281"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ANALYZE</span> <span class="token keyword">PARTITION</span> p3<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> <b> Repairing partitions. </b> This repairs corrupted partitions. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa13725463"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">REPAIR</span> <span class="token keyword">PARTITION</span> p0<span class="token punctuation">,</span>p1<span class="token punctuation">;</span></code></pre> </div> <p> Normally, <code class="literal"> REPAIR PARTITION </code> fails when the partition contains duplicate key errors. You can use <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER IGNORE TABLE </code> </a> with this option, in which case all rows that cannot be moved due to the presence of duplicate keys are removed from the partition (Bug #16900947). </p> </li> <li class="listitem"> <p> <b> Checking partitions. </b> You can check partitions for errors in much the same way that you can use <code class="literal"> CHECK TABLE </code> with nonpartitioned tables. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa37180981"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> trb3 <span class="token keyword">CHECK</span> <span class="token keyword">PARTITION</span> p1<span class="token punctuation">;</span></code></pre> </div> <p> This statement tells you whether the data or indexes in partition <code class="literal"> p1 </code> of table <code class="literal"> t1 </code> are corrupted. If this is the case, use <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE ... REPAIR PARTITION </code> </a> to repair the partition. </p> <p> Normally, <code class="literal"> CHECK PARTITION </code> fails when the partition contains duplicate key errors. You can use <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER IGNORE TABLE </code> </a> with this option, in which case the statement returns the contents of each row in the partition where a duplicate key violation is found. Only the values for the columns in the partitioning expression for the table are reported. (Bug #16900947) </p> </li> </ul> </div> <p> Each of the statements in the list just shown also supports the keyword <code class="literal"> ALL </code> in place of the list of partition names. Using <code class="literal"> ALL </code> causes the statement to act on all partitions in the table. </p> <p> You can also truncate partitions using <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE ... TRUNCATE PARTITION </code> </a> . This statement can be used to delete all rows from one or more partitions in much the same way that <a class="link" href="truncate-table.html" title="15.1.37 TRUNCATE TABLE Statement"> <code class="literal"> TRUNCATE TABLE </code> </a> deletes all rows from a table. </p> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE ... TRUNCATE PARTITION ALL </code> </a> truncates all partitions in the table. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/password-security-user.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="password-security-user"> </a> 8.1.2.1 End-User Guidelines for Password Security </h4> </div> </div> </div> <a class="indexterm" name="idm46045252899392"> </a> <p> MySQL users should use the following guidelines to keep passwords secure. </p> <p> When you run a client program to connect to the MySQL server, it is inadvisable to specify your password in a way that exposes it to discovery by other users. The methods you can use to specify your password when you run client programs are listed here, along with an assessment of the risks of each method. In short, the safest methods are to have the client program prompt for the password or to specify the password in a properly protected option file. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Use the <a class="link" href="mysql-config-editor.html" title="6.6.7 mysql_config_editor — MySQL Configuration Utility"> <span class="command"> <strong> mysql_config_editor </strong> </span> </a> utility, which enables you to store authentication credentials in an encrypted login path file named <code class="filename"> .mylogin.cnf </code> . The file can be read later by MySQL client programs to obtain authentication credentials for connecting to MySQL Server. See <a class="xref" href="mysql-config-editor.html" title="6.6.7 mysql_config_editor — MySQL Configuration Utility"> Section 6.6.7, “mysql_config_editor — MySQL Configuration Utility” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045252892048"> </a> <a class="indexterm" name="idm46045252890976"> </a> Use a <code class="option"> --password= <em class="replaceable"> <code> password </code> </em> </code> or <code class="option"> -p <em class="replaceable"> <code> password </code> </em> </code> option on the command line. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa36429482"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> francis <span class="token property">-pfrank</span> <em class="replaceable">db_name</em></code></pre> </div> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> This is convenient <span class="emphasis"> <em> but insecure </em> </span> . On some systems, your password becomes visible to system status programs such as <span class="command"> <strong> ps </strong> </span> that may be invoked by other users to display command lines. MySQL clients typically overwrite the command-line password argument with zeros during their initialization sequence. However, there is still a brief interval during which the value is visible. Also, on some systems this overwriting strategy is ineffective and the password remains visible to <span class="command"> <strong> ps </strong> </span> . (SystemV Unix systems and perhaps others are subject to this problem.) </p> </div> <p> If your operating environment is set up to display your current command in the title bar of your terminal window, the password remains visible as long as the command is running, even if the command has scrolled out of view in the window content area. </p> </li> <li class="listitem"> <p> Use the <a class="link" href="connection-options.html#option_general_password"> <code class="option"> --password </code> </a> or <code class="option"> -p </code> option on the command line with no password value specified. In this case, the client program solicits the password interactively: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa65622640"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> francis <span class="token property">-p</span> <em class="replaceable">db_name</em> Enter password<span class="token punctuation">:</span> *******</code></pre> </div> <p> The <code class="literal"> </code> characters indicate where you enter your password. The password is not displayed as you enter it. </p> <p> It is more secure to enter your password this way than to specify it on the command line because it is not visible to other users. However, this method of entering a password is suitable only for programs that you run interactively. If you want to invoke a client from a script that runs noninteractively, there is no opportunity to enter the password from the keyboard. On some systems, you may even find that the first line of your script is read and interpreted (incorrectly) as your password. </p> </li> <li class="listitem"> <p> Store your password in an option file. For example, on Unix, you can list your password in the <code class="literal"> [client] </code> section of the <code class="filename"> .my.cnf </code> file in your home directory: </p> <a class="indexterm" name="idm46045252873376"> </a> <a class="indexterm" name="idm46045252872304"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa11164331"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[client]</span> <span class="token constant">password</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">password</em></span></code></pre> </div> <p> To keep the password safe, the file should not be accessible to anyone but yourself. To ensure this, set the file access mode to <code class="literal"> 400 </code> or <code class="literal"> 600 </code> . For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa6131574"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">chmod</span> 600 <span class="token punctuation">.</span>my<span class="token punctuation">.</span>cnf</code></pre> </div> <p> To name from the command line a specific option file containing the password, use the <a class="link" href="option-file-options.html#option_general_defaults-file"> <code class="option"> --defaults-file= <em class="replaceable"> <code> file_name </code> </em> </code> </a> option, where <code class="filename"> file_name </code> is the full path name to the file. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa68688795"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token constant">--defaults-file</span><span class="token attr-value"><span class="token punctuation">=</span>/home/francis/mysql-opts</span></code></pre> </div> <p> <a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files"> Section 6.2.2.2, “Using Option Files” </a> , discusses option files in more detail. </p> </li> </ul> </div> <a class="indexterm" name="idm46045252860208"> </a> <p> On Unix, the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client writes a record of executed statements to a history file (see <a class="xref" href="mysql-logging.html" title="6.5.1.3 mysql Client Logging"> Section 6.5.1.3, “mysql Client Logging” </a> ). By default, this file is named <code class="filename"> .mysql_history </code> and is created in your home directory. Passwords can be written as plain text in SQL statements such as <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> and <a class="link" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> <code class="literal"> ALTER USER </code> </a> , so if you use these statements, they are logged in the history file. To keep this file safe, use a restrictive access mode, the same way as described earlier for the <code class="filename"> .my.cnf </code> file. </p> <p> If your command interpreter maintains a history, any file in which the commands are saved contains MySQL passwords entered on the command line. For example, <span class="command"> <strong> bash </strong> </span> uses <code class="filename"> ~/.bash_history </code> . Any such file should have a restrictive access mode. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replication-auto-sync.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-replication-auto-sync"> </a> 25.7.9.1 NDB Cluster Replication: Automating Synchronization of the Replica to the Source Binary Log </h4> </div> </div> </div> <a class="indexterm" name="idm46045085828912"> </a> <a class="indexterm" name="idm46045085827456"> </a> <p> It is possible to automate much of the process described in the previous section (see <a class="xref" href="mysql-cluster-replication-backups.html" title="25.7.9 NDB Cluster Backups With NDB Cluster Replication"> Section 25.7.9, “NDB Cluster Backups With NDB Cluster Replication” </a> ). The following Perl script <code class="filename"> reset-replica.pl </code> serves as an example of how you can do this. </p> <a class="indexterm" name="idm46045085823936"> </a> <a class="indexterm" name="idm46045085822416"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-perl"><div class="docs-select-all right" id="sa18724443"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-perl"><span class="token comment" spellcheck="true">#!/user/bin/perl -w</span> <span class="token comment" spellcheck="true"># file: reset-replica.pl</span> <span class="token comment" spellcheck="true"># Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.</span> <span class="token comment" spellcheck="true"># This program is free software; you can redistribute it and/or modify</span> <span class="token comment" spellcheck="true"># it under the terms of the GNU General Public License as published by</span> <span class="token comment" spellcheck="true"># the Free Software Foundation; either version 2 of the License, or</span> <span class="token comment" spellcheck="true"># (at your option) any later version.</span> <span class="token comment" spellcheck="true"># This program is distributed in the hope that it will be useful,</span> <span class="token comment" spellcheck="true"># but WITHOUT ANY WARRANTY; without even the implied warranty of</span> <span class="token comment" spellcheck="true"># MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</span> <span class="token comment" spellcheck="true"># GNU General Public License for more details.</span> <span class="token comment" spellcheck="true"># You should have received a copy of the GNU General Public License</span> <span class="token comment" spellcheck="true"># along with this program; if not, write to:</span> <span class="token comment" spellcheck="true"># Free Software Foundation, Inc.</span> <span class="token comment" spellcheck="true"># 59 Temple Place, Suite 330</span> <span class="token comment" spellcheck="true"># Boston, MA 02111-1307 USA</span> <span class="token comment" spellcheck="true">#</span> <span class="token comment" spellcheck="true"># Version 1.1</span> <span class="token comment" spellcheck="true">######################## Includes ###############################</span> <span class="token keyword">use</span> DBI<span class="token punctuation">;</span> <span class="token comment" spellcheck="true">######################## Globals ################################</span> <span class="token keyword">my</span> <span class="token variable">$m_host</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$m_port</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$m_user</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$m_pass</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$s_host</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$s_port</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$s_user</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$s_pass</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$dbhM</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$dbhS</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">####################### Sub Prototypes ##########################</span> <span class="token function"><span class="token keyword">sub</span> CollectCommandPromptInfo</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> ConnectToDatabases</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> DisconnectFromDatabases</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> GetReplicaEpoch</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> GetSourceInfo</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> UpdateReplica</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">######################## Program Main ###########################</span> CollectCommandPromptInfo<span class="token punctuation">;</span> ConnectToDatabases<span class="token punctuation">;</span> GetReplicaEpoch<span class="token punctuation">;</span> GetSourceInfo<span class="token punctuation">;</span> UpdateReplica<span class="token punctuation">;</span> DisconnectFromDatabases<span class="token punctuation">;</span> <span class="token comment" spellcheck="true">################## Collect Command Prompt Info ##################</span> <span class="token function"><span class="token keyword">sub</span> CollectCommandPromptInfo</span> <span class="token punctuation">{</span> <span class="token comment" spellcheck="true">### Check that user has supplied correct number of command line args</span> <span class="token keyword">die</span> <span class="token string">"Usage:\n reset-replica >source MySQL host< >source MySQL port< \n >source user< >source pass< >replica MySQL host< \n >replica MySQL port< >replica user< >replica pass< \n All 8 arguments must be passed. Use BLANK for NULL passwords\n"</span> <span class="token keyword">unless</span> <span class="token variable">@ARGV</span> <span class="token operator">==</span> <span class="token number">8</span><span class="token punctuation">;</span> <span class="token variable">$m_host</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$m_port</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$m_user</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$m_pass</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">3</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$s_host</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">4</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$s_port</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">5</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$s_user</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">6</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$s_pass</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">7</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token variable">$m_pass</span> <span class="token operator">eq</span> <span class="token string">"BLANK"</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token variable">$m_pass</span> <span class="token operator">=</span> <span class="token string">''</span><span class="token punctuation">;</span><span class="token punctuation">}</span> <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token variable">$s_pass</span> <span class="token operator">eq</span> <span class="token string">"BLANK"</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token variable">$s_pass</span> <span class="token operator">=</span> <span class="token string">''</span><span class="token punctuation">;</span><span class="token punctuation">}</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">############### Make connections to both databases #############</span> <span class="token function"><span class="token keyword">sub</span> ConnectToDatabases</span> <span class="token punctuation">{</span> <span class="token comment" spellcheck="true">### Connect to both source and replica cluster databases</span> <span class="token comment" spellcheck="true">### Connect to source</span> <span class="token variable">$dbhM</span> <span class="token operator">=</span> DBI<span class="token operator">-></span>connect<span class="token punctuation">(</span> <span class="token string">"dbi:mysql:database=mysql;host=$m_host;port=$m_port"</span><span class="token punctuation">,</span> <span class="token string">"$m_user"</span><span class="token punctuation">,</span> <span class="token string">"$m_pass"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Can't connect to source cluster MySQL process! Error: $DBI::errstr\n"</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">### Connect to replica</span> <span class="token variable">$dbhS</span> <span class="token operator">=</span> DBI<span class="token operator">-></span>connect<span class="token punctuation">(</span> <span class="token string">"dbi:mysql:database=mysql;host=$s_host"</span><span class="token punctuation">,</span> <span class="token string">"$s_user"</span><span class="token punctuation">,</span> <span class="token string">"$s_pass"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Can't connect to replica cluster MySQL process! Error: $DBI::errstr\n"</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">################ Disconnect from both databases ################</span> <span class="token function"><span class="token keyword">sub</span> DisconnectFromDatabases</span> <span class="token punctuation">{</span> <span class="token comment" spellcheck="true">### Disconnect from source</span> <span class="token variable">$dbhM</span><span class="token operator">-></span>disconnect <span class="token operator">or</span> warn <span class="token string">" Disconnection failed: $DBI::errstr\n"</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">### Disconnect from replica</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>disconnect <span class="token operator">or</span> warn <span class="token string">" Disconnection failed: $DBI::errstr\n"</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">###################### Find the last good GCI ##################</span> <span class="token function"><span class="token keyword">sub</span> GetReplicaEpoch</span> <span class="token punctuation">{</span> <span class="token variable">$sth</span> <span class="token operator">=</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>prepare<span class="token punctuation">(</span><span class="token string">"SELECT MAX(epoch) FROM mysql.ndb_apply_status;"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Error while preparing to select epoch from replica: "</span><span class="token punctuation">,</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>execute <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Selecting epoch from replica error: "</span><span class="token punctuation">,</span> <span class="token variable">$sth</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>bind_col <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token operator">\</span><span class="token variable">$epoch</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>fetch<span class="token punctuation">;</span> <span class="token keyword">print</span> <span class="token string">"\tReplica epoch = $epoch\n"</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>finish<span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">####### Find the position of the last GCI in the binary log ########</span> <span class="token function"><span class="token keyword">sub</span> GetSourceInfo</span> <span class="token punctuation">{</span> <span class="token variable">$sth</span> <span class="token operator">=</span> <span class="token variable">$dbhM</span><span class="token operator">-></span>prepare<span class="token punctuation">(</span><span class="token string">"SELECT SUBSTRING_INDEX(File, '/', -1), Position FROM mysql.ndb_binlog_index WHERE epoch > $epoch ORDER BY epoch ASC LIMIT 1;"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Prepare to select from source error: "</span><span class="token punctuation">,</span> <span class="token variable">$dbhM</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>execute <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Selecting from source error: "</span><span class="token punctuation">,</span> <span class="token variable">$sth</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>bind_col <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token operator">\</span><span class="token variable">$binlog</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>bind_col <span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token operator">\</span><span class="token variable">$binpos</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>fetch<span class="token punctuation">;</span> <span class="token keyword">print</span> <span class="token string">"\tSource binary log file = $binlog\n"</span><span class="token punctuation">;</span> <span class="token keyword">print</span> <span class="token string">"\tSource binary log position = $binpos\n"</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>finish<span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">########## Set the replica to process from that location #########</span> <span class="token function"><span class="token keyword">sub</span> UpdateReplica</span> <span class="token punctuation">{</span> <span class="token variable">$sth</span> <span class="token operator">=</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>prepare<span class="token punctuation">(</span><span class="token string">"CHANGE REPLICATION SOURCE TO SOURCE_LOG_FILE='$binlog', SOURCE_LOG_POS=$binpos;"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Prepare to CHANGE REPLICATION SOURCE error: "</span><span class="token punctuation">,</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>execute <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"CHANGE REPLICATION SOURCE on replica error: "</span><span class="token punctuation">,</span> <span class="token variable">$sth</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>finish<span class="token punctuation">;</span> <span class="token keyword">print</span> <span class="token string">"\tReplica has been updated. You may now start the replica.\n"</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true"># end reset-replica.pl</span></code></pre> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-general-info.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="mysql-cluster-general-info"> </a> 25.1 General Information </h2> </div> </div> </div> <p> MySQL NDB Cluster uses the MySQL server with the <code class="literal"> NDB </code> storage engine. Support for the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine is not included in standard MySQL Server 8.4 binaries built by Oracle. Instead, users of NDB Cluster binaries from Oracle should upgrade to the most recent binary release of NDB Cluster for supported platforms—these include RPMs that should work with most Linux distributions. NDB Cluster 8.4 users who build from source should use the sources provided for MySQL 8.4 and build with the options required to provide NDB support. (Locations where the sources can be obtained are listed later in this section.) </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> MySQL NDB Cluster does not support InnoDB Cluster, which must be deployed using MySQL Server <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> storage engine as well as additional applications that are not included in the NDB Cluster distribution. MySQL Server 8.4 binaries cannot be used with MySQL NDB Cluster. For more information about deploying and using InnoDB Cluster, see <a class="ulink" href="/doc/mysql-shell/8.4/en/admin-api-userguide.html" target="_top"> MySQL AdminAPI </a> . <a class="xref" href="mysql-cluster-compared.html" title="25.2.6 MySQL Server Using InnoDB Compared with NDB Cluster"> Section 25.2.6, “MySQL Server Using InnoDB Compared with NDB Cluster” </a> , discusses differences between the <code class="literal"> NDB </code> and <code class="literal"> InnoDB </code> storage engines. </p> </div> <a class="indexterm" name="idm46045124441728"> </a> <p> <b> Supported Platforms. </b> NDB Cluster is currently available and supported on a number of platforms. For exact levels of support available for on specific combinations of operating system versions, operating system distributions, and hardware platforms, please refer to <a class="ulink" href="https://www.mysql.com/support/supportedplatforms/cluster.html" target="_blank"> https://www.mysql.com/support/supportedplatforms/cluster.html </a> . </p> <p> <b> Availability. </b> NDB Cluster binary and source packages are available for supported platforms from <a class="ulink" href="https://dev.mysql.com/downloads/cluster/" target="_top"> https://dev.mysql.com/downloads/cluster/ </a> . </p> <p> <a name="mysql-cluster-version-strings"> </a> <b> Version strings used in NDB Cluster software. </b> The version string displayed by the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client supplied with the MySQL NDB Cluster distribution uses this format: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa81826473"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">mysql<span class="token operator">-</span><em class="replaceable">mysql_server_version</em><span class="token operator">-</span>cluster</code></pre> </div> <p> <em class="replaceable"> <code> mysql_server_version </code> </em> represents the version of the MySQL Server on which the NDB Cluster release is based. Building from source using <a class="link" href="source-configuration-options.html#option_cmake_with_ndb"> <code class="option"> -DWITH_NDB </code> </a> or the equivalent adds the <code class="literal"> -cluster </code> suffix to the version string. (See <a class="xref" href="mysql-cluster-install-linux-source.html" title="25.3.1.4 Building NDB Cluster from Source on Linux"> Section 25.3.1.4, “Building NDB Cluster from Source on Linux” </a> , and <a class="xref" href="mysql-cluster-install-windows-source.html" title="25.3.2.2 Compiling and Installing NDB Cluster from Source on Windows"> Section 25.3.2.2, “Compiling and Installing NDB Cluster from Source on Windows” </a> .) You can see this format used in the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client, as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa30579575"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> Welcome to the MySQL monitor<span class="token punctuation">.</span> Commands end with <span class="token punctuation">;</span> or \g<span class="token punctuation">.</span> Your MySQL connection id is 2 Server version<span class="token punctuation">:</span> 8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0-cluster Source distribution Type <span class="token atrule">'help;'</span> or <span class="token atrule">'\h'</span> for help<span class="token punctuation">.</span> Type <span class="token atrule">'\c'</span> to clear the buffer<span class="token punctuation">.</span> <span class="token prompt">mysql></span><span class="token command"> SELECT</span> VERSION<span class="token punctuation">(</span><span class="token punctuation">)</span>\G <span class="token output"><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> 1. row <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> VERSION()<span class="token punctuation">:</span> 8.4.0-cluster </span><span class="token output">1 row in set (0.00 sec)</span></code></pre> </div> <p> The version string displayed by other NDB Cluster programs not normally included with the MySQL 8.4 distribution uses this format: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa31892298"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">mysql<span class="token operator">-</span><em class="replaceable">mysql_server_version</em> ndb<span class="token operator">-</span><em class="replaceable">ndb_engine_version</em></code></pre> </div> <p> <em class="replaceable"> <code> mysql_server_version </code> </em> represents the version of the MySQL Server on which the NDB Cluster release is based. For NDB Cluster 8.4, this is <code class="literal"> 8.4. <em class="replaceable"> <code> n </code> </em> </code> , where <em class="replaceable"> <code> n </code> </em> is the release number. <em class="replaceable"> <code> ndb_engine_version </code> </em> is the version of the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine used by this release of the NDB Cluster software. For NDB 8.4, this number is the same as the MySQL Server version. You can see this format used in the output of the <code class="literal"> SHOW </code> command in the <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> client, like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ndbmgm"><div class="docs-select-all right" id="sa30381207"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ndbmgm"><span class="token prompt">ndb_mgm></span> <span class="token keyword">SHOW</span> Connected to Management Server at<span class="token operator">:</span> localhost<span class="token operator">:</span>1186 <span class="token punctuation">(</span>using cleartext<span class="token punctuation">)</span> Cluster Configuration <span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">-</span> <span class="token selector">[ndbd(NDB)]</span> 2 node<span class="token punctuation">(</span>s<span class="token punctuation">)</span> id<span class="token operator">=</span>1 @10<span class="token punctuation">.</span>0<span class="token punctuation">.</span>10<span class="token punctuation">.</span>6 <span class="token punctuation">(</span>mysql<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0 ndb<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0<span class="token punctuation">,</span> Nodegroup<span class="token operator">:</span> 0<span class="token punctuation">,</span> <span class="token operator">*</span><span class="token punctuation">)</span> id<span class="token operator">=</span>2 @10<span class="token punctuation">.</span>0<span class="token punctuation">.</span>10<span class="token punctuation">.</span>8 <span class="token punctuation">(</span>mysql<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0 ndb<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0<span class="token punctuation">,</span> Nodegroup<span class="token operator">:</span> 0<span class="token punctuation">)</span> <span class="token selector">[ndb_mgmd(MGM)]</span> 1 node<span class="token punctuation">(</span>s<span class="token punctuation">)</span> id<span class="token operator">=</span>3 @10<span class="token punctuation">.</span>0<span class="token punctuation">.</span>10<span class="token punctuation">.</span>2 <span class="token punctuation">(</span>mysql<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0 ndb<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0<span class="token punctuation">)</span> <span class="token selector">[mysqld(API)]</span> 2 node<span class="token punctuation">(</span>s<span class="token punctuation">)</span> id<span class="token operator">=</span>4 @10<span class="token punctuation">.</span>0<span class="token punctuation">.</span>10<span class="token punctuation">.</span>10 <span class="token punctuation">(</span>mysql<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0 ndb<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0<span class="token punctuation">)</span> id<span class="token operator">=</span>5 <span class="token punctuation">(</span>not connected<span class="token punctuation">,</span> accepting connect from any host<span class="token punctuation">)</span></code></pre> </div> <p> <b> Compatibility with standard MySQL 8.4 releases. </b> While many standard MySQL schemas and applications can work using NDB Cluster, it is also true that unmodified applications and database schemas may be slightly incompatible or have suboptimal performance when run using NDB Cluster (see <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> ). Most of these issues can be overcome, but this also means that you are very unlikely to be able to switch an existing application datastore—that currently uses, for example, <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> or <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> —to use the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine without allowing for the possibility of changes in schemas, queries, and applications. A <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> compiled without <code class="literal"> NDB </code> support (that is, built without <a class="link" href="source-configuration-options.html#option_cmake_with_ndb"> <code class="option"> -DWITH_NDB </code> </a> or <a class="link" href="source-configuration-options.html#option_cmake_with_ndbcluster_storage_engine"> <code class="option"> -DWITH_NDBCLUSTER_STORAGE_ENGINE </code> </a> ) cannot function as a drop-in replacement for a <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> that is built with it. </p> <p> <b> NDB Cluster development source trees. </b> NDB Cluster development trees can also be accessed from <a class="ulink" href="https://github.com/mysql/mysql-server" target="_blank"> https://github.com/mysql/mysql-server </a> . </p> <p> The NDB Cluster development sources maintained at <a class="ulink" href="https://github.com/mysql/mysql-server" target="_blank"> https://github.com/mysql/mysql-server </a> are licensed under the GPL. For information about obtaining MySQL sources using Git and building them yourself, see <a class="xref" href="installing-development-tree.html" title="2.8.5 Installing MySQL Using a Development Source Tree"> Section 2.8.5, “Installing MySQL Using a Development Source Tree” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> As with MySQL Server 8.4, NDB Cluster 8.4 releases are built using <span class="command"> <strong> CMake </strong> </span> . </p> </div> <p class="ndb-rel-level"> NDB Cluster 8.4 is available as an LTS release, and is recommended for new deployments. NDB Cluster 8.0 is the previous GA release series (see <a class="ulink" href="/doc/refman/8.0/en/mysql-cluster.html" target="_top"> MySQL NDB Cluster 8.0 </a> ), still supported in production. NDB Cluster 7.6 and 7.5 are earlier GA releases still supported in production, although we recommend NDB Cluster 8.4 for new deployments intended for use in production. </p> <p> NDB Cluster 7.4 and 7.3 were previous GA releases which have been discontinued; they are no longer maintained or supported. </p> <p> Additional information regarding NDB Cluster can be found on the MySQL website at <a class="ulink" href="https://www.mysql.com/products/cluster/" target="_blank"> https://www.mysql.com/products/cluster/ </a> . </p> <a class="indexterm" name="idm46045124391344"> </a> <p> <b> Additional Resources. </b> More information about NDB Cluster can be found in the following places: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For answers to some commonly asked questions about NDB Cluster, see <a class="xref" href="faqs-mysql-cluster.html" title="A.10 MySQL 8.4 FAQ: NDB Cluster"> Section A.10, “MySQL 8.4 FAQ: NDB Cluster” </a> . </p> </li> <li class="listitem"> <p> The NDB Cluster Forum: <a class="ulink" href="https://forums.mysql.com/list.php?25" target="_blank"> https://forums.mysql.com/list.php?25 </a> . </p> </li> <li class="listitem"> <p> Many NDB Cluster users and developers blog about their experiences with NDB Cluster, and make feeds of these available through <a class="ulink" href="http://www.planetmysql.org/" target="_blank"> PlanetMySQL </a> . </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/data-directory.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="data-directory"> </a> 7.2 The MySQL Data Directory </h2> </div> </div> </div> <p> Information managed by the MySQL server is stored under a directory known as the data directory. The following list briefly describes the items typically found in the data directory, with cross references for additional information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Data directory subdirectories. Each subdirectory of the data directory is a database directory and corresponds to a database managed by the server. All MySQL installations have certain standard databases: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> The <code class="literal"> mysql </code> directory corresponds to the <code class="literal"> mysql </code> system schema, which contains information required by the MySQL server as it runs. This database contains data dictionary tables and system tables. See <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> . </p> </li> <li class="listitem"> <p> The <code class="literal"> performance_schema </code> directory corresponds to the Performance Schema, which provides information used to inspect the internal execution of the server at runtime. See <a class="xref" href="performance-schema.html" title="Chapter 29 MySQL Performance Schema"> Chapter 29, <i> MySQL Performance Schema </i> </a> . </p> </li> <li class="listitem"> <p> The <code class="literal"> sys </code> directory corresponds to the <code class="literal"> sys </code> schema, which provides a set of objects to help interpret Performance Schema information more easily. See <a class="xref" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> Chapter 30, <i> MySQL sys Schema </i> </a> . </p> </li> <li class="listitem"> <p> The <code class="literal"> ndbinfo </code> directory corresponds to the <code class="literal"> ndbinfo </code> database that stores information specific to NDB Cluster (present only for installations built to include NDB Cluster). See <a class="xref" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> Section 25.6.17, “ndbinfo: The NDB Cluster Information Database” </a> . </p> </li> </ul> </div> <p> Other subdirectories correspond to databases created by users or applications. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <a class="link" href="information-schema.html" title="Chapter 28 INFORMATION_SCHEMA Tables"> <code class="literal"> INFORMATION_SCHEMA </code> </a> is a standard database, but its implementation uses no corresponding database directory. </p> </div> </li> <li class="listitem"> <p> Log files written by the server. See <a class="xref" href="server-logs.html" title="7.4 MySQL Server Logs"> Section 7.4, “MySQL Server Logs” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> InnoDB </code> tablespace and log files. See <a class="xref" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> Chapter 17, <i> The InnoDB Storage Engine </i> </a> . </p> </li> <li class="listitem"> <p> Default/autogenerated SSL and RSA certificate and key files. See <a class="xref" href="creating-ssl-rsa-files.html" title="8.3.3 Creating SSL and RSA Certificates and Keys"> Section 8.3.3, “Creating SSL and RSA Certificates and Keys” </a> . </p> </li> <li class="listitem"> <p> The server process ID file (while the server is running). </p> </li> <li class="listitem"> <p> The <code class="filename"> mysqld-auto.cnf </code> file that stores persisted global system variable settings. See <a class="xref" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> Section 15.7.6.1, “SET Syntax for Variable Assignment” </a> . </p> </li> </ul> </div> <p> Some items in the preceding list can be relocated elsewhere by reconfiguring the server. In addition, the <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="option"> --datadir </code> </a> option enables the location of the data directory itself to be changed. For a given MySQL installation, check the server configuration to determine whether items have been moved. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/optimize-numeric.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="optimize-numeric"> </a> 10.4.2.1 Optimizing for Numeric Data </h4> </div> </div> </div> <a class="indexterm" name="idm46045226771088"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For unique IDs or other values that can be represented as either strings or numbers, prefer numeric columns to string columns. Since large numeric values can be stored in fewer bytes than the corresponding strings, it is faster and takes less memory to transfer and compare them. </p> </li> <li class="listitem"> <p> If you are using numeric data, it is faster in many cases to access information from a database (using a live connection) than to access a text file. Information in the database is likely to be stored in a more compact format than in the text file, so accessing it involves fewer disk accesses. You also save code in your application because you can avoid parsing the text file to find line and column boundaries. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/server-status-variable-reference.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="server-status-variable-reference"> </a> 7.1.6 Server Status Variable Reference </h3> </div> </div> </div> <p> The following table lists all status variables applicable within <code class="literal"> mysqld </code> . </p> <p> The table lists each variable's data type and scope. The last column indicates whether the scope for each variable is Global, Session, or both. Please see the corresponding item descriptions for details on setting and using the variables. Where appropriate, direct links to further information about the items are provided. </p> <div class="table"> <a name="idm46045283116784"> </a> <p class="title"> <b> Table 7.3 Status Variable Summary </b> </p> <div class="table-contents"> <table frame="box" rules="all" summary="Reference for status variables."> <colgroup> <col style="width: 40%"/> <col style="width: 20%"/> <col align="center" style="width: 20%"/> </colgroup> <thead> <tr> <th scope="col"> Variable Name </th> <th scope="col"> Variable Type </th> <th scope="col"> Variable Scope </th> </tr> </thead> <tbody> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Aborted_clients"> Aborted_clients </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Aborted_connects"> Aborted_connects </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Acl_cache_items_count"> Acl_cache_items_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_current_size"> Audit_log_current_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_direct_writes"> Audit_log_direct_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_event_max_drop_size"> Audit_log_event_max_drop_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_events"> Audit_log_events </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_events_filtered"> Audit_log_events_filtered </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_events_lost"> Audit_log_events_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_events_written"> Audit_log_events_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_total_size"> Audit_log_total_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_write_waits"> Audit_log_write_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Authentication_ldap_sasl_supported_methods"> Authentication_ldap_sasl_supported_methods </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Binlog_cache_disk_use"> Binlog_cache_disk_use </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Binlog_cache_use"> Binlog_cache_use </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Binlog_stmt_cache_disk_use"> Binlog_stmt_cache_disk_use </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Binlog_stmt_cache_use"> Binlog_stmt_cache_use </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Bytes_received"> Bytes_received </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Bytes_sent"> Bytes_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Caching_sha2_password_rsa_public_key"> Caching_sha2_password_rsa_public_key </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_admin_commands </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_event </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_function </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_procedure </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_resource_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_server </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_tablespace </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_user_default_role </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_analyze </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_assign_to_keycache </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_begin </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_binlog </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_call_procedure </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_change_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_change_repl_filter </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_change_replication_source </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_check </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_checksum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_clone </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_commit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_event </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_function </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_index </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_procedure </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_resource_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_role </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_server </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_trigger </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_udf </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_dealloc_sql </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_delete </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_delete_multi </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_do </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_event </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_function </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_index </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_procedure </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_resource_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_role </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_server </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_trigger </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_empty_query </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_execute_sql </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_explain_other </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_flush </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_get_diagnostics </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_grant </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_grant_roles </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_group_replication_start </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_group_replication_stop </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_ha_close </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_ha_open </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_ha_read </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_help </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_insert </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_insert_select </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_install_component </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_install_plugin </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_kill </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_load </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_lock_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_optimize </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_preload_keys </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_prepare_sql </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_purge </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_purge_before_date </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_release_savepoint </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_rename_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_rename_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_repair </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_replace </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_replace_select </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_replica_start </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_replica_stop </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_reset </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_resignal </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_restart </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_revoke </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_revoke_all </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_revoke_roles </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_rollback </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_rollback_to_savepoint </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_savepoint </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_select </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_set_option </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_set_resource_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_set_role </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_authors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_binary_log_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_binlog_events </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_binlogs </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_charsets </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_collations </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_contributors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_event </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_func </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_proc </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_trigger </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_databases </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_engine_logs </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_engine_mutex </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_engine_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_errors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_events </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_fields </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_function_code </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_function_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_grants </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_keys </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_ndb_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_open_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_plugins </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_privileges </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_procedure_code </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_procedure_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_processlist </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_profile </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_profiles </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_relaylog_events </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_replica_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_replicas </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_storage_engines </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_table_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_triggers </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_variables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_warnings </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_shutdown </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_signal </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_close </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_execute </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_fetch </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_prepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_reprepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_reset </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_send_long_data </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_truncate </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_uninstall_component </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_uninstall_plugin </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_unlock_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_update </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_update_multi </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_commit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_end </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_prepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_recover </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_rollback </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_start </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Compression"> Compression </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Compression_algorithm"> Compression_algorithm </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Compression_level"> Compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="connection-control-variables.html#statvar_Connection_control_delay_generated"> Connection_control_delay_generated </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_accept"> Connection_errors_accept </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_internal"> Connection_errors_internal </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_max_connections"> Connection_errors_max_connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_peer_address"> Connection_errors_peer_address </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_select"> Connection_errors_select </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_tcpwrap"> Connection_errors_tcpwrap </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connections"> Connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Created_tmp_disk_tables"> Created_tmp_disk_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Created_tmp_files"> Created_tmp_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Created_tmp_tables"> Created_tmp_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_ca"> Current_tls_ca </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_capath"> Current_tls_capath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_cert"> Current_tls_cert </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_cipher"> Current_tls_cipher </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_ciphersuites"> Current_tls_ciphersuites </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_crl"> Current_tls_crl </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_crlpath"> Current_tls_crlpath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_key"> Current_tls_key </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_version"> Current_tls_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Delayed_errors"> Delayed_errors </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Delayed_insert_threads"> Delayed_insert_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Delayed_writes"> Delayed_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Deprecated_use_i_s_processlist_count"> Deprecated_use_i_s_processlist_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Deprecated_use_i_s_processlist_last_timestamp"> Deprecated_use_i_s_processlist_last_timestamp </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_dragnet.Status"> dragnet.Status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Error_log_buffered_bytes"> Error_log_buffered_bytes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Error_log_buffered_events"> Error_log_buffered_events </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Error_log_expired_events"> Error_log_expired_events </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Error_log_latest_write"> Error_log_latest_write </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#statvar_Firewall_access_denied"> Firewall_access_denied </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#statvar_Firewall_access_granted"> Firewall_access_granted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#statvar_Firewall_cached_entries"> Firewall_cached_entries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Flush_commands"> Flush_commands </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Global_connection_memory"> Global_connection_memory </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_all_consensus_proposals_count"> Gr_all_consensus_proposals_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_all_consensus_time_sum"> Gr_all_consensus_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_certification_garbage_collector_count"> Gr_certification_garbage_collector_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_certification_garbage_collector_time_sum"> Gr_certification_garbage_collector_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_consensus_bytes_received_sum"> Gr_consensus_bytes_received_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_consensus_bytes_sent_sum"> Gr_consensus_bytes_sent_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_control_messages_sent_bytes_sum"> Gr_control_messages_sent_bytes_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_control_messages_sent_count"> Gr_control_messages_sent_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_control_messages_sent_roundtrip_time_sum"> Gr_control_messages_sent_roundtrip_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_data_messages_sent_bytes_sum"> Gr_data_messages_sent_bytes_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_data_messages_sent_count"> Gr_data_messages_sent_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_data_messages_sent_roundtrip_time_sum"> Gr_data_messages_sent_roundtrip_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_empty_consensus_proposals_count"> Gr_empty_consensus_proposals_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_extended_consensus_count"> Gr_extended_consensus_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> Gr_flow_control_throttle_active_count </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> Gr_flow_control_throttle_count </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> Gr_flow_control_throttle_last_throttle_timestamp </th> <td> Datetime </td> <td> Global </td> </tr> <tr> <th scope="row"> Gr_flow_control_throttle_time_sum </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_last_consensus_end_timestamp"> Gr_last_consensus_end_timestamp </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_total_messages_sent_count"> Gr_total_messages_sent_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_after_sync_count"> Gr_transactions_consistency_after_sync_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_after_sync_time_sum"> Gr_transactions_consistency_after_sync_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_after_termination_count"> Gr_transactions_consistency_after_termination_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_after_termination_time_sum"> Gr_transactions_consistency_after_termination_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_before_begin_count"> Gr_transactions_consistency_before_begin_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_before_begin_time_sum"> Gr_transactions_consistency_before_begin_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_commit"> Handler_commit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_delete"> Handler_delete </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Handler_discover"> Handler_discover </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_external_lock"> Handler_external_lock </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_mrr_init"> Handler_mrr_init </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_prepare"> Handler_prepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_first"> Handler_read_first </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_key"> Handler_read_key </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_last"> Handler_read_last </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_next"> Handler_read_next </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_prev"> Handler_read_prev </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_rnd"> Handler_read_rnd </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_rnd_next"> Handler_read_rnd_next </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_rollback"> Handler_rollback </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_savepoint"> Handler_savepoint </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_savepoint_rollback"> Handler_savepoint_rollback </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_update"> Handler_update </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_write"> Handler_write </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_data"> Innodb_buffer_pool_bytes_data </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_dirty"> Innodb_buffer_pool_bytes_dirty </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_dump_status"> Innodb_buffer_pool_dump_status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_load_status"> Innodb_buffer_pool_load_status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_data"> Innodb_buffer_pool_pages_data </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_dirty"> Innodb_buffer_pool_pages_dirty </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_flushed"> Innodb_buffer_pool_pages_flushed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_free"> Innodb_buffer_pool_pages_free </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_latched"> Innodb_buffer_pool_pages_latched </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_misc"> Innodb_buffer_pool_pages_misc </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_total"> Innodb_buffer_pool_pages_total </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead"> Innodb_buffer_pool_read_ahead </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_evicted"> Innodb_buffer_pool_read_ahead_evicted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_rnd"> Innodb_buffer_pool_read_ahead_rnd </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_requests"> Innodb_buffer_pool_read_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_reads"> Innodb_buffer_pool_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status"> Innodb_buffer_pool_resize_status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status_code"> Innodb_buffer_pool_resize_status_code </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status_progress"> Innodb_buffer_pool_resize_status_progress </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_wait_free"> Innodb_buffer_pool_wait_free </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_write_requests"> Innodb_buffer_pool_write_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_fsyncs"> Innodb_data_fsyncs </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_fsyncs"> Innodb_data_pending_fsyncs </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_reads"> Innodb_data_pending_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_writes"> Innodb_data_pending_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_read"> Innodb_data_read </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_reads"> Innodb_data_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_writes"> Innodb_data_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_written"> Innodb_data_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_pages_written"> Innodb_dblwr_pages_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_writes"> Innodb_dblwr_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_have_atomic_builtins"> Innodb_have_atomic_builtins </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_waits"> Innodb_log_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_write_requests"> Innodb_log_write_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_writes"> Innodb_log_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_num_open_files"> Innodb_num_open_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_fsyncs"> Innodb_os_log_fsyncs </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_fsyncs"> Innodb_os_log_pending_fsyncs </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_writes"> Innodb_os_log_pending_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_written"> Innodb_os_log_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_page_size"> Innodb_page_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_created"> Innodb_pages_created </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_read"> Innodb_pages_read </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_written"> Innodb_pages_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_capacity_resized"> Innodb_redo_log_capacity_resized </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_checkpoint_lsn"> Innodb_redo_log_checkpoint_lsn </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_current_lsn"> Innodb_redo_log_current_lsn </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_enabled"> Innodb_redo_log_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_flushed_to_disk_lsn"> Innodb_redo_log_flushed_to_disk_lsn </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_logical_size"> Innodb_redo_log_logical_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_physical_size"> Innodb_redo_log_physical_size </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_read_only"> Innodb_redo_log_read_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_resize_status"> Innodb_redo_log_resize_status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_uuid"> Innodb_redo_log_uuid </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_current_waits"> Innodb_row_lock_current_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time"> Innodb_row_lock_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_avg"> Innodb_row_lock_time_avg </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_max"> Innodb_row_lock_time_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_waits"> Innodb_row_lock_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_deleted"> Innodb_rows_deleted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_inserted"> Innodb_rows_inserted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_read"> Innodb_rows_read </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_updated"> Innodb_rows_updated </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_deleted"> Innodb_system_rows_deleted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_inserted"> Innodb_system_rows_inserted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_read"> Innodb_system_rows_read </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_updated"> Innodb_system_rows_updated </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_truncated_status_writes"> Innodb_truncated_status_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_active"> Innodb_undo_tablespaces_active </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_explicit"> Innodb_undo_tablespaces_explicit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_implicit"> Innodb_undo_tablespaces_implicit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_total"> Innodb_undo_tablespaces_total </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_blocks_not_flushed"> Key_blocks_not_flushed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_blocks_unused"> Key_blocks_unused </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_blocks_used"> Key_blocks_used </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_read_requests"> Key_read_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_reads"> Key_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_write_requests"> Key_write_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_writes"> Key_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Last_query_cost"> Last_query_cost </a> </th> <td> Numeric </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Last_query_partial_plans"> Last_query_partial_plans </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Locked_connects"> Locked_connects </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_exceeded"> Max_execution_time_exceeded </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_set"> Max_execution_time_set </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_set_failed"> Max_execution_time_set_failed </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_used_connections"> Max_used_connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_used_connections_time"> Max_used_connections_time </a> </th> <td> Datetime </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_mecab_charset"> mecab_charset </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_aborted_clients"> Mysqlx_aborted_clients </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_address"> Mysqlx_address </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received"> Mysqlx_bytes_received </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_compressed_payload"> Mysqlx_bytes_received_compressed_payload </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_uncompressed_frame"> Mysqlx_bytes_received_uncompressed_frame </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent"> Mysqlx_bytes_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_compressed_payload"> Mysqlx_bytes_sent_compressed_payload </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_uncompressed_frame"> Mysqlx_bytes_sent_uncompressed_frame </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_compression_algorithm"> Mysqlx_compression_algorithm </a> </th> <td> String </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_compression_level"> Mysqlx_compression_level </a> </th> <td> String </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_accept_errors"> Mysqlx_connection_accept_errors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_errors"> Mysqlx_connection_errors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_accepted"> Mysqlx_connections_accepted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_closed"> Mysqlx_connections_closed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_rejected"> Mysqlx_connections_rejected </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_create_view"> Mysqlx_crud_create_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_delete"> Mysqlx_crud_delete </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_drop_view"> Mysqlx_crud_drop_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_find"> Mysqlx_crud_find </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_insert"> Mysqlx_crud_insert </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_modify_view"> Mysqlx_crud_modify_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_update"> Mysqlx_crud_update </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_close"> Mysqlx_cursor_close </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_fetch"> Mysqlx_cursor_fetch </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_open"> Mysqlx_cursor_open </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_sent"> Mysqlx_errors_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_unknown_message_type"> Mysqlx_errors_unknown_message_type </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_close"> Mysqlx_expect_close </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_open"> Mysqlx_expect_open </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_init_error"> Mysqlx_init_error </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_messages_sent"> Mysqlx_messages_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_global_sent"> Mysqlx_notice_global_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_other_sent"> Mysqlx_notice_other_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_warning_sent"> Mysqlx_notice_warning_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notified_by_group_replication"> Mysqlx_notified_by_group_replication </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_port"> Mysqlx_port </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_deallocate"> Mysqlx_prep_deallocate </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_execute"> Mysqlx_prep_execute </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_prepare"> Mysqlx_prep_prepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_rows_sent"> Mysqlx_rows_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions"> Mysqlx_sessions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_accepted"> Mysqlx_sessions_accepted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_closed"> Mysqlx_sessions_closed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_fatal_error"> Mysqlx_sessions_fatal_error </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_killed"> Mysqlx_sessions_killed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_rejected"> Mysqlx_sessions_rejected </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_socket"> Mysqlx_socket </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_accept_renegotiates"> Mysqlx_ssl_accept_renegotiates </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_accepts"> Mysqlx_ssl_accepts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_active"> Mysqlx_ssl_active </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_cipher"> Mysqlx_ssl_cipher </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_cipher_list"> Mysqlx_ssl_cipher_list </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_ctx_verify_depth"> Mysqlx_ssl_ctx_verify_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_ctx_verify_mode"> Mysqlx_ssl_ctx_verify_mode </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_finished_accepts"> Mysqlx_ssl_finished_accepts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_server_not_after"> Mysqlx_ssl_server_not_after </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_server_not_before"> Mysqlx_ssl_server_not_before </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_verify_depth"> Mysqlx_ssl_verify_depth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_verify_mode"> Mysqlx_ssl_verify_mode </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_version"> Mysqlx_ssl_version </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection"> Mysqlx_stmt_create_collection </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection_index"> Mysqlx_stmt_create_collection_index </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_disable_notices"> Mysqlx_stmt_disable_notices </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection"> Mysqlx_stmt_drop_collection </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection_index"> Mysqlx_stmt_drop_collection_index </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_enable_notices"> Mysqlx_stmt_enable_notices </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ensure_collection"> Mysqlx_stmt_ensure_collection </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_mysqlx"> Mysqlx_stmt_execute_mysqlx </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_sql"> Mysqlx_stmt_execute_sql </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_xplugin"> Mysqlx_stmt_execute_xplugin </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_get_collection_options"> Mysqlx_stmt_get_collection_options </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_kill_client"> Mysqlx_stmt_kill_client </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_clients"> Mysqlx_stmt_list_clients </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_notices"> Mysqlx_stmt_list_notices </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_objects"> Mysqlx_stmt_list_objects </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_modify_collection_options"> Mysqlx_stmt_modify_collection_options </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ping"> Mysqlx_stmt_ping </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads"> Mysqlx_worker_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads_active"> Mysqlx_worker_threads_active </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_deferred_count"> Ndb_api_adaptive_send_deferred_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_deferred_count_replica"> Ndb_api_adaptive_send_deferred_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_deferred_count_session"> Ndb_api_adaptive_send_deferred_count_session </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_deferred_count_slave"> Ndb_api_adaptive_send_deferred_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_forced_count"> Ndb_api_adaptive_send_forced_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_forced_count_replica"> Ndb_api_adaptive_send_forced_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_forced_count_session"> Ndb_api_adaptive_send_forced_count_session </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_forced_count_slave"> Ndb_api_adaptive_send_forced_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_unforced_count"> Ndb_api_adaptive_send_unforced_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_unforced_count_replica"> Ndb_api_adaptive_send_unforced_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_unforced_count_session"> Ndb_api_adaptive_send_unforced_count_session </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_unforced_count_slave"> Ndb_api_adaptive_send_unforced_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_received_count"> Ndb_api_bytes_received_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_received_count_replica"> Ndb_api_bytes_received_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_received_count_session"> Ndb_api_bytes_received_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_received_count_slave"> Ndb_api_bytes_received_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_sent_count"> Ndb_api_bytes_sent_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_sent_count_replica"> Ndb_api_bytes_sent_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_sent_count_session"> Ndb_api_bytes_sent_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_sent_count_slave"> Ndb_api_bytes_sent_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_bytes_count"> Ndb_api_event_bytes_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_bytes_count_injector"> Ndb_api_event_bytes_count_injector </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_data_count"> Ndb_api_event_data_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_data_count_injector"> Ndb_api_event_data_count_injector </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_nondata_count"> Ndb_api_event_nondata_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_nondata_count_injector"> Ndb_api_event_nondata_count_injector </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pk_op_count"> Ndb_api_pk_op_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pk_op_count_replica"> Ndb_api_pk_op_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pk_op_count_session"> Ndb_api_pk_op_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pk_op_count_slave"> Ndb_api_pk_op_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pruned_scan_count"> Ndb_api_pruned_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pruned_scan_count_replica"> Ndb_api_pruned_scan_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pruned_scan_count_session"> Ndb_api_pruned_scan_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pruned_scan_count_slave"> Ndb_api_pruned_scan_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_range_scan_count"> Ndb_api_range_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_range_scan_count_replica"> Ndb_api_range_scan_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_range_scan_count_session"> Ndb_api_range_scan_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_range_scan_count_slave"> Ndb_api_range_scan_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_read_row_count"> Ndb_api_read_row_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_read_row_count_replica"> Ndb_api_read_row_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_read_row_count_session"> Ndb_api_read_row_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_read_row_count_slave"> Ndb_api_read_row_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_scan_batch_count"> Ndb_api_scan_batch_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_scan_batch_count_replica"> Ndb_api_scan_batch_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_scan_batch_count_session"> Ndb_api_scan_batch_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_scan_batch_count_slave"> Ndb_api_scan_batch_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_table_scan_count"> Ndb_api_table_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_table_scan_count_replica"> Ndb_api_table_scan_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_table_scan_count_session"> Ndb_api_table_scan_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_table_scan_count_slave"> Ndb_api_table_scan_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_abort_count"> Ndb_api_trans_abort_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_abort_count_replica"> Ndb_api_trans_abort_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_abort_count_session"> Ndb_api_trans_abort_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_abort_count_slave"> Ndb_api_trans_abort_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_close_count"> Ndb_api_trans_close_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_close_count_replica"> Ndb_api_trans_close_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_close_count_session"> Ndb_api_trans_close_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_close_count_slave"> Ndb_api_trans_close_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_commit_count"> Ndb_api_trans_commit_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_commit_count_replica"> Ndb_api_trans_commit_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_commit_count_session"> Ndb_api_trans_commit_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_commit_count_slave"> Ndb_api_trans_commit_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_local_read_row_count"> Ndb_api_trans_local_read_row_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_local_read_row_count_replica"> Ndb_api_trans_local_read_row_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_local_read_row_count_session"> Ndb_api_trans_local_read_row_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_local_read_row_count_slave"> Ndb_api_trans_local_read_row_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_start_count"> Ndb_api_trans_start_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_start_count_replica"> Ndb_api_trans_start_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_start_count_session"> Ndb_api_trans_start_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_start_count_slave"> Ndb_api_trans_start_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_uk_op_count"> Ndb_api_uk_op_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_uk_op_count_replica"> Ndb_api_uk_op_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_uk_op_count_session"> Ndb_api_uk_op_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_uk_op_count_slave"> Ndb_api_uk_op_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_exec_complete_count"> Ndb_api_wait_exec_complete_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_exec_complete_count_replica"> Ndb_api_wait_exec_complete_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_exec_complete_count_session"> Ndb_api_wait_exec_complete_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_exec_complete_count_slave"> Ndb_api_wait_exec_complete_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_meta_request_count"> Ndb_api_wait_meta_request_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_meta_request_count_replica"> Ndb_api_wait_meta_request_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_meta_request_count_session"> Ndb_api_wait_meta_request_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_meta_request_count_slave"> Ndb_api_wait_meta_request_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_nanos_count"> Ndb_api_wait_nanos_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_nanos_count_replica"> Ndb_api_wait_nanos_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_nanos_count_session"> Ndb_api_wait_nanos_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_nanos_count_slave"> Ndb_api_wait_nanos_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_scan_result_count"> Ndb_api_wait_scan_result_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_scan_result_count_replica"> Ndb_api_wait_scan_result_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_scan_result_count_session"> Ndb_api_wait_scan_result_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_scan_result_count_slave"> Ndb_api_wait_scan_result_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_cluster_node_id"> Ndb_cluster_node_id </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_config_from_host"> Ndb_config_from_host </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_config_from_port"> Ndb_config_from_port </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_config_generation"> Ndb_config_generation </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_epoch"> Ndb_conflict_fn_epoch </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_epoch_trans"> Ndb_conflict_fn_epoch_trans </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_epoch2"> Ndb_conflict_fn_epoch2 </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_epoch2_trans"> Ndb_conflict_fn_epoch2_trans </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_max"> Ndb_conflict_fn_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_max_del_win"> Ndb_conflict_fn_max_del_win </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_max_del_win_ins"> Ndb_conflict_fn_max_del_win_ins </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_max_ins"> Ndb_conflict_fn_max_ins </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_old"> Ndb_conflict_fn_old </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_last_conflict_epoch"> Ndb_conflict_last_conflict_epoch </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_last_stable_epoch"> Ndb_conflict_last_stable_epoch </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_reflected_op_discard_count"> Ndb_conflict_reflected_op_discard_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_reflected_op_prepare_count"> Ndb_conflict_reflected_op_prepare_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_refresh_op_count"> Ndb_conflict_refresh_op_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_conflict_commit_count"> Ndb_conflict_trans_conflict_commit_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_detect_iter_count"> Ndb_conflict_trans_detect_iter_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_reject_count"> Ndb_conflict_trans_reject_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_row_conflict_count"> Ndb_conflict_trans_row_conflict_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_row_reject_count"> Ndb_conflict_trans_row_reject_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_epoch_delete_delete_count"> Ndb_epoch_delete_delete_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_execute_count"> Ndb_execute_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_last_commit_epoch_server"> Ndb_last_commit_epoch_server </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_last_commit_epoch_session"> Ndb_last_commit_epoch_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_metadata_detected_count"> Ndb_metadata_detected_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_metadata_excluded_count"> Ndb_metadata_excluded_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_metadata_synced_count"> Ndb_metadata_synced_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_cluster_node_id"> Ndb_cluster_node_id </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_number_of_data_nodes"> Ndb_number_of_data_nodes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pruned_scan_count"> Ndb_pruned_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pushed_queries_defined"> Ndb_pushed_queries_defined </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pushed_queries_dropped"> Ndb_pushed_queries_dropped </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pushed_queries_executed"> Ndb_pushed_queries_executed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pushed_reads"> Ndb_pushed_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_scan_count"> Ndb_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_slave_max_replicated_epoch"> Ndb_slave_max_replicated_epoch </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_trans_hint_count_session"> Ndb_trans_hint_count_session </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Not_flushed_delayed_rows"> Not_flushed_delayed_rows </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ongoing_anonymous_gtid_violating_transaction_count"> Ongoing_anonymous_gtid_violating_transaction_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ongoing_anonymous_transaction_count"> Ongoing_anonymous_transaction_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ongoing_automatic_gtid_violating_transaction_count"> Ongoing_automatic_gtid_violating_transaction_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Open_files"> Open_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Open_streams"> Open_streams </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Open_table_definitions"> Open_table_definitions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Open_tables"> Open_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Opened_files"> Opened_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Opened_table_definitions"> Opened_table_definitions </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Opened_tables"> Opened_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_accounts_lost"> Performance_schema_accounts_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_cond_classes_lost"> Performance_schema_cond_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_cond_instances_lost"> Performance_schema_cond_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_digest_lost"> Performance_schema_digest_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_classes_lost"> Performance_schema_file_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_handles_lost"> Performance_schema_file_handles_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_instances_lost"> Performance_schema_file_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_hosts_lost"> Performance_schema_hosts_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_index_stat_lost"> Performance_schema_index_stat_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_locker_lost"> Performance_schema_locker_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_memory_classes_lost"> Performance_schema_memory_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_metadata_lock_lost"> Performance_schema_metadata_lock_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_meter_lost"> Performance_schema_meter_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_metric_lost"> Performance_schema_metric_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_mutex_classes_lost"> Performance_schema_mutex_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_mutex_instances_lost"> Performance_schema_mutex_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_nested_statement_lost"> Performance_schema_nested_statement_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_prepared_statements_lost"> Performance_schema_prepared_statements_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_program_lost"> Performance_schema_program_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_rwlock_classes_lost"> Performance_schema_rwlock_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_rwlock_instances_lost"> Performance_schema_rwlock_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_session_connect_attrs_longest_seen"> Performance_schema_session_connect_attrs_longest_seen </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_session_connect_attrs_lost"> Performance_schema_session_connect_attrs_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_socket_classes_lost"> Performance_schema_socket_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_socket_instances_lost"> Performance_schema_socket_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_stage_classes_lost"> Performance_schema_stage_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_statement_classes_lost"> Performance_schema_statement_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_handles_lost"> Performance_schema_table_handles_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_instances_lost"> Performance_schema_table_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_lock_stat_lost"> Performance_schema_table_lock_stat_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_thread_classes_lost"> Performance_schema_thread_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_thread_instances_lost"> Performance_schema_thread_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_users_lost"> Performance_schema_users_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Prepared_stmt_count"> Prepared_stmt_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Queries"> Queries </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Questions"> Questions </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Replica_open_temp_tables"> Replica_open_temp_tables </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Resource_group_supported"> Resource_group_supported </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#statvar_Rewriter_number_loaded_rules"> Rewriter_number_loaded_rules </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#statvar_Rewriter_number_reloads"> Rewriter_number_reloads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#statvar_Rewriter_number_rewritten_queries"> Rewriter_number_rewritten_queries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#statvar_Rewriter_reload_error"> Rewriter_reload_error </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_clients"> Rpl_semi_sync_master_clients </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_net_avg_wait_time"> Rpl_semi_sync_master_net_avg_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_net_wait_time"> Rpl_semi_sync_master_net_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_net_waits"> Rpl_semi_sync_master_net_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_no_times"> Rpl_semi_sync_master_no_times </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_no_tx"> Rpl_semi_sync_master_no_tx </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_status"> Rpl_semi_sync_master_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_timefunc_failures"> Rpl_semi_sync_master_timefunc_failures </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_tx_avg_wait_time"> Rpl_semi_sync_master_tx_avg_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_tx_wait_time"> Rpl_semi_sync_master_tx_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_tx_waits"> Rpl_semi_sync_master_tx_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_wait_pos_backtraverse"> Rpl_semi_sync_master_wait_pos_backtraverse </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_wait_sessions"> Rpl_semi_sync_master_wait_sessions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_yes_tx"> Rpl_semi_sync_master_yes_tx </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_replica_status"> Rpl_semi_sync_replica_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_slave_status"> Rpl_semi_sync_slave_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_clients"> Rpl_semi_sync_source_clients </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_net_avg_wait_time"> Rpl_semi_sync_source_net_avg_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_net_wait_time"> Rpl_semi_sync_source_net_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_net_waits"> Rpl_semi_sync_source_net_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_no_times"> Rpl_semi_sync_source_no_times </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_no_tx"> Rpl_semi_sync_source_no_tx </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_status"> Rpl_semi_sync_source_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_timefunc_failures"> Rpl_semi_sync_source_timefunc_failures </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_tx_avg_wait_time"> Rpl_semi_sync_source_tx_avg_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_tx_wait_time"> Rpl_semi_sync_source_tx_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_tx_waits"> Rpl_semi_sync_source_tx_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_wait_pos_backtraverse"> Rpl_semi_sync_source_wait_pos_backtraverse </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_wait_sessions"> Rpl_semi_sync_source_wait_sessions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_yes_tx"> Rpl_semi_sync_source_yes_tx </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rsa_public_key"> Rsa_public_key </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Secondary_engine_execution_count"> Secondary_engine_execution_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_full_join"> Select_full_join </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_full_range_join"> Select_full_range_join </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_range"> Select_range </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_range_check"> Select_range_check </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_scan"> Select_scan </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Slave_open_temp_tables"> Slave_open_temp_tables </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Slave_rows_last_search_algorithm_used"> Slave_rows_last_search_algorithm_used </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Slow_launch_threads"> Slow_launch_threads </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Slow_queries"> Slow_queries </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Sort_merge_passes"> Sort_merge_passes </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Sort_range"> Sort_range </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Sort_rows"> Sort_rows </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Sort_scan"> Sort_scan </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_accept_renegotiates"> Ssl_accept_renegotiates </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_accepts"> Ssl_accepts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_callback_cache_hits"> Ssl_callback_cache_hits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_cipher"> Ssl_cipher </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_cipher_list"> Ssl_cipher_list </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_client_connects"> Ssl_client_connects </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_connect_renegotiates"> Ssl_connect_renegotiates </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_ctx_verify_depth"> Ssl_ctx_verify_depth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_ctx_verify_mode"> Ssl_ctx_verify_mode </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_default_timeout"> Ssl_default_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_finished_accepts"> Ssl_finished_accepts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_finished_connects"> Ssl_finished_connects </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_server_not_after"> Ssl_server_not_after </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_server_not_before"> Ssl_server_not_before </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_hits"> Ssl_session_cache_hits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_misses"> Ssl_session_cache_misses </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_mode"> Ssl_session_cache_mode </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_overflows"> Ssl_session_cache_overflows </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_size"> Ssl_session_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_timeout"> Ssl_session_cache_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_timeouts"> Ssl_session_cache_timeouts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_sessions_reused"> Ssl_sessions_reused </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_used_session_cache_entries"> Ssl_used_session_cache_entries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_verify_depth"> Ssl_verify_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_verify_mode"> Ssl_verify_mode </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_version"> Ssl_version </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_locks_immediate"> Table_locks_immediate </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_locks_waited"> Table_locks_waited </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_hits"> Table_open_cache_hits </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_misses"> Table_open_cache_misses </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_overflows"> Table_open_cache_overflows </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tc_log_max_pages_used"> Tc_log_max_pages_used </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tc_log_page_size"> Tc_log_page_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tc_log_page_waits"> Tc_log_page_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Telemetry_metrics_supported"> Telemetry_metrics_supported </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Telemetry_traces_supported"> Telemetry_traces_supported </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_telemetry.live_sessions"> telemetry.live_sessions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Threads_cached"> Threads_cached </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Threads_connected"> Threads_connected </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Threads_created"> Threads_created </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Threads_running"> Threads_running </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tls_library_version"> Tls_library_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tls_sni_server_name"> Tls_sni_server_name </a> </th> <td> String </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Uptime"> Uptime </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Uptime_since_flush_status"> Uptime_since_flush_status </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#statvar_validate_password_dictionary_file_last_parsed"> validate_password_dictionary_file_last_parsed </a> </th> <td> Datetime </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#statvar_validate_password_dictionary_file_words_count"> validate_password_dictionary_file_words_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#statvar_validate_password.dictionary_file_last_parsed"> validate_password.dictionary_file_last_parsed </a> </th> <td> Datetime </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#statvar_validate_password.dictionary_file_words_count"> validate_password.dictionary_file_words_count </a> </th> <td> Integer </td> <td> Global </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th scope="col" style="width: 430.609px;"> Variable Name </th> <th scope="col" style="width: 153.688px;"> Variable Type </th> <th scope="col" style="width: 153.703px;"> Variable Scope </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/general-tablespaces.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="general-tablespaces"> </a> 17.6.3.3 General Tablespaces </h4> </div> </div> </div> <p> A general tablespace is a shared <code class="literal"> InnoDB </code> tablespace that is created using <a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> <code class="literal"> CREATE TABLESPACE </code> </a> syntax. General tablespace capabilities and features are described under the following topics in this section: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-capabilities" title="General Tablespace Capabilities"> General Tablespace Capabilities </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-creating" title="Creating a General Tablespace"> Creating a General Tablespace </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-adding-tables" title="Adding Tables to a General Tablespace"> Adding Tables to a General Tablespace </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-row-format-support" title="General Tablespace Row Format Support"> General Tablespace Row Format Support </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-moving-non-partitioned-tables" title="Moving Tables Between Tablespaces Using ALTER TABLE"> Moving Tables Between Tablespaces Using ALTER TABLE </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-renaming" title="Renaming a General Tablespace"> Renaming a General Tablespace </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-dropping" title="Dropping a General Tablespace"> Dropping a General Tablespace </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-limitations" title="General Tablespace Limitations"> General Tablespace Limitations </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-capabilities"> </a> General Tablespace Capabilities </h5> </div> </div> </div> <p> General tablespaces provide the following capabilities: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Similar to the system tablespace, general tablespaces are shared tablespaces capable of storing data for multiple tables. </p> </li> <li class="listitem"> <p> General tablespaces have a potential memory advantage over <a class="link" href="innodb-file-per-table-tablespaces.html" title="17.6.3.2 File-Per-Table Tablespaces"> file-per-table tablespaces </a> . The server keeps tablespace metadata in memory for the lifetime of a tablespace. Multiple tables in fewer general tablespaces consume less memory for tablespace metadata than the same number of tables in separate file-per-table tablespaces. </p> </li> <li class="listitem"> <p> General tablespace data files can be placed in a directory relative to or independent of the MySQL data directory, which provides you with many of the data file and storage management capabilities of <a class="link" href="innodb-file-per-table-tablespaces.html" title="17.6.3.2 File-Per-Table Tablespaces"> file-per-table tablespaces </a> . As with file-per-table tablespaces, the ability to place data files outside of the MySQL data directory allows you to manage performance of critical tables separately, setup RAID or DRBD for specific tables, or bind tables to particular disks, for example. </p> </li> <li class="listitem"> <p> General tablespaces support all table row formats and associated features. </p> </li> <li class="listitem"> <p> The <code class="literal"> TABLESPACE </code> option can be used with <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> to create tables in a general tablespaces, file-per-table tablespace, or in the system tablespace. </p> </li> <li class="listitem"> <p> The <code class="literal"> TABLESPACE </code> option can be used with <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> to move tables between general tablespaces, file-per-table tablespaces, and the system tablespace. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-creating"> </a> Creating a General Tablespace </h5> </div> </div> </div> <p> General tablespaces are created using <a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> <code class="literal"> CREATE TABLESPACE </code> </a> syntax. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa22223263"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <em class="replaceable">tablespace_name</em> <span class="token punctuation">[</span><span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'<em class="replaceable">file_name</em>'</span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">FILE_BLOCK_SIZE</span> <span class="token operator">=</span> <span class="token keyword"><em class="replaceable">value</em></span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">ENGINE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <em class="replaceable">engine_name</em><span class="token punctuation">]</span></code></pre> </div> <p> A general tablespace can be created in the data directory or outside of it. To avoid conflicts with implicitly created file-per-table tablespaces, creating a general tablespace in a subdirectory under the data directory is not supported. When creating a general tablespace outside of the data directory, the directory must exist and must be known to <code class="literal"> InnoDB </code> prior to creating the tablespace. To make an unknown directory known to <code class="literal"> InnoDB </code> , add the directory to the <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> argument value. <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> is a read-only startup option. Configuring it requires restarting the server. </p> <p> Examples: </p> <p> Creating a general tablespace in the data directory: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa90744458"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts1.ibd'</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span></code></pre> </div> <p> or </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa34549756"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span></code></pre> </div> <p> The <code class="literal"> ADD DATAFILE </code> clause is optional. If the <code class="literal"> ADD DATAFILE </code> clause is not specified when creating a tablespace, a tablespace data file with a unique file name is created implicitly. The unique file name is a 128 bit UUID formatted into five groups of hexadecimal numbers separated by dashes ( <em class="replaceable"> <code> aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee </code> </em> ). General tablespace data files include an <code class="filename"> .ibd </code> file extension. In a replication environment, the data file name created on the source is not the same as the data file name created on the replica. </p> <p> Creating a general tablespace in a directory outside of the data directory: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa77995652"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'/my/tablespace/directory/ts1.ibd'</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span></code></pre> </div> <p> You can specify a path that is relative to the data directory as long as the tablespace directory is not under the data directory. In this example, the <code class="filename"> my_tablespace </code> directory is at the same level as the data directory: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa48485064"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'../my_tablespace/ts1.ibd'</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The <code class="literal"> ENGINE = InnoDB </code> clause must be defined as part of the <a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> <code class="literal"> CREATE TABLESPACE </code> </a> statement, or <code class="literal"> InnoDB </code> must be defined as the default storage engine ( <a class="link" href="server-system-variables.html#sysvar_default_storage_engine"> <code class="literal"> default_storage_engine=InnoDB </code> </a> ). </p> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-adding-tables"> </a> Adding Tables to a General Tablespace </h5> </div> </div> </div> <p> After creating a general tablespace, <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE <em class="replaceable"> <code> tbl_name </code> </em> ... TABLESPACE [=] <em class="replaceable"> <code> tablespace_name </code> </em> </code> </a> or <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE <em class="replaceable"> <code> tbl_name </code> </em> TABLESPACE [=] <em class="replaceable"> <code> tablespace_name </code> </em> </code> </a> statements can be used to add tables to the tablespace, as shown in the following examples: </p> <p> <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa7562109"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts1<span class="token punctuation">;</span></code></pre> </div> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa69231378"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t2 <span class="token keyword">TABLESPACE</span> ts1<span class="token punctuation">;</span></code></pre> </div> <p> Adding table partitions to shared tablespaces is not supported. Shared tablespaces include the <code class="literal"> InnoDB </code> system tablespace and general tablespaces. </p> <p> For detailed syntax information, see <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> and <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-row-format-support"> </a> General Tablespace Row Format Support </h5> </div> </div> </div> <p> General tablespaces support all table row formats ( <code class="literal"> REDUNDANT </code> , <code class="literal"> COMPACT </code> , <code class="literal"> DYNAMIC </code> , <code class="literal"> COMPRESSED </code> ) with the caveat that compressed and uncompressed tables cannot coexist in the same general tablespace due to different physical page sizes. </p> <p> For a general tablespace to contain compressed tables ( <code class="literal"> ROW_FORMAT=COMPRESSED </code> ), the <code class="literal"> FILE_BLOCK_SIZE </code> option must be specified, and the <code class="literal"> FILE_BLOCK_SIZE </code> value must be a valid compressed page size in relation to the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value. Also, the physical page size of the compressed table ( <code class="literal"> KEY_BLOCK_SIZE </code> ) must be equal to <code class="literal"> FILE_BLOCK_SIZE/1024 </code> . For example, if <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size=16KB </code> </a> and <code class="literal"> FILE_BLOCK_SIZE=8K </code> , the <code class="literal"> KEY_BLOCK_SIZE </code> of the table must be 8. </p> <p> The following table shows permitted <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> , <code class="literal"> FILE_BLOCK_SIZE </code> , and <code class="literal"> KEY_BLOCK_SIZE </code> combinations. <code class="literal"> FILE_BLOCK_SIZE </code> values may also be specified in bytes. To determine a valid <code class="literal"> KEY_BLOCK_SIZE </code> value for a given <code class="literal"> FILE_BLOCK_SIZE </code> , divide the <code class="literal"> FILE_BLOCK_SIZE </code> value by 1024. Table compression is not support for 32K and 64K <code class="literal"> InnoDB </code> page sizes. For more information about <code class="literal"> KEY_BLOCK_SIZE </code> , see <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> , and <a class="xref" href="innodb-compression-usage.html" title="17.9.1.2 Creating Compressed Tables"> Section 17.9.1.2, “Creating Compressed Tables” </a> . </p> <div class="table"> <a name="idm46045165437104"> </a> <p class="title"> <b> Table 17.3 Permitted Page Size, FILE_BLOCK_SIZE, and KEY_BLOCK_SIZE Combinations for Compressed Tables </b> </p> <div class="table-contents"> <table frame="all"> <colgroup> <col style="width: 33%"/> <col style="width: 33%"/> <col style="width: 34%"/> </colgroup> <thead> <tr> <th scope="col"> InnoDB Page Size (innodb_page_size) </th> <th scope="col"> Permitted FILE_BLOCK_SIZE Value </th> <th scope="col"> Permitted KEY_BLOCK_SIZE Value </th> </tr> </thead> <tbody> <tr> <th scope="row"> 64KB </th> <td> 64K (65536) </td> <td> Compression is not supported </td> </tr> <tr> <th scope="row"> 32KB </th> <td> 32K (32768) </td> <td> Compression is not supported </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 16K (16384) </td> <td> None. If <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> is equal to <code class="literal"> FILE_BLOCK_SIZE </code> , the tablespace cannot contain a compressed table. </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 8K (8192) </td> <td> 8 </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 4K (4096) </td> <td> 4 </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 2K (2048) </td> <td> 2 </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 1K (1024) </td> <td> 1 </td> </tr> <tr> <th scope="row"> 8KB </th> <td> 8K (8192) </td> <td> None. If <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> is equal to <code class="literal"> FILE_BLOCK_SIZE </code> , the tablespace cannot contain a compressed table. </td> </tr> <tr> <th scope="row"> 8KB </th> <td> 4K (4096) </td> <td> 4 </td> </tr> <tr> <th scope="row"> 8KB </th> <td> 2K (2048) </td> <td> 2 </td> </tr> <tr> <th scope="row"> 8KB </th> <td> 1K (1024) </td> <td> 1 </td> </tr> <tr> <th scope="row"> 4KB </th> <td> 4K (4096) </td> <td> None. If <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> is equal to <code class="literal"> FILE_BLOCK_SIZE </code> , the tablespace cannot contain a compressed table. </td> </tr> <tr> <th scope="row"> 4KB </th> <td> 2K (2048) </td> <td> 2 </td> </tr> <tr> <th scope="row"> 4KB </th> <td> 1K (1024) </td> <td> 1 </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th scope="col" style="width: 243.531px;"> InnoDB Page Size (innodb_page_size) </th> <th scope="col" style="width: 243.531px;"> Permitted FILE_BLOCK_SIZE Value </th> <th scope="col" style="width: 250.938px;"> Permitted KEY_BLOCK_SIZE Value </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> <p> This example demonstrates creating a general tablespace and adding a compressed table. The example assumes a default <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> of 16KB. The <code class="literal"> FILE_BLOCK_SIZE </code> of 8192 requires that the compressed table have a <code class="literal"> KEY_BLOCK_SIZE </code> of 8. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa46936737"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts2<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts2.ibd'</span> <span class="token keyword">FILE_BLOCK_SIZE</span> <span class="token operator">=</span> <span class="token number">8192</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t4 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts2 <span class="token keyword">ROW_FORMAT</span><span class="token operator">=</span><span class="token keyword">COMPRESSED</span> <span class="token keyword">KEY_BLOCK_SIZE</span><span class="token operator">=</span><span class="token number">8</span><span class="token punctuation">;</span></code></pre> </div> <p> If you do not specify <code class="literal"> FILE_BLOCK_SIZE </code> when creating a general tablespace, <code class="literal"> FILE_BLOCK_SIZE </code> defaults to <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> . When <code class="literal"> FILE_BLOCK_SIZE </code> is equal to <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> , the tablespace may only contain tables with an uncompressed row format ( <code class="literal"> COMPACT </code> , <code class="literal"> REDUNDANT </code> , and <code class="literal"> DYNAMIC </code> row formats). </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-moving-non-partitioned-tables"> </a> Moving Tables Between Tablespaces Using ALTER TABLE </h5> </div> </div> </div> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> with the <code class="literal"> TABLESPACE </code> option can be used to move a table to an existing general tablespace, to a new file-per-table tablespace, or to the system tablespace. </p> <p> Adding table partitions to shared tablespaces is not supported. Shared tablespaces include the <code class="literal"> InnoDB </code> system tablespace and general tablespaces. </p> <p> To move a table from a file-per-table tablespace or from the system tablespace to a general tablespace, specify the name of the general tablespace. The general tablespace must exist. See <a class="link" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement"> <code class="literal"> ALTER TABLESPACE </code> </a> for more information. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa26357229"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> tbl_name <span class="token keyword">TABLESPACE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <em class="replaceable">tablespace_name</em><span class="token punctuation">;</span></code></pre> </div> <p> To move a table from a general tablespace or file-per-table tablespace to the system tablespace, specify <code class="literal"> innodb_system </code> as the tablespace name. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa76237607"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> tbl_name <span class="token keyword">TABLESPACE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> innodb_system<span class="token punctuation">;</span></code></pre> </div> <p> To move a table from the system tablespace or a general tablespace to a file-per-table tablespace, specify <code class="literal"> innodb_file_per_table </code> as the tablespace name. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa81104879"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> tbl_name <span class="token keyword">TABLESPACE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> innodb_file_per_table<span class="token punctuation">;</span></code></pre> </div> <p> <code class="literal"> ALTER TABLE ... TABLESPACE </code> operations cause a full table rebuild, even if the <code class="literal"> TABLESPACE </code> attribute has not changed from its previous value. </p> <p> <code class="literal"> ALTER TABLE ... TABLESPACE </code> syntax does not support moving a table from a temporary tablespace to a persistent tablespace. </p> <p> The <code class="literal"> DATA DIRECTORY </code> clause is permitted with <code class="literal"> CREATE TABLE ... TABLESPACE=innodb_file_per_table </code> but is otherwise not supported for use in combination with the <code class="literal"> TABLESPACE </code> option. The directory specified in a <code class="literal"> DATA DIRECTORY </code> clause must be known to <code class="literal"> InnoDB </code> . For more information, see <a class="xref" href="innodb-create-table-external.html#innodb-create-table-external-data-directory" title="Using the DATA DIRECTORY Clause"> Using the DATA DIRECTORY Clause </a> . </p> <p> Restrictions apply when moving tables from encrypted tablespaces. See <a class="xref" href="innodb-data-encryption.html#innodb-data-encryption-limitations" title="Encryption Limitations"> Encryption Limitations </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-renaming"> </a> Renaming a General Tablespace </h5> </div> </div> </div> <p> Renaming a general tablespace is supported using <a class="link" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement"> <code class="literal"> ALTER TABLESPACE ... RENAME TO </code> </a> syntax. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa67453619"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLESPACE</span> s1 <span class="token keyword">RENAME</span> <span class="token keyword">TO</span> s2<span class="token punctuation">;</span></code></pre> </div> <p> The <a class="link" href="privileges-provided.html#priv_create-tablespace"> <code class="literal"> CREATE TABLESPACE </code> </a> privilege is required to rename a general tablespace. </p> <p> <code class="literal"> RENAME TO </code> operations are implicitly performed in <a class="link" href="server-system-variables.html#sysvar_autocommit"> <code class="literal"> autocommit </code> </a> mode regardless of the <a class="link" href="server-system-variables.html#sysvar_autocommit"> <code class="literal"> autocommit </code> </a> setting. </p> <p> A <code class="literal"> RENAME TO </code> operation cannot be performed while <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES </code> </a> or <a class="link" href="flush.html" title="15.7.8.3 FLUSH Statement"> <code class="literal"> FLUSH TABLES WITH READ LOCK </code> </a> is in effect for tables that reside in the tablespace. </p> <p> Exclusive <a class="link" href="glossary.html#glos_metadata_lock" title="metadata lock"> metadata locks </a> are taken on tables within a general tablespace while the tablespace is renamed, which prevents concurrent DDL. Concurrent DML is supported. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-dropping"> </a> Dropping a General Tablespace </h5> </div> </div> </div> <p> The <a class="link" href="drop-tablespace.html" title="15.1.33 DROP TABLESPACE Statement"> <code class="literal"> DROP TABLESPACE </code> </a> statement is used to drop an <code class="literal"> InnoDB </code> general tablespace. </p> <p> All tables must be dropped from the tablespace prior to a <a class="link" href="drop-tablespace.html" title="15.1.33 DROP TABLESPACE Statement"> <code class="literal"> DROP TABLESPACE </code> </a> operation. If the tablespace is not empty, <a class="link" href="drop-tablespace.html" title="15.1.33 DROP TABLESPACE Statement"> <code class="literal"> DROP TABLESPACE </code> </a> returns an error. </p> <p> Use a query similar to the following to identify tables in a general tablespace. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa28439679"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> a<span class="token punctuation">.</span><span class="token keyword">NAME</span> <span class="token keyword">AS</span> space_name<span class="token punctuation">,</span> b<span class="token punctuation">.</span><span class="token keyword">NAME</span> <span class="token keyword">AS</span> <span class="token keyword">table_name</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_TABLESPACES a<span class="token punctuation">,</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_TABLES b <span class="token keyword">WHERE</span> a<span class="token punctuation">.</span>SPACE<span class="token operator">=</span>b<span class="token punctuation">.</span>SPACE <span class="token operator">AND</span> a<span class="token punctuation">.</span><span class="token keyword">NAME</span> <span class="token operator">LIKE</span> <span class="token string">'ts1'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> space_name <span class="token punctuation">\|</span> table_name <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> ts1 <span class="token punctuation">\|</span> test/t1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> ts1 <span class="token punctuation">\|</span> test/t2 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> ts1 <span class="token punctuation">\|</span> test/t3 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> A general <code class="literal"> InnoDB </code> tablespace is not deleted automatically when the last table in the tablespace is dropped. The tablespace must be dropped explicitly using <a class="link" href="drop-tablespace.html" title="15.1.33 DROP TABLESPACE Statement"> <code class="literal"> DROP TABLESPACE <em class="replaceable"> <code> tablespace_name </code> </em> </code> </a> . </p> <p> A general tablespace does not belong to any particular database. A <a class="link" href="drop-database.html" title="15.1.24 DROP DATABASE Statement"> <code class="literal"> DROP DATABASE </code> </a> operation can drop tables that belong to a general tablespace but it cannot drop the tablespace, even if the <a class="link" href="drop-database.html" title="15.1.24 DROP DATABASE Statement"> <code class="literal"> DROP DATABASE </code> </a> operation drops all tables that belong to the tablespace. </p> <p> Similar to the system tablespace, truncating or dropping tables stored in a general tablespace creates free space internally in the general tablespace <a class="link" href="glossary.html#glos_ibd_file" title=".ibd file"> .ibd data file </a> which can only be used for new <code class="literal"> InnoDB </code> data. Space is not released back to the operating system as it is when a file-per-table tablespace is deleted during a <a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement"> <code class="literal"> DROP TABLE </code> </a> operation. </p> <p> This example demonstrates how to drop an <code class="literal"> InnoDB </code> general tablespace. The general tablespace <code class="literal"> ts1 </code> is created with a single table. The table must be dropped before dropping the tablespace. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa34621784"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts1.ibd'</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts1 <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">DROP</span> <span class="token keyword">TABLE</span> t1<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">DROP</span> <span class="token keyword">TABLESPACE</span> ts1<span class="token punctuation">;</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <code class="literal"> <em class="replaceable"> <code> tablespace_name </code> </em> </code> is a case-sensitive identifier in MySQL. </p> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-limitations"> </a> General Tablespace Limitations </h5> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A generated or existing tablespace cannot be changed to a general tablespace. </p> </li> <li class="listitem"> <p> Creation of temporary general tablespaces is not supported. </p> </li> <li class="listitem"> <p> General tablespaces do not support temporary tables. </p> </li> <li class="listitem"> <p> Similar to the system tablespace, truncating or dropping tables stored in a general tablespace creates free space internally in the general tablespace <a class="link" href="glossary.html#glos_ibd_file" title=".ibd file"> .ibd data file </a> which can only be used for new <code class="literal"> InnoDB </code> data. Space is not released back to the operating system as it is for <a class="link" href="glossary.html#glos_file_per_table" title="file-per-table"> file-per-table </a> tablespaces. </p> <p> Additionally, a table-copying <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operation on table that resides in a shared tablespace (a general tablespace or the system tablespace) can increase the amount of space used by the tablespace. Such operations require as much additional space as the data in the table plus indexes. The additional space required for the table-copying <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operation is not released back to the operating system as it is for file-per-table tablespaces. </p> </li> <li class="listitem"> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE ... DISCARD TABLESPACE </code> </a> and <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE ...IMPORT TABLESPACE </code> </a> are not supported for tables that belong to a general tablespace. </p> </li> <li class="listitem"> <p> Placing table partitions in general tablespaces is not supported. </p> </li> <li class="listitem"> <p> The <code class="literal"> ADD DATAFILE </code> clause is not supported in a replication environment where the source and replica reside on the same host, as it would cause the source and replica to create a tablespace of the same name in the same location, which is not supported. However, if the <code class="literal"> ADD DATAFILE </code> clause is omitted, the tablespace is created in the data directory with a generated file name that is unique, which is permitted. </p> </li> <li class="listitem"> <p> General tablespaces cannot be created in the undo tablespace directory ( <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> ) unless that directly is known to <code class="literal"> InnoDB </code> . Known directories are those defined by the <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="literal"> datadir </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> , and <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> variables. </p> </li> </ul> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/x-plugin-sha2-cache-plugin.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="x-plugin-sha2-cache-plugin"> </a> 22.5.4 Using X Plugin with the Caching SHA-2 Authentication Plugin </h3> </div> </div> </div> <p> X Plugin supports MySQL user accounts created with the <code class="literal"> caching_sha2_password </code> authentication plugin. For more information on this plugin, see <a class="xref" href="caching-sha2-pluggable-authentication.html" title="8.4.1.2 Caching SHA-2 Pluggable Authentication"> Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication” </a> . You can use X Plugin to authenticate against such accounts using non-SSL connections with <code class="literal"> SHA256_MEMORY </code> authentication and SSL connections with <code class="literal"> PLAIN </code> authentication. </p> <p> Although the <code class="literal"> caching_sha2_password </code> authentication plugin holds an authentication cache, this cache is not shared with X Plugin, so X Plugin uses its own authentication cache for <code class="literal"> SHA256_MEMORY </code> authentication. The X Plugin authentication cache stores hashes of user account passwords, and cannot be accessed using SQL. If a user account is modified or removed, the relevant entries are removed from the cache. The X Plugin authentication cache is maintained by the <code class="literal"> mysqlx_cache_cleaner </code> plugin, which is enabled by default, and has no related system variables or status variables. </p> <p> Before you can use non-SSL X Protocol connections to authenticate an account that uses the <code class="literal"> caching_sha2_password </code> authentication plugin, the account must have authenticated at least once over an X Protocol connection with SSL, to supply the password to the X Plugin authentication cache. Once this initial authentication over SSL has succeeded, non-SSL X Protocol connections can be used. </p> <p> It is possible to disable the <code class="literal"> mysqlx_cache_cleaner </code> plugin by starting the MySQL server with the option <code class="literal"> --mysqlx_cache_cleaner=0 </code> . If you do this, the X Plugin authentication cache is disabled, and therefore SSL must always be used for X Protocol connections when authenticating with <code class="literal"> SHA256_MEMORY </code> authentication. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/charset-introducer.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="charset-introducer"> </a> 12.3.8 Character Set Introducers </h3> </div> </div> </div> <a class="indexterm" name="idm46045217606656"> </a> <a class="indexterm" name="idm46045217605200"> </a> <p> A character string literal, hexadecimal literal, or bit-value literal may have an optional character set introducer and <code class="literal"> COLLATE </code> clause, to designate it as a string that uses a particular character set and collation: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa58358720"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">[</span>_<em class="replaceable">charset_name</em><span class="token punctuation">]</span> <em class="replaceable">literal</em> <span class="token punctuation">[</span><span class="token keyword">COLLATE</span> <em class="replaceable">collation_name</em><span class="token punctuation">]</span></code></pre> </div> <p> The <code class="literal"> _ <em class="replaceable"> <code> charset_name </code> </em> </code> expression is formally called an <span class="emphasis"> <em> introducer </em> </span> . It tells the parser, <span class="quote"> “ <span class="quote"> the string that follows uses character set <em class="replaceable"> <code> charset_name </code> </em> . </span> ” </span> An introducer does not change the string to the introducer character set like <a class="link" href="cast-functions.html#function_convert"> <code class="literal"> CONVERT() </code> </a> would do. It does not change the string value, although padding may occur. The introducer is just a signal. </p> <p> For character string literals, space between the introducer and the string is permitted but optional. </p> <p> For character set literals, an introducer indicates the character set for the following string, but does not change how the parser performs escape processing within the string. Escapes are always interpreted by the parser according to the character set given by <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> <code class="literal"> character_set_connection </code> </a> . For additional discussion and examples, see <a class="xref" href="charset-literal.html" title="12.3.6 Character String Literal Character Set and Collation"> Section 12.3.6, “Character String Literal Character Set and Collation” </a> . </p> <p> Examples: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78023428"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token string">'abc'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1<span class="token string">'abc'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _binary<span class="token string">'abc'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4<span class="token string">'abc'</span> <span class="token keyword">COLLATE</span> utf8mb4_danish_ci<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1 X<span class="token string">'4D7953514C'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4 <span class="token number">0x4D7953514C</span> <span class="token keyword">COLLATE</span> utf8mb4_danish_ci<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1 b<span class="token string">'1000001'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4 <span class="token number">0b1000001</span> <span class="token keyword">COLLATE</span> utf8mb4_danish_ci<span class="token punctuation">;</span></code></pre> </div> <p> Character set introducers and the <code class="literal"> COLLATE </code> clause are implemented according to standard SQL specifications. </p> <p> Character string literals can be designated as binary strings by using the <code class="literal"> _binary </code> introducer. Hexadecimal literals and bit-value literals are binary strings by default, so <code class="literal"> _binary </code> is permitted, but normally unnecessary. <code class="literal"> _binary </code> may be useful to preserve a hexadecimal or bit literal as a binary string in contexts for which the literal is otherwise treated as a number. For example, bit operations permit numeric or binary string arguments in MySQL 8.4 and higher, but treat hexadecimal and bit literals as numbers by default. To explicitly specify binary string context for such literals, use a <code class="literal"> _binary </code> introducer for at least one of the arguments: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa66025281"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@v1</span> <span class="token operator">=</span> X<span class="token string">'000D'</span> <span class="token operator">\|</span> X<span class="token string">'0BC0'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@v2</span> <span class="token operator">=</span> _binary X<span class="token string">'000D'</span> <span class="token operator">\|</span> X<span class="token string">'0BC0'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">HEX</span><span class="token punctuation">(</span><span class="token variable">@v1</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">HEX</span><span class="token punctuation">(</span><span class="token variable">@v2</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> HEX(@v1) <span class="token punctuation">\|</span> HEX(@v2) <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> BCD <span class="token punctuation">\|</span> 0BCD <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> The displayed result appears similar for both bit operations, but the result without <code class="literal"> _binary </code> is a <code class="literal"> BIGINT </code> value, whereas the result with <code class="literal"> _binary </code> is a binary string. Due to the difference in result types, the displayed values differ: High-order 0 digits are not displayed for the numeric result. </p> <p> MySQL determines the character set and collation of a character string literal, hexadecimal literal, or bit-value literal in the following manner: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If both <em class="replaceable"> <code> _charset_name </code> </em> and <code class="literal"> COLLATE <em class="replaceable"> <code> collation_name </code> </em> </code> are specified, character set <em class="replaceable"> <code> charset_name </code> </em> and collation <em class="replaceable"> <code> collation_name </code> </em> are used. <em class="replaceable"> <code> collation_name </code> </em> must be a permitted collation for <em class="replaceable"> <code> charset_name </code> </em> . </p> </li> <li class="listitem"> <p> If <em class="replaceable"> <code> _charset_name </code> </em> is specified but <code class="literal"> COLLATE </code> is not specified, character set <em class="replaceable"> <code> charset_name </code> </em> and its default collation are used. To see the default collation for each character set, use the <a class="link" href="show-character-set.html" title="15.7.7.4 SHOW CHARACTER SET Statement"> <code class="literal"> SHOW CHARACTER SET </code> </a> statement or query the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-character-sets-table.html" title="28.3.4 The INFORMATION_SCHEMA CHARACTER_SETS Table"> <code class="literal"> CHARACTER_SETS </code> </a> table. </p> </li> <li class="listitem"> <p> If <em class="replaceable"> <code> _charset_name </code> </em> is not specified but <code class="literal"> COLLATE <em class="replaceable"> <code> collation_name </code> </em> </code> is specified: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> For a character string literal, the connection default character set given by the <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> <code class="literal"> character_set_connection </code> </a> system variable and collation <em class="replaceable"> <code> collation_name </code> </em> are used. <em class="replaceable"> <code> collation_name </code> </em> must be a permitted collation for the connection default character set. </p> </li> <li class="listitem"> <p> For a hexadecimal literal or bit-value literal, the only permitted collation is <code class="literal"> binary </code> because these types of literals are binary strings by default. </p> </li> </ul> </div> </li> <li class="listitem"> <p> Otherwise (neither <em class="replaceable"> <code> _charset_name </code> </em> nor <code class="literal"> COLLATE <em class="replaceable"> <code> collation_name </code> </em> </code> is specified): </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> For a character string literal, the connection default character set and collation given by the <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> <code class="literal"> character_set_connection </code> </a> and <a class="link" href="server-system-variables.html#sysvar_collation_connection"> <code class="literal"> collation_connection </code> </a> system variables are used. </p> </li> <li class="listitem"> <p> For a hexadecimal literal or bit-value literal, the character set and collation are <code class="literal"> binary </code> . </p> </li> </ul> </div> </li> </ul> </div> <p> Examples: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Nonbinary strings with <code class="literal"> latin1 </code> character set and <code class="literal"> latin1_german1_ci </code> collation: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa91008324"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> _latin1<span class="token string">'Müller'</span> <span class="token keyword">COLLATE</span> latin1_german1_ci<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1 X<span class="token string">'0A0D'</span> <span class="token keyword">COLLATE</span> latin1_german1_ci<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1 b<span class="token string">'0110'</span> <span class="token keyword">COLLATE</span> latin1_german1_ci<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> Nonbinary strings with <code class="literal"> utf8mb4 </code> character set and its default collation (that is, <code class="literal"> utf8mb4_0900_ai_ci </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa39178445"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> _utf8mb4<span class="token string">'Müller'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4 X<span class="token string">'0A0D'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4 b<span class="token string">'0110'</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> Binary strings with <code class="literal"> binary </code> character set and its default collation (that is, <code class="literal"> binary </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa39233732"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> _binary<span class="token string">'Müller'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> X<span class="token string">'0A0D'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> b<span class="token string">'0110'</span><span class="token punctuation">;</span></code></pre> </div> <p> The hexadecimal literal and bit-value literal need no introducer because they are binary strings by default. </p> </li> <li class="listitem"> <p> A nonbinary string with the connection default character set and <code class="literal"> utf8mb4_0900_ai_ci </code> collation (fails if the connection character set is not <code class="literal"> utf8mb4 </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa13055279"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token string">'Müller'</span> <span class="token keyword">COLLATE</span> utf8mb4_0900_ai_ci<span class="token punctuation">;</span></code></pre> </div> <p> This construction ( <code class="literal"> COLLATE </code> only) does not work for hexadecimal literals or bit literals because their character set is <code class="literal"> binary </code> no matter the connection character set, and <code class="literal"> binary </code> is not compatible with the <code class="literal"> utf8mb4_0900_ai_ci </code> collation. The only permitted <code class="literal"> COLLATE </code> clause in the absence of an introducer is <code class="literal"> COLLATE binary </code> . </p> </li> <li class="listitem"> <p> A string with the connection default character set and collation: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa12154941"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token string">'Müller'</span><span class="token punctuation">;</span></code></pre> </div> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/ipv6-system-support.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="ipv6-system-support"> </a> 7.1.13.1 Verifying System Support for IPv6 </h4> </div> </div> </div> <p> Before MySQL Server can accept IPv6 connections, the operating system on your server host must support IPv6. As a simple test to determine whether that is true, try this command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa79199387"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">ping6</span> <span class="token punctuation">:</span><span class="token punctuation">:</span>1 16 bytes from <span class="token punctuation">:</span><span class="token punctuation">:</span>1<span class="token punctuation">,</span> icmp_seq<span class="token attr-value"><span class="token punctuation">=</span>0</span> hlim<span class="token attr-value"><span class="token punctuation">=</span>64</span> time<span class="token attr-value"><span class="token punctuation">=</span>0.171</span> ms 16 bytes from <span class="token punctuation">:</span><span class="token punctuation">:</span>1<span class="token punctuation">,</span> icmp_seq<span class="token attr-value"><span class="token punctuation">=</span>1</span> hlim<span class="token attr-value"><span class="token punctuation">=</span>64</span> time<span class="token attr-value"><span class="token punctuation">=</span>0.077</span> ms <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> To produce a description of your system's network interfaces, invoke <span class="command"> <strong> ifconfig -a </strong> </span> and look for IPv6 addresses in the output. </p> <p> If your host does not support IPv6, consult your system documentation for instructions on enabling it. It might be that you need only reconfigure an existing network interface to add an IPv6 address. Or a more extensive change might be needed, such as rebuilding the kernel with IPv6 options enabled. </p> <p> These links may be helpful in setting up IPv6 on various platforms: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="ulink" href="https://msdn.microsoft.com/en-us/library/dd163569.aspx" target="_blank"> Windows </a> </p> </li> <li class="listitem"> <p> <a class="ulink" href="http://www.gentoo.org/doc/en/ipv6.xml" target="_blank"> Gentoo Linux </a> </p> </li> <li class="listitem"> <p> <a class="ulink" href="https://wiki.ubuntu.com/IPv6" target="_blank"> Ubuntu Linux </a> </p> </li> <li class="listitem"> <p> <a class="ulink" href="http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/" target="_blank"> Linux (Generic) </a> </p> </li> <li class="listitem"> <p> <a class="ulink" href="https://support.apple.com/en-us/HT202237" target="_blank"> macOS </a> </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/linux-installation-docker.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="linux-installation-docker"> </a> 2.5.6 Deploying MySQL on Linux with Docker Containers </h3> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="docker-mysql-getting-started.html"> 2.5.6.1 Basic Steps for MySQL Server Deployment with Docker </a> </span> </dt> <dt> <span class="section"> <a href="docker-mysql-more-topics.html"> 2.5.6.2 More Topics on Deploying MySQL Server with Docker </a> </span> </dt> <dt> <span class="section"> <a href="deploy-mysql-nonlinux-docker.html"> 2.5.6.3 Deploying MySQL on Windows and Other Non-Linux Platforms with Docker </a> </span> </dt> </dl> </div> <p> This section explains how to deploy MySQL Server using Docker containers. </p> <p> While the <code class="literal"> docker </code> client is used in the following instructions for demonstration purposes, in general, the MySQL container images provided by Oracle work with any container tools that are compliant with the <a class="ulink" href="https://opencontainers.org/posts/announcements/2021-05-04-oci-dist-spec-v1/" target="_blank"> OCI 1.0 specification </a> . </p> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> Before deploying MySQL with Docker containers, make sure you understand the security risks of running containers and mitigate them properly. </p> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/data-directory-initialization.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="data-directory-initialization"> </a> 2.9.1 Initializing the Data Directory </h3> </div> </div> </div> <p> After MySQL is installed, the data directory must be initialized, including the tables in the <code class="literal"> mysql </code> system schema: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For some MySQL installation methods, data directory initialization is automatic, as described in <a class="xref" href="postinstallation.html" title="2.9 Postinstallation Setup and Testing"> Section 2.9, “Postinstallation Setup and Testing” </a> . </p> </li> <li class="listitem"> <p> For other installation methods, you must initialize the data directory manually. These include installation from generic binary and source distributions on Unix and Unix-like systems, and installation from a ZIP Archive package on Windows. </p> </li> </ul> </div> <p> This section describes how to initialize the data directory manually for MySQL installation methods for which data directory initialization is not automatic. For some suggested commands that enable testing whether the server is accessible and working properly, see <a class="xref" href="testing-server.html" title="2.9.3 Testing the Server"> Section 2.9.3, “Testing the Server” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The default authentication plugin is <code class="literal"> caching_sha2_password </code> , and the <code class="literal"> 'root'@'localhost' </code> administrative account uses <code class="literal"> caching_sha2_password </code> by default. </p> <p> <a class="link" href="native-pluggable-authentication.html" title="8.4.1.1 Native Pluggable Authentication"> mysql_native_password </a> (the default authentication plugin prior to MySQL 8.0) is still supported but disabled by default as of MySQL 8.4.0 and removed as of MySQL 9.0.0. </p> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="data-directory-initialization.html#data-directory-initialization-overview" title="Data Directory Initialization Overview"> Data Directory Initialization Overview </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="data-directory-initialization.html#data-directory-initialization-procedure" title="Data Directory Initialization Procedure"> Data Directory Initialization Procedure </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="data-directory-initialization.html#data-directory-initialization-server-actions" title="Server Actions During Data Directory Initialization"> Server Actions During Data Directory Initialization </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="data-directory-initialization.html#data-directory-initialization-password-assignment" title="Post-Initialization root Password Assignment"> Post-Initialization root Password Assignment </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="data-directory-initialization-overview"> </a> Data Directory Initialization Overview </h4> </div> </div> </div> <p> In the examples shown here, the server is intended to run under the user ID of the <code class="literal"> mysql </code> login account. Either create the account if it does not exist (see <a class="xref" href="binary-installation.html#binary-installation-createsysuser" title="Create a mysql User and Group"> Create a mysql User and Group </a> ), or substitute the name of a different existing login account that you plan to use for running the server. </p> <a class="indexterm" name="idm46045327073952"> </a> <a class="indexterm" name="idm46045327072464"> </a> <a class="indexterm" name="idm46045327070976"> </a> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Change location to the top-level directory of your MySQL installation, which is typically <code class="filename"> /usr/local/mysql </code> (adjust the path name for your system as necessary): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa90223312"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cd /usr/local/mysql</code></pre> </div> <p> Within this directory you can find several files and subdirectories, including the <code class="filename"> bin </code> subdirectory that contains the server, as well as client and utility programs. </p> </li> <li class="listitem"> <p> The <a class="link" href="server-system-variables.html#sysvar_secure_file_priv"> <code class="literal"> secure_file_priv </code> </a> system variable limits import and export operations to a specific directory. Create a directory whose location can be specified as the value of that variable: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa23812799"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mkdir mysql-files</code></pre> </div> <p> Grant directory user and group ownership to the <code class="literal"> mysql </code> user and <code class="literal"> mysql </code> group, and set the directory permissions appropriately: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa47169968"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">chown mysql<span class="token punctuation">:</span>mysql mysql-files chmod 750 mysql-files</code></pre> </div> </li> <li class="listitem"> <p> Use the server to initialize the data directory, including the <code class="literal"> mysql </code> schema containing the initial MySQL grant tables that determine how users are permitted to connect to the server. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa12273579"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld <span class="token property">--initialize</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span></code></pre> </div> <p> For important information about the command, especially regarding command options you might use, see <a class="xref" href="data-directory-initialization.html#data-directory-initialization-procedure" title="Data Directory Initialization Procedure"> Data Directory Initialization Procedure </a> . For details about how the server performs initialization, see <a class="xref" href="data-directory-initialization.html#data-directory-initialization-server-actions" title="Server Actions During Data Directory Initialization"> Server Actions During Data Directory Initialization </a> . </p> <p> Typically, data directory initialization need be done only after you first install MySQL. (For upgrades to an existing installation, perform the upgrade procedure instead; see <a class="xref" href="upgrading.html" title="Chapter 3 Upgrading MySQL"> Chapter 3, <i> Upgrading MySQL </i> </a> .) However, the command that initializes the data directory does not overwrite any existing <code class="literal"> mysql </code> schema tables, so it is safe to run in any circumstances. </p> </li> <li class="listitem"> <p> In the absence of any option files, the server starts with its default settings. (See <a class="xref" href="server-configuration-defaults.html" title="7.1.2 Server Configuration Defaults"> Section 7.1.2, “Server Configuration Defaults” </a> .) To explicitly specify options that the MySQL server should use at startup, put them in an option file such as <code class="filename"> /etc/my.cnf </code> or <code class="filename"> /etc/mysql/my.cnf </code> . (See <a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files"> Section 6.2.2.2, “Using Option Files” </a> .) For example, you can use an option file to set the <a class="link" href="server-system-variables.html#sysvar_secure_file_priv"> <code class="literal"> secure_file_priv </code> </a> system variable. </p> </li> <li class="listitem"> <p> To arrange for MySQL to start without manual intervention at system boot time, see <a class="xref" href="automatic-start.html" title="2.9.5 Starting and Stopping MySQL Automatically"> Section 2.9.5, “Starting and Stopping MySQL Automatically” </a> . </p> </li> <li class="listitem"> <p> Data directory initialization creates time zone tables in the <code class="literal"> mysql </code> schema but does not populate them. To do so, use the instructions in <a class="xref" href="time-zone-support.html" title="7.1.15 MySQL Server Time Zone Support"> Section 7.1.15, “MySQL Server Time Zone Support” </a> . </p> </li> </ol> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="data-directory-initialization-procedure"> </a> Data Directory Initialization Procedure </h4> </div> </div> </div> <p> Change location to the top-level directory of your MySQL installation, which is typically <code class="filename"> /usr/local/mysql </code> (adjust the path name for your system as necessary): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa63496349"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cd /usr/local/mysql</code></pre> </div> <p> To initialize the data directory, invoke <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> with the <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> or <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> option, depending on whether you want the server to generate a random initial password for the <code class="literal"> 'root'@'localhost' </code> account, or to create that account with no password: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Use <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> for <span class="quote"> “ <span class="quote"> secure by default </span> ” </span> installation (that is, including generation of a random initial <code class="literal"> root </code> password). In this case, the password is marked as expired and you must choose a new one. </p> </li> <li class="listitem"> <p> With <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> , no <code class="literal"> root </code> password is generated. This is insecure; it is assumed that you intend to assign a password to the account in a timely fashion before putting the server into production use. </p> </li> </ul> </div> <p> For instructions on assigning a new <code class="literal"> 'root'@'localhost' </code> password, see <a class="xref" href="data-directory-initialization.html#data-directory-initialization-password-assignment" title="Post-Initialization root Password Assignment"> Post-Initialization root Password Assignment </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The server writes any messages (including any initial password) to its standard error output. This may be redirected to the error log, so look there if you do not see the messages on your screen. For information about the error log, including where it is located, see <a class="xref" href="error-log.html" title="7.4.2 The Error Log"> Section 7.4.2, “The Error Log” </a> . </p> <p> On Windows, use the <a class="link" href="server-options.html#option_mysqld_console"> <code class="option"> --console </code> </a> option to direct messages to the console. </p> </div> <p> On Unix and Unix-like systems, it is important for the database directories and files to be owned by the <code class="literal"> mysql </code> login account so that the server has read and write access to them when you run it later. To ensure this, start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> from the system <code class="literal"> root </code> account and include the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user </code> </a> option as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa69089509"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld <span class="token property">--initialize</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span> bin/mysqld <span class="token property">--initialize-insecure</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span></code></pre> </div> <p> Alternatively, execute <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> while logged in as <code class="literal"> mysql </code> , in which case you can omit the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user </code> </a> option from the command. </p> <p> On Windows, use one of these commands: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa83067570"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin\mysqld <span class="token property">--initialize</span> <span class="token property">--console</span> bin\mysqld <span class="token property">--initialize-insecure</span> <span class="token property">--console</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Data directory initialization might fail if required system libraries are missing. For example, you might see an error like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa55693411"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld<span class="token punctuation">:</span> error while loading shared libraries<span class="token punctuation">:</span> libnuma<span class="token punctuation">.</span>so<span class="token punctuation">.</span>1<span class="token punctuation">:</span> cannot open shared object file<span class="token punctuation">:</span> No such file or directory</code></pre> </div> <p> If this happens, you must install the missing libraries manually or with your system's package manager. Then retry the data directory initialization command. </p> </div> <p> It might be necessary to specify other options such as <a class="link" href="server-system-variables.html#sysvar_basedir"> <code class="option"> --basedir </code> </a> or <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="option"> --datadir </code> </a> if <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> cannot identify the correct locations for the installation directory or data directory. For example (enter the command on a single line): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa80670114"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld <span class="token property">--initialize</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span> <span class="token constant">--basedir</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql</span> <span class="token constant">--datadir</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql/data</span></code></pre> </div> <p> Alternatively, put the relevant option settings in an option file and pass the name of that file to <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . For Unix and Unix-like systems, suppose that the option file name is <code class="filename"> /opt/mysql/mysql/etc/my.cnf </code> . Put these lines in the file: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa73864818"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">basedir</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql</span> <span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql/data</span></code></pre> </div> <p> Then invoke <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as follows (enter the command on a single line, with the <a class="link" href="option-file-options.html#option_general_defaults-file"> <code class="option"> --defaults-file </code> </a> option first): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa83307501"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld <span class="token constant">--defaults-file</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql/etc/my.cnf</span> <span class="token property">--initialize</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span></code></pre> </div> <p> On Windows, suppose that <code class="filename"> C:\my.ini </code> contains these lines: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa43791165"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">basedir</span><span class="token attr-value"><span class="token punctuation">=</span>C:\\Program Files\\MySQL\\MySQL Server 8.4</span> <span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>D:\\MySQLdata</span></code></pre> </div> <p> Then invoke <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as follows (again, you should enter the command on a single line, with the <a class="link" href="option-file-options.html#option_general_defaults-file"> <code class="option"> --defaults-file </code> </a> option first): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa35560823"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin\mysqld <span class="token constant">--defaults-file</span><span class="token attr-value"><span class="token punctuation">=</span>C:\my.ini</span> <span class="token property">--initialize</span> <span class="token property">--console</span></code></pre> </div> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> When initializing the data directory, you should not specify any options other than those used for setting directory locations such as <a class="link" href="server-system-variables.html#sysvar_basedir"> <code class="option"> --basedir </code> </a> or <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="option"> --datadir </code> </a> , and the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user </code> </a> option if needed. Options to be employed by the MySQL server during normal use can be set when restarting it following initialization. See the description of the <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> option for further information. </p> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="data-directory-initialization-server-actions"> </a> Server Actions During Data Directory Initialization </h4> </div> </div> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The data directory initialization sequence performed by the server does not substitute for the actions performed by <a class="link" href="mysql-secure-installation.html" title="6.4.2 mysql_secure_installation — Improve MySQL Installation Security"> <span class="command"> <strong> mysql_secure_installation </strong> </span> </a> . </p> </div> <p> When invoked with the <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> or <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> option, <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> performs the following actions during the data directory initialization sequence: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> The server checks for the existence of the data directory as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If no data directory exists, the server creates it. </p> </li> <li class="listitem"> <p> If the data directory exists but is not empty (that is, it contains files or subdirectories), the server exits after producing an error message: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa4231181"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[ERROR] --initialize specified but the data directory exists. Aborting.</code></pre> </div> <p> In this case, remove or rename the data directory and try again. </p> <p> An existing data directory is permitted to be nonempty if every entry has a name that begins with a period ( <code class="literal"> . </code> ). </p> </li> </ul> </div> </li> <li class="listitem"> <p> Within the data directory, the server creates the <code class="literal"> mysql </code> system schema and its tables, including the data dictionary tables, grant tables, time zone tables, and server-side help tables. See <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> . </p> </li> <li class="listitem"> <p> The server initializes the <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> and related data structures needed to manage <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> tables. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> After <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> sets up the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> , certain changes to tablespace characteristics require setting up a whole new <a class="link" href="glossary.html#glos_instance" title="instance"> instance </a> . Qualifying changes include the file name of the first file in the system tablespace and the number of undo logs. If you do not want to use the default values, make sure that the settings for the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> configuration parameters are in place in the MySQL <a class="link" href="glossary.html#glos_configuration_file" title="configuration file"> configuration file </a> <span class="emphasis"> <em> before </em> </span> running <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . Also make sure to specify as necessary other parameters that affect the creation and location of <code class="literal"> InnoDB </code> files, such as <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> <code class="literal"> innodb_log_group_home_dir </code> </a> . </p> <p> If those options are in your configuration file but that file is not in a location that MySQL reads by default, specify the file location using the <a class="link" href="server-options.html#option_mysqld_defaults-extra-file"> <code class="option"> --defaults-extra-file </code> </a> option when you run <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . </p> </div> </li> <li class="listitem"> <p> The server creates a <code class="literal"> 'root'@'localhost' </code> superuser account and other reserved accounts (see <a class="xref" href="reserved-accounts.html" title="8.2.9 Reserved Accounts"> Section 8.2.9, “Reserved Accounts” </a> ). Some reserved accounts are locked and cannot be used by clients, but <code class="literal"> 'root'@'localhost' </code> is intended for administrative use and you should assign it a password. </p> <p> Server actions with respect to a password for the <code class="literal"> 'root'@'localhost' </code> account depend on how you invoke it: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> With <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> but not <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> , the server generates a random password, marks it as expired, and writes a message displaying the password: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa62666523"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[Warning] A temporary password is generated for root@localhost: iTag*AfrH5ej</code></pre> </div> </li> <li class="listitem"> <p> With <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> , (either with or without <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> because <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> implies <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> ), the server does not generate a password or mark it expired, and writes a warning message: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa3187855"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[Warning] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option.</code></pre> </div> </li> </ul> </div> <p> For instructions on assigning a new <code class="literal"> 'root'@'localhost' </code> password, see <a class="xref" href="data-directory-initialization.html#data-directory-initialization-password-assignment" title="Post-Initialization root Password Assignment"> Post-Initialization root Password Assignment </a> . </p> </li> <li class="listitem"> <p> The server populates the server-side help tables used for the <a class="link" href="help.html" title="15.8.3 HELP Statement"> <code class="literal"> HELP </code> </a> statement (see <a class="xref" href="help.html" title="15.8.3 HELP Statement"> Section 15.8.3, “HELP Statement” </a> ). The server does not populate the time zone tables. To do so manually, see <a class="xref" href="time-zone-support.html" title="7.1.15 MySQL Server Time Zone Support"> Section 7.1.15, “MySQL Server Time Zone Support” </a> . </p> </li> <li class="listitem"> <p> If the <a class="link" href="server-system-variables.html#sysvar_init_file"> <code class="literal"> init_file </code> </a> system variable was given to name a file of SQL statements, the server executes the statements in the file. This option enables you to perform custom bootstrapping sequences. </p> <p> When the server operates in bootstrap mode, some functionality is unavailable that limits the statements permitted in the file. These include statements that relate to account management (such as <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> or <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> ), replication, and global transaction identifiers. </p> </li> <li class="listitem"> <p> The server exits. </p> </li> </ol> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="data-directory-initialization-password-assignment"> </a> Post-Initialization root Password Assignment </h4> </div> </div> </div> <p> After you initialize the data directory by starting the server with <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> or <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> , start the server normally (that is, without either of those options) and assign the <code class="literal"> 'root'@'localhost' </code> account a new password: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Start the server. For instructions, see <a class="xref" href="starting-server.html" title="2.9.2 Starting the Server"> Section 2.9.2, “Starting the Server” </a> . </p> </li> <li class="listitem"> <p> Connect to the server: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If you used <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> but not <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> to initialize the data directory, connect to the server as <code class="literal"> root </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa63561512"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token property">-u</span> root <span class="token property">-p</span></code></pre> </div> <p> Then, at the password prompt, enter the random password that the server generated during the initialization sequence: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa6595132"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">Enter password: <em class="replaceable">(enter the random root password here)</em></code></pre> </div> <p> Look in the server error log if you do not know this password. </p> </li> <li class="listitem"> <p> If you used <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> to initialize the data directory, connect to the server as <code class="literal"> root </code> without a password: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa45198081"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token property">-u</span> root <span class="token property">--skip-password</span></code></pre> </div> </li> </ul> </div> </li> <li class="listitem"> <p> After connecting, use an <a class="link" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> <code class="literal"> ALTER USER </code> </a> statement to assign a new <code class="literal"> root </code> password: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa71794246"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">USER</span> <span class="token string">'root'</span>@<span class="token string">'localhost'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">root-password'</em></span><span class="token punctuation">;</span></code></pre> </div> </li> </ol> </div> <p> See also <a class="xref" href="default-privileges.html" title="2.9.4 Securing the Initial MySQL Account"> Section 2.9.4, “Securing the Initial MySQL Account” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Attempts to connect to the host <code class="literal"> 127.0.0.1 </code> normally resolve to the <code class="literal"> localhost </code> account. However, this fails if the server is run with <a class="link" href="server-system-variables.html#sysvar_skip_name_resolve"> <code class="literal"> skip_name_resolve </code> </a> enabled. If you plan to do that, make sure that an account exists that can accept a connection. For example, to be able to connect as <code class="literal"> root </code> using <code class="option"> --host=127.0.0.1 </code> or <code class="option"> --host=::1 </code> , create these accounts: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa46116313"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'root'</span>@<span class="token string">'127.0.0.1'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">root-password</em>'</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'root'</span>@<span class="token string">'::1'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">root-password</em>'</span><span class="token punctuation">;</span></code></pre> </div> <p> It is possible to put those statements in a file to be executed using the <a class="link" href="server-system-variables.html#sysvar_init_file"> <code class="literal"> init_file </code> </a> system variable, as discussed in <a class="xref" href="data-directory-initialization.html#data-directory-initialization-server-actions" title="Server Actions During Data Directory Initialization"> Server Actions During Data Directory Initialization </a> . </p> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-oci-marketplace-prereqs.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="mysql-oci-marketplace-prereqs"> </a> 34.1 Prerequisites to Deploying MySQL EE on Oracle Cloud Infrastructure </h2> </div> </div> </div> <p> The following assumptions are made: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> You are familiar with OCI terminology. If you are new to OCI, see <a class="ulink" href="https://docs.cloud.oracle.com/iaas/Content/GSG/Concepts/baremetalintro.htm" target="_blank"> Getting Started </a> . </p> </li> <li class="listitem"> <p> You have access to a properly configured Virtual Cloud Network (VCN) and subnet. For more information, see <a class="ulink" href="https://docs.cloud.oracle.com/iaas/Content/Network/Tasks/quickstartnetworking.htm" target="_blank"> Virtual Networking </a> . </p> </li> <li class="listitem"> <p> You have the permissions required to deploy OCI Marketplace applications in a compartment of your tenancy. For more information, see <a class="ulink" href="https://docs.cloud.oracle.com/iaas/Content/Identity/Concepts/policies.htm" target="_blank"> How Policies Work </a> . </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/request-access.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="request-access"> </a> 8.2.7 Access Control, Stage 2: Request Verification </h3> </div> </div> </div> <p> After the server accepts a connection, it enters Stage 2 of access control. For each request that you issue through the connection, the server determines what operation you want to perform, then checks whether your privileges are sufficient. This is where the privilege columns in the grant tables come into play. These privileges can come from any of the <code class="literal"> user </code> , <code class="literal"> global_grants </code> , <code class="literal"> db </code> , <code class="literal"> tables_priv </code> , <code class="literal"> columns_priv </code> , or <code class="literal"> procs_priv </code> tables. (You may find it helpful to refer to <a class="xref" href="grant-tables.html" title="8.2.3 Grant Tables"> Section 8.2.3, “Grant Tables” </a> , which lists the columns present in each grant table.) </p> <a class="indexterm" name="idm46045249694096"> </a> <p> The <code class="literal"> user </code> and <code class="literal"> global_grants </code> tables grant global privileges. The rows in these tables for a given account indicate the account privileges that apply on a global basis no matter what the default database is. For example, if the <code class="literal"> user </code> table grants you the <a class="link" href="privileges-provided.html#priv_delete"> <code class="literal"> DELETE </code> </a> privilege, you can delete rows from any table in any database on the server host. It is wise to grant privileges in the <code class="literal"> user </code> table only to people who need them, such as database administrators. For other users, leave all privileges in the <code class="literal"> user </code> table set to <code class="literal"> 'N' </code> and grant privileges at more specific levels only (for particular databases, tables, columns, or routines). It is also possible to grant database privileges globally but use partial revokes to restrict them from being exercised on specific databases (see <a class="xref" href="partial-revokes.html" title="8.2.12 Privilege Restriction Using Partial Revokes"> Section 8.2.12, “Privilege Restriction Using Partial Revokes” </a> ). </p> <a class="indexterm" name="idm46045249685728"> </a> <a class="indexterm" name="idm46045249684656"> </a> <p> The <code class="literal"> db </code> table grants database-specific privileges. Values in the scope columns of this table can take the following forms: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A blank <code class="literal"> User </code> value matches the anonymous user. A nonblank value matches literally; there are no wildcards in user names. </p> </li> <li class="listitem"> <p> The wildcard characters <code class="literal"> % </code> and <code class="literal"> _ </code> can be used in the <code class="literal"> Host </code> and <code class="literal"> Db </code> columns. These have the same meaning as for pattern-matching operations performed with the <a class="link" href="string-comparison-functions.html#operator_like"> <code class="literal"> LIKE </code> </a> operator. If you want to use either character literally when granting privileges, you must escape it with a backslash. For example, to include the underscore character ( <code class="literal"> _ </code> ) as part of a database name, specify it as <code class="literal"> \_ </code> in the <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> statement. </p> </li> <li class="listitem"> <p> A <code class="literal"> '%' </code> or blank <code class="literal"> Host </code> value means <span class="quote"> “ <span class="quote"> any host. </span> ” </span> </p> </li> <li class="listitem"> <p> A <code class="literal"> '%' </code> or blank <code class="literal"> Db </code> value means <span class="quote"> “ <span class="quote"> any database. </span> ” </span> </p> </li> </ul> </div> <a class="indexterm" name="idm46045249666928"> </a> <a class="indexterm" name="idm46045249665440"> </a> <a class="indexterm" name="idm46045249663952"> </a> <p> The server reads the <code class="literal"> db </code> table into memory and sorts it at the same time that it reads the <code class="literal"> user </code> table. The server sorts the <code class="literal"> db </code> table based on the <code class="literal"> Host </code> , <code class="literal"> Db </code> , and <code class="literal"> User </code> scope columns. As with the <code class="literal"> user </code> table, sorting puts the most-specific values first and least-specific values last, and when the server looks for matching rows, it uses the first match that it finds. </p> <a class="indexterm" name="idm46045249656816"> </a> <a class="indexterm" name="idm46045249655312"> </a> <a class="indexterm" name="idm46045249653808"> </a> <p> The <code class="literal"> tables_priv </code> , <code class="literal"> columns_priv </code> , and <code class="literal"> procs_priv </code> tables grant table-specific, column-specific, and routine-specific privileges. Values in the scope columns of these tables can take the following forms: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The wildcard characters <code class="literal"> % </code> and <code class="literal"> _ </code> can be used in the <code class="literal"> Host </code> column. These have the same meaning as for pattern-matching operations performed with the <a class="link" href="string-comparison-functions.html#operator_like"> <code class="literal"> LIKE </code> </a> operator. </p> </li> <li class="listitem"> <p> A <code class="literal"> '%' </code> or blank <code class="literal"> Host </code> value means <span class="quote"> “ <span class="quote"> any host. </span> ” </span> </p> </li> <li class="listitem"> <p> The <code class="literal"> Db </code> , <code class="literal"> Table_name </code> , <code class="literal"> Column_name </code> , and <code class="literal"> Routine_name </code> columns cannot contain wildcards or be blank. </p> </li> </ul> </div> <p> The server sorts the <code class="literal"> tables_priv </code> , <code class="literal"> columns_priv </code> , and <code class="literal"> procs_priv </code> tables based on the <code class="literal"> Host </code> , <code class="literal"> Db </code> , and <code class="literal"> User </code> columns. This is similar to <code class="literal"> db </code> table sorting, but simpler because only the <code class="literal"> Host </code> column can contain wildcards. </p> <p> The server uses the sorted tables to verify each request that it receives. For requests that require administrative privileges such as <a class="link" href="privileges-provided.html#priv_shutdown"> <code class="literal"> SHUTDOWN </code> </a> or <a class="link" href="privileges-provided.html#priv_reload"> <code class="literal"> RELOAD </code> </a> , the server checks only the <code class="literal"> user </code> and <code class="literal"> global_privilege </code> tables because those are the only tables that specify administrative privileges. The server grants access if a row for the account in those tables permits the requested operation and denies access otherwise. For example, if you want to execute <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin shutdown </strong> </span> </a> but your <code class="literal"> user </code> table row does not grant the <a class="link" href="privileges-provided.html#priv_shutdown"> <code class="literal"> SHUTDOWN </code> </a> privilege to you, the server denies access without even checking the <code class="literal"> db </code> table. (The latter table contains no <code class="literal"> Shutdown_priv </code> column, so there is no need to check it.) </p> <p> For database-related requests ( <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , and so on), the server first checks the user's global privileges in the <code class="literal"> user </code> table row (less any privilege restrictions imposed by partial revokes). If the row permits the requested operation, access is granted. If the global privileges in the <code class="literal"> user </code> table are insufficient, the server determines the user's database-specific privileges from the <code class="literal"> db </code> table: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The server looks in the <code class="literal"> db </code> table for a match on the <code class="literal"> Host </code> , <code class="literal"> Db </code> , and <code class="literal"> User </code> columns. </p> </li> <li class="listitem"> <p> The <code class="literal"> Host </code> and <code class="literal"> User </code> columns are matched to the connecting user's host name and MySQL user name. </p> </li> <li class="listitem"> <p> The <code class="literal"> Db </code> column is matched to the database that the user wants to access. </p> </li> <li class="listitem"> <p> If there is no row for the <code class="literal"> Host </code> and <code class="literal"> User </code> , access is denied. </p> </li> </ul> </div> <p> After determining the database-specific privileges granted by the <code class="literal"> db </code> table rows, the server adds them to the global privileges granted by the <code class="literal"> user </code> table. If the result permits the requested operation, access is granted. Otherwise, the server successively checks the user's table and column privileges in the <code class="literal"> tables_priv </code> and <code class="literal"> columns_priv </code> tables, adds those to the user's privileges, and permits or denies access based on the result. For stored-routine operations, the server uses the <code class="literal"> procs_priv </code> table rather than <code class="literal"> tables_priv </code> and <code class="literal"> columns_priv </code> . </p> <p> Expressed in boolean terms, the preceding description of how a user's privileges are calculated may be summarized like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa72483520"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">global</span> <span class="token keyword">privileges</span> <span class="token operator">OR</span> <span class="token keyword">database</span> <span class="token keyword">privileges</span> <span class="token operator">OR</span> <span class="token keyword">table</span> <span class="token keyword">privileges</span> <span class="token operator">OR</span> <span class="token keyword">column</span> <span class="token keyword">privileges</span> <span class="token operator">OR</span> <span class="token keyword">routine</span> <span class="token keyword">privileges</span></code></pre> </div> <p> It may not be apparent why, if the global privileges are initially found to be insufficient for the requested operation, the server adds those privileges to the database, table, and column privileges later. The reason is that a request might require more than one type of privilege. For example, if you execute an <a class="link" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement"> <code class="literal"> INSERT INTO ... SELECT </code> </a> statement, you need both the <a class="link" href="privileges-provided.html#priv_insert"> <code class="literal"> INSERT </code> </a> and the <a class="link" href="privileges-provided.html#priv_select"> <code class="literal"> SELECT </code> </a> privileges. Your privileges might be such that the <code class="literal"> user </code> table row grants one privilege global and the <code class="literal"> db </code> table row grants the other specifically for the relevant database. In this case, you have the necessary privileges to perform the request, but the server cannot tell that from either your global or database privileges alone. It must make an access-control decision based on the combined privileges. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/sys-statements-with-full-table-scans.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-statements-with-full-table-scans"> </a> 30.4.3.37 The statements_with_full_table_scans and x$statements_with_full_table_scans Views </h4> </div> </div> </div> <a class="indexterm" name="idm46045062134736"> </a> <a class="indexterm" name="idm46045062133280"> </a> <a class="indexterm" name="idm46045062131776"> </a> <a class="indexterm" name="idm46045062130272"> </a> <p> These views display normalized statements that have done full table scans. By default, rows are sorted by descending percentage of time a full scan was done and descending total latency. </p> <p> The <a class="link" href="sys-statements-with-full-table-scans.html" title="30.4.3.37 The statements_with_full_table_scans and x$statements_with_full_table_scans Views"> <code class="literal"> statements_with_full_table_scans </code> </a> and <a class="link" href="sys-statements-with-full-table-scans.html" title="30.4.3.37 The statements_with_full_table_scans and x$statements_with_full_table_scans Views"> <code class="literal"> x$statements_with_full_table_scans </code> </a> views have these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> query </code> </p> <p> The normalized statement string. </p> </li> <li class="listitem"> <p> <code class="literal"> db </code> </p> <p> The default database for the statement, or <code class="literal"> NULL </code> if there is none. </p> </li> <li class="listitem"> <p> <code class="literal"> exec_count </code> </p> <p> The total number of times the statement has executed. </p> </li> <li class="listitem"> <p> <code class="literal"> total_latency </code> </p> <p> The total wait time of timed statement events for the statement. </p> </li> <li class="listitem"> <p> <code class="literal"> no_index_used_count </code> </p> <p> The total number of times no index was used to scan the table. </p> </li> <li class="listitem"> <p> <code class="literal"> no_good_index_used_count </code> </p> <p> The total number of times no good index was used to scan the table. </p> </li> <li class="listitem"> <p> <code class="literal"> no_index_used_pct </code> </p> <p> The percentage of the time no index was used to scan the table. </p> </li> <li class="listitem"> <p> <code class="literal"> rows_sent </code> </p> <p> The total number of rows returned from the table. </p> </li> <li class="listitem"> <p> <code class="literal"> rows_examined </code> </p> <p> The total number of rows read from the storage engine for the table. </p> </li> <li class="listitem"> <p> <code class="literal"> rows_sent_avg </code> </p> <p> The average number of rows returned from the table. </p> </li> <li class="listitem"> <p> <code class="literal"> rows_examined_avg </code> </p> <p> The average number of rows read from the storage engine for the table. </p> </li> <li class="listitem"> <p> <code class="literal"> first_seen </code> </p> <p> The time at which the statement was first seen. </p> </li> <li class="listitem"> <p> <code class="literal"> last_seen </code> </p> <p> The time at which the statement was most recently seen. </p> </li> <li class="listitem"> <p> <code class="literal"> digest </code> </p> <p> The statement digest. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/foreign-key-optimization.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="foreign-key-optimization"> </a> 10.3.4 Foreign Key Optimization </h3> </div> </div> </div> <a class="indexterm" name="idm46045227474336"> </a> <p> If a table has many columns, and you query many different combinations of columns, it might be efficient to split the less-frequently used data into separate tables with a few columns each, and relate them back to the main table by duplicating the numeric ID column from the main table. That way, each small table can have a primary key for fast lookups of its data, and you can query just the set of columns that you need using a join operation. Depending on how the data is distributed, the queries might perform less I/O and take up less cache memory because the relevant columns are packed together on disk. (To maximize performance, queries try to read as few data blocks as possible from disk; tables with only a few columns can fit more rows in each data block.) </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/index-statistics.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="index-statistics"> </a> 10.3.8 InnoDB and MyISAM Index Statistics Collection </h3> </div> </div> </div> <p> Storage engines collect statistics about tables for use by the optimizer. Table statistics are based on value groups, where a value group is a set of rows with the same key prefix value. For optimizer purposes, an important statistic is the average value group size. </p> <p> MySQL uses the average value group size in the following ways: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> To estimate how many rows must be read for each <a class="link" href="explain-output.html#jointype_ref"> <code class="literal"> ref </code> </a> access </p> </li> <li class="listitem"> <p> To estimate how many rows a partial join produces, that is, the number of rows produced by an operation of the form </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa538586"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token keyword">JOIN</span> <em class="replaceable">tbl_name</em> <span class="token keyword">ON</span> <em class="replaceable">tbl_name</em><span class="token punctuation">.</span><span class="token keyword"><em class="replaceable">key</em></span> <span class="token operator">=</span> <em class="replaceable">expr</em></code></pre> </div> </li> </ul> </div> <p> As the average value group size for an index increases, the index is less useful for those two purposes because the average number of rows per lookup increases: For the index to be good for optimization purposes, it is best that each index value target a small number of rows in the table. When a given index value yields a large number of rows, the index is less useful and MySQL is less likely to use it. </p> <p> The average value group size is related to table cardinality, which is the number of value groups. The <a class="link" href="show-index.html" title="15.7.7.23 SHOW INDEX Statement"> <code class="literal"> SHOW INDEX </code> </a> statement displays a cardinality value based on <em class="replaceable"> <code> N/S </code> </em> , where <em class="replaceable"> <code> N </code> </em> is the number of rows in the table and <em class="replaceable"> <code> S </code> </em> is the average value group size. That ratio yields an approximate number of value groups in the table. </p> <p> For a join based on the <code class="literal"> <=> </code> comparison operator, <code class="literal"> NULL </code> is not treated differently from any other value: <code class="literal"> NULL <=> NULL </code> , just as <code class="literal"> <em class="replaceable"> <code> N </code> </em> <=> <em class="replaceable"> <code> N </code> </em> </code> for any other <em class="replaceable"> <code> N </code> </em> . </p> <p> However, for a join based on the <code class="literal"> = </code> operator, <code class="literal"> NULL </code> is different from non- <code class="literal"> NULL </code> values: <code class="literal"> <em class="replaceable"> <code> expr1 </code> </em> = <em class="replaceable"> <code> expr2 </code> </em> </code> is not true when <em class="replaceable"> <code> expr1 </code> </em> or <em class="replaceable"> <code> expr2 </code> </em> (or both) are <code class="literal"> NULL </code> . This affects <a class="link" href="explain-output.html#jointype_ref"> <code class="literal"> ref </code> </a> accesses for comparisons of the form <code class="literal"> <em class="replaceable"> <code> tbl_name.key </code> </em> = <em class="replaceable"> <code> expr </code> </em> </code> : MySQL does not access the table if the current value of <em class="replaceable"> <code> expr </code> </em> is <code class="literal"> NULL </code> , because the comparison cannot be true. </p> <p> For <code class="literal"> = </code> comparisons, it does not matter how many <code class="literal"> NULL </code> values are in the table. For optimization purposes, the relevant value is the average size of the non- <code class="literal"> NULL </code> value groups. However, MySQL does not currently enable that average size to be collected or used. </p> <p> For <code class="literal"> InnoDB </code> and <code class="literal"> MyISAM </code> tables, you have some control over collection of table statistics by means of the <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> and <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> system variables, respectively. These variables have three possible values, which differ as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> When the variable is set to <code class="literal"> nulls_equal </code> , all <code class="literal"> NULL </code> values are treated as identical (that is, they all form a single value group). </p> <p> If the <code class="literal"> NULL </code> value group size is much higher than the average non- <code class="literal"> NULL </code> value group size, this method skews the average value group size upward. This makes index appear to the optimizer to be less useful than it really is for joins that look for non- <code class="literal"> NULL </code> values. Consequently, the <code class="literal"> nulls_equal </code> method may cause the optimizer not to use the index for <a class="link" href="explain-output.html#jointype_ref"> <code class="literal"> ref </code> </a> accesses when it should. </p> </li> <li class="listitem"> <p> When the variable is set to <code class="literal"> nulls_unequal </code> , <code class="literal"> NULL </code> values are not considered the same. Instead, each <code class="literal"> NULL </code> value forms a separate value group of size 1. </p> <p> If you have many <code class="literal"> NULL </code> values, this method skews the average value group size downward. If the average non- <code class="literal"> NULL </code> value group size is large, counting <code class="literal"> NULL </code> values each as a group of size 1 causes the optimizer to overestimate the value of the index for joins that look for non- <code class="literal"> NULL </code> values. Consequently, the <code class="literal"> nulls_unequal </code> method may cause the optimizer to use this index for <a class="link" href="explain-output.html#jointype_ref"> <code class="literal"> ref </code> </a> lookups when other methods may be better. </p> </li> <li class="listitem"> <p> When the variable is set to <code class="literal"> nulls_ignored </code> , <code class="literal"> NULL </code> values are ignored. </p> </li> </ul> </div> <p> If you tend to use many joins that use <code class="literal"> <=> </code> rather than <code class="literal"> = </code> , <code class="literal"> NULL </code> values are not special in comparisons and one <code class="literal"> NULL </code> is equal to another. In this case, <code class="literal"> nulls_equal </code> is the appropriate statistics method. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> system variable has a global value; the <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> system variable has both global and session values. Setting the global value affects statistics collection for tables from the corresponding storage engine. Setting the session value affects statistics collection only for the current client connection. This means that you can force a table's statistics to be regenerated with a given method without affecting other clients by setting the session value of <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> . </p> <p> To regenerate <code class="literal"> MyISAM </code> table statistics, you can use any of the following methods: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Execute <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --stats_method= <em class="replaceable"> <code> method_name </code> </em> --analyze </strong> </span> </a> </p> </li> <li class="listitem"> <p> Change the table to cause its statistics to go out of date (for example, insert a row and then delete it), and then set <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> and issue an <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> statement </p> </li> </ul> </div> <p> Some caveats regarding the use of <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> and <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> : </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> You can force table statistics to be collected explicitly, as just described. However, MySQL may also collect statistics automatically. For example, if during the course of executing statements for a table, some of those statements modify the table, MySQL may collect statistics. (This may occur for bulk inserts or deletes, or some <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements, for example.) If this happens, the statistics are collected using whatever value <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> or <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> has at the time. Thus, if you collect statistics using one method, but the system variable is set to the other method when a table's statistics are collected automatically later, the other method is used. </p> </li> <li class="listitem"> <p> There is no way to tell which method was used to generate statistics for a given table. </p> </li> <li class="listitem"> <p> These variables apply only to <code class="literal"> InnoDB </code> and <code class="literal"> MyISAM </code> tables. Other storage engines have only one method for collecting table statistics. Usually it is closer to the <code class="literal"> nulls_equal </code> method. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/spatial-function-argument-handling.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="spatial-function-argument-handling"> </a> 14.16.2 Argument Handling by Spatial Functions </h3> </div> </div> </div> <p> Spatial values, or geometries, have the properties described in <a class="xref" href="gis-class-geometry.html" title="13.4.2.2 Geometry Class"> Section 13.4.2.2, “Geometry Class” </a> . The following discussion lists general spatial function argument-handling characteristics. Specific functions or groups of functions may have additional or different argument-handling characteristics, as discussed in the sections where those function descriptions occur. Where that is true, those descriptions take precedence over the general discussion here. </p> <p> Spatial functions are defined only for valid geometry values. See <a class="xref" href="geometry-well-formedness-validity.html" title="13.4.4 Geometry Well-Formedness and Validity"> Section 13.4.4, “Geometry Well-Formedness and Validity” </a> . </p> <p> Each geometry value is associated with a spatial reference system (SRS), which is a coordinate-based system for geographic locations. See <a class="xref" href="spatial-reference-systems.html" title="13.4.5 Spatial Reference System Support"> Section 13.4.5, “Spatial Reference System Support” </a> . </p> <a class="indexterm" name="idm46045198057408"> </a> <p> The spatial reference identifier (SRID) of a geometry identifies the SRS in which the geometry is defined. In MySQL, the SRID value is an integer associated with the geometry value. The maximum usable SRID value is 2 <sup> 32 </sup> −1. If a larger value is given, only the lower 32 bits are used. </p> <p> SRID 0 represents an infinite flat Cartesian plane with no units assigned to its axes. To ensure SRID 0 behavior, create geometry values using SRID 0. SRID 0 is the default for new geometry values if no SRID is specified. </p> <p> For computations on multiple geometry values, all values must be in the same SRS or an error occurs. Thus, spatial functions that take multiple geometry arguments require those arguments to be in the same SRS. If a spatial function returns <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_gis_different_srids" target="_top"> <code class="literal"> ER_GIS_DIFFERENT_SRIDS </code> </a> , it means that the geometry arguments were not all in the same SRS. You must modify them to have the same SRS. </p> <p> A geometry returned by a spatial function is in the SRS of the geometry arguments because geometry values produced by any spatial function inherit the SRID of the geometry arguments. </p> <p> The <a class="ulink" href="http://www.opengeospatial.org" target="_blank"> Open Geospatial Consortium </a> guidelines require that input polygons already be closed, so unclosed polygons are rejected as invalid rather than being closed. </p> <p> In MySQL, the only valid empty geometry is represented in the form of an empty geometry collection. Empty geometry collection handling is as follows: An empty WKT input geometry collection may be specified as <code class="literal"> 'GEOMETRYCOLLECTION()' </code> . This is also the output WKT resulting from a spatial operation that produces an empty geometry collection. </p> <p> During parsing of a nested geometry collection, the collection is flattened and its basic components are used in various GIS operations to compute results. This provides additional flexibility to users because it is unnecessary to be concerned about the uniqueness of geometry data. Nested geometry collections may be produced from nested GIS function calls without having to be explicitly flattened first. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/faqs-mysql-cluster.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="faqs-mysql-cluster"> </a> A.10 MySQL 8.4 FAQ: NDB Cluster </h2> </div> </div> </div> <a class="indexterm" name="idm46045056063952"> </a> <a class="indexterm" name="idm46045056062480"> </a> <a class="indexterm" name="idm46045056061024"> </a> <p> In the following section, we answer questions that are frequently asked about MySQL NDB Cluster and the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine. </p> <div class="qandaset"> <a name="idm46045056057808"> </a> <dl> <dt> A.10.1. <a href="faqs-mysql-cluster.html#faq-cluster-which-versions-support-cluster"> Which versions of the MySQL software support NDB Cluster? Do I have to compile from source? </a> </dt> <dt> A.10.2. <a href="faqs-mysql-cluster.html#faq-cluster-what-is-ndb"> What do “NDB” and “NDBCLUSTER” mean? </a> </dt> <dt> A.10.3. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-vs-replication"> What is the difference between using NDB Cluster versus using MySQL Replication? </a> </dt> <dt> A.10.4. <a href="faqs-mysql-cluster.html#faq-cluster-how-cluster-network-need"> Do I need any special networking to run NDB Cluster? How do computers in a cluster communicate? </a> </dt> <dt> A.10.5. <a href="faqs-mysql-cluster.html#faq-cluster-what-min-hosts-cluster"> How many computers do I need to run an NDB Cluster, and why? </a> </dt> <dt> A.10.6. <a href="faqs-mysql-cluster.html#faq-cluster-what-hosts-do-clustering"> What do the different computers do in an NDB Cluster? </a> </dt> <dt> A.10.7. <a href="faqs-mysql-cluster.html#faq-cluster-what-show-nodegroup-star"> When I run the SHOW command in the NDB Cluster management client, I see a line of output that looks like this: </a> </dt> <dt> A.10.8. <a href="faqs-mysql-cluster.html#faq-cluster-which-os-clustering"> With which operating systems can I use NDB Cluster? </a> </dt> <dt> A.10.9. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-requirements"> What are the hardware requirements for running NDB Cluster? </a> </dt> <dt> A.10.10. <a href="faqs-mysql-cluster.html#faq-cluster-what-memory-needed-cluster"> How much RAM do I need to use NDB Cluster? Is it possible to use disk memory at all? </a> </dt> <dt> A.10.11. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-file-systems"> What file systems can I use with NDB Cluster? What about network file systems or network shares? </a> </dt> <dt> A.10.12. <a href="faqs-mysql-cluster.html#faq-cluster-can-cluster-vm"> Can I run NDB Cluster nodes inside virtual machines (such as those created by VMWare, VirtualBox, Parallels, or Xen)? </a> </dt> <dt> A.10.13. <a href="faqs-mysql-cluster.html#faq-cluster-why-error-1114"> I am trying to populate an NDB Cluster database. The loading process terminates prematurely and I get an error message like this one: </a> </dt> <dt> A.10.14. <a href="faqs-mysql-cluster.html#faq-cluster-can-cluster-remote-network"> NDB Cluster uses TCP/IP. Does this mean that I can run it over the Internet, with one or more nodes in remote locations? </a> </dt> <dt> A.10.15. <a href="faqs-mysql-cluster.html#faq-cluster-what-language-needed-cluster"> Do I have to learn a new programming or query language to use NDB Cluster? </a> </dt> <dt> A.10.16. <a href="faqs-mysql-cluster.html#faq-cluster-what-api-cluster-support"> What programming languages and APIs are supported by NDB Cluster? </a> </dt> <dt> A.10.17. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-management-tools"> Does NDB Cluster include any management tools? </a> </dt> <dt> A.10.18. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-errors-are"> How do I find out what an error or warning message means when using NDB Cluster? </a> </dt> <dt> A.10.19. <a href="faqs-mysql-cluster.html#faq-cluster-is-cluster-transaction-safe"> Is NDB Cluster transaction-safe? What isolation levels are supported? </a> </dt> <dt> A.10.20. <a href="faqs-mysql-cluster.html#faq-cluster-what-storage-engines-cluster"> What storage engines are supported by NDB Cluster? </a> </dt> <dt> A.10.21. <a href="faqs-mysql-cluster.html#faq-cluster-is-data-loss-no-power"> In the event of a catastrophic failure— for example, the whole city loses power and my UPS fails—would I lose all my data? </a> </dt> <dt> A.10.22. <a href="faqs-mysql-cluster.html#faq-cluster-can-cluster-fullindex"> Is it possible to use FULLTEXT indexes with NDB Cluster? </a> </dt> <dt> A.10.23. <a href="faqs-mysql-cluster.html#faq-cluster-can-multinode-cluster-one-host"> Can I run multiple nodes on a single computer? </a> </dt> <dt> A.10.24. <a href="faqs-mysql-cluster.html#faq-cluster-how-add-nodes-no-restart"> Can I add data nodes to an NDB Cluster without restarting it? </a> </dt> <dt> A.10.25. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-limitations"> Are there any limitations that I should be aware of when using NDB Cluster? </a> </dt> <dt> A.10.26. <a href="faqs-mysql-cluster.html#faq-cluster-have-foreign-keys-cluster"> Does NDB Cluster support foreign keys? </a> </dt> <dt> A.10.27. <a href="faqs-mysql-cluster.html#faq-cluster-how-import-db-cluster"> How do I import an existing MySQL database into an NDB Cluster? </a> </dt> <dt> A.10.28. <a href="faqs-mysql-cluster.html#faq-cluster-how-nodes-communicate"> How do NDB Cluster nodes communicate with one another? </a> </dt> <dt> A.10.29. <a href="faqs-mysql-cluster.html#faq-cluster-what-is-arbitrator"> What is an arbitrator? </a> </dt> <dt> A.10.30. <a href="faqs-mysql-cluster.html#faq-cluster-what-types-cluster-support"> What data types are supported by NDB Cluster? </a> </dt> <dt> A.10.31. <a href="faqs-mysql-cluster.html#faq-cluster-how-start-stop-cluster"> How do I start and stop NDB Cluster? </a> </dt> <dt> A.10.32. <a href="faqs-mysql-cluster.html#faq-cluster-what-shutdown-do-data"> What happens to NDB Cluster data when the cluster is shut down? </a> </dt> <dt> A.10.33. <a href="faqs-mysql-cluster.html#faq-cluster-have-multiple-node-managers"> Is it a good idea to have more than one management node for an NDB Cluster? </a> </dt> <dt> A.10.34. <a href="faqs-mysql-cluster.html#faq-cluster-have-different-cluster-hosts"> Can I mix different kinds of hardware and operating systems in one NDB Cluster? </a> </dt> <dt> A.10.35. <a href="faqs-mysql-cluster.html#faq-cluster-have-multiple-nodes-one-host"> Can I run two data nodes on a single host? Two SQL nodes? </a> </dt> <dt> A.10.36. <a href="faqs-mysql-cluster.html#faq-cluster-have-host-names-cluster"> Can I use host names with NDB Cluster? </a> </dt> <dt> A.10.37. <a href="faqs-mysql-cluster.html#faq-cluster-have-ipv6-support-cluster"> Does NDB Cluster support IPv6? </a> </dt> <dt> A.10.38. <a href="faqs-mysql-cluster.html#faq-cluster-have-multiple-users-servers-cluster"> How do I handle MySQL users in an NDB Cluster having multiple MySQL servers? </a> </dt> <dt> A.10.39. <a href="faqs-mysql-cluster.html#faq-cluster-how-continue-after-node-error"> How do I continue to send queries in the event that one of the SQL nodes fails? </a> </dt> <dt> A.10.40. <a href="faqs-mysql-cluster.html#faq-cluster-how-backup-restore-cluster"> How do I back up and restore an NDB Cluster? </a> </dt> <dt> A.10.41. <a href="faqs-mysql-cluster.html#faq-cluster-what-angel-process"> What is an “angel process”? </a> </dt> </dl> <table border="0" style="width: 100%;"> <colgroup> <col align="left" width="1%"/> <col/> </colgroup> <tbody> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-which-versions-support-cluster"> </a> <a name="idm46045056057008"> </a> <p> <b> A.10.1. </b> </p> </td> <td align="left" valign="top"> <p> Which versions of the MySQL software support NDB Cluster? Do I have to compile from source? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster is not supported in standard MySQL Server releases. Instead, MySQL NDB Cluster is provided as a separate product. Available NDB Cluster release series include the following: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <b> NDB Cluster 7.3 / NDB Cluster 7.4. </b> These two series are no longer maintained or supported for new deployments. Users of NDB Cluster 7.3 or 7.4 should upgrade to NDB 7.5 or newer as soon as possible. We recommend that new deployments use the latest NDB Cluster 8.0 release. </p> </li> <li class="listitem"> <p> <b> NDB Cluster 7.5. </b> This series is a previous General Availability (GA) version of NDB Cluster, still available for production use, although we recommend that new deployments use the latest NDB Cluster 8.0 release. The latest NDB Cluster 7.5 releases can be obtained from <a class="ulink" href="https://dev.mysql.com/downloads/cluster/" target="_top"> https://dev.mysql.com/downloads/cluster/ </a> . </p> </li> <li class="listitem"> <p> <b> NDB Cluster 7.6. </b> This series is a previous General Availability (GA) version of NDB Cluster, still available for production use, although we recommend that new deployments use the latest NDB Cluster 8.0 release. The latest NDB Cluster 7.6 releases can be obtained from <a class="ulink" href="https://dev.mysql.com/downloads/cluster/" target="_top"> https://dev.mysql.com/downloads/cluster/ </a> . </p> </li> <li class="listitem"> <p> <b> NDB Cluster 8.0. </b> This series is the most recent General Availability (GA) version of NDB Cluster, based on version 8.0 of the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine and MySQL Server 8.0. NDB Cluster 8.0 is available for production use; new deployments intended for production should use the latest GA release in this series, which is currently NDB Cluster 8.0.41. You can obtain the most recent NDB Cluster 8.0 release from <a class="ulink" href="https://dev.mysql.com/downloads/cluster/" target="_top"> https://dev.mysql.com/downloads/cluster/ </a> . For information about new features and other important changes in this series, see <a class="ulink" href="/doc/refman/8.0/en/mysql-cluster-what-is-new.html" target="_top"> What is New in MySQL NDB Cluster 8.0 </a> . </p> </li> </ul> </div> <p> You can obtain and compile NDB Cluster from source (see <a class="xref" href="mysql-cluster-install-linux-source.html" title="25.3.1.4 Building NDB Cluster from Source on Linux"> Section 25.3.1.4, “Building NDB Cluster from Source on Linux” </a> , and <a class="xref" href="mysql-cluster-install-windows-source.html" title="25.3.2.2 Compiling and Installing NDB Cluster from Source on Windows"> Section 25.3.2.2, “Compiling and Installing NDB Cluster from Source on Windows” </a> ), but for all but the most specialized cases, we recommend using one of the following installers provided by Oracle that is appropriate to your operating platform and circumstances: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Linux <a class="link" href="mysql-cluster-install-linux-binary.html" title="25.3.1.1 Installing an NDB Cluster Binary Release on Linux"> binary release </a> ( <code class="filename"> tar.gz </code> file) </p> </li> <li class="listitem"> <p> Linux <a class="link" href="mysql-cluster-install-linux-rpm.html" title="25.3.1.2 Installing NDB Cluster from RPM"> RPM package </a> </p> </li> <li class="listitem"> <p> Linux <a class="link" href="mysql-cluster-install-debian.html" title="25.3.1.3 Installing NDB Cluster Using .deb Files"> <code class="filename"> .deb </code> file </a> </p> </li> <li class="listitem"> <p> Windows <a class="link" href="mysql-cluster-install-windows-binary.html" title="25.3.2.1 Installing NDB Cluster on Windows from a Binary Release"> binary <span class="quote"> “ <span class="quote"> no-install </span> ” </span> release </a> </p> </li> <li class="listitem"> <p> Windows <a class="ulink" href="/doc/refman/8.0/en/mysql-installer.html" target="_top"> MSI Installer </a> </p> </li> </ul> </div> <p> Installation packages may also be available from your platform's package management system. </p> <p> You can determine whether your MySQL Server has <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> support using one of the statements <code class="literal"> SHOW VARIABLES LIKE 'have_%' </code> , <a class="link" href="show-engines.html" title="15.7.7.17 SHOW ENGINES Statement"> <code class="literal"> SHOW ENGINES </code> </a> , or <a class="link" href="show-plugins.html" title="15.7.7.27 SHOW PLUGINS Statement"> <code class="literal"> SHOW PLUGINS </code> </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-is-ndb"> </a> <a name="idm46045056024704"> </a> <p> <b> A.10.2. </b> </p> </td> <td align="left" valign="top"> <p> What do <span class="quote"> “ <span class="quote"> NDB </span> ” </span> and <span class="quote"> “ <span class="quote"> NDBCLUSTER </span> ” </span> mean? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> <span class="quote"> “ <span class="quote"> NDB </span> ” </span> stands for <span class="quote"> “ <span class="quote"> <span class="bold"> <strong> N </strong> </span> etwork <span class="bold"> <strong> D </strong> </span> ata <span class="bold"> <strong> b </strong> </span> ase </span> ” </span> . <code class="literal"> NDB </code> and <code class="literal"> NDBCLUSTER </code> are both names for the storage engine that enables clustering support with MySQL. <code class="literal"> NDB </code> is preferred, but either name is correct. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-vs-replication"> </a> <a name="idm46045056017008"> </a> <p> <b> A.10.3. </b> </p> </td> <td align="left" valign="top"> <p> What is the difference between using NDB Cluster versus using MySQL Replication? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> In traditional MySQL replication, a source MySQL server updates one or more replicas. Transactions are committed sequentially, and a slow transaction can cause the replica to lag behind the source. This means that if the source fails, it is possible that the replica might not have recorded the last few transactions. If a transaction-safe engine such as <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> is being used, a transaction is either completed on the replica or not applied at all, but replication does not guarantee that all data on the source and the replica remains consistent at all times. In NDB Cluster, all data nodes are kept in synchrony, and a transaction committed by any one data node is committed for all data nodes. In the event of a data node failure, all remaining data nodes remain in a consistent state. </p> <p> In short, whereas standard MySQL replication is <span class="firstterm"> asynchronous </span> , NDB Cluster is <span class="firstterm"> synchronous </span> . </p> <p> Asynchronous replication is also available in NDB Cluster. <span class="firstterm"> NDB Cluster Replication </span> (also sometimes known as <span class="quote"> “ <span class="quote"> geo-replication </span> ” </span> ) includes the capability to replicate both between two NDB Clusters, and from an NDB Cluster to a non-Cluster MySQL server. See <a class="xref" href="mysql-cluster-replication.html" title="25.7 NDB Cluster Replication"> Section 25.7, “NDB Cluster Replication” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-cluster-network-need"> </a> <a name="idm46045056008384"> </a> <p> <b> A.10.4. </b> </p> </td> <td align="left" valign="top"> <p> Do I need any special networking to run NDB Cluster? How do computers in a cluster communicate? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster is intended to be used in a high-bandwidth environment, with computers connecting using TCP/IP. Its performance depends directly upon the connection speed between the cluster's computers. The minimum connectivity requirements for NDB Cluster include a typical 100-megabit Ethernet network or the equivalent. We recommend you use gigabit Ethernet whenever available. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-min-hosts-cluster"> </a> <a name="idm46045056005872"> </a> <p> <b> A.10.5. </b> </p> </td> <td align="left" valign="top"> <p> How many computers do I need to run an NDB Cluster, and why? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> A minimum of three computers is required to run a viable cluster. However, the minimum <span class="emphasis"> <em> recommended </em> </span> number of computers in an NDB Cluster is four: one each to run the management and SQL nodes, and two computers to serve as data nodes. The purpose of the two data nodes is to provide redundancy; the management node must run on a separate machine to guarantee continued arbitration services in the event that one of the data nodes fails. </p> <p> To provide increased throughput and high availability, you should use multiple SQL nodes (MySQL Servers connected to the cluster). It is also possible (although not strictly necessary) to run multiple management servers. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-hosts-do-clustering"> </a> <a name="idm46045056002304"> </a> <p> <b> A.10.6. </b> </p> </td> <td align="left" valign="top"> <p> What do the different computers do in an NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> An NDB Cluster has both a physical and logical organization, with computers being the physical elements. The logical or functional elements of a cluster are referred to as <span class="firstterm"> nodes </span> , and a computer housing a cluster node is sometimes referred to as a <span class="firstterm"> cluster host </span> . There are three types of nodes, each corresponding to a specific role within the cluster. These are: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <b> Management node. </b> This node provides management services for the cluster as a whole, including startup, shutdown, backups, and configuration data for the other nodes. The management node server is implemented as the application <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> ; the management client used to control NDB Cluster is <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> . See <a class="xref" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> Section 25.5.4, “ndb_mgmd — The NDB Cluster Management Server Daemon” </a> , and <a class="xref" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> Section 25.5.5, “ndb_mgm — The NDB Cluster Management Client” </a> , for information about these programs. </p> </li> <li class="listitem"> <p> <b> Data node. </b> This type of node stores and replicates data. Data node functionality is handled by instances of the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> data node process <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> . For more information, see <a class="xref" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> Section 25.5.1, “ndbd — The NDB Cluster Data Node Daemon” </a> . </p> </li> <li class="listitem"> <p> <b> SQL node. </b> This is simply an instance of MySQL Server ( <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> ) that is built with support for the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> storage engine and started with the <code class="option"> --ndb-cluster </code> option to enable the engine and the <code class="option"> --ndb-connectstring </code> option to enable it to connect to an NDB Cluster management server. For more about these options, see <a class="xref" href="mysql-cluster-options-variables.html#mysql-cluster-program-options-mysqld" title="25.4.3.9.1 MySQL Server Options for NDB Cluster"> Section 25.4.3.9.1, “MySQL Server Options for NDB Cluster” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> An <span class="firstterm"> API node </span> is any application that makes direct use of Cluster data nodes for data storage and retrieval. An SQL node can thus be considered a type of API node that uses a MySQL Server to provide an SQL interface to the Cluster. You can write such applications (that do not depend on a MySQL Server) using the NDB API, which supplies a direct, object-oriented transaction and scanning interface to NDB Cluster data; see <a class="ulink" href="/doc/ndbapi/en/overview-ndb-api.html" target="_top"> NDB Cluster API Overview: The NDB API </a> , for more information. </p> </div> </li> </ul> </div> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-show-nodegroup-star"> </a> <a name="idm46045055978416"> </a> <p> <b> A.10.7. </b> </p> </td> <td align="left" valign="top"> <p> When I run the <code class="literal"> SHOW </code> command in the NDB Cluster management client, I see a line of output that looks like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa77586617"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">id=2 @10.100.10.32 (Version: 8.0.41-ndb-8.0.41 Nodegroup: 0, )</code></pre> </div> <p> What does the <code class="literal"> </code> mean? How is this node different from the others? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> The simplest answer is, <span class="quote"> “ <span class="quote"> It's not something you can control, and it's nothing that you need to worry about in any case, unless you're a software engineer writing or analyzing the NDB Cluster source code </span> ” </span> . </p> <p> If you don't find that answer satisfactory, here's a longer and more technical version: </p> <p> A number of mechanisms in NDB Cluster require distributed coordination among the data nodes. These distributed algorithms and protocols include global checkpointing, DDL (schema) changes, and node restart handling. To make this coordination simpler, the data nodes <span class="quote"> “ <span class="quote"> elect </span> ” </span> one of their number to act as leader. There is no user-facing mechanism for influencing this selection, which is completely automatic; the fact that it <span class="emphasis"> <em> is </em> </span> automatic is a key part of NDB Cluster's internal architecture. </p> <p> When a node acts as the <span class="quote"> “ <span class="quote"> leader </span> ” </span> for any of these mechanisms, it is usually the point of coordination for the activity, and the other nodes act as <span class="quote"> “ <span class="quote"> followers </span> ” </span> , carrying out their parts of the activity as directed by the leader. If the node acting as leader fails, then the remaining nodes elect a new leader. Tasks in progress that were being coordinated by the old leader may either fail or be continued by the new leader, depending on the actual mechanism involved. </p> <p> It is possible for some of these different mechanisms and protocols to have different leader nodes, but in general the same leader is chosen for all of them. The node indicated as the leader in the output of <a class="link" href="mysql-cluster-mgm-client-commands.html#ndbclient-show"> <code class="literal"> SHOW </code> </a> in the management client is known internally as the <a class="ulink" href="/doc/ndb-internals/en/ndb-internals-kernel-blocks-dbdict.html" target="_top"> <code class="literal"> DICT </code> </a> manager, responsible for coordinating DDL and metadata activity. </p> <p> NDB Cluster is designed in such a way that the choice of leader has no discernible effect outside the cluster itself. For example, the current leader does not have significantly higher CPU or resource usage than the other data nodes, and failure of the leader should not have a significantly different impact on the cluster than the failure of any other data node. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-which-os-clustering"> </a> <a name="idm46045055964784"> </a> <p> <b> A.10.8. </b> </p> </td> <td align="left" valign="top"> <p> With which operating systems can I use NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster is supported on most Unix-like operating systems. NDB Cluster is also supported in production settings on Microsoft Windows operating systems. </p> <p> For more detailed information concerning the level of support which is offered for NDB Cluster on various operating system versions, operating system distributions, and hardware platforms, please refer to <a class="ulink" href="https://www.mysql.com/support/supportedplatforms/cluster.html" target="_blank"> https://www.mysql.com/support/supportedplatforms/cluster.html </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-requirements"> </a> <a name="idm46045055961392"> </a> <p> <b> A.10.9. </b> </p> </td> <td align="left" valign="top"> <p> What are the hardware requirements for running NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster should run on any platform for which <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> -enabled binaries are available. For data nodes and API nodes, faster CPUs and more memory are likely to improve performance, and 64-bit CPUs are likely to be more effective than 32-bit processors. There must be sufficient memory on machines used for data nodes to hold each node's share of the database (see <span class="emphasis"> <em> How much RAM do I Need? </em> </span> for more information). For a computer which is used only for running the NDB Cluster management server, the requirements are minimal; a common desktop PC (or the equivalent) is generally sufficient for this task. Nodes can communicate through the standard TCP/IP network and hardware. They can also use the high-speed SCI protocol; however, special networking hardware and software are required to use SCI (see <a class="xref" href="mysql-cluster-interconnects.html" title="25.4.4 Using High-Speed Interconnects with NDB Cluster"> Section 25.4.4, “Using High-Speed Interconnects with NDB Cluster” </a> ). </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-memory-needed-cluster"> </a> <a name="idm46045055956080"> </a> <p> <b> A.10.10. </b> </p> </td> <td align="left" valign="top"> <p> How much RAM do I need to use NDB Cluster? Is it possible to use disk memory at all? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster was originally implemented as in-memory only, but all versions currently available also provide the ability to store NDB Cluster on disk. See <a class="xref" href="mysql-cluster-disk-data.html" title="25.6.11 NDB Cluster Disk Data Tables"> Section 25.6.11, “NDB Cluster Disk Data Tables” </a> , for more information. </p> <p> For in-memory <code class="literal"> NDB </code> tables, you can use the following formula for obtaining a rough estimate of how much RAM is needed for each data node in the cluster: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa30747490"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple"><span class="token punctuation">(</span>SizeofDatabase × NumberOfReplicas × 1<span class="token punctuation">.</span>1 <span class="token punctuation">)</span> <span class="token operator">/</span> NumberOfDataNodes</code></pre> </div> <p> To calculate the memory requirements more exactly requires determining, for each table in the cluster database, the storage space required per row (see <a class="xref" href="storage-requirements.html" title="13.7 Data Type Storage Requirements"> Section 13.7, “Data Type Storage Requirements” </a> , for details), and multiplying this by the number of rows. You must also remember to account for any column indexes as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Each primary key or hash index created for an <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> table requires 21−25 bytes per record. These indexes use <code class="literal"> IndexMemory </code> . </p> </li> <li class="listitem"> <p> Each ordered index requires 10 bytes storage per record, using <code class="literal"> DataMemory </code> . </p> </li> <li class="listitem"> <p> Creating a primary key or unique index also creates an ordered index, unless this index is created with <code class="literal"> USING HASH </code> . In other words: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> A primary key or unique index on a Cluster table normally takes up 31 to 35 bytes per record. </p> </li> <li class="listitem"> <p> However, if the primary key or unique index is created with <code class="literal"> USING HASH </code> , then it requires only 21 to 25 bytes per record. </p> </li> </ul> </div> </li> </ul> </div> <p> Creating NDB Cluster tables with <code class="literal"> USING HASH </code> for all primary keys and unique indexes generally causes table updates to run more quickly—in some cases by a much as 20 to 30 percent faster than updates on tables where <code class="literal"> USING HASH </code> was not used in creating primary and unique keys. This is due to the fact that less memory is required (because no ordered indexes are created), and that less CPU must be utilized (because fewer indexes must be read and possibly updated). However, it also means that queries that could otherwise use range scans must be satisfied by other means, which can result in slower selects. </p> <p> When calculating Cluster memory requirements, you may find useful the <a class="link" href="mysql-cluster-programs-ndb-size-pl.html" title="25.5.29 ndb_size.pl — NDBCLUSTER Size Requirement Estimator"> <span class="command"> <strong> ndb_size.pl </strong> </span> </a> utility which is available in recent MySQL 8.4 releases. This Perl script connects to a current (non-Cluster) MySQL database and creates a report on how much space that database would require if it used the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> storage engine. For more information, see <a class="xref" href="mysql-cluster-programs-ndb-size-pl.html" title="25.5.29 ndb_size.pl — NDBCLUSTER Size Requirement Estimator"> Section 25.5.29, “ndb_size.pl — NDBCLUSTER Size Requirement Estimator” </a> . </p> <p> It is especially important to keep in mind that <span class="emphasis"> <em> every NDB Cluster table must have a primary key </em> </span> . The <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine creates a primary key automatically if none is defined; this primary key is created without <code class="literal"> USING HASH </code> . </p> <p> You can determine how much memory is being used for storage of NDB Cluster data and indexes at any given time using the <code class="literal"> REPORT MEMORYUSAGE </code> command in the <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> client; see <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> , for more information. In addition, warnings are written to the cluster log when 80% of available <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> or (prior to NDB 7.6) <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-indexmemory"> <code class="literal"> IndexMemory </code> </a> is in use, and again when usage reaches 90%, 99%, and 100%. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-file-systems"> </a> <a name="idm46045055924320"> </a> <p> <b> A.10.11. </b> </p> </td> <td align="left" valign="top"> <p> What file systems can I use with NDB Cluster? What about network file systems or network shares? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Generally, any file system that is native to the host operating system should work well with NDB Cluster. If you find that a given file system works particularly well (or not so especially well) with NDB Cluster, we invite you to discuss your findings in the <a class="ulink" href="https://forums.mysql.com/list.php?25" target="_blank"> NDB Cluster Forums </a> . </p> <p> For Windows, we recommend that you use <code class="literal"> NTFS </code> file systems for NDB Cluster, just as we do for standard MySQL. We do not test NDB Cluster with <code class="literal"> FAT </code> or <code class="literal"> VFAT </code> file systems. Because of this, we do not recommend their use with MySQL or NDB Cluster. </p> <p> NDB Cluster is implemented as a shared-nothing solution; the idea behind this is that the failure of a single piece of hardware should not cause the failure of multiple cluster nodes, or possibly even the failure of the cluster as a whole. For this reason, the use of network shares or network file systems is not supported for NDB Cluster. This also applies to shared storage devices such as SANs. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-can-cluster-vm"> </a> <a name="idm46045055917584"> </a> <p> <b> A.10.12. </b> </p> </td> <td align="left" valign="top"> <p> Can I run NDB Cluster nodes inside virtual machines (such as those created by VMWare, VirtualBox, Parallels, or Xen)? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster is supported for use in virtual machines. We currently support and test using <a class="ulink" href="http://www.oracle.com/technetwork/server-storage/vm/index.html" target="_blank"> Oracle VM </a> . </p> <p> Some NDB Cluster users have successfully deployed NDB Cluster using other virtualization products; in such cases, Oracle can provide NDB Cluster support, but issues specific to the virtual environment must be referred to that product's vendor. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-why-error-1114"> </a> <a name="idm46045055913984"> </a> <p> <b> A.10.13. </b> </p> </td> <td align="left" valign="top"> <p> I am trying to populate an NDB Cluster database. The loading process terminates prematurely and I get an error message like this one: </p> <p> <code class="literal"> <span class="errortext"> ERROR 1114: The table 'my_cluster_table' is full </span> </code> </p> <p> Why is this happening? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> The cause is very likely to be that your setup does not provide sufficient RAM for all table data and all indexes, <span class="emphasis"> <em> including the primary key required by the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine and automatically created in the event that the table definition does not include the definition of a primary key </em> </span> . </p> <p> It is also worth noting that all data nodes should have the same amount of RAM, since no data node in a cluster can use more memory than the least amount available to any individual data node. For example, if there are four computers hosting Cluster data nodes, and three of these have 3GB of RAM available to store Cluster data while the remaining data node has only 1GB RAM, then each data node can devote at most 1GB to NDB Cluster data and indexes. </p> <p> In some cases it is possible to get <span class="errortext"> Table is full </span> errors in MySQL client applications even when <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm -e "ALL REPORT MEMORYUSAGE" </strong> </span> </a> shows significant free <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> . You can force <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> to create extra partitions for NDB Cluster tables and thus have more memory available for hash indexes by using the <code class="literal"> MAX_ROWS </code> option for <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> . In general, setting <code class="literal"> MAX_ROWS </code> to twice the number of rows that you expect to store in the table should be sufficient. </p> <p> For similar reasons, you can also sometimes encounter problems with data node restarts on nodes that are heavily loaded with data. The <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-minfreepct" title="MinFreePct"> <code class="literal"> MinFreePct </code> </a> parameter can help with this issue by reserving a portion (5% by default) of <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> and (prior to NDB 7.6) <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-indexmemory"> <code class="literal"> IndexMemory </code> </a> for use in restarts. This reserved memory is not available for storing <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables or data. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-can-cluster-remote-network"> </a> <a name="idm46045055893952"> </a> <p> <b> A.10.14. </b> </p> </td> <td align="left" valign="top"> <p> NDB Cluster uses TCP/IP. Does this mean that I can run it over the Internet, with one or more nodes in remote locations? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It is <span class="emphasis"> <em> very </em> </span> unlikely that a cluster would perform reliably under such conditions, as NDB Cluster was designed and implemented with the assumption that it would be run under conditions guaranteeing dedicated high-speed connectivity such as that found in a LAN setting using 100 Mbps or gigabit Ethernet—preferably the latter. We neither test nor warrant its performance using anything slower than this. </p> <p> Also, it is extremely important to keep in mind that communications between the nodes in an NDB Cluster are not secure; they are neither encrypted nor safeguarded by any other protective mechanism. The most secure configuration for a cluster is in a private network behind a firewall, with no direct access to any Cluster data or management nodes from outside. (For SQL nodes, you should take the same precautions as you would with any other instance of the MySQL server.) For more information, see <a class="xref" href="mysql-cluster-security.html" title="25.6.21 NDB Cluster Security Issues"> Section 25.6.21, “NDB Cluster Security Issues” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-language-needed-cluster"> </a> <a name="idm46045055888880"> </a> <p> <b> A.10.15. </b> </p> </td> <td align="left" valign="top"> <p> Do I have to learn a new programming or query language to use NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> <span class="emphasis"> <em> No </em> </span> . Although some specialized commands are used to manage and configure the cluster itself, only standard (My)SQL statements are required for the following operations: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Creating, altering, and dropping tables </p> </li> <li class="listitem"> <p> Inserting, updating, and deleting table data </p> </li> <li class="listitem"> <p> Creating, changing, and dropping primary and unique indexes </p> </li> </ul> </div> <p> Some specialized configuration parameters and files are required to set up an NDB Cluster—see <a class="xref" href="mysql-cluster-config-file.html" title="25.4.3 NDB Cluster Configuration Files"> Section 25.4.3, “NDB Cluster Configuration Files” </a> , for information about these. </p> <p> A few simple commands are used in the NDB Cluster management client ( <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> ) for tasks such as starting and stopping cluster nodes. See <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-api-cluster-support"> </a> <a name="idm46045055879440"> </a> <p> <b> A.10.16. </b> </p> </td> <td align="left" valign="top"> <p> What programming languages and APIs are supported by NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster supports the same programming APIs and languages as the standard MySQL Server, including ODBC, .Net, the MySQL C API, and numerous drivers for popular scripting languages such as PHP, Perl, and Python. NDB Cluster applications written using these APIs behave similarly to other MySQL applications; they transmit SQL statements to a MySQL Server (in the case of NDB Cluster, an SQL node), and receive responses containing rows of data. For more information about these APIs, see <a class="xref" href="connectors-apis.html" title="Chapter 31 Connectors and APIs"> Chapter 31, <i> Connectors and APIs </i> </a> . </p> <p> NDB Cluster also supports application programming using the NDB API, which provides a low-level C++ interface to NDB Cluster data without needing to go through a MySQL Server. See <a class="ulink" href="/doc/ndbapi/en/ndbapi.html" target="_top"> The NDB API </a> . In addition, many <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> management functions are exposed by the C-language MGM API; see <a class="ulink" href="/doc/ndbapi/en/mgm-api.html" target="_top"> The MGM API </a> , for more information. </p> <p> NDB Cluster also supports Java application programming using ClusterJ, which supports a domain object model of data using sessions and transactions. See <a class="ulink" href="/doc/ndbapi/en/mccj-overview-java.html" target="_top"> Java and NDB Cluster </a> , for more information. </p> <p> NDB Cluster 8.0 also includes adapters supporting NoSQL applications written against <code class="literal"> Node.js </code> , with NDB Cluster as the data store. See <a class="ulink" href="/doc/ndbapi/en/ndb-nodejs.html" target="_top"> MySQL NoSQL Connector for JavaScript </a> , for more information. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-management-tools"> </a> <a name="idm46045055869328"> </a> <p> <b> A.10.17. </b> </p> </td> <td align="left" valign="top"> <p> Does NDB Cluster include any management tools? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster includes a command line client for performing basic management functions. See <a class="xref" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> Section 25.5.5, “ndb_mgm — The NDB Cluster Management Client” </a> , and <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> . </p> <p> NDB Cluster is also supported by MySQL Cluster Manager, a separate product providing an advanced command line interface that can automate many NDB Cluster management tasks such as rolling restarts and configuration changes. For more information about MySQL Cluster Manager, see <a class="ulink" href="/doc/mysql-cluster-manager/8.4/en/" target="_top"> MySQL Cluster Manager 8.4.3 User Manual </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-errors-are"> </a> <a name="idm46045055864320"> </a> <p> <b> A.10.18. </b> </p> </td> <td align="left" valign="top"> <p> How do I find out what an error or warning message means when using NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> There are two ways in which this can be done: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> From within the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client, use <span class="command"> <strong> SHOW ERRORS </strong> </span> or <span class="command"> <strong> SHOW WARNINGS </strong> </span> immediately upon being notified of the error or warning condition. </p> </li> <li class="listitem"> <p> From a system shell prompt, use <a class="link" href="perror.html" title="6.8.1 perror — Display MySQL Error Message Information"> <span class="command"> <strong> perror --ndb <em class="replaceable"> <code> error_code </code> </em> </strong> </span> </a> . </p> </li> </ul> </div> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-is-cluster-transaction-safe"> </a> <a name="idm46045055855840"> </a> <p> <b> A.10.19. </b> </p> </td> <td align="left" valign="top"> <p> Is NDB Cluster transaction-safe? What isolation levels are supported? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> <span class="emphasis"> <em> Yes </em> </span> . For tables created with the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine, transactions are supported. Currently, NDB Cluster supports only the <a class="link" href="innodb-transaction-isolation-levels.html#isolevel_read-committed"> <code class="literal"> READ COMMITTED </code> </a> transaction isolation level. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-storage-engines-cluster"> </a> <a name="idm46045055850784"> </a> <p> <b> A.10.20. </b> </p> </td> <td align="left" valign="top"> <p> What storage engines are supported by NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster requires the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine. That is, in order for a table to be shared between nodes in an NDB Cluster, the table must be created using <code class="literal"> ENGINE=NDB </code> (or the equivalent option <code class="literal"> ENGINE=NDBCLUSTER </code> ). </p> <p> It is possible to create tables using other storage engines (such as <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> or <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> ) on a MySQL server being used with NDB Cluster, but since these tables do not use <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> , they do not participate in clustering; each such table is strictly local to the individual MySQL server instance on which it is created. </p> <p> NDB Cluster is quite different from <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> clustering with regard to architecture, requirements, and implementation; despite any similarity in their names, the two are not compatible. For more information about <code class="literal"> InnoDB </code> clustering, see <a class="ulink" href="/doc/mysql-shell/8.4/en/admin-api-userguide.html" target="_top"> MySQL AdminAPI </a> . See also <a class="xref" href="mysql-cluster-compared.html" title="25.2.6 MySQL Server Using InnoDB Compared with NDB Cluster"> Section 25.2.6, “MySQL Server Using InnoDB Compared with NDB Cluster” </a> , for information about the differences between the <code class="literal"> NDB </code> and <code class="literal"> InnoDB </code> storage engines. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-is-data-loss-no-power"> </a> <a name="idm46045055836096"> </a> <p> <b> A.10.21. </b> </p> </td> <td align="left" valign="top"> <p> In the event of a catastrophic failure— for example, the whole city loses power <span class="emphasis"> <em> and </em> </span> my UPS fails—would I lose all my data? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> All committed transactions are logged. Therefore, although it is possible that some data could be lost in the event of a catastrophe, this should be quite limited. Data loss can be further reduced by minimizing the number of operations per transaction. (It is not a good idea to perform large numbers of operations per transaction in any case.) </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-can-cluster-fullindex"> </a> <a name="idm46045055833040"> </a> <p> <b> A.10.22. </b> </p> </td> <td align="left" valign="top"> <p> Is it possible to use <code class="literal"> FULLTEXT </code> indexes with NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> <code class="literal"> FULLTEXT </code> indexing is currently supported only by the <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> and <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> storage engines. See <a class="xref" href="fulltext-search.html" title="14.9 Full-Text Search Functions"> Section 14.9, “Full-Text Search Functions” </a> , for more information. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-can-multinode-cluster-one-host"> </a> <a name="idm46045055826320"> </a> <p> <b> A.10.23. </b> </p> </td> <td align="left" valign="top"> <p> Can I run multiple nodes on a single computer? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It is possible but not always advisable. One of the chief reasons to run a cluster is to provide redundancy. To obtain the full benefits of this redundancy, each node should reside on a separate machine. If you place multiple nodes on a single machine and that machine fails, you lose all of those nodes. For this reason, if you do run multiple data nodes on a single machine, it is <span class="emphasis"> <em> extremely </em> </span> important that they be set up in such a way that the failure of this machine does not cause the loss of all the data nodes in a given node group. </p> <p> Given that NDB Cluster can be run on commodity hardware loaded with a low-cost (or even no-cost) operating system, the expense of an extra machine or two is well worth it to safeguard mission-critical data. It also worth noting that the requirements for a cluster host running a management node are minimal. This task can be accomplished with a 300 MHz Pentium or equivalent CPU and sufficient RAM for the operating system, plus a small amount of overhead for the <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> and <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> processes. </p> <p> It is acceptable to run multiple cluster data nodes on a single host that has multiple CPUs, cores, or both. The NDB Cluster distribution also provides a multithreaded version of the data node binary intended for use on such systems. For more information, see <a class="xref" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> Section 25.5.3, “ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)” </a> . </p> <p> It is also possible in some cases to run data nodes and SQL nodes concurrently on the same machine; how well such an arrangement performs is dependent on a number of factors such as number of cores and CPUs as well as the amount of disk and memory available to the data node and SQL node processes, and you must take these factors into account when planning such a configuration. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-add-nodes-no-restart"> </a> <a name="idm46045055817584"> </a> <p> <b> A.10.24. </b> </p> </td> <td align="left" valign="top"> <p> Can I add data nodes to an NDB Cluster without restarting it? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It is possible to add new data nodes to a running NDB Cluster without taking the cluster offline. For more information, see <a class="xref" href="mysql-cluster-online-add-node.html" title="25.6.7 Adding NDB Cluster Data Nodes Online"> Section 25.6.7, “Adding NDB Cluster Data Nodes Online” </a> . </p> <p> For other types of NDB Cluster nodes, a rolling restart is all that is required (see <a class="xref" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster"> Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster” </a> ). </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-limitations"> </a> <a name="idm46045055813488"> </a> <p> <b> A.10.25. </b> </p> </td> <td align="left" valign="top"> <p> Are there any limitations that I should be aware of when using NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Limitations on <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables in MySQL NDB Cluster include the following: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Temporary tables are not supported; a <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TEMPORARY TABLE </code> </a> statement using <code class="literal"> ENGINE=NDB </code> or <code class="literal"> ENGINE=NDBCLUSTER </code> fails with an error. </p> </li> <li class="listitem"> <p> The only types of user-defined partitioning supported for <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> tables are <code class="literal"> KEY </code> and <code class="literal"> LINEAR KEY </code> . Trying to create an <code class="literal"> NDB </code> table using any other partitioning type fails with an error. </p> </li> <li class="listitem"> <p> <code class="literal"> FULLTEXT </code> indexes are not supported. </p> </li> <li class="listitem"> <p> Index prefixes are not supported. Only complete columns may be indexed. </p> </li> <li class="listitem"> <p> Spatial indexes are not supported (although spatial columns can be used). See <a class="xref" href="spatial-types.html" title="13.4 Spatial Data Types"> Section 13.4, “Spatial Data Types” </a> . </p> </li> <li class="listitem"> <p> Support for partial transactions and partial rollbacks is comparable to that of other transactional storage engines such as <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> that can roll back individual statements. </p> </li> <li class="listitem"> <p> The maximum number of attributes allowed per table is 512. Attribute names cannot be any longer than 31 characters. For each table, the maximum combined length of the table and database names is 122 characters. </p> </li> <li class="listitem"> <p> Priot to NDB 8.0, the maximum size for a table row is 14 kilobytes, not counting <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> values. In NDB 8.0, this maximum is increased to 30000 bytes. See <a class="xref" href="mysql-cluster-limitations-database-objects.html" title="25.2.7.5 Limits Associated with Database Objects in NDB Cluster"> Section 25.2.7.5, “Limits Associated with Database Objects in NDB Cluster” </a> , for more information. </p> <p> There is no set limit for the number of rows per <code class="literal"> NDB </code> table. Limits on table size depend on a number of factors, in particular on the amount of RAM available to each data node. </p> </li> </ul> </div> <p> For a complete listing of limitations in NDB Cluster, see <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> . See also <a class="xref" href="mysql-cluster-limitations-resolved.html" title="25.2.7.11 Previous NDB Cluster Issues Resolved in NDB Cluster 8.4"> Section 25.2.7.11, “Previous NDB Cluster Issues Resolved in NDB Cluster 8.4” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-foreign-keys-cluster"> </a> <a name="idm46045055788576"> </a> <p> <b> A.10.26. </b> </p> </td> <td align="left" valign="top"> <p> Does NDB Cluster support foreign keys? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster provides support for foreign key constraints which is comparable to that found in the <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> storage engine; see <a class="xref" href="constraint-foreign-key.html" title="1.7.3.2 FOREIGN KEY Constraints"> Section 1.7.3.2, “FOREIGN KEY Constraints” </a> , for more detailed information, as well as <a class="xref" href="create-table-foreign-keys.html" title="15.1.20.5 FOREIGN KEY Constraints"> Section 15.1.20.5, “FOREIGN KEY Constraints” </a> . Applications requiring foreign key support should use NDB Cluster 7.3, 7.4, 7.5, or later. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-import-db-cluster"> </a> <a name="idm46045055783744"> </a> <p> <b> A.10.27. </b> </p> </td> <td align="left" valign="top"> <p> How do I import an existing MySQL database into an NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> You can import databases into NDB Cluster much as you would with any other version of MySQL. Other than the limitations mentioned elsewhere in this FAQ, the only other special requirement is that any tables to be included in the cluster must use the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine. This means that the tables must be created with <code class="literal"> ENGINE=NDB </code> or <code class="literal"> ENGINE=NDBCLUSTER </code> . </p> <p> It is also possible to convert existing tables that use other storage engines to <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> using one or more <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statement. However, the definition of the table must be compatible with the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> storage engine prior to making the conversion. In MySQL 8.4, an additional workaround is also required; see <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> , for details. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-nodes-communicate"> </a> <a name="idm46045055773680"> </a> <p> <b> A.10.28. </b> </p> </td> <td align="left" valign="top"> <p> How do NDB Cluster nodes communicate with one another? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Cluster nodes can communicate through any of three different transport mechanisms: TCP/IP, SHM (shared memory), and SCI (Scalable Coherent Interface). Where available, SHM is used by default between nodes residing on the same cluster host; however, this is considered experimental. SCI is a high-speed (1 gigabit per second and higher), high-availability protocol used in building scalable multi-processor systems; it requires special hardware and drivers. See <a class="xref" href="mysql-cluster-interconnects.html" title="25.4.4 Using High-Speed Interconnects with NDB Cluster"> Section 25.4.4, “Using High-Speed Interconnects with NDB Cluster” </a> , for more about using SCI as a transport mechanism for NDB Cluster. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-is-arbitrator"> </a> <a name="idm46045055770432"> </a> <p> <b> A.10.29. </b> </p> </td> <td align="left" valign="top"> <p> What is an <span class="firstterm"> arbitrator </span> ? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> If one or more data nodes in a cluster fail, it is possible that not all cluster data nodes are able to <span class="quote"> “ <span class="quote"> see </span> ” </span> one another. In fact, it is possible that two sets of data nodes might become isolated from one another in a network partitioning, also known as a <span class="quote"> “ <span class="quote"> split-brain </span> ” </span> scenario. This type of situation is undesirable because each set of data nodes tries to behave as though it is the entire cluster. An arbitrator is required to decide between the competing sets of data nodes. </p> <p> When all data nodes in at least one node group are alive, network partitioning is not an issue, because no single subset of the cluster can form a functional cluster on its own. The real problem arises when no single node group has all its nodes alive, in which case network partitioning (the <span class="quote"> “ <span class="quote"> split-brain </span> ” </span> scenario) becomes possible. Then an arbitrator is required. All cluster nodes recognize the same node as the arbitrator, which is normally the management server; however, it is possible to configure any of the MySQL Servers in the cluster to act as the arbitrator instead. The arbitrator accepts the first set of cluster nodes to contact it, and tells the remaining set to shut down. Arbitrator selection is controlled by the <code class="literal"> ArbitrationRank </code> configuration parameter for MySQL Server and management server nodes. You can also use the <code class="literal"> ArbitrationRank </code> configuration parameter to control the arbitrator selection process. For more information about these parameters, see <a class="xref" href="mysql-cluster-mgm-definition.html" title="25.4.3.5 Defining an NDB Cluster Management Server"> Section 25.4.3.5, “Defining an NDB Cluster Management Server” </a> . </p> <p> The role of arbitrator does not in and of itself impose any heavy demands upon the host so designated, and thus the arbitrator host does not need to be particularly fast or to have extra memory especially for this purpose. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-types-cluster-support"> </a> <a name="idm46045055761744"> </a> <p> <b> A.10.30. </b> </p> </td> <td align="left" valign="top"> <p> What data types are supported by NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster supports all of the usual MySQL data types, including those associated with MySQL's spatial extensions; however, the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine does not support spatial indexes. (Spatial indexes are supported only by <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> ; see <a class="xref" href="spatial-types.html" title="13.4 Spatial Data Types"> Section 13.4, “Spatial Data Types” </a> , for more information.) In addition, there are some differences with regard to indexes when used with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> NDB Cluster Disk Data tables (that is, tables created with <code class="literal"> TABLESPACE ... STORAGE DISK ENGINE=NDB </code> or <code class="literal"> TABLESPACE ... STORAGE DISK ENGINE=NDBCLUSTER </code> ) have only fixed-width rows. This means that (for example) each Disk Data table record containing a <a class="link" href="char.html" title="13.3.2 The CHAR and VARCHAR Types"> <code class="literal"> VARCHAR(255) </code> </a> column requires space for 255 characters (as required for the character set and collation being used for the table), regardless of the actual number of characters stored therein. </p> </div> <p> See <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> , for more information about these issues. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-start-stop-cluster"> </a> <a name="idm46045055750000"> </a> <p> <b> A.10.31. </b> </p> </td> <td align="left" valign="top"> <p> How do I start and stop NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It is necessary to start each node in the cluster separately, in the following order: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Start the management node, using the <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> command. </p> <p> When starting the cluster for the first time, you must include the <a class="link" href="mysql-cluster-programs-ndb-mgmd.html#option_ndb_mgmd_config-file"> <code class="option"> -f </code> </a> or <a class="link" href="mysql-cluster-programs-ndb-mgmd.html#option_ndb_mgmd_config-file"> <code class="option"> --config-file </code> </a> option to tell the management node where its configuration file can be found. </p> </li> <li class="listitem"> <p> Start each data node with the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> command. </p> <p> Each data node must be started with the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> -c </code> </a> or <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> option so that the data node knows how to connect to the management server. </p> </li> <li class="listitem"> <p> Start each MySQL Server (SQL node) using your preferred startup script, such as <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> . </p> <p> Each MySQL Server must be started with the <a class="link" href="mysql-cluster-options-variables.html#option_mysqld_ndbcluster"> <code class="option"> --ndbcluster </code> </a> and <a class="link" href="mysql-cluster-options-variables.html#option_mysqld_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> options. These options cause <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> to enable <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> storage engine support and how to connect to the management server. </p> </li> </ol> </div> <p> Each of these commands must be run from a system shell on the machine housing the affected node. (You do not have to be physically present at the machine—a remote login shell can be used for this purpose.) You can verify that the cluster is running by starting the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> management client <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> on the machine housing the management node and issuing the <code class="literal"> SHOW </code> or <code class="literal"> ALL STATUS </code> command. </p> <p> To shut down a running cluster, issue the command <code class="literal"> SHUTDOWN </code> in the management client. Alternatively, you may enter the following command in a system shell: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa71880820"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">ndb_mgm</span> <span class="token property">-e</span> <span class="token atrule">"SHUTDOWN"</span></code></pre> </div> <p> (The quotation marks in this example are optional, since there are no spaces in the command string following the <code class="option"> -e </code> option; in addition, the <code class="literal"> SHUTDOWN </code> command, like other management client commands, is not case-sensitive.) </p> <p> Either of these commands causes the <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> , <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> , and any <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> processes to terminate gracefully. MySQL servers running as SQL nodes can be stopped using <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin shutdown </strong> </span> </a> . </p> <p> For more information, see <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> , and <a class="xref" href="mysql-cluster-install-shutdown-restart.html" title="25.3.6 Safe Shutdown and Restart of NDB Cluster"> Section 25.3.6, “Safe Shutdown and Restart of NDB Cluster” </a> . </p> <p> MySQL Cluster Manager provides additional ways to handle starting ansd stopping of NDB Cluster nodes. See <a class="ulink" href="/doc/mysql-cluster-manager/8.4/en/" target="_top"> MySQL Cluster Manager 8.4.3 User Manual </a> , for more information about this tool. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-shutdown-do-data"> </a> <a name="idm46045055712032"> </a> <p> <b> A.10.32. </b> </p> </td> <td align="left" valign="top"> <p> What happens to NDB Cluster data when the cluster is shut down? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> The data that was held in memory by the cluster's data nodes is written to disk, and is reloaded into memory the next time that the cluster is started. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-multiple-node-managers"> </a> <a name="idm46045055709824"> </a> <p> <b> A.10.33. </b> </p> </td> <td align="left" valign="top"> <p> Is it a good idea to have more than one management node for an NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It can be helpful as a fail-safe. Only one management node controls the cluster at any given time, but it is possible to configure one management node as primary, and one or more additional management nodes to take over in the event that the primary management node fails. </p> <p> See <a class="xref" href="mysql-cluster-config-file.html" title="25.4.3 NDB Cluster Configuration Files"> Section 25.4.3, “NDB Cluster Configuration Files” </a> , for information on how to configure NDB Cluster management nodes. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-different-cluster-hosts"> </a> <a name="idm46045055706288"> </a> <p> <b> A.10.34. </b> </p> </td> <td align="left" valign="top"> <p> Can I mix different kinds of hardware and operating systems in one NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Yes, as long as all machines and operating systems have the same <span class="quote"> “ <span class="quote"> endianness </span> ” </span> (all big-endian or all little-endian). </p> <p> It is also possible to use software from different NDB Cluster releases on different nodes. However, we support such use only as part of a rolling upgrade procedure (see <a class="xref" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster"> Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster” </a> ). </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-multiple-nodes-one-host"> </a> <a name="idm46045055702336"> </a> <p> <b> A.10.35. </b> </p> </td> <td align="left" valign="top"> <p> Can I run two data nodes on a single host? Two SQL nodes? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Yes, it is possible to do this. In the case of multiple data nodes, it is advisable (but not required) for each node to use a different data directory. If you want to run multiple SQL nodes on one machine, each instance of <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> must use a different TCP/IP port. </p> <p> Running data nodes and SQL nodes together on the same host is possible, but you should be aware that the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> processes may compete for memory with <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-host-names-cluster"> </a> <a name="idm46045055694544"> </a> <p> <b> A.10.36. </b> </p> </td> <td align="left" valign="top"> <p> Can I use host names with NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Yes, it is possible to use DNS and DHCP for cluster hosts. However, if your application requires <span class="quote"> “ <span class="quote"> five nines </span> ” </span> availability, you should use fixed (numeric) IP addresses, since making communication between Cluster hosts dependent on services such as DNS and DHCP introduces additional potential points of failure. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-ipv6-support-cluster"> </a> <a name="idm46045055691824"> </a> <p> <b> A.10.37. </b> </p> </td> <td align="left" valign="top"> <p> Does NDB Cluster support IPv6? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> IPv6 is supported for connections between SQL nodes (MySQL servers), but connections between all other types of NDB Cluster nodes must use IPv4. </p> <p> In practical terms, this means that you can use IPv6 for replication between NDB Clusters, but connections between nodes in the same NDB Cluster must use IPv4. For more information, see <a class="xref" href="mysql-cluster-replication-issues.html" title="25.7.3 Known Issues in NDB Cluster Replication"> Section 25.7.3, “Known Issues in NDB Cluster Replication” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-multiple-users-servers-cluster"> </a> <a name="idm46045055688336"> </a> <p> <b> A.10.38. </b> </p> </td> <td align="left" valign="top"> <p> How do I handle MySQL users in an NDB Cluster having multiple MySQL servers? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> MySQL user accounts and privileges are normally not automatically propagated between different MySQL servers accessing the same NDB Cluster. MySQL NDB Cluster provides support for shared and synchronized users and privileges using the <a class="link" href="privileges-provided.html#priv_ndb-stored-user"> <code class="literal"> NDB_STORED_USER </code> </a> privilege; see <a class="ulink" href="/doc/refman/5.7/en/mysql-cluster-privilege-distribution.html" target="_top"> Distributed Privileges Using Shared Grant Tables </a> , for more information. You should be aware that this implementation was introduced in NDB 8.0, and is not compatible with the shared privileges mechanism employed in earlier versions of NDB Cluster. The older implementation is no longer supported in NDB 8.0. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-continue-after-node-error"> </a> <a name="idm46045055683632"> </a> <p> <b> A.10.39. </b> </p> </td> <td align="left" valign="top"> <p> How do I continue to send queries in the event that one of the SQL nodes fails? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> MySQL NDB Cluster does not provide any sort of automatic failover between SQL nodes. Your application must be prepared to handle the loss of SQL nodes and to fail over between them. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-backup-restore-cluster"> </a> <a name="idm46045055681440"> </a> <p> <b> A.10.40. </b> </p> </td> <td align="left" valign="top"> <p> How do I back up and restore an NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> You can use the NDB Cluster native backup and restore functionality in the NDB management client and the <a class="link" href="mysql-cluster-programs-ndb-restore.html" title="25.5.23 ndb_restore — Restore an NDB Cluster Backup"> <span class="command"> <strong> ndb_restore </strong> </span> </a> program. See <a class="xref" href="mysql-cluster-backup.html" title="25.6.8 Online Backup of NDB Cluster"> Section 25.6.8, “Online Backup of NDB Cluster” </a> , and <a class="xref" href="mysql-cluster-programs-ndb-restore.html" title="25.5.23 ndb_restore — Restore an NDB Cluster Backup"> Section 25.5.23, “ndb_restore — Restore an NDB Cluster Backup” </a> . </p> <p> You can also use the traditional functionality provided for this purpose in <a class="link" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program"> <span class="command"> <strong> mysqldump </strong> </span> </a> and the MySQL server. See <a class="xref" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program"> Section 6.5.4, “mysqldump — A Database Backup Program” </a> , for more information. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-angel-process"> </a> <a name="idm46045055674256"> </a> <p> <b> A.10.41. </b> </p> </td> <td align="left" valign="top"> <p> What is an <span class="quote"> “ <span class="quote"> angel process </span> ” </span> ? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> This process monitors and, if necessary, attempts to restart the data node process. If you check the list of active processes on your system after starting <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> , you can see that there are actually 2 processes running by that name, as shown here (we omit the output from <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> and <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> for brevity): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa98953940"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">./ndb_mgmd</span> <span class="token prompt">$> </span><span class="token command">ps</span> aux \| grep ndb me 23002 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 122948 3104 ? Ssl 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 <span class="token punctuation">.</span>/ndb_mgmd me 23025 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 5284 820 pts/2 S+ 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 grep ndb <span class="token prompt">$> </span><span class="token command">./ndbd</span> <span class="token property">-c</span> 127<span class="token punctuation">.</span>0<span class="token punctuation">.</span>0<span class="token punctuation">.</span>1 <span class="token property">--initial</span> <span class="token prompt">$> </span><span class="token command">ps</span> aux \| grep ndb me 23002 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 123080 3356 ? Ssl 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 <span class="token punctuation">.</span>/ndb_mgmd me 23096 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 35876 2036 ? Ss 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 <span class="token punctuation">.</span>/ndbmtd <span class="token property">-c</span> 127<span class="token punctuation">.</span>0<span class="token punctuation">.</span>0<span class="token punctuation">.</span>1 <span class="token property">--initial</span> me 23097 1<span class="token punctuation">.</span>0 2<span class="token punctuation">.</span>4 524116 91096 ? Sl 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 <span class="token punctuation">.</span>/ndbmtd <span class="token property">-c</span> 127<span class="token punctuation">.</span>0<span class="token punctuation">.</span>0<span class="token punctuation">.</span>1 <span class="token property">--initial</span> me 23168 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 5284 812 pts/2 R+ 14<span class="token punctuation">:</span>15 0<span class="token punctuation">:</span>00 grep ndb</code></pre> </div> <p> The <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process showing <code class="literal"> 0.0 </code> for both memory and CPU usage is the angel process (although it actually does use a very small amount of each). This process merely checks to see if the main <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> process (the primary data node process which actually handles the data) is running. If permitted to do so (for example, if the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-stoponerror"> <code class="literal"> StopOnError </code> </a> configuration parameter is set to <code class="literal"> false </code> ), the angel process tries to restart the primary data node process. </p> </td> </tr> </tbody> </table> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/group-replication-offline-upgrade.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="group-replication-offline-upgrade"> </a> 20.8.2 Group Replication Offline Upgrade </h3> </div> </div> </div> <a class="indexterm" name="idm46045131618032"> </a> <p> To perform an offline upgrade of a Group Replication group, you remove each member from the group, perform an upgrade of the member and then restart the group as usual. In a multi-primary group you can shutdown the members in any order. In a single-primary group, shutdown each secondary first and then finally the primary. See <a class="xref" href="group-replication-upgrading-member.html" title="20.8.3.2 Upgrading a Group Replication Member"> Section 20.8.3.2, “Upgrading a Group Replication Member” </a> for how to remove members from a group and shutdown MySQL. </p> <p> Once the group is offline, upgrade all of the members. See <a class="xref" href="upgrading.html" title="Chapter 3 Upgrading MySQL"> Chapter 3, <i> Upgrading MySQL </i> </a> for how to perform an upgrade. When all members have been upgraded, restart the members. </p> <p> If you upgrade all the members of a replication group when they are offline and then restart the group, the members join using the new release's Group Replication communication protocol version, so that becomes the group's communication protocol version. If you have a requirement to allow members at earlier releases to join, you can use the <a class="link" href="group-replication-functions-for-communication-protocol.html#function_group-replication-set-communication-protocol"> <code class="literal"> group_replication_set_communication_protocol() </code> </a> function to downgrade the communication protocol version, specifying the MySQL Server version of the prospective group member that has the oldest installed server version. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/audit-log-file-reading.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="audit-log-file-reading"> </a> 8.4.5.6 Reading Audit Log Files </h4> </div> </div> </div> <p> The audit log plugin supports functions that provide an SQL interface for reading JSON-format audit log files. (This capability does not apply to log files written in other formats.) </p> <p> When the audit log plugin initializes and is configured for JSON logging, it uses the directory containing the current audit log file as the location to search for readable audit log files. The plugin determines the file location, base name, and suffix from the value of the <a class="link" href="audit-log-reference.html#sysvar_audit_log_file"> <code class="literal"> audit_log_file </code> </a> system variable, then looks for files with names that match the following pattern, where <code class="literal"> [...] </code> indicates optional file name parts: </p> <a class="indexterm" name="idm46045237488976"> </a> <a class="indexterm" name="idm46045237487888"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa96385302"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none"><em class="replaceable">basename</em>[.<em class="replaceable">timestamp</em>].<em class="replaceable">suffix</em>[.gz][[.<em class="replaceable">pwd_id</em>].enc]</code></pre> </div> <p> If a file name ends with <code class="filename"> .enc </code> , the file is encrypted and reading its unencrypted contents requires a decryption password obtained from the keyring. The audit log plugin determines the keyring ID of the decryption password as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If <code class="filename"> .enc </code> is preceded by <em class="replaceable"> <code> pwd_id </code> </em> , the keyring ID is <code class="literal"> audit_log- <em class="replaceable"> <code> pwd_id </code> </em> </code> . </p> </li> <li class="listitem"> <p> If <code class="filename"> .enc </code> is not preceded by <em class="replaceable"> <code> pwd_id </code> </em> , the file has an old name from before audit log encryption password history was implemented. The keyring ID is <code class="literal"> audit_log </code> . </p> </li> </ul> </div> <p> For more information about encrypted audit log files, see <a class="xref" href="audit-log-logging-configuration.html#audit-log-file-encryption" title="Encrypting Audit Log Files"> Encrypting Audit Log Files </a> . </p> <p> The plugin ignores files that have been renamed manually and do not match the pattern, and files that were encrypted with a password no longer available in the keyring. The plugin opens each remaining candidate file, verifies that the file actually contains <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> audit events, and sorts the files using the timestamps from the first event of each file. The result is a sequence of files that are subject to access using the log-reading functions: </p> <a class="indexterm" name="idm46045237472912"> </a> <a class="indexterm" name="idm46045237471808"> </a> <a class="indexterm" name="idm46045237470304"> </a> <a class="indexterm" name="idm46045237469200"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> reads events from the audit log or closes the reading process. </p> </li> <li class="listitem"> <p> <a class="link" href="audit-log-reference.html#function_audit-log-read-bookmark"> <code class="literal"> audit_log_read_bookmark() </code> </a> returns a bookmark for the most recently written audit log event. This bookmark is suitable for passing to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> to indicate where to begin reading. </p> </li> </ul> </div> <p> <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> takes an optional <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> string argument, and the result returned from a successful call to either function is a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> string. </p> <p> To use the functions to read the audit log, follow these principles: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Call <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> to read events beginning from a given position or the current position, or to close reading: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> To initialize an audit log read sequence, pass an argument that indicates the position at which to begin. One way to do so is to pass the bookmark returned by <a class="link" href="audit-log-reference.html#function_audit-log-read-bookmark"> <code class="literal"> audit_log_read_bookmark() </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa5892792"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> audit_log_read<span class="token punctuation">(</span>audit_log_read_bookmark<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> To continue reading from the current position in the sequence, call <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> with no position specified: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa96699573"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> audit_log_read<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> To explicitly close the read sequence, pass a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> argument: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa68600731"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> audit_log_read<span class="token punctuation">(</span><span class="token string">'null'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> It is unnecessary to close reading explicitly. Reading is closed implicitly when the session ends or a new read sequence is initialized by calling <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> with an argument that indicates the position at which to begin. </p> </li> </ul> </div> </li> <li class="listitem"> <p> A successful call to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> to read events returns a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> string containing an array of audit events: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If the final value of the returned array is not a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value, there are more events following those just read and <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> can be called again to read more of them. </p> </li> <li class="listitem"> <p> If the final value of the returned array is a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value, there are no more events left to be read in the current read sequence. </p> </li> </ul> </div> <p> Each non- <code class="literal"> null </code> array element is an event represented as a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> hash. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-json"><div class="docs-select-all right" id="sa78882737"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-json"><span class="token punctuation">[</span> <span class="token punctuation">{</span> <span class="token property">"timestamp"</span><span class="token operator">:</span> <span class="token string">"2020-05-18 13:39:33"</span><span class="token punctuation">,</span> <span class="token property">"id"</span><span class="token operator">:</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token property">"class"</span><span class="token operator">:</span> <span class="token string">"connection"</span><span class="token punctuation">,</span> <span class="token property">"event"</span><span class="token operator">:</span> <span class="token string">"connect"</span><span class="token punctuation">,</span> ... <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span> <span class="token property">"timestamp"</span><span class="token operator">:</span> <span class="token string">"2020-05-18 13:39:33"</span><span class="token punctuation">,</span> <span class="token property">"id"</span><span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token property">"class"</span><span class="token operator">:</span> <span class="token string">"general"</span><span class="token punctuation">,</span> <span class="token property">"event"</span><span class="token operator">:</span> <span class="token string">"status"</span><span class="token punctuation">,</span> ... <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span> <span class="token property">"timestamp"</span><span class="token operator">:</span> <span class="token string">"2020-05-18 13:39:33"</span><span class="token punctuation">,</span> <span class="token property">"id"</span><span class="token operator">:</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token property">"class"</span><span class="token operator">:</span> <span class="token string">"connection"</span><span class="token punctuation">,</span> <span class="token property">"event"</span><span class="token operator">:</span> <span class="token string">"disconnect"</span><span class="token punctuation">,</span> ... <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token null">null</span> <span class="token punctuation">]</span></code></pre> </div> <p> For more information about the content of JSON-format audit events, see <a class="xref" href="audit-log-file-formats.html#audit-log-file-json-format" title="JSON Audit Log File Format"> JSON Audit Log File Format </a> . </p> </li> <li class="listitem"> <p> An <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> call to read events that does not specify a position produces an error under any of these conditions: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> A read sequence has not yet been initialized by passing a position to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> . </p> </li> <li class="listitem"> <p> There are no more events left to be read in the current read sequence; that is, <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> previously returned an array ending with a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value. </p> </li> <li class="listitem"> <p> The most recent read sequence has been closed by passing a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> . </p> </li> </ul> </div> <p> To read events under those conditions, it is necessary to first initialize a read sequence by calling <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> with an argument that specifies a position. </p> </li> </ul> </div> <p> To specify a position to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> , include an argument that indicates where to begin reading. For example, pass a bookmark, which is a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> hash containing <code class="literal"> timestamp </code> and <code class="literal"> id </code> elements that uniquely identify a particular event. Here is an example bookmark, obtained by calling the <a class="link" href="audit-log-reference.html#function_audit-log-read-bookmark"> <code class="literal"> audit_log_read_bookmark() </code> </a> function: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa85144958"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> audit_log_read_bookmark<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> audit_log_read_bookmark() <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> { "timestamp": "2020<span class="token punctuation">-</span>05<span class="token punctuation">-</span>18 21:03:44", "id": 0 } <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> Passing the current bookmark to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> initializes event reading beginning at the bookmark position: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa25164799"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> audit_log_read<span class="token punctuation">(</span>audit_log_read_bookmark<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> audit_log_read(audit_log_read_bookmark()) <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> [ {"timestamp":"2020<span class="token punctuation">-</span>05<span class="token punctuation">-</span>18 22:41:24","id":0,"class":"connection", ... <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> The argument to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> is optional. If present, it can be a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value to close the read sequence, or a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> hash. </p> <p> Within a hash argument to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> , items are optional and control aspects of the read operation such as the position at which to begin reading or how many events to read. The following items are significant (other items are ignored): </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> start </code> : The position within the audit log of the first event to read. The position is given as a timestamp and the read starts from the first event that occurs on or after the timestamp value. The <code class="literal"> start </code> item has this format, where <em class="replaceable"> <code> value </code> </em> is a literal timestamp value: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-json"><div class="docs-select-all right" id="sa24668904"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-json"><span class="token property">"start"</span><span class="token operator">:</span> <span class="token punctuation">{</span> <span class="token property">"timestamp"</span><span class="token operator">:</span> <span class="token string">"<em class="replaceable">value</em>"</span> <span class="token punctuation">}</span></code></pre> </div> </li> <li class="listitem"> <p> <code class="literal"> timestamp </code> , <code class="literal"> id </code> : The position within the audit log of the first event to read. The <code class="literal"> timestamp </code> and <code class="literal"> id </code> items together comprise a bookmark that uniquely identify a particular event. If an <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> argument includes either item, it must include both to completely specify a position or an error occurs. </p> </li> <li class="listitem"> <p> <code class="literal"> max_array_length </code> : The maximum number of events to read from the log. If this item is omitted, the default is to read to the end of the log or until the read buffer is full, whichever comes first. </p> </li> </ul> </div> <p> To specify a starting position to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> , pass a hash argument that includes either a <code class="literal"> start </code> item or a bookmark consisting of <code class="literal"> timestamp </code> and <code class="literal"> id </code> items. If a hash argument includes both a <code class="literal"> start </code> item and a bookmark, an error occurs. </p> <p> If a hash argument specifies no starting position, reading continues from the current position. </p> <p> If a timestamp value includes no time part, a time part of <code class="literal"> 00:00:00 </code> is assumed. </p> <p> Example arguments accepted by <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> : </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Read events starting with the first event that occurs on or after the given timestamp: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa82908806"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "start": { "timestamp": "2020-05-24 12:30:00" } }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Like the previous example, but read at most 3 events: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa8352805"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "start": { "timestamp": "2020-05-24 12:30:00" }, "max_array_length": 3 }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Read events starting with the first event that occurs on or after <code class="literal"> 2020-05-24 00:00:00 </code> (the timestamp includes no time part, so <code class="literal"> 00:00:00 </code> is assumed): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa15585267"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "start": { "timestamp": "2020-05-24" } }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Read events starting with the event that has the exact timestamp and event ID: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa41723971"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "timestamp": "2020-05-24 12:30:00", "id": 0 }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Like the previous example, but read at most 3 events: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa53440569"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "timestamp": "2020-05-24 12:30:00", "id": 0, "max_array_length": 3 }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Read events from the current position in the read sequence: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa3992450"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Read at most 5 events beginning at the current position in the read sequence: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa37238954"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "max_array_length": 5 }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Close the current read sequence: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa45503142"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'null'</span><span class="token punctuation">)</span></code></pre> </div> </li> </ul> </div> <p> A <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> string returned from either log-reading function can be manipulated as necessary. Suppose that a call to obtain a bookmark produces this value: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa6428293"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@mark</span> <span class="token operator">:=</span> audit_log_read_bookmark<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token variable">@mark</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> @mark <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> { "timestamp": "2020<span class="token punctuation">-</span>05<span class="token punctuation">-</span>18 16:10:28", "id": 2 } <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> Calling <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> with that argument can return multiple events. To limit <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> to reading at most <em class="replaceable"> <code> N </code> </em> events, add to the string a <code class="literal"> max_array_length </code> item with that value. For example, to read a single event, modify the string as follows: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa18444196"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@mark</span> <span class="token operator">:=</span> <span class="token function">JSON_SET</span><span class="token punctuation">(</span><span class="token variable">@mark</span><span class="token punctuation">,</span> <span class="token string">'$.max_array_length'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token variable">@mark</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> @mark <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> {"id": 2, "timestamp": "2020<span class="token punctuation">-</span>05<span class="token punctuation">-</span>18 16:10:28", "max_array_length": 1} <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> The modified string, when passed to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> , produces a result containing at most one event, no matter how many are available. </p> <p> If an audit log function is invoked from within the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client, binary string results display using hexadecimal notation, depending on the value of the <a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex"> <code class="option"> --binary-as-hex </code> </a> . For more information about that option, see <a class="xref" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> Section 6.5.1, “mysql — The MySQL Command-Line Client” </a> . </p> <p> To set a limit on the number of bytes that <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> reads, set the <a class="link" href="audit-log-reference.html#sysvar_audit_log_read_buffer_size"> <code class="literal"> audit_log_read_buffer_size </code> </a> system variable. This variable has a default of 32KB and can be set at runtime. Each client should set its session value of <a class="link" href="audit-log-reference.html#sysvar_audit_log_read_buffer_size"> <code class="literal"> audit_log_read_buffer_size </code> </a> appropriately for its use of <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> . </p> <a class="indexterm" name="idm46045237334768"> </a> <a class="indexterm" name="idm46045237333664"> </a> <p> Each call to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> returns as many available events as fit within the buffer size. Events that do not fit within the buffer size are skipped and generate warnings. Given this behavior, consider these factors when assessing the proper buffer size for an application: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> There is a tradeoff between number of calls to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> and events returned per call: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> With a smaller buffer size, calls return fewer events, so more calls are needed. </p> </li> <li class="listitem"> <p> With a larger buffer size, calls return more events, so fewer calls are needed. </p> </li> </ul> </div> </li> <li class="listitem"> <p> With a smaller buffer size, such as the default size of 32KB, there is a greater chance for events to exceed the buffer size and thus to be skipped. </p> </li> </ul> </div> <p> For additional information about audit log-reading functions, see <a class="xref" href="audit-log-reference.html#audit-log-routines" title="Audit Log Functions"> Audit Log Functions </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/optimizer-trace-implementation.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="optimizer-trace-implementation"> </a> 10.15.16 Optimizer Trace Implementation </h3> </div> </div> </div> <p> See the files <code class="filename"> sql/opt_trace* </code> , starting with <code class="filename"> sql/opt_trace.h </code> . A trace is started by creating an instance of <code class="literal"> Opt_trace_start </code> ; information is added to this trace by creating instances of <code class="literal"> Opt_trace_object </code> and <code class="literal"> Opt_trace_array </code> , and by using the <code class="literal"> add() </code> methods of these classes. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/replication-options-source.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-options-source"> </a> 19.1.6.2 Replication Source Options and Variables </h4> </div> </div> </div> <p> This section describes the server options and system variables that you can use on replication source servers. You can specify the options either on the <a class="link" href="command-line-options.html" title="6.2.2.1 Using Options on the Command Line"> command line </a> or in an <a class="link" href="option-files.html" title="6.2.2.2 Using Option Files"> option file </a> . You can specify system variable values using <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> . </p> <p> On the source and each replica, you must set the <a class="link" href="replication-options.html#sysvar_server_id"> <code class="literal"> server_id </code> </a> system variable to establish a unique replication ID. For each server, you should pick a unique positive integer in the range from 1 to 2 <sup> 32 </sup> − 1, and each ID must be different from every other ID in use by any other source or replica in the replication topology. Example: <code class="literal"> server-id=3 </code> . </p> <p> For options used on the source for controlling binary logging, see <a class="xref" href="replication-options-binary-log.html" title="19.1.6.4 Binary Logging Options and Variables"> Section 19.1.6.4, “Binary Logging Options and Variables” </a> . </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="replication-optvars-masters"> </a> Startup Options for Replication Source Servers </h5> </div> </div> </div> <p> The following list describes startup options for controlling replication source servers. Replication-related system variables are discussed later in this section. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_mysqld_show-replica-auth-info"> </a> <a class="link" href="replication-options-source.html#option_mysqld_show-replica-auth-info"> <code class="option"> --show-replica-auth-info </code> </a> </p> <a class="indexterm" name="idm46045144569168"> </a> <a class="indexterm" name="idm46045144567664"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for show-replica-auth-info"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --show-replica-auth-info[={OFF\|ON}] </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Use <a class="link" href="replication-options-source.html#option_mysqld_show-replica-auth-info"> <code class="option"> --show-replica-auth-info </code> </a> , which displays replication user names and passwords in the output of <a class="link" href="show-replicas.html" title="15.7.7.36 SHOW REPLICAS Statement"> <code class="literal"> SHOW REPLICAS </code> </a> on the source for replicas started with the <a class="link" href="replication-options-replica.html#sysvar_report_user"> <code class="option"> --report-user </code> </a> and <a class="link" href="replication-options-replica.html#sysvar_report_password"> <code class="option"> --report-password </code> </a> options. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_show-slave-auth-info"> </a> <a class="link" href="replication-options-source.html#option_mysqld_show-slave-auth-info"> <code class="option"> --show-slave-auth-info </code> </a> </p> <a class="indexterm" name="idm46045144549280"> </a> <a class="indexterm" name="idm46045144547824"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for show-slave-auth-info"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --show-slave-auth-info[={OFF\|ON}] </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Deprecated alias for <a class="link" href="replication-options-source.html#option_mysqld_show-replica-auth-info"> <code class="option"> --show-replica-auth-info </code> </a> . </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="replication-sysvars-masters"> </a> System Variables Used on Replication Source Servers </h5> </div> </div> </div> <p> The following system variables are used for or by replication source servers: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="sysvar_auto_increment_increment"> </a> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> </p> <a class="indexterm" name="idm46045144528208"> </a> <a class="indexterm" name="idm46045144527104"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for auto_increment_increment"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --auto-increment-increment=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> auto_increment_increment </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> Yes </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> and <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> are intended for use with circular (source-to-source) replication, and can be used to control the operation of <code class="literal"> AUTO_INCREMENT </code> columns. Both variables have global and session values, and each can assume an integer value between 1 and 65,535 inclusive. Setting the value of either of these two variables to 0 causes its value to be set to 1 instead. Attempting to set the value of either of these two variables to an integer greater than 65,535 or less than 0 causes its value to be set to 65,535 instead. Attempting to set the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> or <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> to a noninteger value produces an error, and the actual value of the variable remains unchanged. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> is also supported for use with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables. </p> </div> <p> When Group Replication is started on a server, the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> is changed to the value of <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_auto_increment_increment"> <code class="literal"> group_replication_auto_increment_increment </code> </a> , which defaults to 7, and the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> is changed to the server ID. The changes are reverted when Group Replication is stopped. These changes are only made and reverted if <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> and <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> each have their default value of 1. If their values have already been modified from the default, Group Replication does not alter them. These system variables are also not modified when Group Replication is in single-primary mode, where only one server writes. </p> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> and <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> affect <code class="literal"> AUTO_INCREMENT </code> column behavior as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> controls the interval between successive column values. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa12559337"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'auto_inc%'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Variable_name <span class="token punctuation">\|</span> Value <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> auto_increment_increment <span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> auto_increment_offset <span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">2 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> autoinc1 <span class="token prompt"> -></span> <span class="token punctuation">(</span>col <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">Query</span> OK<span class="token punctuation">,</span> <span class="token number">0</span> <span class="token keyword">rows</span> affected <span class="token punctuation">(</span><span class="token number">0.04</span> sec<span class="token punctuation">)</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@@auto_increment_increment</span><span class="token operator">=</span><span class="token number">10</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'auto_inc%'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Variable_name <span class="token punctuation">\|</span> Value <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> auto_increment_increment <span class="token punctuation">\|</span> 10 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> auto_increment_offset <span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">2 rows in set (0.01 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> autoinc1 <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 4 rows affected (0.00 sec)</span> <span class="token output">Records: 4 Duplicates: 0 Warnings: 0</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> col <span class="token keyword">FROM</span> autoinc1<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> col <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 11 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 21 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 31 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">4 rows in set (0.00 sec)</span></code></pre> </div> </li> <li class="listitem"> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> determines the starting point for the <code class="literal"> AUTO_INCREMENT </code> column value. Consider the following, assuming that these statements are executed during the same session as the example given in the description for <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa65560444"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@@auto_increment_offset</span><span class="token operator">=</span><span class="token number">5</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'auto_inc%'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Variable_name <span class="token punctuation">\|</span> Value <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> auto_increment_increment <span class="token punctuation">\|</span> 10 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> auto_increment_offset <span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">2 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> autoinc2 <span class="token prompt"> -></span> <span class="token punctuation">(</span>col <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.06 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> autoinc2 <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 4 rows affected (0.00 sec)</span> <span class="token output">Records: 4 Duplicates: 0 Warnings: 0</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> col <span class="token keyword">FROM</span> autoinc2<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> col <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 15 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 25 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 35 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">4 rows in set (0.02 sec)</span></code></pre> </div> <p> When the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> is greater than that of <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> , the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> is ignored. </p> </li> </ul> </div> <p> If either of these variables is changed, and then new rows inserted into a table containing an <code class="literal"> AUTO_INCREMENT </code> column, the results may seem counterintuitive because the series of <code class="literal"> AUTO_INCREMENT </code> values is calculated without regard to any values already present in the column, and the next value inserted is the least value in the series that is greater than the maximum existing value in the <code class="literal"> AUTO_INCREMENT </code> column. The series is calculated like this: </p> <p> <code class="literal"> auto_increment_offset </code> + <em class="replaceable"> <code> N </code> </em> × <code class="literal"> auto_increment_increment </code> </p> <p> where <em class="replaceable"> <code> N </code> </em> is a positive integer value in the series [1, 2, 3, ...]. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa24423883"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'auto_inc%'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> Variable_name <span class="token punctuation">\|</span> Value <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> auto_increment_increment <span class="token punctuation">\|</span> 10 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> auto_increment_offset <span class="token punctuation">\|</span> 5 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">2 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> col <span class="token keyword">FROM</span> autoinc1<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> col <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 11 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 21 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 31 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">4 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> autoinc1 <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 4 rows affected (0.00 sec)</span> <span class="token output">Records: 4 Duplicates: 0 Warnings: 0</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> col <span class="token keyword">FROM</span> autoinc1<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> col <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 11 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 21 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 31 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 35 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 45 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 55 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> 65 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">8 rows in set (0.00 sec)</span></code></pre> </div> <p> The values shown for <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> and <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> generate the series 5 + <em class="replaceable"> <code> N </code> </em> × 10, that is, [5, 15, 25, 35, 45, ...]. The highest value present in the <code class="literal"> col </code> column prior to the <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> is 31, and the next available value in the <code class="literal"> AUTO_INCREMENT </code> series is 35, so the inserted values for <code class="literal"> col </code> begin at that point and the results are as shown for the <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> query. </p> <p> It is not possible to restrict the effects of these two variables to a single table; these variables control the behavior of all <code class="literal"> AUTO_INCREMENT </code> columns in <span class="emphasis"> <em> all </em> </span> tables on the MySQL server. If the global value of either variable is set, its effects persist until the global value is changed or overridden by setting the session value, or until <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> is restarted. If the local value is set, the new value affects <code class="literal"> AUTO_INCREMENT </code> columns for all tables into which new rows are inserted by the current user for the duration of the session, unless the values are changed during that session. </p> <p> The default value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> is 1. See <a class="xref" href="replication-features-auto-increment.html" title="19.5.1.1 Replication and AUTO_INCREMENT"> Section 19.5.1.1, “Replication and AUTO_INCREMENT” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_auto_increment_offset"> </a> <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> </p> <a class="indexterm" name="idm46045144425840"> </a> <a class="indexterm" name="idm46045144424800"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for auto_increment_offset"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --auto-increment-offset=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> auto_increment_offset </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> Yes </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> This variable has a default value of 1. If it is left with its default value, and Group Replication is started on the server in multi-primary mode, it is changed to the server ID. For more information, see the description for <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <code class="literal"> auto_increment_offset </code> is also supported for use with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables. </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_immediate_server_version"> </a> <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> <code class="literal"> immediate_server_version </code> </a> </p> <a class="indexterm" name="idm46045144391200"> </a> <a class="indexterm" name="idm46045144390096"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for immediate_server_version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> immediate_server_version </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 999999 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 999999 </code> </td> </tr> </tbody> </table> </div> <p> For internal use by replication. This session system variable holds the MySQL Server release number of the server that is the immediate source in a replication topology (for example, <code class="literal"> 80403 </code> for a MySQL 8.4.4 server instance). If this immediate server is at a release that does not support the session system variable, the value of the variable is set to 0 ( <code class="literal"> UNKNOWN_SERVER_VERSION </code> ). </p> <p> The value of the variable is replicated from a source to a replica. With this information the replica can correctly process data originating from a source at an older release, by recognizing where syntax changes or semantic changes have occurred between the releases involved and handling these appropriately. The information can also be used in a Group Replication environment where one or more members of the replication group is at a newer release than the others. The value of the variable can be viewed in the binary log for each transaction (as part of the <code class="literal"> Gtid_log_event </code> , or <code class="literal"> Anonymous_gtid_log_event </code> if GTIDs are not in use on the server), and could be helpful in debugging cross-version replication issues. </p> <p> Setting the session value of this system variable is a restricted operation. The session user must have either the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege (see <a class="xref" href="replication-privilege-checks.html" title="19.3.3 Replication Privilege Checks"> Section 19.3.3, “Replication Privilege Checks” </a> ), or privileges sufficient to set restricted session variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ). However, note that the variable is not intended for users to set; it is set automatically by the replication infrastructure. </p> </li> <li class="listitem"> <p> <a name="sysvar_original_server_version"> </a> <a class="link" href="replication-options-source.html#sysvar_original_server_version"> <code class="literal"> original_server_version </code> </a> </p> <a class="indexterm" name="idm46045144355760"> </a> <a class="indexterm" name="idm46045144354720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for original_server_version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_original_server_version"> original_server_version </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 999999 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 999999 </code> </td> </tr> </tbody> </table> </div> <p> For internal use by replication. This session system variable holds the MySQL Server release number of the server where a transaction was originally committed (for example, <code class="literal"> 80403 </code> for a MySQL 8.4.3 server instance). If this original server is at a release that does not support the session system variable, the value of the variable is set to 0 ( <code class="literal"> UNKNOWN_SERVER_VERSION </code> ). Note that when a release number is set by the original server, the value of the variable is reset to 0 if the immediate server or any other intervening server in the replication topology does not support the session system variable, and so does not replicate its value. </p> <p> The value of the variable is set and used in the same ways as for the <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> <code class="literal"> immediate_server_version </code> </a> system variable. If the value of the variable is the same as that for the <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> <code class="literal"> immediate_server_version </code> </a> system variable, only the latter is recorded in the binary log, with an indicator that the original server version is the same. </p> <p> In a Group Replication environment, view change log events, which are special transactions queued by each group member when a new member joins the group, are tagged with the server version of the group member queuing the transaction. This ensures that the server version of the original donor is known to the joining member. Because the view change log events queued for a particular view change have the same GTID on all members, for this case only, instances of the same GTID might have a different original server version. </p> <p> Setting the session value of this system variable is a restricted operation. The session user must have either the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege (see <a class="xref" href="replication-privilege-checks.html" title="19.3.3 Replication Privilege Checks"> Section 19.3.3, “Replication Privilege Checks” </a> ), or privileges sufficient to set restricted session variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ). However, note that the variable is not intended for users to set; it is set automatically by the replication infrastructure. </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_enabled"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_enabled"> <code class="literal"> rpl_semi_sync_master_enabled </code> </a> </p> <a class="indexterm" name="idm46045144317824"> </a> <a class="indexterm" name="idm46045144316720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_enabled"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-enabled[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_enabled"> rpl_semi_sync_master_enabled </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> <code class="literal"> rpl_semi_sync_source_enabled </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_timeout"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_timeout"> <code class="literal"> rpl_semi_sync_master_timeout </code> </a> </p> <a class="indexterm" name="idm46045144290880"> </a> <a class="indexterm" name="idm46045144289776"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-timeout=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_timeout"> rpl_semi_sync_master_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> <tr> <th> Unit </th> <td> milliseconds </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_trace_level"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_trace_level"> <code class="literal"> rpl_semi_sync_master_trace_level </code> </a> </p> <a class="indexterm" name="idm46045144257008"> </a> <a class="indexterm" name="idm46045144255904"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_trace_level"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-trace-level=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_trace_level"> rpl_semi_sync_master_trace_level </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 32 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> <code class="literal"> rpl_semi_sync_source_trace_level </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_wait_for_slave_count"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_for_slave_count"> <code class="literal"> rpl_semi_sync_master_wait_for_slave_count </code> </a> </p> <a class="indexterm" name="idm46045144225136"> </a> <a class="indexterm" name="idm46045144224016"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_wait_for_slave_count"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-wait-for-slave-count=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_for_slave_count"> rpl_semi_sync_master_wait_for_slave_count </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_wait_no_slave"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_no_slave"> <code class="literal"> rpl_semi_sync_master_wait_no_slave </code> </a> </p> <a class="indexterm" name="idm46045144193056"> </a> <a class="indexterm" name="idm46045144192016"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_wait_no_slave"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-wait-no-slave[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_no_slave"> rpl_semi_sync_master_wait_no_slave </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_wait_point"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_point"> <code class="literal"> rpl_semi_sync_master_wait_point </code> </a> </p> <a class="indexterm" name="idm46045144166112"> </a> <a class="indexterm" name="idm46045144165008"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_wait_point"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-wait-point=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_point"> rpl_semi_sync_master_wait_point </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> AFTER_SYNC </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> AFTER_SYNC </code> </p> <p class="valid-value"> <code class="literal"> AFTER_COMMIT </code> </p> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> <code class="literal"> rpl_semi_sync_source_wait_point </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_enabled"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> <code class="literal"> rpl_semi_sync_source_enabled </code> </a> </p> <a class="indexterm" name="idm46045144135344"> </a> <a class="indexterm" name="idm46045144134240"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_enabled"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-enabled[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> rpl_semi_sync_source_enabled </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> <code class="literal"> rpl_semi_sync_source_enabled </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="literal"> semisync_source.so </code> library) plugin was installed on the replica to set up semisynchronous replication. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> <code class="literal"> rpl_semi_sync_source_enabled </code> </a> controls whether semisynchronous replication is enabled on the source server. To enable or disable the plugin, set this variable to <code class="literal"> ON </code> or <code class="literal"> OFF </code> (or 1 or 0), respectively. The default is <code class="literal"> OFF </code> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_timeout"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> </p> <a class="indexterm" name="idm46045144102960"> </a> <a class="indexterm" name="idm46045144101856"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-timeout=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> rpl_semi_sync_source_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> <tr> <th> Unit </th> <td> milliseconds </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="filename"> semisync_source.so </code> library) plugin is installed on the replica. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> controls how long the source waits on a commit for acknowledgment from a replica before timing out and reverting to asynchronous replication. The value is specified in milliseconds, and the default value is 10000 (10 seconds). </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_trace_level"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> <code class="literal"> rpl_semi_sync_source_trace_level </code> </a> </p> <a class="indexterm" name="idm46045144065616"> </a> <a class="indexterm" name="idm46045144064512"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_trace_level"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-trace-level=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> rpl_semi_sync_source_trace_level </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 32 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> <code class="literal"> rpl_semi_sync_source_trace_level </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="filename"> semisync_source.so </code> library) plugin is installed on the replica. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> <code class="literal"> rpl_semi_sync_source_trace_level </code> </a> specifies the semisynchronous replication debug trace level on the source server. Four levels are defined: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> 1 = general level (for example, time function failures) </p> </li> <li class="listitem"> <p> 16 = detail level (more verbose information) </p> </li> <li class="listitem"> <p> 32 = net wait level (more information about network waits) </p> </li> <li class="listitem"> <p> 64 = function level (information about function entry and exit) </p> </li> </ul> </div> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_wait_for_replica_count"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> </p> <a class="indexterm" name="idm46045144026592"> </a> <a class="indexterm" name="idm46045144025472"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_wait_for_replica_count"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-wait-for-replica-count=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> rpl_semi_sync_source_wait_for_replica_count </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="literal"> semisync_source.so </code> library) plugin is installed on the replica to set up semisynchronous replication. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> specifies the number of replica acknowledgments the source must receive per transaction before proceeding. By default <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> is <code class="literal"> 1 </code> , meaning that semisynchronous replication proceeds after receiving a single replica acknowledgment. Performance is best for small values of this variable. </p> <p> For example, if <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> is <code class="literal"> 2 </code> , then 2 replicas must acknowledge receipt of the transaction before the timeout period configured by <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> for semisynchronous replication to proceed. If fewer replicas acknowledge receipt of the transaction during the timeout period, the source reverts to normal replication. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> This behavior also depends on <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> . </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_wait_no_replica"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> </p> <a class="indexterm" name="idm46045143983856"> </a> <a class="indexterm" name="idm46045143982816"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_wait_no_replica"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-wait-no-replica[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> rpl_semi_sync_source_wait_no_replica </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="filename"> semisync_source.so </code> library) plugin is installed on the replica. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> controls whether the source waits for the timeout period configured by <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> to expire, even if the replica count drops to less than the number of replicas configured by <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> during the timeout period. </p> <p> When the value of <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> is <code class="literal"> ON </code> (the default), it is permissible for the replica count to drop to less than <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> during the timeout period. As long as enough replicas acknowledge the transaction before the timeout period expires, semisynchronous replication continues. </p> <p> When the value of <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> is <code class="literal"> OFF </code> , if the replica count drops to less than the number configured in <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> at any time during the timeout period configured by <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> , the source reverts to normal replication. </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_wait_point"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> <code class="literal"> rpl_semi_sync_source_wait_point </code> </a> </p> <a class="indexterm" name="idm46045143942704"> </a> <a class="indexterm" name="idm46045143941600"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_wait_point"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-wait-point=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> rpl_semi_sync_source_wait_point </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> AFTER_SYNC </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> AFTER_SYNC </code> </p> <p class="valid-value"> <code class="literal"> AFTER_COMMIT </code> </p> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> <code class="literal"> rpl_semi_sync_source_wait_point </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="filename"> semisync_source.so </code> library) plugin is installed on the replica. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> <code class="literal"> rpl_semi_sync_source_wait_point </code> </a> controls the point at which a semisynchronous replication source server waits for replica acknowledgment of transaction receipt before returning a status to the client that committed the transaction. These values are permitted: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> AFTER_SYNC </code> (the default): The source writes each transaction to its binary log and the replica, and syncs the binary log to disk. The source waits for replica acknowledgment of transaction receipt after the sync. Upon receiving acknowledgment, the source commits the transaction to the storage engine and returns a result to the client, which then can proceed. </p> </li> <li class="listitem"> <p> <code class="literal"> AFTER_COMMIT </code> : The source writes each transaction to its binary log and the replica, syncs the binary log, and commits the transaction to the storage engine. The source waits for replica acknowledgment of transaction receipt after the commit. Upon receiving acknowledgment, the source returns a result to the client, which then can proceed. </p> </li> </ul> </div> <p> The replication characteristics of these settings differ as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> With <code class="literal"> AFTER_SYNC </code> , all clients see the committed transaction at the same time: After it has been acknowledged by the replica and committed to the storage engine on the source. Thus, all clients see the same data on the source. </p> <p> In the event of source failure, all transactions committed on the source have been replicated to the replica (saved to its relay log). An unexpected exit of the source server and failover to the replica is lossless because the replica is up to date. Note, however, that the source cannot be restarted in this scenario and must be discarded, because its binary log might contain uncommitted transactions that would cause a conflict with the replica when externalized after binary log recovery. </p> </li> <li class="listitem"> <p> With <code class="literal"> AFTER_COMMIT </code> , the client issuing the transaction gets a return status only after the server commits to the storage engine and receives replica acknowledgment. After the commit and before replica acknowledgment, other clients can see the committed transaction before the committing client. </p> <p> If something goes wrong such that the replica does not process the transaction, then in the event of an unexpected source server exit and failover to the replica, it is possible for such clients to see a loss of data relative to what they saw on the source. </p> </li> </ul> </div> </li> </ul> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/charset-collation-coercibility.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="charset-collation-coercibility"> </a> 12.8.4 Collation Coercibility in Expressions </h3> </div> </div> </div> <a class="indexterm" name="idm46045217092592"> </a> <a class="indexterm" name="idm46045217091104"> </a> <p> In the great majority of statements, it is obvious what collation MySQL uses to resolve a comparison operation. For example, in the following cases, it should be clear that the collation is the collation of column <code class="literal"> x </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa92754765"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> x <span class="token keyword">FROM</span> T <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> x<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> x <span class="token keyword">FROM</span> T <span class="token keyword">WHERE</span> x <span class="token operator">=</span> x<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> <span class="token keyword">DISTINCT</span> x <span class="token keyword">FROM</span> T<span class="token punctuation">;</span></code></pre> </div> <p> However, with multiple operands, there can be ambiguity. For example, this statement performs a comparison between the column <code class="literal"> x </code> and the string literal <code class="literal"> 'Y' </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa92406400"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> x <span class="token keyword">FROM</span> T <span class="token keyword">WHERE</span> x <span class="token operator">=</span> <span class="token string">'Y'</span><span class="token punctuation">;</span></code></pre> </div> <p> If <code class="literal"> x </code> and <code class="literal"> 'Y' </code> have the same collation, there is no ambiguity about the collation to use for the comparison. But if they have different collations, should the comparison use the collation of <code class="literal"> x </code> , or of <code class="literal"> 'Y' </code> ? Both <code class="literal"> x </code> and <code class="literal"> 'Y' </code> have collations, so which collation takes precedence? </p> <p> A mix of collations may also occur in contexts other than comparison. For example, a multiple-argument concatenation operation such as <a class="link" href="string-functions.html#function_concat"> <code class="literal"> CONCAT(x,'Y') </code> </a> combines its arguments to produce a single string. What collation should the result have? </p> <p> To resolve questions like these, MySQL checks whether the collation of one item can be coerced to the collation of the other. MySQL assigns coercibility values as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> An explicit <code class="literal"> COLLATE </code> clause has a coercibility of 0 (not coercible at all). </p> </li> <li class="listitem"> <p> The concatenation of two strings with different collations has a coercibility of 1. </p> </li> <li class="listitem"> <p> The collation of a column or a stored routine parameter or local variable has a coercibility of 2. </p> </li> <li class="listitem"> <p> A <span class="quote"> “ <span class="quote"> system constant </span> ” </span> (the string returned by functions such as <a class="link" href="information-functions.html#function_user"> <code class="literal"> USER() </code> </a> or <a class="link" href="information-functions.html#function_version"> <code class="literal"> VERSION() </code> </a> ) has a coercibility of 3. </p> </li> <li class="listitem"> <p> The collation of a literal has a coercibility of 4. </p> </li> <li class="listitem"> <p> The collation of a numeric or temporal value has a coercibility of 5. </p> </li> <li class="listitem"> <p> <code class="literal"> NULL </code> or an expression that is derived from <code class="literal"> NULL </code> has a coercibility of 6. </p> </li> </ul> </div> <p> MySQL uses coercibility values with the following rules to resolve ambiguities: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Use the collation with the lowest coercibility value. </p> </li> <li class="listitem"> <p> If both sides have the same coercibility, then: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If both sides are Unicode, or both sides are not Unicode, it is an error. </p> </li> <li class="listitem"> <p> If one of the sides has a Unicode character set, and another side has a non-Unicode character set, the side with Unicode character set wins, and automatic character set conversion is applied to the non-Unicode side. For example, the following statement does not return an error: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa73424587"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token function">CONCAT</span><span class="token punctuation">(</span>utf8mb4_column<span class="token punctuation">,</span> latin1_column<span class="token punctuation">)</span> <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span></code></pre> </div> <p> It returns a result that has a character set of <code class="literal"> utf8mb4 </code> and the same collation as <code class="literal"> utf8mb4_column </code> . Values of <code class="literal"> latin1_column </code> are automatically converted to <code class="literal"> utf8mb4 </code> before concatenating. </p> </li> <li class="listitem"> <p> For an operation with operands from the same character set but that mix a <code class="literal"> _bin </code> collation and a <code class="literal"> _ci </code> or <code class="literal"> _cs </code> collation, the <code class="literal"> _bin </code> collation is used. This is similar to how operations that mix nonbinary and binary strings evaluate the operands as binary strings, applied to collations rather than data types. </p> </li> </ul> </div> </li> </ul> </div> <p> Although automatic conversion is not in the SQL standard, the standard does say that every character set is (in terms of supported characters) a <span class="quote"> “ <span class="quote"> subset </span> ” </span> of Unicode. Because it is a well-known principle that <span class="quote"> “ <span class="quote"> what applies to a superset can apply to a subset, </span> ” </span> we believe that a collation for Unicode can apply for comparisons with non-Unicode strings. More generally, MySQL uses the concept of character set repertoire, which can sometimes be used to determine subset relationships among character sets and enable conversion of operands in operations that would otherwise produce an error. See <a class="xref" href="charset-repertoire.html" title="12.2.1 Character Set Repertoire"> Section 12.2.1, “Character Set Repertoire” </a> . </p> <p> The following table illustrates some applications of the preceding rules. </p> <div class="informaltable"> <table summary="Comparisons and the collation used for each comparison."> <colgroup> <col style="width: 50%"/> <col style="width: 50%"/> </colgroup> <thead> <tr> <th> Comparison </th> <th> Collation Used </th> </tr> </thead> <tbody> <tr> <td> <code class="literal"> column1 = 'A' </code> </td> <td> Use collation of <code class="literal"> column1 </code> </td> </tr> <tr> <td> <code class="literal"> column1 = 'A' COLLATE x </code> </td> <td> Use collation of <code class="literal"> 'A' COLLATE x </code> </td> </tr> <tr> <td> <code class="literal"> column1 COLLATE x = 'A' COLLATE y </code> </td> <td> Error </td> </tr> </tbody> </table> </div> <p> To determine the coercibility of a string expression, use the <a class="link" href="information-functions.html#function_coercibility"> <code class="literal"> COERCIBILITY() </code> </a> function (see <a class="xref" href="information-functions.html" title="14.15 Information Functions"> Section 14.15, “Information Functions” </a> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa24199754"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span>_utf8mb4<span class="token string">'A'</span> <span class="token keyword">COLLATE</span> utf8mb4_bin<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">0</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span><span class="token function">VERSION</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">3</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span><span class="token string">'A'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">4</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">5</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">6</span></code></pre> </div> <p> For implicit conversion of a numeric or temporal value to a string, such as occurs for the argument <code class="literal"> 1 </code> in the expression <a class="link" href="string-functions.html#function_concat"> <code class="literal"> CONCAT(1, 'abc') </code> </a> , the result is a character (nonbinary) string that has a character set and collation determined by the <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> <code class="literal"> character_set_connection </code> </a> and <a class="link" href="server-system-variables.html#sysvar_collation_connection"> <code class="literal"> collation_connection </code> </a> system variables. See <a class="xref" href="type-conversion.html" title="14.3 Type Conversion in Expression Evaluation"> Section 14.3, “Type Conversion in Expression Evaluation” </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/windows-restrictions.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="windows-restrictions"> </a> 2.3.6 Windows Platform Restrictions </h3> </div> </div> </div> <a class="indexterm" name="idm46045331758656"> </a> <p> The following restrictions apply to use of MySQL on the Windows platform: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <span class="bold"> <strong> Process memory </strong> </span> </p> <p> On Windows 32-bit platforms, it is not possible by default to use more than 2GB of RAM within a single process, including MySQL. This is because the physical address limit on Windows 32-bit is 4GB and the default setting within Windows is to split the virtual address space between kernel (2GB) and user/applications (2GB). </p> <p> Some versions of Windows have a boot time setting to enable larger applications by reducing the kernel application. Alternatively, to use more than 2GB, use a 64-bit version of Windows. </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> File system aliases </strong> </span> </p> <p> When using <code class="literal"> MyISAM </code> tables, you cannot use aliases within Windows link to the data files on another volume and then link back to the main MySQL <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="option"> datadir </code> </a> location. </p> <p> This facility is often used to move the data and index files to a RAID or other fast solution. </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> Limited number of ports </strong> </span> </p> <p> Windows systems have about 4,000 ports available for client connections, and after a connection on a port closes, it takes two to four minutes before the port can be reused. In situations where clients connect to and disconnect from the server at a high rate, it is possible for all available ports to be used up before closed ports become available again. If this happens, the MySQL server appears to be unresponsive even though it is running. Ports may be used by other applications running on the machine as well, in which case the number of ports available to MySQL is lower. </p> <p> For more information about this problem, see <a class="ulink" href="https://support.microsoft.com/kb/196271" target="_blank"> https://support.microsoft.com/kb/196271 </a> . </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> <code class="literal"> DATA DIRECTORY </code> and <code class="literal"> INDEX DIRECTORY </code> </strong> </span> </p> <p> The <code class="literal"> DATA DIRECTORY </code> clause of the <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> statement is supported on Windows for <code class="literal"> InnoDB </code> tables only, as described in <a class="xref" href="innodb-create-table-external.html" title="17.6.1.2 Creating Tables Externally"> Section 17.6.1.2, “Creating Tables Externally” </a> . For <code class="literal"> MyISAM </code> and other storage engines, the <code class="literal"> DATA DIRECTORY </code> and <code class="literal"> INDEX DIRECTORY </code> clauses for <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> are ignored on Windows and any other platforms with a nonfunctional <code class="literal"> realpath() </code> call. </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> <a class="link" href="drop-database.html" title="15.1.24 DROP DATABASE Statement"> <code class="literal"> DROP DATABASE </code> </a> </strong> </span> </p> <p> You cannot drop a database that is in use by another session. </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> Case-insensitive names </strong> </span> </p> <p> File names are not case-sensitive on Windows, so MySQL database and table names are also not case-sensitive on Windows. The only restriction is that database and table names must be specified using the same case throughout a given statement. See <a class="xref" href="identifier-case-sensitivity.html" title="11.2.3 Identifier Case Sensitivity"> Section 11.2.3, “Identifier Case Sensitivity” </a> . </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> Directory and file names </strong> </span> </p> <p> On Windows, MySQL Server supports only directory and file names that are compatible with the current ANSI code pages. For example, the following Japanese directory name does not work in the Western locale (code page 1252): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa84914064"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>"C:/私たちのプロジェクトのデータ"</span></code></pre> </div> <p> The same limitation applies to directory and file names referred to in SQL statements, such as the data file path name in <a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement"> <code class="literal"> LOAD DATA </code> </a> . </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> The <code class="literal"> \ </code> path name separator character </strong> </span> </p> <p> Path name components in Windows are separated by the <code class="literal"> \ </code> character, which is also the escape character in MySQL. If you are using <a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement"> <code class="literal"> LOAD DATA </code> </a> or <a class="link" href="select-into.html" title="15.2.13.1 SELECT ... INTO Statement"> <code class="literal"> SELECT ... INTO OUTFILE </code> </a> , use Unix-style file names with <code class="literal"> / </code> characters: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa98652142"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">DATA</span> <span class="token keyword">INFILE</span> <span class="token string">'C:/tmp/skr.txt'</span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> skr<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">INTO</span> <span class="token keyword">OUTFILE</span> <span class="token string">'C:/tmp/skr.txt'</span> <span class="token keyword">FROM</span> skr<span class="token punctuation">;</span></code></pre> </div> <p> Alternatively, you must double the <code class="literal"> \ </code> character: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59595940"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">DATA</span> <span class="token keyword">INFILE</span> <span class="token string">'C:\\tmp\\skr.txt'</span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> skr<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator"></span> <span class="token keyword">INTO</span> <span class="token keyword">OUTFILE</span> <span class="token string">'C:\\tmp\\skr.txt'</span> <span class="token keyword">FROM</span> skr<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> <span class="bold"> <strong> Problems with pipes </strong> </span> </p> <p> Pipes do not work reliably from the Windows command-line prompt. If the pipe includes the character <code class="literal"> ^Z </code> / <code class="literal"> CHAR(24) </code> , Windows thinks that it has encountered end-of-file and aborts the program. </p> <p> This is mainly a problem when you try to apply a binary log as follows: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa75711259"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> mysqlbinlog</span> <em class="replaceable">binary_log_file</em> \| mysql <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>root</span></code></pre> </div> <p> If you have a problem applying the log and suspect that it is because of a <code class="literal"> ^Z </code> / <code class="literal"> CHAR(24) </code> character, you can use the following workaround: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa21360665"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> mysqlbinlog</span> <em class="replaceable">binary_log_file</em> <span class="token constant">--result-file</span><span class="token attr-value"><span class="token punctuation">=</span>/tmp/bin.sql</span> <span class="token prompt">C:\></span><span class="token command"> mysql</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>root</span> <span class="token property">--execute</span> <span class="token atrule">"source /tmp/bin.sql"</span></code></pre> </div> <p> The latter command also can be used to reliably read any SQL file that may contain binary data. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/innodb-online-ddl-single-multi.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="innodb-online-ddl-single-multi"> </a> 17.12.6 Simplifying DDL Statements with Online DDL </h3> </div> </div> </div> <p> Before the introduction of <a class="link" href="glossary.html#glos_online_ddl" title="online DDL"> online DDL </a> , it was common practice to combine many DDL operations into a single <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statement. Because each <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statement involved copying and rebuilding the table, it was more efficient to make several changes to the same table at once, since those changes could all be done with a single rebuild operation for the table. The downside was that SQL code involving DDL operations was harder to maintain and to reuse in different scripts. If the specific changes were different each time, you might have to construct a new complex <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> for each slightly different scenario. </p> <p> For DDL operations that can be done online, you can separate them into individual <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements for easier scripting and maintenance, without sacrificing efficiency. For example, you might take a complicated statement such as: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa5246341"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ADD</span> <span class="token keyword">INDEX</span> i1<span class="token punctuation">(</span>c1<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">ADD</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">INDEX</span> i2<span class="token punctuation">(</span>c2<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">CHANGE</span> c4_old_name c4_new_name <span class="token datatype">INTEGER</span> <span class="token keyword">UNSIGNED</span><span class="token punctuation">;</span></code></pre> </div> <p> and break it down into simpler parts that can be tested and performed independently, such as: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa47106219"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ADD</span> <span class="token keyword">INDEX</span> i1<span class="token punctuation">(</span>c1<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ADD</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">INDEX</span> i2<span class="token punctuation">(</span>c2<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">CHANGE</span> c4_old_name c4_new_name <span class="token datatype">INTEGER</span> <span class="token keyword">UNSIGNED</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">;</span></code></pre> </div> <p> You might still use multi-part <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements for: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Operations that must be performed in a specific sequence, such as creating an index followed by a foreign key constraint that uses that index. </p> </li> <li class="listitem"> <p> Operations all using the same specific <code class="literal"> LOCK </code> clause, that you want to either succeed or fail as a group. </p> </li> <li class="listitem"> <p> Operations that cannot be performed online, that is, that still use the table-copy method. </p> </li> <li class="listitem"> <p> Operations for which you specify <code class="literal"> ALGORITHM=COPY </code> or <a class="link" href="server-system-variables.html#sysvar_old_alter_table"> <code class="literal"> old_alter_table=1 </code> </a> , to force the table-copying behavior if needed for precise backward-compatibility in specialized scenarios. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-variables-info-table.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="performance-schema-variables-info-table"> </a> 29.12.14.2 Performance Schema variables_info Table </h4> </div> </div> </div> <p> The <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table shows, for each system variable, the source from which it was most recently set, and its range of values. </p> <p> The <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> VARIABLE_NAME </code> </p> <p> The variable name. </p> </li> <li class="listitem"> <p> <code class="literal"> VARIABLE_SOURCE </code> </p> <p> The source from which the variable was most recently set: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> COMMAND_LINE </code> </p> <p> The variable was set on the command line. </p> </li> <li class="listitem"> <p> <code class="literal"> COMPILED </code> </p> <p> The variable has its compiled-in default value. <code class="literal"> COMPILED </code> is the value used for variables not set any other way. </p> </li> <li class="listitem"> <p> <code class="literal"> DYNAMIC </code> </p> <p> The variable was set at runtime. This includes variables set within files specified using the <a class="link" href="server-system-variables.html#sysvar_init_file"> <code class="literal"> init_file </code> </a> system variable. </p> </li> <li class="listitem"> <p> <code class="literal"> EXPLICIT </code> </p> <p> The variable was set from an option file named with the <a class="link" href="server-options.html#option_mysqld_defaults-file"> <code class="option"> --defaults-file </code> </a> option. </p> </li> <li class="listitem"> <p> <code class="literal"> EXTRA </code> </p> <p> The variable was set from an option file named with the <a class="link" href="server-options.html#option_mysqld_defaults-extra-file"> <code class="option"> --defaults-extra-file </code> </a> option. </p> </li> <li class="listitem"> <p> <code class="literal"> GLOBAL </code> </p> <p> The variable was set from a global option file. This includes option files not covered by <code class="literal"> EXPLICIT </code> , <code class="literal"> EXTRA </code> , <code class="literal"> LOGIN </code> , <code class="literal"> PERSISTED </code> , <code class="literal"> SERVER </code> , or <code class="literal"> USER </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> LOGIN </code> </p> <p> The variable was set from a user-specific login path file ( <code class="filename"> ~/.mylogin.cnf </code> ). </p> </li> <li class="listitem"> <p> <code class="literal"> PERSISTED </code> </p> <p> The variable was set from a server-specific <code class="filename"> mysqld-auto.cnf </code> option file. No row has this value if the server was started with <a class="link" href="server-system-variables.html#sysvar_persisted_globals_load"> <code class="literal"> persisted_globals_load </code> </a> disabled. </p> </li> <li class="listitem"> <p> <code class="literal"> SERVER </code> </p> <p> The variable was set from a server-specific <code class="filename"> <code class="literal"> $MYSQL_HOME </code> /my.cnf </code> option file. For details about how <code class="literal"> MYSQL_HOME </code> is set, see <a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files"> Section 6.2.2.2, “Using Option Files” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> USER </code> </p> <p> The variable was set from a user-specific <code class="filename"> ~/.my.cnf </code> option file. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> VARIABLE_PATH </code> </p> <p> If the variable was set from an option file, <code class="literal"> VARIABLE_PATH </code> is the path name of that file. Otherwise, the value is the empty string. </p> </li> <li class="listitem"> <p> <code class="literal"> MIN_VALUE </code> </p> <p> The minimum permitted value for the variable. For a variable whose type is not numeric, this is always 0. </p> </li> <li class="listitem"> <p> <code class="literal"> MAX_VALUE </code> </p> <p> The maximum permitted value for the variable. For a variable whose type is not numeric, this is always 0. </p> </li> <li class="listitem"> <p> <code class="literal"> SET_TIME </code> </p> <p> The time at which the variable was most recently set. The default is the time at which the server initialized global system variables during startup. </p> </li> <li class="listitem"> <p> <code class="literal"> SET_USER </code> , <code class="literal"> SET_HOST </code> </p> <p> The user name and host name of the client user that most recently set the variable. If a client connects as <code class="literal"> user17 </code> from host <code class="literal"> host34.example.com </code> using the account <code class="literal"> 'user17'@'%.example.com </code> , <code class="literal"> SET_USER </code> and <code class="literal"> SET_HOST </code> are <code class="literal"> user17 </code> and <code class="literal"> host34.example.com </code> , respectively. For proxy user connections, these values correspond to the external (proxy) user, not the proxied user against which privilege checking is performed. The default for each column is the empty string, indicating that the variable has not been set since server startup. </p> </li> </ul> </div> <p> The <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table has no indexes. </p> <p> <a class="link" href="truncate-table.html" title="15.1.37 TRUNCATE TABLE Statement"> <code class="literal"> TRUNCATE TABLE </code> </a> is not permitted for the <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table. </p> <p> If a variable with a <code class="literal"> VARIABLE_SOURCE </code> value other than <code class="literal"> DYNAMIC </code> is set at runtime, <code class="literal"> VARIABLE_SOURCE </code> becomes <code class="literal"> DYNAMIC </code> and <code class="literal"> VARIABLE_PATH </code> becomes the empty string. </p> <p> A system variable that has only a session value (such as <a class="link" href="server-system-variables.html#sysvar_debug_sync"> <code class="literal"> debug_sync </code> </a> ) cannot be set at startup or persisted. For session-only system variables, <code class="literal"> VARIABLE_SOURCE </code> can be only <code class="literal"> COMPILED </code> or <code class="literal"> DYNAMIC </code> . </p> <p> If a system variable has an unexpected <code class="literal"> VARIABLE_SOURCE </code> value, consider your server startup method. For example, <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> reads option files and passes certain options it finds there as part of the command line that it uses to start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . Consequently, some system variables that you set in option files might display in <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> as <code class="literal"> COMMAND_LINE </code> , rather than as <code class="literal"> GLOBAL </code> or <code class="literal"> SERVER </code> as you might otherwise expect. </p> <p> Some sample queries that use the <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table, with representative output: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Display variables set on the command line: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa67978398"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> VARIABLE_NAME <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>variables_info <span class="token keyword">WHERE</span> VARIABLE_SOURCE <span class="token operator">=</span> <span class="token string">'COMMAND_LINE'</span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> VARIABLE_NAME<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> VARIABLE_NAME <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> basedir <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> datadir <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> log_error <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> pid_file <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> plugin_dir <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> port <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </li> <li class="listitem"> <p> Display variables set from persistent storage: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa21616866"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> VARIABLE_NAME <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>variables_info <span class="token keyword">WHERE</span> VARIABLE_SOURCE <span class="token operator">=</span> <span class="token string">'PERSISTED'</span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> VARIABLE_NAME<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> VARIABLE_NAME <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> event_scheduler <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> max_connections <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> validate_password.policy <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </li> <li class="listitem"> <p> Join <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> with the <a class="link" href="performance-schema-system-variable-tables.html" title="29.12.14 Performance Schema System Variable Tables"> <code class="literal"> global_variables </code> </a> table to display the current values of persisted variables, together with their range of values: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59996176"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> VI<span class="token punctuation">.</span>VARIABLE_NAME<span class="token punctuation">,</span> GV<span class="token punctuation">.</span>VARIABLE_VALUE<span class="token punctuation">,</span> VI<span class="token punctuation">.</span>MIN_VALUE<span class="token punctuation">,</span>VI<span class="token punctuation">.</span>MAX_VALUE <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>variables_info <span class="token keyword">AS</span> VI <span class="token keyword">INNER</span> <span class="token keyword">JOIN</span> performance_schema<span class="token punctuation">.</span>global_variables <span class="token keyword">AS</span> GV <span class="token keyword">USING</span><span class="token punctuation">(</span>VARIABLE_NAME<span class="token punctuation">)</span> <span class="token keyword">WHERE</span> VI<span class="token punctuation">.</span>VARIABLE_SOURCE <span class="token operator">=</span> <span class="token string">'PERSISTED'</span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> VARIABLE_NAME<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> VARIABLE_NAME <span class="token punctuation">\|</span> VARIABLE_VALUE <span class="token punctuation">\|</span> MIN_VALUE <span class="token punctuation">\|</span> MAX_VALUE <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">\|</span> event_scheduler <span class="token punctuation">\|</span> ON <span class="token punctuation">\|</span> 0 <span class="token punctuation">\|</span> 0 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> max_connections <span class="token punctuation">\|</span> 200 <span class="token punctuation">\|</span> 1 <span class="token punctuation">\|</span> 100000 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">\|</span> validate_password.policy <span class="token punctuation">\|</span> STRONG <span class="token punctuation">\|</span> 0 <span class="token punctuation">\|</span> 0 <span class="token punctuation">\|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysqld-multi.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysqld-multi"> </a> 6.3.4 mysqld_multi — Manage Multiple MySQL Servers </h3> </div> </div> </div> <a class="indexterm" name="idm46045321240832"> </a> <a class="indexterm" name="idm46045321239920"> </a> <a class="indexterm" name="idm46045321238560"> </a> <a class="indexterm" name="idm46045321237616"> </a> <p> <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> is designed to manage several <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> processes that listen for connections on different Unix socket files and TCP/IP ports. It can start or stop servers, or report their current status. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> For some Linux platforms, MySQL installation from RPM or Debian packages includes systemd support for managing MySQL server startup and shutdown. On these platforms, <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> is not installed because it is unnecessary. For information about using systemd to handle multiple MySQL instances, see <a class="xref" href="using-systemd.html" title="2.5.9 Managing MySQL Server with systemd"> Section 2.5.9, “Managing MySQL Server with systemd” </a> . </p> </div> <p> <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> searches for groups named <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> in <code class="filename"> my.cnf </code> (or in the file named by the <a class="link" href="mysqld-multi.html#option_mysqld_multi_defaults-file"> <code class="option"> --defaults-file </code> </a> option). <em class="replaceable"> <code> N </code> </em> can be any positive integer. This number is referred to in the following discussion as the option group number, or <em class="replaceable"> <code> GNR </code> </em> . Group numbers distinguish option groups from one another and are used as arguments to <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> to specify which servers you want to start, stop, or obtain a status report for. Options listed in these groups are the same that you would use in the <code class="literal"> [mysqld] </code> group used for starting <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . (See, for example, <a class="xref" href="automatic-start.html" title="2.9.5 Starting and Stopping MySQL Automatically"> Section 2.9.5, “Starting and Stopping MySQL Automatically” </a> .) However, when using multiple servers, it is necessary that each one use its own value for options such as the Unix socket file and TCP/IP port number. For more information on which options must be unique per server in a multiple-server environment, see <a class="xref" href="multiple-servers.html" title="7.8 Running Multiple MySQL Instances on One Machine"> Section 7.8, “Running Multiple MySQL Instances on One Machine” </a> . </p> <p> To invoke <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> , use the following syntax: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa20955579"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld_multi <span class="token punctuation">[</span><em class="replaceable">options</em><span class="token punctuation">]</span> <span class="token punctuation">{</span>start\|stop\|reload\|report<span class="token punctuation">}</span> <span class="token punctuation">[</span><em class="replaceable">GNR</em><span class="token punctuation">[</span><span class="token punctuation">,</span><em class="replaceable">GNR</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">]</span></code></pre> </div> <p> <code class="literal"> start </code> , <code class="literal"> stop </code> , <code class="literal"> reload </code> (stop and restart), and <code class="literal"> report </code> indicate which operation to perform. You can perform the designated operation for a single server or multiple servers, depending on the <em class="replaceable"> <code> GNR </code> </em> list that follows the option name. If there is no list, <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> performs the operation for all servers in the option file. </p> <p> Each <em class="replaceable"> <code> GNR </code> </em> value represents an option group number or range of group numbers. The value should be the number at the end of the group name in the option file. For example, the <em class="replaceable"> <code> GNR </code> </em> for a group named <code class="literal"> [mysqld17] </code> is <code class="literal"> 17 </code> . To specify a range of numbers, separate the first and last numbers by a dash. The <em class="replaceable"> <code> GNR </code> </em> value <code class="literal"> 10-13 </code> represents groups <code class="literal"> [mysqld10] </code> through <code class="literal"> [mysqld13] </code> . Multiple groups or group ranges can be specified on the command line, separated by commas. There must be no whitespace characters (spaces or tabs) in the <em class="replaceable"> <code> GNR </code> </em> list; anything after a whitespace character is ignored. </p> <p> This command starts a single server using option group <code class="literal"> [mysqld17] </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa155460"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld_multi start 17</code></pre> </div> <p> This command stops several servers, using option groups <code class="literal"> [mysqld8] </code> and <code class="literal"> [mysqld10] </code> through <code class="literal"> [mysqld13] </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa87031173"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld_multi stop 8<span class="token punctuation">,</span>10-13</code></pre> </div> <p> For an example of how you might set up an option file, use this command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa2113699"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld_multi <span class="token property">--example</span></code></pre> </div> <p> <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> searches for option files as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_mysqld_multi_no-defaults"> </a> With <a class="link" href="mysqld-multi.html#option_mysqld_multi_no-defaults"> <code class="option"> --no-defaults </code> </a> , no option files are read. </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-defaults </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321183152"> </a> <a class="indexterm" name="idm46045321181664"> </a> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_defaults-file"> </a> With <a class="link" href="mysqld-multi.html#option_mysqld_multi_defaults-file"> <code class="option"> --defaults-file= <em class="replaceable"> <code> file_name </code> </em> </code> </a> , only the named file is read. </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-file=filename </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321167552"> </a> <a class="indexterm" name="idm46045321166064"> </a> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_defaults-extra-file"> </a> Otherwise, option files in the standard list of locations are read, including any file named by the <a class="link" href="mysqld-multi.html#option_mysqld_multi_defaults-extra-file"> <code class="option"> --defaults-extra-file= <em class="replaceable"> <code> file_name </code> </em> </code> </a> option, if one is given. (If the option is given multiple times, the last value is used.) </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-extra-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-extra-file=filename </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321151648"> </a> <a class="indexterm" name="idm46045321150144"> </a> </li> </ul> </div> <p> For additional information about these and other option-file options, see <a class="xref" href="option-file-options.html" title="6.2.2.3 Command-Line Options that Affect Option-File Handling"> Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling” </a> . </p> <p> Option files read are searched for <code class="literal"> [mysqld_multi] </code> and <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> option groups. The <code class="literal"> [mysqld_multi] </code> group can be used for options to <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> itself. <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> groups can be used for options passed to specific <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> instances. </p> <p> The <code class="literal"> [mysqld] </code> or <code class="literal"> [mysqld_safe] </code> groups can be used for common options read by all instances of <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> or <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> . You can specify a <a class="link" href="server-options.html#option_mysqld_defaults-file"> <code class="option"> --defaults-file= <em class="replaceable"> <code> file_name </code> </em> </code> </a> option to use a different configuration file for that instance, in which case the <code class="literal"> [mysqld] </code> or <code class="literal"> [mysqld_safe] </code> groups from that file are used for that instance. </p> <p> <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> supports the following options. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_mysqld_multi_help"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_help"> <code class="option"> --help </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for help"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --help </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321119200"> </a> <a class="indexterm" name="idm46045321117712"> </a> <p> Display a help message and exit. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_example"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_example"> <code class="option"> --example </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for example"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --example </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321103456"> </a> <a class="indexterm" name="idm46045321101968"> </a> <p> Display a sample option file. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_log"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_log"> <code class="option"> --log= <em class="replaceable"> <code> file_name </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for log"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --log=path </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> /var/log/mysqld_multi.log </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321087472"> </a> <a class="indexterm" name="idm46045321085984"> </a> <p> Specify the name of the log file. If the file exists, log output is appended to it. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_mysqladmin"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_mysqladmin"> <code class="option"> --mysqladmin= <em class="replaceable"> <code> prog_name </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for mysqladmin"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --mysqladmin=file </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321071424"> </a> <a class="indexterm" name="idm46045321069936"> </a> <p> The <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin </strong> </span> </a> binary to be used to stop servers. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_mysqld"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_mysqld"> <code class="option"> --mysqld= <em class="replaceable"> <code> prog_name </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for mysqld"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --mysqld=file </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321054160"> </a> <a class="indexterm" name="idm46045321052672"> </a> <p> The <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> binary to be used. Note that you can specify <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> as the value for this option also. If you use <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> to start the server, you can include the <code class="literal"> mysqld </code> or <code class="literal"> ledir </code> options in the corresponding <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> option group. These options indicate the name of the server that <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> should start and the path name of the directory where the server is located. (See the descriptions for these options in <a class="xref" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> Section 6.3.2, “mysqld_safe — MySQL Server Startup Script” </a> .) Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa74266999"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld38]</span> <span class="token constant">mysqld</span> <span class="token attr-value"><span class="token punctuation">=</span> mysqld-debug</span> <span class="token constant">ledir</span> <span class="token attr-value"><span class="token punctuation">=</span> /opt/local/mysql/libexec</span></code></pre> </div> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_no-log"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_no-log"> <code class="option"> --no-log </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-log"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-log </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321028960"> </a> <a class="indexterm" name="idm46045321027472"> </a> <p> Print log information to <code class="literal"> stdout </code> rather than to the log file. By default, output goes to the log file. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_password"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_password"> <code class="option"> --password= <em class="replaceable"> <code> password </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for password"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --password=string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321012144"> </a> <a class="indexterm" name="idm46045321010656"> </a> <p> The password of the MySQL account to use when invoking <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin </strong> </span> </a> . Note that the password value is not optional for this option, unlike for other MySQL programs. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_silent"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_silent"> <code class="option"> --silent </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for silent"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --silent </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320995104"> </a> <a class="indexterm" name="idm46045320993616"> </a> <p> Silent mode; disable warnings. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_tcp-ip"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_tcp-ip"> <code class="option"> --tcp-ip </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for tcp-ip"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --tcp-ip </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320979424"> </a> <a class="indexterm" name="idm46045320977936"> </a> <p> Connect to each MySQL server through the TCP/IP port instead of the Unix socket file. (If a socket file is missing, the server might still be running, but accessible only through the TCP/IP port.) By default, connections are made using the Unix socket file. This option affects <code class="literal"> stop </code> and <code class="literal"> report </code> operations. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_user"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_user"> <code class="option"> --user= <em class="replaceable"> <code> user_name </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for user"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --user=name </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> root </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320961648"> </a> <a class="indexterm" name="idm46045320960160"> </a> <p> The user name of the MySQL account to use when invoking <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin </strong> </span> </a> . </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_verbose"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_verbose"> <code class="option"> --verbose </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for verbose"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --verbose </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320944656"> </a> <a class="indexterm" name="idm46045320943168"> </a> <p> Be more verbose. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_version"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_version"> <code class="option"> --version </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --version </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320928928"> </a> <a class="indexterm" name="idm46045320927440"> </a> <p> Display version information and exit. </p> </li> </ul> </div> <p> Some notes about <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> : </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <span class="bold"> <strong> Most important </strong> </span> : Before using <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> be sure that you understand the meanings of the options that are passed to the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> servers and <span class="emphasis"> <em> why </em> </span> you would want to have separate <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> processes. Beware of the dangers of using multiple <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> servers with the same data directory. Use separate data directories, unless you <span class="emphasis"> <em> know </em> </span> what you are doing. Starting multiple servers with the same data directory does <span class="emphasis"> <em> not </em> </span> give you extra performance in a threaded system. See <a class="xref" href="multiple-servers.html" title="7.8 Running Multiple MySQL Instances on One Machine"> Section 7.8, “Running Multiple MySQL Instances on One Machine” </a> . </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> Make sure that the data directory for each server is fully accessible to the Unix account that the specific <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process is started as. <span class="emphasis"> <em> Do not </em> </span> use the Unix <em class="replaceable"> <code> root </code> </em> account for this, unless you <span class="emphasis"> <em> know </em> </span> what you are doing. See <a class="xref" href="changing-mysql-user.html" title="8.1.5 How to Run MySQL as a Normal User"> Section 8.1.5, “How to Run MySQL as a Normal User” </a> . </p> </div> </li> <li class="listitem"> <p> Make sure that the MySQL account used for stopping the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> servers (with the <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin </strong> </span> </a> program) has the same user name and password for each server. Also, make sure that the account has the <a class="link" href="privileges-provided.html#priv_shutdown"> <code class="literal"> SHUTDOWN </code> </a> privilege. If the servers that you want to manage have different user names or passwords for the administrative accounts, you might want to create an account on each server that has the same user name and password. For example, you might set up a common <code class="literal"> multi_admin </code> account by executing the following commands for each server: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa99522857"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> root <span class="token property">-S</span> /tmp/mysql<span class="token punctuation">.</span>sock <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> <span class="token prompt">mysql></span><span class="token command"> CREATE</span> USER <span class="token atrule">'multi_admin'</span>@<span class="token atrule">'localhost'</span> IDENTIFIED BY <span class="token atrule">'multipass'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span><span class="token command"> GRANT</span> SHUTDOWN ON <span class="token punctuation">.</span> TO <span class="token atrule">'multi_admin'</span>@<span class="token atrule">'localhost'</span><span class="token punctuation">;</span></code></pre> </div> <p> See <a class="xref" href="access-control.html" title="8.2 Access Control and Account Management"> Section 8.2, “Access Control and Account Management” </a> . You have to do this for each <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> server. Change the connection parameters appropriately when connecting to each one. Note that the host name part of the account name must permit you to connect as <code class="literal"> multi_admin </code> from the host where you want to run <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> . </p> </li> <li class="listitem"> <p> The Unix socket file and the TCP/IP port number must be different for every <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . (Alternatively, if the host has multiple network addresses, you can set the <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> system variable to cause different servers to listen to different interfaces.) </p> </li> <li class="listitem"> <p> The <a class="link" href="mysqld-safe.html#option_mysqld_safe_pid-file"> <code class="option"> --pid-file </code> </a> option is very important if you are using <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> to start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> (for example, <a class="link" href="mysqld-safe.html#option_mysqld_safe_mysqld"> <code class="option"> --mysqld=mysqld_safe </code> </a> ) Every <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> should have its own process ID file. The advantage of using <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> instead of <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> is that <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> monitors its <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process and restarts it if the process terminates due to a signal sent using <code class="literal"> kill -9 </code> or for other reasons, such as a segmentation fault. </p> </li> <li class="listitem"> <p> You might want to use the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user </code> </a> option for <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> , but to do this you need to run the <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> script as the Unix superuser ( <code class="literal"> root </code> ). Having the option in the option file doesn't matter; you just get a warning if you are not the superuser and the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> processes are started under your own Unix account. </p> </li> </ul> </div> <p> The following example shows how you might set up an option file for use with <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> . The order in which the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> programs are started or stopped depends on the order in which they appear in the option file. Group numbers need not form an unbroken sequence. The first and fifth <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> groups were intentionally omitted from the example to illustrate that you can have <span class="quote"> “ <span class="quote"> gaps </span> ” </span> in the option file. This gives you more flexibility. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa46676424"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># This is an example of a my.cnf file for mysqld_multi.</span> <span class="token comment" spellcheck="true"># Usually this file is located in home dir ~/.my.cnf or /etc/my.cnf</span> <span class="token selector">[mysqld_multi]</span> <span class="token constant">mysqld</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/bin/mysqld_safe</span> <span class="token constant">mysqladmin</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/bin/mysqladmin</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> multi_admin</span> <span class="token constant">password</span> <span class="token attr-value"><span class="token punctuation">=</span> my_password</span> <span class="token selector">[mysqld2]</span> <span class="token constant">socket</span> <span class="token attr-value"><span class="token punctuation">=</span> /tmp/mysql.sock2</span> <span class="token constant">port</span> <span class="token attr-value"><span class="token punctuation">=</span> 3307</span> <span class="token constant">pid-file</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data2/hostname.pid2</span> <span class="token constant">datadir</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data2</span> <span class="token constant">language</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/share/mysql/english</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> unix_user1</span> <span class="token selector">[mysqld3]</span> <span class="token constant">mysqld</span> <span class="token attr-value"><span class="token punctuation">=</span> /path/to/mysqld_safe</span> <span class="token constant">ledir</span> <span class="token attr-value"><span class="token punctuation">=</span> /path/to/mysqld-binary/</span> <span class="token constant">mysqladmin</span> <span class="token attr-value"><span class="token punctuation">=</span> /path/to/mysqladmin</span> <span class="token constant">socket</span> <span class="token attr-value"><span class="token punctuation">=</span> /tmp/mysql.sock3</span> <span class="token constant">port</span> <span class="token attr-value"><span class="token punctuation">=</span> 3308</span> <span class="token constant">pid-file</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data3/hostname.pid3</span> <span class="token constant">datadir</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data3</span> <span class="token constant">language</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/share/mysql/swedish</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> unix_user2</span> <span class="token selector">[mysqld4]</span> <span class="token constant">socket</span> <span class="token attr-value"><span class="token punctuation">=</span> /tmp/mysql.sock4</span> <span class="token constant">port</span> <span class="token attr-value"><span class="token punctuation">=</span> 3309</span> <span class="token constant">pid-file</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data4/hostname.pid4</span> <span class="token constant">datadir</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data4</span> <span class="token constant">language</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/share/mysql/estonia</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> unix_user3</span> <span class="token selector">[mysqld6]</span> <span class="token constant">socket</span> <span class="token attr-value"><span class="token punctuation">=</span> /tmp/mysql.sock6</span> <span class="token constant">port</span> <span class="token attr-value"><span class="token punctuation">=</span> 3311</span> <span class="token constant">pid-file</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data6/hostname.pid6</span> <span class="token constant">datadir</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data6</span> <span class="token constant">language</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/share/mysql/japanese</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> unix_user4</span></code></pre> </div> <p> See <a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files"> Section 6.2.2.2, “Using Option Files” </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/security-against-attack.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="security-against-attack"> </a> 8.1.3 Making MySQL Secure Against Attackers </h3> </div> </div> </div> <a class="indexterm" name="idm46045252803024"> </a> <a class="indexterm" name="idm46045252801568"> </a> <a class="indexterm" name="idm46045252800080"> </a> <a class="indexterm" name="idm46045252799008"> </a> <a class="indexterm" name="idm46045252797968"> </a> <p> When you connect to a MySQL server, you should use a password. The password is not transmitted as cleartext over the connection. </p> <p> All other information is transferred as text, and can be read by anyone who is able to watch the connection. If the connection between the client and the server goes through an untrusted network, and you are concerned about this, you can use the compressed protocol to make traffic much more difficult to decipher. You can also use MySQL's internal SSL support to make the connection even more secure. See <a class="xref" href="encrypted-connections.html" title="8.3 Using Encrypted Connections"> Section 8.3, “Using Encrypted Connections” </a> . Alternatively, use SSH to get an encrypted TCP/IP connection between a MySQL server and a MySQL client. You can find an Open Source SSH client at <a class="ulink" href="http://www.openssh.org/" target="_blank"> http://www.openssh.org/ </a> , and a comparison of both Open Source and Commercial SSH clients at <a class="ulink" href="http://en.wikipedia.org/wiki/Comparison_of_SSH_clients" target="_blank"> http://en.wikipedia.org/wiki/Comparison_of_SSH_clients </a> . </p> <p> To make a MySQL system secure, you should strongly consider the following suggestions: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Require all MySQL accounts to have a password. A client program does not necessarily know the identity of the person running it. It is common for client/server applications that the user can specify any user name to the client program. For example, anyone can use the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> program to connect as any other person simply by invoking it as <code class="literal"> mysql -u <em class="replaceable"> <code> other_user </code> </em> <em class="replaceable"> <code> db_name </code> </em> </code> if <em class="replaceable"> <code> other_user </code> </em> has no password. If all accounts have a password, connecting using another user's account becomes much more difficult. </p> <p> For a discussion of methods for setting passwords, see <a class="xref" href="assigning-passwords.html" title="8.2.14 Assigning Account Passwords"> Section 8.2.14, “Assigning Account Passwords” </a> . </p> </li> <li class="listitem"> <p> Make sure that the only Unix user account with read or write privileges in the database directories is the account that is used for running <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . </p> </li> <li class="listitem"> <p> Never run the MySQL server as the Unix <code class="literal"> root </code> user. This is extremely dangerous, because any user with the <a class="link" href="privileges-provided.html#priv_file"> <code class="literal"> FILE </code> </a> privilege is able to cause the server to create files as <code class="literal"> root </code> (for example, <code class="literal"> ~root/.bashrc </code> ). To prevent this, <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> refuses to run as <code class="literal"> root </code> unless that is specified explicitly using the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user=root </code> </a> option. </p> <p> <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> can (and should) be run as an ordinary, unprivileged user instead. You can create a separate Unix account named <code class="literal"> mysql </code> to make everything even more secure. Use this account only for administering MySQL. To start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as a different Unix user, add a <code class="literal"> user </code> option that specifies the user name in the <code class="literal"> [mysqld] </code> group of the <code class="filename"> my.cnf </code> option file where you specify server options. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa75167223"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span></code></pre> </div> <p> This causes the server to start as the designated user whether you start it manually or by using <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> or <a class="link" href="mysql-server.html" title="6.3.3 mysql.server — MySQL Server Startup Script"> <span class="command"> <strong> mysql.server </strong> </span> </a> . For more details, see <a class="xref" href="changing-mysql-user.html" title="8.1.5 How to Run MySQL as a Normal User"> Section 8.1.5, “How to Run MySQL as a Normal User” </a> . </p> <p> Running <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as a Unix user other than <code class="literal"> root </code> does not mean that you need to change the <code class="literal"> root </code> user name in the <code class="literal"> user </code> table. <span class="emphasis"> <em> User names for MySQL accounts have nothing to do with user names for Unix accounts </em> </span> . </p> </li> <li class="listitem"> <p> Do not grant the <a class="link" href="privileges-provided.html#priv_file"> <code class="literal"> FILE </code> </a> privilege to nonadministrative users. Any user that has this privilege can write a file anywhere in the file system with the privileges of the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> daemon. This includes the server's data directory containing the files that implement the privilege tables. To make <a class="link" href="privileges-provided.html#priv_file"> <code class="literal"> FILE </code> </a> -privilege operations a bit safer, files generated with <a class="link" href="select-into.html" title="15.2.13.1 SELECT ... INTO Statement"> <code class="literal"> SELECT ... INTO OUTFILE </code> </a> do not overwrite existing files and are writable by everyone. </p> <a class="indexterm" name="idm46045252756304"> </a> <p> The <a class="link" href="privileges-provided.html#priv_file"> <code class="literal"> FILE </code> </a> privilege may also be used to read any file that is world-readable or accessible to the Unix user that the server runs as. With this privilege, you can read any file into a database table. This could be abused, for example, by using <a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement"> <code class="literal"> LOAD DATA </code> </a> to load <code class="filename"> /etc/passwd </code> into a table, which then can be displayed with <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> . </p> <p> To limit the location in which files can be read and written, set the <a class="link" href="server-system-variables.html#sysvar_secure_file_priv"> <code class="literal"> secure_file_priv </code> </a> system to a specific directory. See <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> . </p> </li> <li class="listitem"> <p> Encrypt binary log files and relay log files. Encryption helps to protect these files and the potentially sensitive data contained in them from being misused by outside attackers, and also from unauthorized viewing by users of the operating system where they are stored. You enable encryption on a MySQL server by setting the <a class="link" href="replication-options-binary-log.html#sysvar_binlog_encryption"> <code class="literal"> binlog_encryption </code> </a> system variable to <code class="literal"> ON </code> . For more information, see <a class="xref" href="replication-binlog-encryption.html" title="19.3.2 Encrypting Binary Log Files and Relay Log Files"> Section 19.3.2, “Encrypting Binary Log Files and Relay Log Files” </a> . </p> </li> <li class="listitem"> <p> Do not grant the <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> or <a class="link" href="privileges-provided.html#priv_super"> <code class="literal"> SUPER </code> </a> privilege to nonadministrative users. The output of <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin processlist </strong> </span> </a> and <a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement"> <code class="literal"> SHOW PROCESSLIST </code> </a> shows the text of any statements currently being executed, so any user who is permitted to see the server process list might be able to see statements issued by other users. </p> <p> <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> reserves an extra connection for users who have the <a class="link" href="privileges-provided.html#priv_connection-admin"> <code class="literal"> CONNECTION_ADMIN </code> </a> or <a class="link" href="privileges-provided.html#priv_super"> <code class="literal"> SUPER </code> </a> privilege, so that a MySQL <code class="literal"> root </code> user can log in and check server activity even if all normal connections are in use. </p> <p> The <a class="link" href="privileges-provided.html#priv_super"> <code class="literal"> SUPER </code> </a> privilege can be used to terminate client connections, change server operation by changing the value of system variables, and control replication servers. </p> </li> <li class="listitem"> <p> Do not permit the use of symlinks to tables. (This capability can be disabled with the <a class="link" href="server-options.html#option_mysqld_symbolic-links"> <code class="option"> --skip-symbolic-links </code> </a> option.) This is especially important if you run <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as <code class="literal"> root </code> , because anyone that has write access to the server's data directory then could delete any file in the system! See <a class="xref" href="symbolic-links-to-tables.html" title="10.12.2.2 Using Symbolic Links for MyISAM Tables on Unix"> Section 10.12.2.2, “Using Symbolic Links for MyISAM Tables on Unix” </a> . </p> </li> <li class="listitem"> <p> Stored programs and views should be written using the security guidelines discussed in <a class="xref" href="stored-objects-security.html" title="27.6 Stored Object Access Control"> Section 27.6, “Stored Object Access Control” </a> . </p> </li> <li class="listitem"> <p> If you do not trust your DNS, you should use IP addresses rather than host names in the grant tables. In any case, you should be very careful about creating grant table entries using host name values that contain wildcards. </p> </li> <li class="listitem"> <p> If you want to restrict the number of connections permitted to a single account, you can do so by setting the <a class="link" href="server-system-variables.html#sysvar_max_user_connections"> <code class="literal"> max_user_connections </code> </a> variable in <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . The <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> and <a class="link" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> <code class="literal"> ALTER USER </code> </a> statements also support resource control options for limiting the extent of server use permitted to an account. See <a class="xref" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> Section 15.7.1.3, “CREATE USER Statement” </a> , and <a class="xref" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> Section 15.7.1.1, “ALTER USER Statement” </a> . </p> </li> <li class="listitem"> <p> If the plugin directory is writable by the server, it may be possible for a user to write executable code to a file in the directory using <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT ... INTO DUMPFILE </code> </a> . This can be prevented by making <a class="link" href="server-system-variables.html#sysvar_plugin_dir"> <code class="literal"> plugin_dir </code> </a> read only to the server or by setting <a class="link" href="server-system-variables.html#sysvar_secure_file_priv"> <code class="literal"> secure_file_priv </code> </a> to a directory where <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> writes can be made safely. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/windows-server-first-start.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="windows-server-first-start"> </a> 2.3.3.5 Starting the Server for the First Time </h4> </div> </div> </div> <p> This section gives a general overview of starting the MySQL server. The following sections provide more specific information for starting the MySQL server from the command line or as a Windows service. </p> <p> The information here applies primarily if you installed MySQL using the <code class="literal"> noinstall </code> version, or if you wish to configure and test MySQL manually rather than using MySQL Configurator. </p> <p> The examples in these sections assume that MySQL is installed under the default location of <code class="filename"> C:\Program Files\MySQL\MySQL Server 8.4 </code> . Adjust the path names shown in the examples if you have MySQL installed in a different location. </p> <p> Clients have two options. They can use TCP/IP, or they can use a named pipe if the server supports named-pipe connections. </p> <p> MySQL for Windows also supports shared-memory connections if the server is started with the <a class="link" href="server-system-variables.html#sysvar_shared_memory"> <code class="literal"> shared_memory </code> </a> system variable enabled. Clients can connect through shared memory by using the <a class="link" href="connection-options.html#option_general_protocol"> <code class="option"> --protocol=MEMORY </code> </a> option. </p> <p> For information about which server binary to run, see <a class="xref" href="windows-select-server.html" title="2.3.3.3 Selecting a MySQL Server Type"> Section 2.3.3.3, “Selecting a MySQL Server Type” </a> . </p> <p> Testing is best done from a command prompt in a console window (or <span class="quote"> “ <span class="quote"> DOS window </span> ” </span> ). In this way you can have the server display status messages in the window where they are easy to see. If something is wrong with your configuration, these messages make it easier for you to identify and fix any problems. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The database must be initialized before MySQL can be started. For additional information about the initialization process, see <a class="xref" href="data-directory-initialization.html" title="2.9.1 Initializing the Data Directory"> Section 2.9.1, “Initializing the Data Directory” </a> . </p> </div> <p> To start the server, enter this command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa25924138"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span> <span class="token atrule">"C:\Program Files\MySQL\MySQL Server 8.4\bin\mysqld"</span> <span class="token property">--console</span></code></pre> </div> <p> You should see messages similar to those following as it starts (the path names and sizes may differ). The <code class="literal"> ready for connections </code> messages indicate that the server is ready to service client connections. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa94118152"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[Server] C:\mysql\bin\mysqld.exe (mysqld 8.0.30) starting as process 21236 [InnoDB] InnoDB initialization has started. [InnoDB] InnoDB initialization has ended. [Server] CA certificate ca.pem is self signed. [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel. [Server] X Plugin ready for connections. Bind-address: '::' port: 33060 [Server] C:\mysql\bin\mysqld.exe: ready for connections. Version: '8.0.30' socket: '' port: 3306 MySQL Community Server - GPL.</code></pre> </div> <p> You can now open a new console window in which to run client programs. </p> <p> If you omit the <a class="link" href="server-options.html#option_mysqld_console"> <code class="option"> --console </code> </a> option, the server writes diagnostic output to the error log in the data directory ( <code class="filename"> C:\Program Files\MySQL\MySQL Server 8.4\data </code> by default). The error log is the file with the <code class="filename"> .err </code> extension, and may be set using the <a class="link" href="server-options.html#option_mysqld_log-error"> <code class="option"> --log-error </code> </a> option. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The initial <code class="literal"> root </code> account in the MySQL grant tables has no password. After starting the server, you should set up a password for it using the instructions in <a class="xref" href="default-privileges.html" title="2.9.4 Securing the Initial MySQL Account"> Section 2.9.4, “Securing the Initial MySQL Account” </a> . </p> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-locks-per-fragment.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-ndbinfo-locks-per-fragment"> </a> 25.6.17.42 The ndbinfo locks_per_fragment Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045089088032"> </a> <p> The <code class="literal"> locks_per_fragment </code> table provides information about counts of lock claim requests, and the outcomes of these requests on a per-fragment basis, serving as a companion table to <a class="link" href="mysql-cluster-ndbinfo-operations-per-fragment.html" title="25.6.17.49 The ndbinfo operations_per_fragment Table"> <code class="literal"> operations_per_fragment </code> </a> and <a class="link" href="mysql-cluster-ndbinfo-memory-per-fragment.html" title="25.6.17.47 The ndbinfo memory_per_fragment Table"> <code class="literal"> memory_per_fragment </code> </a> . This table also shows the total time spent waiting for locks successfully and unsuccessfully since fragment or table creation, or since the most recent restart. </p> <p> The <code class="literal"> locks_per_fragment </code> table contains the following columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> fq_name </code> </p> <p> Fully qualified table name </p> </li> <li class="listitem"> <p> <code class="literal"> parent_fq_name </code> </p> <p> Fully qualified name of parent object </p> </li> <li class="listitem"> <p> <code class="literal"> type </code> </p> <p> Table type; see text for possible values </p> </li> <li class="listitem"> <p> <code class="literal"> table_id </code> </p> <p> Table ID </p> </li> <li class="listitem"> <p> <code class="literal"> node_id </code> </p> <p> Reporting node ID </p> </li> <li class="listitem"> <p> <code class="literal"> block_instance </code> </p> <p> LDM instance ID </p> </li> <li class="listitem"> <p> <code class="literal"> fragment_num </code> </p> <p> Fragment identifier </p> </li> <li class="listitem"> <p> <code class="literal"> ex_req </code> </p> <p> Exclusive lock requests started </p> </li> <li class="listitem"> <p> <code class="literal"> ex_imm_ok </code> </p> <p> Exclusive lock requests immediately granted </p> </li> <li class="listitem"> <p> <code class="literal"> ex_wait_ok </code> </p> <p> Exclusive lock requests granted following wait </p> </li> <li class="listitem"> <p> <code class="literal"> ex_wait_fail </code> </p> <p> Exclusive lock requests not granted </p> </li> <li class="listitem"> <p> <code class="literal"> sh_req </code> </p> <p> Shared lock requests started </p> </li> <li class="listitem"> <p> <code class="literal"> sh_imm_ok </code> </p> <p> Shared lock requests immediately granted </p> </li> <li class="listitem"> <p> <code class="literal"> sh_wait_ok </code> </p> <p> Shared lock requests granted following wait </p> </li> <li class="listitem"> <p> <code class="literal"> sh_wait_fail </code> </p> <p> Shared lock requests not granted </p> </li> <li class="listitem"> <p> <code class="literal"> wait_ok_millis </code> </p> <p> Time spent waiting for lock requests that were granted, in milliseconds </p> </li> <li class="listitem"> <p> <code class="literal"> wait_fail_millis </code> </p> <p> Time spent waiting for lock requests that failed, in milliseconds </p> </li> </ul> </div> <h5> <a name="idm46045089048400"> </a> Notes </h5> <p> <code class="literal"> block_instance </code> refers to an instance of a kernel block. Together with the block name, this number can be used to look up a given instance in the <a class="link" href="mysql-cluster-ndbinfo-threadblocks.html" title="25.6.17.62 The ndbinfo threadblocks Table"> <code class="literal"> threadblocks </code> </a> table. </p> <p> <code class="literal"> fq_name </code> is a fully qualified database object name in <em class="replaceable"> <code> database </code> </em> / <em class="replaceable"> <code> schema </code> </em> / <em class="replaceable"> <code> name </code> </em> format, such as <code class="literal"> test/def/t1 </code> or <code class="literal"> sys/def/10/b$unique </code> . </p> <p> <code class="literal"> parent_fq_name </code> is the fully qualified name of this object's parent object (table). </p> <p> <code class="literal"> table_id </code> is the table's internal ID generated by <code class="literal"> NDB </code> . This is the same internal table ID shown in other <code class="literal"> ndbinfo </code> tables; it is also visible in the output of <a class="link" href="mysql-cluster-programs-ndb-show-tables.html" title="25.5.27 ndb_show_tables — Display List of NDB Tables"> <span class="command"> <strong> ndb_show_tables </strong> </span> </a> . </p> <p> The <code class="literal"> type </code> column shows the type of table. This is always one of <code class="literal"> System table </code> , <code class="literal"> User table </code> , <code class="literal"> Unique hash index </code> , <code class="literal"> Hash index </code> , <code class="literal"> Unique ordered index </code> , <code class="literal"> Ordered index </code> , <code class="literal"> Hash index trigger </code> , <code class="literal"> Subscription trigger </code> , <code class="literal"> Read only constraint </code> , <code class="literal"> Index trigger </code> , <code class="literal"> Reorganize trigger </code> , <code class="literal"> Tablespace </code> , <code class="literal"> Log file group </code> , <code class="literal"> Data file </code> , <code class="literal"> Undo file </code> , <code class="literal"> Hash map </code> , <code class="literal"> Foreign key definition </code> , <code class="literal"> Foreign key parent trigger </code> , <code class="literal"> Foreign key child trigger </code> , or <code class="literal"> Schema transaction </code> . </p> <p> The values shown in all of the columns <code class="literal"> ex_req </code> , <code class="literal"> ex_req_imm_ok </code> , <code class="literal"> ex_wait_ok </code> , <code class="literal"> ex_wait_fail </code> , <code class="literal"> sh_req </code> , <code class="literal"> sh_req_imm_ok </code> , <code class="literal"> sh_wait_ok </code> , and <code class="literal"> sh_wait_fail </code> represent cumulative numbers of requests since the table or fragment was created, or since the last restart of this node, whichever of these occurred later. This is also true for the time values shown in the <code class="literal"> wait_ok_millis </code> and <code class="literal"> wait_fail_millis </code> columns. </p> <p> Every lock request is considered either to be in progress, or to have completed in some way (that is, to have succeeded or failed). This means that the following relationships are true: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa55878428"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">ex_req <span class="token operator">>=</span> <span class="token punctuation">(</span>ex_req_imm_ok <span class="token operator">+</span> ex_wait_ok <span class="token operator">+</span> ex_wait_fail<span class="token punctuation">)</span> sh_req <span class="token operator">>=</span> <span class="token punctuation">(</span>sh_req_imm_ok <span class="token operator">+</span> sh_wait_ok <span class="token operator">+</span> sh_wait_fail<span class="token punctuation">)</span></code></pre> </div> <p> The number of requests currently in progress is the current number of incomplete requests, which can be found as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa40026695"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple"><span class="token punctuation">[</span>exclusive lock requests in progress<span class="token punctuation">]</span> <span class="token operator">=</span> ex_req <span class="token operator">-</span> <span class="token punctuation">(</span>ex_req_imm_ok <span class="token operator">+</span> ex_wait_ok <span class="token operator">+</span> ex_wait_fail<span class="token punctuation">)</span> <span class="token punctuation">[</span>shared lock requests in progress<span class="token punctuation">]</span> <span class="token operator">=</span> sh_req <span class="token operator">-</span> <span class="token punctuation">(</span>sh_req_imm_ok <span class="token operator">+</span> sh_wait_ok <span class="token operator">+</span> sh_wait_fail<span class="token punctuation">)</span></code></pre> </div> <p> A failed wait indicates an aborted transaction, but the abort may or may not be caused by a lock wait timeout. You can obtain the total number of aborts while waiting for locks as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa91462517"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple"><span class="token punctuation">[</span>aborts while waiting for locks<span class="token punctuation">]</span> <span class="token operator">=</span> ex_wait_fail <span class="token operator">+</span> sh_wait_fail</code></pre> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/myisamlog.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="myisamlog"> </a> 6.6.5 myisamlog — Display MyISAM Log File Contents </h3> </div> </div> </div> <a class="indexterm" name="idm46045306541792"> </a> <p> <a class="link" href="myisamlog.html" title="6.6.5 myisamlog — Display MyISAM Log File Contents"> <span class="command"> <strong> myisamlog </strong> </span> </a> processes the contents of a <code class="literal"> MyISAM </code> log file. To create such a file, start the server with a <a class="link" href="server-options.html#option_mysqld_log-isam"> <code class="option"> --log-isam= <code class="filename"> log_file </code> </code> </a> option. </p> <p> Invoke <a class="link" href="myisamlog.html" title="6.6.5 myisamlog — Display MyISAM Log File Contents"> <span class="command"> <strong> myisamlog </strong> </span> </a> like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa46382698"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">myisamlog <span class="token punctuation">[</span><em class="replaceable">options</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><em class="replaceable">file_name</em> <span class="token punctuation">[</span><em class="replaceable">tbl_name</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">]</span></code></pre> </div> <p> The default operation is update ( <code class="option"> -u </code> ). If a recovery is done ( <code class="option"> -r </code> ), all writes and possibly updates and deletes are done and errors are only counted. The default log file name is <code class="filename"> myisam.log </code> if no <em class="replaceable"> <code> log_file </code> </em> argument is given. If tables are named on the command line, only those tables are updated. </p> <p> <a class="link" href="myisamlog.html" title="6.6.5 myisamlog — Display MyISAM Log File Contents"> <span class="command"> <strong> myisamlog </strong> </span> </a> supports the following options: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_myisamlog_help"> </a> <code class="option"> -? </code> , <code class="option"> -I </code> </p> <p> Display a help message and exit. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_commands"> </a> <code class="option"> -c <em class="replaceable"> <code> N </code> </em> </code> </p> <p> Execute only <em class="replaceable"> <code> N </code> </em> commands. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_files"> </a> <code class="option"> -f <em class="replaceable"> <code> N </code> </em> </code> </p> <p> Specify the maximum number of open files. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_filepath"> </a> <code class="option"> -F <em class="replaceable"> <code> filepath/ </code> </em> </code> </p> <p> Specify the file path with a trailing slash. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_information"> </a> <code class="option"> -i </code> </p> <p> Display extra information before exiting. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_offset"> </a> <code class="option"> -o <em class="replaceable"> <code> offset </code> </em> </code> </p> <p> Specify the starting offset. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_path"> </a> <code class="option"> -p <em class="replaceable"> <code> N </code> </em> </code> </p> <p> Remove <em class="replaceable"> <code> N </code> </em> components from path. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_recovery"> </a> <code class="option"> -r </code> </p> <p> Perform a recovery operation. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_record-position"> </a> <code class="option"> -R <em class="replaceable"> <code> record_pos_file record_pos </code> </em> </code> </p> <p> Specify record position file and record position. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_update"> </a> <code class="option"> -u </code> </p> <p> Perform an update operation. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_verbose"> </a> <code class="option"> -v </code> </p> <p> Verbose mode. Print more output about what the program does. This option can be given multiple times to produce more and more output. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_write"> </a> <code class="option"> -w <em class="replaceable"> <code> write_file </code> </em> </code> </p> <p> Specify the write file. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_version"> </a> <code class="option"> -V </code> </p> <p> Display version information. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/federated-create-connection.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="federated-create-connection"> </a> 18.8.2.1 Creating a FEDERATED Table Using CONNECTION </h4> </div> </div> </div> <p> To use the first method, you must specify the <code class="literal"> CONNECTION </code> string after the engine type in a <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> statement. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa81982638"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> federated_table <span class="token punctuation">(</span> id <span class="token datatype">INT</span><span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span><span class="token punctuation">,</span> <span class="token keyword">name</span> <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">32</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">DEFAULT</span> <span class="token string">''</span><span class="token punctuation">,</span> other <span class="token datatype">INT</span><span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">DEFAULT</span> <span class="token string">'0'</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>id<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">INDEX</span> <span class="token keyword">name</span> <span class="token punctuation">(</span><span class="token keyword">name</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">INDEX</span> other_key <span class="token punctuation">(</span>other<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">ENGINE</span><span class="token operator">=</span>FEDERATED <span class="token keyword">DEFAULT</span> <span class="token keyword">CHARSET</span><span class="token operator">=</span>utf8mb4 <span class="token keyword">CONNECTION</span><span class="token operator">=</span><span class="token string">'mysql://fed_user@remote_host:9306/federated/test_table'</span><span class="token punctuation">;</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <code class="literal"> CONNECTION </code> replaces the <code class="literal"> COMMENT </code> used in some previous versions of MySQL. </p> </div> <p> The <code class="literal"> CONNECTION </code> string contains the information required to connect to the remote server containing the table in which the data physically resides. The connection string specifies the server name, login credentials, port number and database/table information. In the example, the remote table is on the server <code class="literal"> remote_host </code> , using port 9306. The name and port number should match the host name (or IP address) and port number of the remote MySQL server instance you want to use as your remote table. </p> <p> The format of the connection string is as follows: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa31285325"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none"><em class="replaceable">scheme</em>://<em class="replaceable">user_name</em>[:<em class="replaceable">password</em>]@<em class="replaceable">host_name</em>[:<em class="replaceable">port_num</em>]/<em class="replaceable">db_name</em>/<em class="replaceable">tbl_name</em></code></pre> </div> <p> Where: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <em class="replaceable"> <code> scheme </code> </em> : A recognized connection protocol. Only <code class="literal"> mysql </code> is supported as the <em class="replaceable"> <code> scheme </code> </em> value at this point. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> user_name </code> </em> : The user name for the connection. This user must have been created on the remote server, and must have suitable privileges to perform the required actions ( <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> , <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , and so forth) on the remote table. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> password </code> </em> : (Optional) The corresponding password for <em class="replaceable"> <code> user_name </code> </em> . </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> host_name </code> </em> : The host name or IP address of the remote server. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> port_num </code> </em> : (Optional) The port number for the remote server. The default is 3306. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> db_name </code> </em> : The name of the database holding the remote table. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> tbl_name </code> </em> : The name of the remote table. The name of the local and the remote table do not have to match. </p> </li> </ul> </div> <p> Sample connection strings: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa33244394"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CONNECTION</span><span class="token operator">=</span><span class="token string">'mysql://username:password@hostname:port/database/tablename'</span> <span class="token keyword">CONNECTION</span><span class="token operator">=</span><span class="token string">'mysql://username@hostname/database/tablename'</span> <span class="token keyword">CONNECTION</span><span class="token operator">=</span><span class="token string">'mysql://username:password@hostname/database/tablename'</span></code></pre> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-cluster-transactions.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-ndbinfo-cluster-transactions"> </a> 25.6.17.9 The ndbinfo cluster_transactions Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045090279856"> </a> <p> The <code class="literal"> cluster_transactions </code> table shows information about all ongoing transactions in an NDB Cluster. </p> <p> The <code class="literal"> cluster_transactions </code> table contains the following columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> node_id </code> </p> <p> Node ID of transaction coordinator </p> </li> <li class="listitem"> <p> <code class="literal"> block_instance </code> </p> <p> TC block instance </p> </li> <li class="listitem"> <p> <code class="literal"> transid </code> </p> <p> Transaction ID </p> </li> <li class="listitem"> <p> <code class="literal"> state </code> </p> <p> Operation state (see text for possible values) </p> </li> <li class="listitem"> <p> <code class="literal"> count_operations </code> </p> <p> Number of stateful primary key operations in transaction (includes reads with locks, as well as DML operations) </p> </li> <li class="listitem"> <p> <code class="literal"> outstanding_operations </code> </p> <p> Operations still being executed in local data management blocks </p> </li> <li class="listitem"> <p> <code class="literal"> inactive_seconds </code> </p> <p> Time spent waiting for API </p> </li> <li class="listitem"> <p> <code class="literal"> client_node_id </code> </p> <p> Client node ID </p> </li> <li class="listitem"> <p> <code class="literal"> client_block_ref </code> </p> <p> Client block reference </p> </li> </ul> </div> <h5> <a name="idm46045090258384"> </a> Notes </h5> <p> The transaction ID is a unique 64-bit number which can be obtained using the NDB API's <a class="ulink" href="/doc/ndbapi/en/ndb-ndbtransaction.html#ndb-ndbtransaction-gettransactionid" target="_top"> <code class="literal"> getTransactionId() </code> </a> method. (Currently, the MySQL Server does not expose the NDB API transaction ID of an ongoing transaction.) </p> <p> <code class="literal"> block_instance </code> refers to an instance of a kernel block. Together with the block name, this number can be used to look up a given instance in the <a class="link" href="mysql-cluster-ndbinfo-threadblocks.html" title="25.6.17.62 The ndbinfo threadblocks Table"> <code class="literal"> threadblocks </code> </a> table. </p> <p> The <code class="literal"> state </code> column can have any one of the values <code class="literal"> CS_ABORTING </code> , <code class="literal"> CS_COMMITTING </code> , <code class="literal"> CS_COMMIT_SENT </code> , <code class="literal"> CS_COMPLETE_SENT </code> , <code class="literal"> CS_COMPLETING </code> , <code class="literal"> CS_CONNECTED </code> , <code class="literal"> CS_DISCONNECTED </code> , <code class="literal"> CS_FAIL_ABORTED </code> , <code class="literal"> CS_FAIL_ABORTING </code> , <code class="literal"> CS_FAIL_COMMITTED </code> , <code class="literal"> CS_FAIL_COMMITTING </code> , <code class="literal"> CS_FAIL_COMPLETED </code> , <code class="literal"> CS_FAIL_PREPARED </code> , <code class="literal"> CS_PREPARE_TO_COMMIT </code> , <code class="literal"> CS_RECEIVING </code> , <code class="literal"> CS_REC_COMMITTING </code> , <code class="literal"> CS_RESTART </code> , <code class="literal"> CS_SEND_FIRE_TRIG_REQ </code> , <code class="literal"> CS_STARTED </code> , <code class="literal"> CS_START_COMMITTING </code> , <code class="literal"> CS_START_SCAN </code> , <code class="literal"> CS_WAIT_ABORT_CONF </code> , <code class="literal"> CS_WAIT_COMMIT_CONF </code> , <code class="literal"> CS_WAIT_COMPLETE_CONF </code> , <code class="literal"> CS_WAIT_FIRE_TRIG_REQ </code> . (If the MySQL Server is running with <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_show_hidden"> <code class="literal"> ndbinfo_show_hidden </code> </a> enabled, you can view this list of states by selecting from the <code class="literal"> ndb$dbtc_apiconnect_state </code> table, which is normally hidden.) </p> <p> In <code class="literal"> client_node_id </code> and <code class="literal"> client_block_ref </code> , <code class="literal"> client </code> refers to an NDB Cluster API or SQL node (that is, an NDB API client or a MySQL Server attached to the cluster). </p> <p> The <code class="literal"> tc_block_instance </code> column provides the <a class="ulink" href="/doc/ndb-internals/en/ndb-internals-kernel-blocks-dbtc.html" target="_top"> <code class="literal"> DBTC </code> </a> block instance number. You can use this along with the block name to obtain information about specific threads from the <a class="link" href="mysql-cluster-ndbinfo-threadblocks.html" title="25.6.17.62 The ndbinfo threadblocks Table"> <code class="literal"> threadblocks </code> </a> table. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/statement-labels.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="statement-labels"> </a> 15.6.2 Statement Labels </h3> </div> </div> </div> <a class="indexterm" name="idm46045176479376"> </a> <a class="indexterm" name="idm46045176477888"> </a> <a class="indexterm" name="idm46045176476400"> </a> <a class="indexterm" name="idm46045176474912"> </a> <a class="indexterm" name="idm46045176473424"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa459480"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">[</span><em class="replaceable">begin_label</em>:<span class="token punctuation">]</span> <span class="token keyword">BEGIN</span> <span class="token punctuation">[</span><em class="replaceable">statement_list</em><span class="token punctuation">]</span> <span class="token keyword">END</span> <span class="token punctuation">[</span><em class="replaceable">end_label</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><em class="replaceable">begin_label</em>:<span class="token punctuation">]</span> <span class="token keyword">LOOP</span> <em class="replaceable">statement_list</em> <span class="token keyword">END</span> <span class="token keyword">LOOP</span> <span class="token punctuation">[</span><em class="replaceable">end_label</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><em class="replaceable">begin_label</em>:<span class="token punctuation">]</span> <span class="token keyword">REPEAT</span> <em class="replaceable">statement_list</em> <span class="token keyword">UNTIL</span> <em class="replaceable">search_condition</em> <span class="token keyword">END</span> <span class="token keyword">REPEAT</span> <span class="token punctuation">[</span><em class="replaceable">end_label</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><em class="replaceable">begin_label</em>:<span class="token punctuation">]</span> <span class="token keyword">WHILE</span> <em class="replaceable">search_condition</em> <span class="token keyword">DO</span> <em class="replaceable">statement_list</em> <span class="token keyword">END</span> <span class="token keyword">WHILE</span> <span class="token punctuation">[</span><em class="replaceable">end_label</em><span class="token punctuation">]</span></code></pre> </div> <p> Labels are permitted for <a class="link" href="begin-end.html" title="15.6.1 BEGIN ... END Compound Statement"> <code class="literal"> BEGIN ... END </code> </a> blocks and for the <a class="link" href="loop.html" title="15.6.5.5 LOOP Statement"> <code class="literal"> LOOP </code> </a> , <a class="link" href="repeat.html" title="15.6.5.6 REPEAT Statement"> <code class="literal"> REPEAT </code> </a> , and <a class="link" href="while.html" title="15.6.5.8 WHILE Statement"> <code class="literal"> WHILE </code> </a> statements. Label use for those statements follows these rules: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <em class="replaceable"> <code> begin_label </code> </em> must be followed by a colon. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> begin_label </code> </em> can be given without <em class="replaceable"> <code> end_label </code> </em> . If <em class="replaceable"> <code> end_label </code> </em> is present, it must be the same as <em class="replaceable"> <code> begin_label </code> </em> . </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> end_label </code> </em> cannot be given without <em class="replaceable"> <code> begin_label </code> </em> . </p> </li> <li class="listitem"> <p> Labels at the same nesting level must be distinct. </p> </li> <li class="listitem"> <p> Labels can be up to 16 characters long. </p> </li> </ul> </div> <p> To refer to a label within the labeled construct, use an <a class="link" href="iterate.html" title="15.6.5.3 ITERATE Statement"> <code class="literal"> ITERATE </code> </a> or <a class="link" href="leave.html" title="15.6.5.4 LEAVE Statement"> <code class="literal"> LEAVE </code> </a> statement. The following example uses those statements to continue iterating or terminate the loop: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa41440835"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">PROCEDURE</span> doiterate<span class="token punctuation">(</span>p1 <span class="token datatype">INT</span><span class="token punctuation">)</span> <span class="token keyword">BEGIN</span> label1: <span class="token keyword">LOOP</span> <span class="token keyword">SET</span> p1 <span class="token operator">=</span> p1 <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">;</span> <span class="token keyword">IF</span> p1 <span class="token operator"><</span> <span class="token number">10</span> <span class="token keyword">THEN</span> <span class="token keyword">ITERATE</span> label1<span class="token punctuation">;</span> <span class="token keyword">END</span> <span class="token keyword">IF</span><span class="token punctuation">;</span> <span class="token keyword">LEAVE</span> label1<span class="token punctuation">;</span> <span class="token keyword">END</span> <span class="token keyword">LOOP</span> label1<span class="token punctuation">;</span> <span class="token keyword">END</span><span class="token punctuation">;</span></code></pre> </div> <p> The scope of a block label does not include the code for handlers declared within the block. For details, see <a class="xref" href="declare-handler.html" title="15.6.7.2 DECLARE ... HANDLER Statement"> Section 15.6.7.2, “DECLARE ... HANDLER Statement” </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/connection-control.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="connection-control"> </a> 8.4.2 The Connection-Control Plugins </h3> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="connection-control-installation.html"> 8.4.2.1 Connection-Control Plugin Installation </a> </span> </dt> <dt> <span class="section"> <a href="connection-control-variables.html"> 8.4.2.2 Connection-Control System and Status Variables </a> </span> </dt> </dl> </div> <p> MySQL Server includes a plugin library that enables administrators to introduce an increasing delay in server response to connection attempts after a configurable number of consecutive failed attempts. This capability provides a deterrent that slows down brute force attacks against MySQL user accounts. The plugin library contains two plugins: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> CONNECTION_CONTROL </code> checks incoming connection attempts and adds a delay to server responses as necessary. This plugin also exposes system variables that enable its operation to be configured and a status variable that provides rudimentary monitoring information. </p> <p> The <code class="literal"> CONNECTION_CONTROL </code> plugin uses the audit plugin interface (see <a class="ulink" href="/doc/extending-mysql/8.4/en/writing-audit-plugins.html" target="_top"> Writing Audit Plugins </a> ). To collect information, it subscribes to the <code class="literal"> MYSQL_AUDIT_CONNECTION_CLASSMASK </code> event class, and processes <code class="literal"> MYSQL_AUDIT_CONNECTION_CONNECT </code> and <code class="literal"> MYSQL_AUDIT_CONNECTION_CHANGE_USER </code> subevents to check whether the server should introduce a delay before responding to connection attempts. </p> </li> <li class="listitem"> <p> <code class="literal"> CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS </code> implements an <code class="literal"> INFORMATION_SCHEMA </code> table that exposes more detailed monitoring information for failed connection attempts. </p> </li> </ul> </div> <p> The following sections provide information about connection-control plugin installation and configuration. For information about the <a class="link" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table"> <code class="literal"> CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS </code> </a> table, see <a class="xref" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table"> Section 28.6.2, “The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table” </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/sys-ps-setup-show-disabled-instruments.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-ps-setup-show-disabled-instruments"> </a> 30.4.4.17 The ps_setup_show_disabled_instruments() Procedure </h4> </div> </div> </div> <a class="indexterm" name="idm46045061350576"> </a> <a class="indexterm" name="idm46045061349056"> </a> <p> Displays all currently disabled Performance Schema instruments. This might be a long list. </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-ps-setup-show-disabled-instruments-parameters"> </a> Parameters </h5> </div> </div> </div> <p> None. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-ps-setup-show-disabled-instruments-example"> </a> Example </h5> </div> </div> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59732337"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_show_disabled_instruments<span class="token punctuation">(</span><span class="token punctuation">)</span>\G <span class="token output"><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> 1. row <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> disabled_instruments<span class="token punctuation">:</span> wait/synch/mutex/sql/TC_LOG_MMAP<span class="token punctuation">:</span><span class="token punctuation">:</span>LOCK_tc timed<span class="token punctuation">:</span> NO <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> 2. row <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> disabled_instruments<span class="token punctuation">:</span> wait/synch/mutex/sql/THD<span class="token punctuation">:</span><span class="token punctuation">:</span>LOCK_query_plan timed<span class="token punctuation">:</span> NO <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> 3. row <span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span><span class="token punctuation"></span> disabled_instruments<span class="token punctuation">:</span> wait/synch/mutex/sql/MYSQL_BIN_LOG<span class="token punctuation">:</span><span class="token punctuation">:</span>LOCK_commit timed<span class="token punctuation">:</span> NO ...</span></code></pre> </div> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/replication-binlog-encryption-key-rotation.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-binlog-encryption-key-rotation"> </a> 19.3.2.3 Binary Log Master Key Rotation </h4> </div> </div> </div> <p> When binary log encryption is enabled, you can rotate the binary log master key at any time while the server is running by issuing <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> . When the binary log master key is rotated manually using this statement, the passwords for the new and subsequent files are encrypted using the new binary log master key, and also the file passwords for existing encrypted binary log files and relay log files are re-encrypted using the new binary log master key, so the encryption is renewed completely. You can rotate the binary log master key on a regular basis to comply with your organization's security policy, and also if you suspect that the current or any of the previous binary log master keys might have been compromised. </p> <p> When you rotate the binary log master key manually, MySQL Server takes the following actions in sequence: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> A new binary log encryption key is generated with the next available sequence number, stored on the keyring, and used as the new binary log master key. </p> </li> <li class="listitem"> <p> The binary log and relay log files are rotated on all channels. </p> </li> <li class="listitem"> <p> The new binary log master key is used to encrypt the file passwords for the new binary log and relay log files, and subsequent files until the key is changed again. </p> </li> <li class="listitem"> <p> The file passwords for existing encrypted binary log files and relay log files on the server are re-encrypted in turn using the new binary log master key, starting with the most recent files. Any unencrypted files are skipped. </p> </li> <li class="listitem"> <p> Binary log encryption keys that are no longer in use for any files after the re-encryption process are removed from the keyring. </p> </li> </ol> </div> <p> The <a class="link" href="privileges-provided.html#priv_binlog-encryption-admin"> <code class="literal"> BINLOG_ENCRYPTION_ADMIN </code> </a> privilege is required to issue <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> , and the statement cannot be used if the <a class="link" href="replication-options-binary-log.html#sysvar_binlog_encryption"> <code class="literal"> binlog_encryption </code> </a> system variable is set to <code class="literal"> OFF </code> . </p> <p> As the final step of the binary log master key rotation process, all binary log encryption keys that no longer apply to any retained binary log files or relay log files are cleaned up from the keyring. If a retained binary log file or relay log file cannot be initialized for re-encryption, the relevant binary log encryption keys are not deleted in case the files can be recovered in the future. For example, this might be the case if a file listed in a binary log index file is currently unreadable, or if a channel fails to initialize. If the server UUID changes, for example because a backup created using MySQL Enterprise Backup is used to set up a new replica, issuing <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> on the new server does not delete any earlier binary log encryption keys that include the original server UUID. </p> <p> If any of the first four steps of the binary log master key rotation process cannot be completed correctly, an error message is issued explaining the situation and the consequences for the encryption status of the binary log files and relay log files. Files that were previously encrypted are always left in an encrypted state, but their file passwords might still be encrypted using an old binary log master key. If you see these errors, first retry the process by issuing <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> again. Then investigate the status of individual files to see what is blocking the process, especially if you suspect that the current or any of the previous binary log master keys might have been compromised. </p> <p> If the final step of the binary log master key rotation process cannot be completed correctly, a warning message is issued explaining the situation. The warning message identifies whether the process could not clean up the auxiliary keys in the keyring for rotating the binary log master key, or could not clean up unused binary log encryption keys. You can choose to ignore the message as the keys are auxiliary keys or no longer in use, or you can issue <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> again to retry the process. </p> <p> If the server stops and is restarted with binary log encryption still set to <code class="literal"> ON </code> during the binary log master key rotation process, new binary log files and relay log files after the restart are encrypted using the new binary log master key. However, the re-encryption of existing files is not continued, so files that did not get re-encrypted before the server stopped are left encrypted using the previous binary log master key. To complete re-encryption and clean up unused binary log encryption keys, issue <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> again after the restart. </p> <p> <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> actions are not written to the binary log and are not executed on replicas. Binary log master key rotation can therefore be carried out in replication environments including a mix of MySQL versions. To schedule regular rotation of the binary log master key on all applicable source and replica servers, you can enable the MySQL Event Scheduler on each server and issue the <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> statement using a <a class="link" href="create-event.html" title="15.1.13 CREATE EVENT Statement"> <code class="literal"> CREATE EVENT </code> </a> statement. If you rotate the binary log master key because you suspect that the current or any of the previous binary log master keys might have been compromised, issue the statement on every applicable source and replica server. Issuing the statement on individual servers ensures that you can verify immediate compliance, even in the case of replicas that are lagging, belong to multiple replication topologies, or are not currently active in the replication topology but have binary log and relay log files. </p> <p> The <a class="link" href="replication-options-binary-log.html#sysvar_binlog_rotate_encryption_master_key_at_startup"> <code class="literal"> binlog_rotate_encryption_master_key_at_startup </code> </a> system variable controls whether the binary log master key is automatically rotated when the server is restarted. If this system variable is set to <code class="literal"> ON </code> , a new binary log encryption key is generated and used as the new binary log master key whenever the server is restarted. If it is set to <code class="literal"> OFF </code> , which is the default, the existing binary log master key is used again after the restart. When the binary log master key is rotated at startup, the file passwords for the new binary log and relay log files are encrypted using the new key. The file passwords for the existing encrypted binary log files and relay log files are not re-encrypted, so they remain encrypted using the old key, which remains available on the keyring. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/dynamic-system-variables.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="dynamic-system-variables"> </a> 7.1.9.2 Dynamic System Variables </h4> </div> </div> </div> <p> Many server system variables are dynamic and can be set at runtime. See <a class="xref" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> Section 15.7.6.1, “SET Syntax for Variable Assignment” </a> . For a description of the privilege requirements for setting system variables, see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> </p> <p> The following table lists all dynamic system variables applicable within <code class="literal"> mysqld </code> . </p> <p> The table lists each variable's data type and scope. The last column indicates whether the scope for each variable is Global, Session, or both. Please see the corresponding item descriptions for details on setting and using the variables. Where appropriate, direct links to further information about the items are provided. </p> <p> Variables that have a type of <span class="quote"> “ <span class="quote"> string </span> ” </span> take a string value. Variables that have a type of <span class="quote"> “ <span class="quote"> numeric </span> ” </span> take a numeric value. Variables that have a type of <span class="quote"> “ <span class="quote"> boolean </span> ” </span> can be set to 0, 1, <code class="literal"> ON </code> or <code class="literal"> OFF </code> . Variables that are marked as <span class="quote"> “ <span class="quote"> enumeration </span> ” </span> normally should be set to one of the available values for the variable, but can also be set to the number that corresponds to the desired enumeration value. For enumerated system variables, the first enumeration value corresponds to 0. This differs from the <a class="link" href="enum.html" title="13.3.5 The ENUM Type"> <code class="literal"> ENUM </code> </a> data type used for table columns, for which the first enumeration value corresponds to 1. </p> <div class="table"> <a name="idm46045266542144"> </a> <p class="title"> <b> Table 7.5 Dynamic System Variable Summary </b> </p> <div class="table-contents"> <table frame="box" rules="all" summary="Reference for dynamic system variables (variables that can be modified at runtime)."> <colgroup> <col style="width: 40%"/> <col style="width: 20%"/> <col align="center" style="width: 20%"/> </colgroup> <thead> <tr> <th scope="col"> Variable Name </th> <th scope="col"> Variable Type </th> <th scope="col"> Variable Scope </th> </tr> </thead> <tbody> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_activate_all_roles_on_login"> activate_all_roles_on_login </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_ca"> admin_ssl_ca </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_capath"> admin_ssl_capath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_cert"> admin_ssl_cert </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_cipher"> admin_ssl_cipher </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_crl"> admin_ssl_crl </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_crlpath"> admin_ssl_crlpath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_key"> admin_ssl_key </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_tls_ciphersuites"> admin_tls_ciphersuites </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_tls_version"> admin_tls_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_connection_policy"> audit_log_connection_policy </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_disable"> audit_log_disable </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_exclude_accounts"> audit_log_exclude_accounts </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_flush"> audit_log_flush </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_format_unix_timestamp"> audit_log_format_unix_timestamp </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_include_accounts"> audit_log_include_accounts </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_max_size"> audit_log_max_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_password_history_keep_days"> audit_log_password_history_keep_days </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_prune_seconds"> audit_log_prune_seconds </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_read_buffer_size"> audit_log_read_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_rotate_on_size"> audit_log_rotate_on_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_statement_policy"> audit_log_statement_policy </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_kerberos_service_principal"> authentication_kerberos_service_principal </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_auth_method_name"> authentication_ldap_sasl_auth_method_name </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_bind_base_dn"> authentication_ldap_sasl_bind_base_dn </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_bind_root_dn"> authentication_ldap_sasl_bind_root_dn </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_bind_root_pwd"> authentication_ldap_sasl_bind_root_pwd </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_ca_path"> authentication_ldap_sasl_ca_path </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_connect_timeout"> authentication_ldap_sasl_connect_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_group_search_attr"> authentication_ldap_sasl_group_search_attr </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_group_search_filter"> authentication_ldap_sasl_group_search_filter </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_init_pool_size"> authentication_ldap_sasl_init_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_log_status"> authentication_ldap_sasl_log_status </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_max_pool_size"> authentication_ldap_sasl_max_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_referral"> authentication_ldap_sasl_referral </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_response_timeout"> authentication_ldap_sasl_response_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_server_host"> authentication_ldap_sasl_server_host </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_server_port"> authentication_ldap_sasl_server_port </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_tls"> authentication_ldap_sasl_tls </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_user_search_attr"> authentication_ldap_sasl_user_search_attr </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_auth_method_name"> authentication_ldap_simple_auth_method_name </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_bind_base_dn"> authentication_ldap_simple_bind_base_dn </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_bind_root_dn"> authentication_ldap_simple_bind_root_dn </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_bind_root_pwd"> authentication_ldap_simple_bind_root_pwd </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_ca_path"> authentication_ldap_simple_ca_path </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_connect_timeout"> authentication_ldap_simple_connect_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_group_search_attr"> authentication_ldap_simple_group_search_attr </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_group_search_filter"> authentication_ldap_simple_group_search_filter </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_init_pool_size"> authentication_ldap_simple_init_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_log_status"> authentication_ldap_simple_log_status </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_max_pool_size"> authentication_ldap_simple_max_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_referral"> authentication_ldap_simple_referral </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_response_timeout"> authentication_ldap_simple_response_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_server_host"> authentication_ldap_simple_server_host </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_server_port"> authentication_ldap_simple_server_port </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_tls"> authentication_ldap_simple_tls </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_user_search_attr"> authentication_ldap_simple_user_search_attr </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_authentication_policy"> authentication_policy </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_webauthn_rp_id"> authentication_webauthn_rp_id </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> auto_increment_increment </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> auto_increment_offset </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_autocommit"> autocommit </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_automatic_sp_privileges"> automatic_sp_privileges </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_big_tables"> big_tables </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_cache_size"> binlog_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_checksum"> binlog_checksum </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_direct_non_transactional_updates"> binlog_direct_non_transactional_updates </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_encryption"> binlog_encryption </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_error_action"> binlog_error_action </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_expire_logs_auto_purge"> binlog_expire_logs_auto_purge </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_expire_logs_seconds"> binlog_expire_logs_seconds </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_format"> binlog_format </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_group_commit_sync_delay"> binlog_group_commit_sync_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_group_commit_sync_no_delay_count"> binlog_group_commit_sync_no_delay_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_max_flush_queue_time"> binlog_max_flush_queue_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_order_commits"> binlog_order_commits </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_row_image"> binlog_row_image </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_row_metadata"> binlog_row_metadata </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_row_value_options"> binlog_row_value_options </a> </th> <td> Set </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_rows_query_log_events"> binlog_rows_query_log_events </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_stmt_cache_size"> binlog_stmt_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_transaction_compression"> binlog_transaction_compression </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_transaction_compression_level_zstd"> binlog_transaction_compression_level_zstd </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_transaction_dependency_history_size"> binlog_transaction_dependency_history_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_block_encryption_mode"> block_encryption_mode </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_bulk_insert_buffer_size"> bulk_insert_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_client"> character_set_client </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> character_set_connection </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_database"> character_set_database </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_filesystem"> character_set_filesystem </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_results"> character_set_results </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_server"> character_set_server </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_check_proxy_users"> check_proxy_users </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_autotune_concurrency"> clone_autotune_concurrency </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_block_ddl"> clone_block_ddl </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_buffer_size"> clone_buffer_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_ddl_timeout"> clone_ddl_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_delay_after_data_drop"> clone_delay_after_data_drop </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_donor_timeout_after_network_failure"> clone_donor_timeout_after_network_failure </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_enable_compression"> clone_enable_compression </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_max_concurrency"> clone_max_concurrency </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_max_data_bandwidth"> clone_max_data_bandwidth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_max_network_bandwidth"> clone_max_network_bandwidth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_ssl_ca"> clone_ssl_ca </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_ssl_cert"> clone_ssl_cert </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_ssl_key"> clone_ssl_key </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_valid_donor_list"> clone_valid_donor_list </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_collation_connection"> collation_connection </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_collation_database"> collation_database </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_collation_server"> collation_server </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_completion_type"> completion_type </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_component_scheduler.enabled"> component_scheduler.enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_concurrent_insert"> concurrent_insert </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_connect_timeout"> connect_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="connection-control-variables.html#sysvar_connection_control_failed_connections_threshold"> connection_control_failed_connections_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay"> connection_control_max_connection_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay"> connection_control_min_connection_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_connection_memory_chunk_size"> connection_memory_chunk_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_connection_memory_limit"> connection_memory_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_cte_max_recursion_depth"> cte_max_recursion_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_debug"> debug </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_debug_sync"> debug_sync </a> </th> <td> String </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_collation_for_utf8mb4"> default_collation_for_utf8mb4 </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_password_lifetime"> default_password_lifetime </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_storage_engine"> default_storage_engine </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_table_encryption"> default_table_encryption </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_tmp_storage_engine"> default_tmp_storage_engine </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_week_format"> default_week_format </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_delay_key_write"> delay_key_write </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_delayed_insert_limit"> delayed_insert_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_delayed_insert_timeout"> delayed_insert_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_delayed_queue_size"> delayed_queue_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_div_precision_increment"> div_precision_increment </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_dragnet.log_error_filter_rules"> dragnet.log_error_filter_rules </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_end_markers_in_json"> end_markers_in_json </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_enforce_gtid_consistency"> enforce_gtid_consistency </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_enterprise_encryption.maximum_rsa_key_size"> enterprise_encryption.maximum_rsa_key_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_enterprise_encryption.rsa_support_legacy_padding"> enterprise_encryption.rsa_support_legacy_padding </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_eq_range_index_dive_limit"> eq_range_index_dive_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_event_scheduler"> event_scheduler </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_explain_format"> explain_format </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_explain_json_format_version"> explain_json_format_version </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_explicit_defaults_for_timestamp"> explicit_defaults_for_timestamp </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_flush"> flush </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_flush_time"> flush_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_foreign_key_checks"> foreign_key_checks </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ft_boolean_syntax"> ft_boolean_syntax </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_general_log"> general_log </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_general_log_file"> general_log_file </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_generated_random_password_length"> generated_random_password_length </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_global_connection_memory_limit"> global_connection_memory_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_global_connection_memory_tracking"> global_connection_memory_tracking </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_group_concat_max_len"> group_concat_max_len </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_advertise_recovery_endpoints"> group_replication_advertise_recovery_endpoints </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_allow_local_lower_version_join"> group_replication_allow_local_lower_version_join </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_auto_increment_increment"> group_replication_auto_increment_increment </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_autorejoin_tries"> group_replication_autorejoin_tries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_bootstrap_group"> group_replication_bootstrap_group </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_clone_threshold"> group_replication_clone_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_communication_debug_options"> group_replication_communication_debug_options </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_communication_max_message_size"> group_replication_communication_max_message_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_communication_stack"> group_replication_communication_stack </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_components_stop_timeout"> group_replication_components_stop_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> group_replication_compression_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_consistency"> group_replication_consistency </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_enforce_update_everywhere_checks"> group_replication_enforce_update_everywhere_checks </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_exit_state_action"> group_replication_exit_state_action </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_applier_threshold"> group_replication_flow_control_applier_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_certifier_threshold"> group_replication_flow_control_certifier_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_hold_percent"> group_replication_flow_control_hold_percent </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_max_quota"> group_replication_flow_control_max_quota </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_member_quota_percent"> group_replication_flow_control_member_quota_percent </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_min_quota"> group_replication_flow_control_min_quota </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_min_recovery_quota"> group_replication_flow_control_min_recovery_quota </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_mode"> group_replication_flow_control_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_period"> group_replication_flow_control_period </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_release_percent"> group_replication_flow_control_release_percent </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_force_members"> group_replication_force_members </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_group_name"> group_replication_group_name </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_group_seeds"> group_replication_group_seeds </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_gtid_assignment_block_size"> group_replication_gtid_assignment_block_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_ip_allowlist"> group_replication_ip_allowlist </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_local_address"> group_replication_local_address </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_member_expel_timeout"> group_replication_member_expel_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_member_weight"> group_replication_member_weight </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_message_cache_size"> group_replication_message_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_paxos_single_leader"> group_replication_paxos_single_leader </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_poll_spin_loops"> group_replication_poll_spin_loops </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_preemptive_garbage_collection"> group_replication_preemptive_garbage_collection </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_preemptive_garbage_collection_rows_threshold"> group_replication_preemptive_garbage_collection_rows_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_compression_algorithms"> group_replication_recovery_compression_algorithms </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_get_public_key"> group_replication_recovery_get_public_key </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_public_key_path"> group_replication_recovery_public_key_path </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_reconnect_interval"> group_replication_recovery_reconnect_interval </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_retry_count"> group_replication_recovery_retry_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_ca"> group_replication_recovery_ssl_ca </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_capath"> group_replication_recovery_ssl_capath </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_cert"> group_replication_recovery_ssl_cert </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_cipher"> group_replication_recovery_ssl_cipher </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_crl"> group_replication_recovery_ssl_crl </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_crlpath"> group_replication_recovery_ssl_crlpath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_key"> group_replication_recovery_ssl_key </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_verify_server_cert"> group_replication_recovery_ssl_verify_server_cert </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_ciphersuites"> group_replication_recovery_tls_ciphersuites </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_version"> group_replication_recovery_tls_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_use_ssl"> group_replication_recovery_use_ssl </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_zstd_compression_level"> group_replication_recovery_zstd_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_single_primary_mode"> group_replication_single_primary_mode </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_ssl_mode"> group_replication_ssl_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_start_on_boot"> group_replication_start_on_boot </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_tls_source"> group_replication_tls_source </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_transaction_size_limit"> group_replication_transaction_size_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_unreachable_majority_timeout"> group_replication_unreachable_majority_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_view_change_uuid"> group_replication_view_change_uuid </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_gtid_executed_compression_period"> gtid_executed_compression_period </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_gtid_mode"> gtid_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_gtid_next"> gtid_next </a> </th> <td> Enumeration </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_gtid_purged"> gtid_purged </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_histogram_generation_max_mem_size"> histogram_generation_max_mem_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_host_cache_size"> host_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_identity"> identity </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> immediate_server_version </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_information_schema_stats_expiry"> information_schema_stats_expiry </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_init_connect"> init_connect </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_init_replica"> init_replica </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_init_slave"> init_slave </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> innodb_adaptive_flushing </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> innodb_adaptive_flushing_lwm </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> innodb_adaptive_hash_index </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> innodb_adaptive_max_sleep_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> innodb_autoextend_increment </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> innodb_background_drop_list_empty </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> innodb_buffer_pool_dump_at_shutdown </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> innodb_buffer_pool_dump_now </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> innodb_buffer_pool_dump_pct </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_filename"> innodb_buffer_pool_filename </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> innodb_buffer_pool_in_core_file </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> innodb_buffer_pool_load_abort </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> innodb_buffer_pool_load_now </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> innodb_buffer_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffer_max_size"> innodb_change_buffer_max_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering"> innodb_change_buffering </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering_debug"> innodb_change_buffering_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checkpoint_disabled"> innodb_checkpoint_disabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> innodb_checksum_algorithm </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_cmp_per_index_enabled"> innodb_cmp_per_index_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> innodb_commit_concurrency </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compress_debug"> innodb_compress_debug </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> innodb_compression_failure_threshold_pct </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_level"> innodb_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> innodb_compression_pad_pct_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> innodb_concurrency_tickets </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> innodb_ddl_buffer_size </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_log_crash_reset_debug"> innodb_ddl_log_crash_reset_debug </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> innodb_ddl_threads </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> innodb_deadlock_detect </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> innodb_default_row_format </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_disable_sort_file_cache"> innodb_disable_sort_file_cache </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> innodb_doublewrite </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_extend_and_initialize"> innodb_extend_and_initialize </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> innodb_fast_shutdown </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> innodb_fil_make_page_dirty_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> innodb_file_per_table </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> innodb_fill_factor </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> innodb_flush_log_at_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> innodb_flush_log_at_trx_commit </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> innodb_flush_neighbors </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> innodb_flush_sync </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> innodb_flushing_avg_loops </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> innodb_fsync_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_aux_table"> innodb_ft_aux_table </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_diag_print"> innodb_ft_enable_diag_print </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> innodb_ft_enable_stopword </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_num_word_optimize"> innodb_ft_num_word_optimize </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> innodb_ft_result_cache_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> innodb_ft_server_stopword_table </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> innodb_ft_user_stopword_table </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> innodb_idle_flush_pct </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> innodb_io_capacity </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> innodb_io_capacity_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_limit_optimistic_insert_debug"> innodb_limit_optimistic_insert_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> innodb_lock_wait_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> innodb_log_buffer_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_fuzzy_now"> innodb_log_checkpoint_fuzzy_now </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_now"> innodb_log_checkpoint_now </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> innodb_log_checksums </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> innodb_log_compressed_pages </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_abs_lwm"> innodb_log_spin_cpu_abs_lwm </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> innodb_log_spin_cpu_pct_hwm </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_wait_for_flush_spin_hwm"> innodb_log_wait_for_flush_spin_hwm </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> innodb_log_write_ahead_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_writer_threads"> innodb_log_writer_threads </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> innodb_lru_scan_depth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> innodb_max_dirty_pages_pct </a> </th> <td> Numeric </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> innodb_max_dirty_pages_pct_lwm </a> </th> <td> Numeric </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> innodb_max_purge_lag </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> innodb_max_purge_lag_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> innodb_max_undo_log_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_merge_threshold_set_all_debug"> innodb_merge_threshold_set_all_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> innodb_monitor_disable </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> innodb_monitor_enable </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> innodb_monitor_reset </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset_all"> innodb_monitor_reset_all </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> innodb_old_blocks_pct </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> innodb_old_blocks_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> innodb_online_alter_log_max_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> innodb_open_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_optimize_fulltext_only"> innodb_optimize_fulltext_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> innodb_parallel_read_threads </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_all_deadlocks"> innodb_print_all_deadlocks </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_ddl_logs"> innodb_print_ddl_logs </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> innodb_purge_batch_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> innodb_purge_rseg_truncate_frequency </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_random_read_ahead"> innodb_random_read_ahead </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> innodb_read_ahead_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_archive_dirs"> innodb_redo_log_archive_dirs </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> innodb_redo_log_capacity </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_encrypt"> innodb_redo_log_encrypt </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_replication_delay"> innodb_replication_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> innodb_rollback_segments </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> innodb_saved_page_number_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> innodb_segment_reserve_factor </a> </th> <td> Numeric </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_delay"> innodb_spin_wait_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> innodb_spin_wait_pause_multiplier </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_auto_recalc"> innodb_stats_auto_recalc </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> innodb_stats_include_delete_marked </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> innodb_stats_method </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> innodb_stats_on_metadata </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> innodb_stats_persistent </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> innodb_stats_persistent_sample_pages </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> innodb_stats_transient_sample_pages </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output"> innodb_status_output </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> innodb_status_output_locks </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> innodb_strict_mode </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_spin_loops"> innodb_sync_spin_loops </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> innodb_table_locks </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> innodb_thread_concurrency </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> innodb_thread_sleep_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> innodb_tmpdir </a> </th> <td> Directory name </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_purge_view_update_only_debug"> innodb_trx_purge_view_update_only_debug </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_rseg_n_slots_debug"> innodb_trx_rseg_n_slots_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_encrypt"> innodb_undo_log_encrypt </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> innodb_undo_log_truncate </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> innodb_undo_tablespaces </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> innodb_use_fdatasync </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_insert_id"> insert_id </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_interactive_timeout"> interactive_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_internal_tmp_mem_storage_engine"> internal_tmp_mem_storage_engine </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_join_buffer_size"> join_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_keep_files_on_create"> keep_files_on_create </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_key_buffer_size"> key_buffer_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_key_cache_age_threshold"> key_cache_age_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_key_cache_block_size"> key_cache_block_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_key_cache_division_limit"> key_cache_division_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_aws_cmk_id"> keyring_aws_cmk_id </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_aws_region"> keyring_aws_region </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_auth_path"> keyring_hashicorp_auth_path </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_ca_path"> keyring_hashicorp_ca_path </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_caching"> keyring_hashicorp_caching </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_role_id"> keyring_hashicorp_role_id </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_secret_id"> keyring_hashicorp_secret_id </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_server_url"> keyring_hashicorp_server_url </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_store_path"> keyring_hashicorp_store_path </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_okv_conf_dir"> keyring_okv_conf_dir </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_operations"> keyring_operations </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_last_insert_id"> last_insert_id </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_lc_messages"> lc_messages </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_lc_time_names"> lc_time_names </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_local_infile"> local_infile </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_lock_wait_timeout"> lock_wait_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_log_bin_trust_function_creators"> log_bin_trust_function_creators </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_error_services"> log_error_services </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_error_suppression_list"> log_error_suppression_list </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> log_error_verbosity </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_output"> log_output </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_queries_not_using_indexes"> log_queries_not_using_indexes </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_raw"> log_raw </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_slow_admin_statements"> log_slow_admin_statements </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_slow_extra"> log_slow_extra </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_log_slow_replica_statements"> log_slow_replica_statements </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_log_slow_slave_statements"> log_slow_slave_statements </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_log_statements_unsafe_for_binlog"> log_statements_unsafe_for_binlog </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_throttle_queries_not_using_indexes"> log_throttle_queries_not_using_indexes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_timestamps"> log_timestamps </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_long_query_time"> long_query_time </a> </th> <td> Numeric </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_low_priority_updates"> low_priority_updates </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_mandatory_roles"> mandatory_roles </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_master_verify_checksum"> master_verify_checksum </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_allowed_packet"> max_allowed_packet </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_max_binlog_cache_size"> max_binlog_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_max_binlog_size"> max_binlog_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_max_binlog_stmt_cache_size"> max_binlog_stmt_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_connect_errors"> max_connect_errors </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_connections"> max_connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_delayed_threads"> max_delayed_threads </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_error_count"> max_error_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_execution_time"> max_execution_time </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_heap_table_size"> max_heap_table_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_insert_delayed_threads"> max_insert_delayed_threads </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_join_size"> max_join_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_length_for_sort_data"> max_length_for_sort_data </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_points_in_geometry"> max_points_in_geometry </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_prepared_stmt_count"> max_prepared_stmt_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_max_relay_log_size"> max_relay_log_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_seeks_for_key"> max_seeks_for_key </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_sort_length"> max_sort_length </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_sp_recursion_depth"> max_sp_recursion_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_user_connections"> max_user_connections </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_write_lock_count"> max_write_lock_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_min_examined_row_limit"> min_examined_row_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_data_pointer_size"> myisam_data_pointer_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_max_sort_file_size"> myisam_max_sort_file_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_sort_buffer_size"> myisam_sort_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> myisam_stats_method </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_use_mmap"> myisam_use_mmap </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#sysvar_mysql_firewall_mode"> mysql_firewall_mode </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#sysvar_mysql_firewall_trace"> mysql_firewall_trace </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_mysql_native_password_proxy_users"> mysql_native_password_proxy_users </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_compression_algorithms"> mysqlx_compression_algorithms </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_connect_timeout"> mysqlx_connect_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_deflate_default_compression_level"> mysqlx_deflate_default_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_deflate_max_client_compression_level"> mysqlx_deflate_max_client_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_document_id_unique_prefix"> mysqlx_document_id_unique_prefix </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_enable_hello_notice"> mysqlx_enable_hello_notice </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_idle_worker_thread_timeout"> mysqlx_idle_worker_thread_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_interactive_timeout"> mysqlx_interactive_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_lz4_default_compression_level"> mysqlx_lz4_default_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_lz4_max_client_compression_level"> mysqlx_lz4_max_client_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_max_allowed_packet"> mysqlx_max_allowed_packet </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_max_connections"> mysqlx_max_connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_min_worker_threads"> mysqlx_min_worker_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_read_timeout"> mysqlx_read_timeout </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_wait_timeout"> mysqlx_wait_timeout </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_write_timeout"> mysqlx_write_timeout </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_zstd_default_compression_level"> mysqlx_zstd_default_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_zstd_max_client_compression_level"> mysqlx_zstd_max_client_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_allow_copying_alter_table </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_autoincrement_prefetch_sz"> ndb_autoincrement_prefetch_sz </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> ndb_batch_size </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> ndb_blob_read_batch_bytes </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> ndb_blob_write_batch_bytes </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_clear_apply_status"> ndb_clear_apply_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_conflict_role"> ndb_conflict_role </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_data_node_neighbour"> ndb_data_node_neighbour </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_dbg_check_shares"> ndb_dbg_check_shares </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_default_column_format"> ndb_default_column_format </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_default_column_format"> ndb_default_column_format </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_deferred_constraints"> ndb_deferred_constraints </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_deferred_constraints"> ndb_deferred_constraints </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_distribution"> ndb_distribution </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_distribution"> ndb_distribution </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_eventbuffer_free_percent"> ndb_eventbuffer_free_percent </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_eventbuffer_max_alloc"> ndb_eventbuffer_max_alloc </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_extra_logging"> ndb_extra_logging </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_force_send"> ndb_force_send </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_fully_replicated"> ndb_fully_replicated </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_index_stat_enable"> ndb_index_stat_enable </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_index_stat_option"> ndb_index_stat_option </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_join_pushdown"> ndb_join_pushdown </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_binlog_index"> ndb_log_binlog_index </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_cache_size"> ndb_log_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_empty_epochs"> ndb_log_empty_epochs </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_empty_epochs"> ndb_log_empty_epochs </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_empty_update"> ndb_log_empty_update </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_empty_update"> ndb_log_empty_update </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_exclusive_reads"> ndb_log_exclusive_reads </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_exclusive_reads"> ndb_log_exclusive_reads </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_transaction_compression"> ndb_log_transaction_compression </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_transaction_compression_level_zstd"> ndb_log_transaction_compression_level_zstd </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_log_update_as_write </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_log_update_minimal </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_log_updated_only </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_metadata_check"> ndb_metadata_check </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_metadata_check_interval"> ndb_metadata_check_interval </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_metadata_sync"> ndb_metadata_sync </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_optimization_delay </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_read_backup"> ndb_read_backup </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_recv_thread_activation_threshold"> ndb_recv_thread_activation_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_recv_thread_cpu_mask"> ndb_recv_thread_cpu_mask </a> </th> <td> Bitmap </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_replica_batch_size"> ndb_replica_batch_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_replica_blob_write_batch_bytes"> ndb_replica_blob_write_batch_bytes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_report_thresh_binlog_epoch_slip"> ndb_report_thresh_binlog_epoch_slip </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_report_thresh_binlog_mem_usage"> ndb_report_thresh_binlog_mem_usage </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_row_checksum"> ndb_row_checksum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_schema_dist_lock_wait_timeout"> ndb_schema_dist_lock_wait_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_show_foreign_key_mock_tables"> ndb_show_foreign_key_mock_tables </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_slave_conflict_role"> ndb_slave_conflict_role </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_table_no_logging"> ndb_table_no_logging </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_table_temporary"> ndb_table_temporary </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_use_exact_count"> ndb_use_exact_count </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_use_transactions"> ndb_use_transactions </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_max_bytes"> ndbinfo_max_bytes </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_max_rows"> ndbinfo_max_rows </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_offline"> ndbinfo_offline </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_show_hidden"> ndbinfo_show_hidden </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_net_buffer_length"> net_buffer_length </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_net_read_timeout"> net_read_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_net_retry_count"> net_retry_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_net_write_timeout"> net_write_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_offline_mode"> offline_mode </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_old_alter_table"> old_alter_table </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_prune_level"> optimizer_prune_level </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> optimizer_search_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_switch"> optimizer_switch </a> </th> <td> Set </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace"> optimizer_trace </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace_features"> optimizer_trace_features </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace_limit"> optimizer_trace_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace_max_mem_size"> optimizer_trace_max_mem_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace_offset"> optimizer_trace_offset </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_original_commit_timestamp"> original_commit_timestamp </a> </th> <td> Numeric </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_original_server_version"> original_server_version </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_parser_max_mem_size"> parser_max_mem_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_partial_revokes"> partial_revokes </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_password_history"> password_history </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_password_require_current"> password_require_current </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_password_reuse_interval"> password_reuse_interval </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-system-variables.html#sysvar_performance_schema_max_digest_sample_age"> performance_schema_max_digest_sample_age </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-system-variables.html#sysvar_performance_schema_show_processlist"> performance_schema_show_processlist </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_preload_buffer_size"> preload_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_print_identified_with_as_hex"> print_identified_with_as_hex </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_profiling"> profiling </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_profiling_history_size"> profiling_history_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_protocol_compression_algorithms"> protocol_compression_algorithms </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_pseudo_replica_mode"> pseudo_replica_mode </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_pseudo_slave_mode"> pseudo_slave_mode </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_pseudo_thread_id"> pseudo_thread_id </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_query_alloc_block_size"> query_alloc_block_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_query_prealloc_size"> query_prealloc_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_rand_seed1"> rand_seed1 </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_rand_seed2"> rand_seed2 </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_range_alloc_block_size"> range_alloc_block_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_range_optimizer_max_mem_size"> range_optimizer_max_mem_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_rbr_exec_mode"> rbr_exec_mode </a> </th> <td> Enumeration </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_read_buffer_size"> read_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_read_only"> read_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_read_rnd_buffer_size"> read_rnd_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_regexp_stack_limit"> regexp_stack_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_regexp_time_limit"> regexp_time_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_relay_log_purge"> relay_log_purge </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_replica_allow_batching"> replica_allow_batching </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_checkpoint_group"> replica_checkpoint_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_checkpoint_period"> replica_checkpoint_period </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_compressed_protocol"> replica_compressed_protocol </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_exec_mode"> replica_exec_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_max_allowed_packet"> replica_max_allowed_packet </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_net_timeout"> replica_net_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_type"> replica_parallel_type </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_workers"> replica_parallel_workers </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_pending_jobs_size_max"> replica_pending_jobs_size_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_preserve_commit_order"> replica_preserve_commit_order </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_sql_verify_checksum"> replica_sql_verify_checksum </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_transaction_retries"> replica_transaction_retries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_type_conversions"> replica_type_conversions </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replication_optimize_for_static_plugin_config"> replication_optimize_for_static_plugin_config </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replication_sender_observe_commit_only"> replication_sender_observe_commit_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_require_row_format"> require_row_format </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_require_secure_transport"> require_secure_transport </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_restrict_fk_on_non_standard_key"> restrict_fk_on_non_standard_key </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_resultset_metadata"> resultset_metadata </a> </th> <td> Enumeration </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#sysvar_rewriter_enabled"> rewriter_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#sysvar_rewriter_enabled_for_threads_without_privilege_checks"> rewriter_enabled_for_threads_without_privilege_checks </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#sysvar_rewriter_verbose"> rewriter_verbose </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_read_size"> rpl_read_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_enabled"> rpl_semi_sync_master_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_timeout"> rpl_semi_sync_master_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_trace_level"> rpl_semi_sync_master_trace_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_for_slave_count"> rpl_semi_sync_master_wait_for_slave_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_no_slave"> rpl_semi_sync_master_wait_no_slave </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_point"> rpl_semi_sync_master_wait_point </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_semi_sync_replica_enabled"> rpl_semi_sync_replica_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_semi_sync_replica_trace_level"> rpl_semi_sync_replica_trace_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_semi_sync_slave_enabled"> rpl_semi_sync_slave_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_semi_sync_slave_trace_level"> rpl_semi_sync_slave_trace_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> rpl_semi_sync_source_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> rpl_semi_sync_source_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> rpl_semi_sync_source_trace_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> rpl_semi_sync_source_wait_for_replica_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> rpl_semi_sync_source_wait_no_replica </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> rpl_semi_sync_source_wait_point </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_stop_replica_timeout"> rpl_stop_replica_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_stop_slave_timeout"> rpl_stop_slave_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_schema_definition_cache"> schema_definition_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_secondary_engine_cost_threshold"> secondary_engine_cost_threshold </a> </th> <td> Numeric </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_select_into_buffer_size"> select_into_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_select_into_disk_sync"> select_into_disk_sync </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_select_into_disk_sync_delay"> select_into_disk_sync_delay </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options.html#sysvar_server_id"> server_id </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_gtids"> session_track_gtids </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_schema"> session_track_schema </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_state_change"> session_track_state_change </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_system_variables"> session_track_system_variables </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_transaction_info"> session_track_transaction_info </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_set_operations_buffer_size"> set_operations_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sha256_password_proxy_users"> sha256_password_proxy_users </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_show_create_table_skip_secondary_engine"> show_create_table_skip_secondary_engine </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_show_create_table_verbosity"> show_create_table_verbosity </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_show_gipk_in_create_table_and_information_schema"> show_gipk_in_create_table_and_information_schema </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_slave_allow_batching"> slave_allow_batching </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_checkpoint_group"> slave_checkpoint_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_checkpoint_period"> slave_checkpoint_period </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_compressed_protocol"> slave_compressed_protocol </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_exec_mode"> slave_exec_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_max_allowed_packet"> slave_max_allowed_packet </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_net_timeout"> slave_net_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_parallel_type"> slave_parallel_type </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_parallel_workers"> slave_parallel_workers </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_pending_jobs_size_max"> slave_pending_jobs_size_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_preserve_commit_order"> slave_preserve_commit_order </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_sql_verify_checksum"> slave_sql_verify_checksum </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_transaction_retries"> slave_transaction_retries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_type_conversions"> slave_type_conversions </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_slow_launch_time"> slow_launch_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_slow_query_log"> slow_query_log </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_slow_query_log_file"> slow_query_log_file </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sort_buffer_size"> sort_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_source_verify_checksum"> source_verify_checksum </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_auto_is_null"> sql_auto_is_null </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_big_selects"> sql_big_selects </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_buffer_result"> sql_buffer_result </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_generate_invisible_primary_key"> sql_generate_invisible_primary_key </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_sql_log_bin"> sql_log_bin </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_log_off"> sql_log_off </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_mode"> sql_mode </a> </th> <td> Set </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_notes"> sql_notes </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_quote_show_create"> sql_quote_show_create </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sql_replica_skip_counter"> sql_replica_skip_counter </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_require_primary_key"> sql_require_primary_key </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_safe_updates"> sql_safe_updates </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_select_limit"> sql_select_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sql_slave_skip_counter"> sql_slave_skip_counter </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_warnings"> sql_warnings </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_ca"> ssl_ca </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_capath"> ssl_capath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_cert"> ssl_cert </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> ssl_cipher </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_crl"> ssl_crl </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_crlpath"> ssl_crlpath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_key"> ssl_key </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_session_cache_mode"> ssl_session_cache_mode </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_session_cache_timeout"> ssl_session_cache_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_stored_program_cache"> stored_program_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_stored_program_definition_cache"> stored_program_definition_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_super_read_only"> super_read_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_sync_binlog"> sync_binlog </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sync_master_info"> sync_master_info </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sync_relay_log"> sync_relay_log </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sync_relay_log_info"> sync_relay_log_info </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sync_source_info"> sync_source_info </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_syseventlog.facility"> syseventlog.facility </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_syseventlog.include_pid"> syseventlog.include_pid </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_syseventlog.tag"> syseventlog.tag </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_table_definition_cache"> table_definition_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_table_encryption_privilege_check"> table_encryption_privilege_check </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_table_open_cache"> table_open_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_tablespace_definition_cache"> tablespace_definition_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="telemetry-trace-configuration.html#sysvar_telemetry.otel_log_level"> telemetry.otel_log_level </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="telemetry-trace-configuration.html#sysvar_telemetry.query_text_enabled"> telemetry.query_text_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="telemetry-trace-configuration.html#sysvar_telemetry.trace_enabled"> telemetry.trace_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_temptable_max_mmap"> temptable_max_mmap </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_temptable_max_ram"> temptable_max_ram </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_temptable_use_mmap"> temptable_use_mmap </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_terminology_use_previous"> terminology_use_previous </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_cache_size"> thread_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_high_priority_connection"> thread_pool_high_priority_connection </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_longrun_trx_limit"> thread_pool_longrun_trx_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_max_active_query_threads"> thread_pool_max_active_query_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_max_transactions_limit"> thread_pool_max_transactions_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_max_unused_threads"> thread_pool_max_unused_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_prio_kickup_timer"> thread_pool_prio_kickup_timer </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_query_threads_per_group"> thread_pool_query_threads_per_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_stall_limit"> thread_pool_stall_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_transaction_delay"> thread_pool_transaction_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_time_zone"> time_zone </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_timestamp"> timestamp </a> </th> <td> Numeric </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> tls_ciphersuites </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_tls_version"> tls_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_tmp_table_size"> tmp_table_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_transaction_alloc_block_size"> transaction_alloc_block_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_transaction_allow_batching"> transaction_allow_batching </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_transaction_isolation"> transaction_isolation </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_transaction_prealloc_size"> transaction_prealloc_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_transaction_read_only"> transaction_read_only </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_unique_checks"> unique_checks </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_updatable_views_with_limit"> updatable_views_with_limit </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_use_secondary_engine"> use_secondary_engine </a> </th> <td> Enumeration </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_check_user_name"> validate_password_check_user_name </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_dictionary_file"> validate_password_dictionary_file </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_length"> validate_password_length </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_mixed_case_count"> validate_password_mixed_case_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_number_count"> validate_password_number_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_policy"> validate_password_policy </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_special_char_count"> validate_password_special_char_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.changed_characters_percentage"> validate_password.changed_characters_percentage </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.check_user_name"> validate_password.check_user_name </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.dictionary_file"> validate_password.dictionary_file </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.length"> validate_password.length </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.mixed_case_count"> validate_password.mixed_case_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.number_count"> validate_password.number_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.policy"> validate_password.policy </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.special_char_count"> validate_password.special_char_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="version-tokens-reference.html#sysvar_version_tokens_session"> version_tokens_session </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_wait_timeout"> wait_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_windowing_use_high_precision"> windowing_use_high_precision </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_xa_detach_on_prepare"> xa_detach_on_prepare </a> </th> <td> Boolean </td> <td> Both </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th scope="col" style="width: 472.031px;"> Variable Name </th> <th scope="col" style="width: 135.375px;"> Variable Type </th> <th scope="col" style="width: 130.594px;"> Variable Scope </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/connecting-disconnecting.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="connecting-disconnecting"> </a> 5.1 Connecting to and Disconnecting from the Server </h2> </div> </div> </div> <a class="indexterm" name="idm46045325684192"> </a> <a class="indexterm" name="idm46045325682704"> </a> <a class="indexterm" name="idm46045325681216"> </a> <a class="indexterm" name="idm46045325679728"> </a> <p> To connect to the server, you usually need to provide a MySQL user name when you invoke <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> and, most likely, a password. If the server runs on a machine other than the one where you log in, you must also specify a host name. Contact your administrator to find out what connection parameters you should use to connect (that is, what host, user name, and password to use). Once you know the proper parameters, you should be able to connect like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa83410438"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-h</span> <em class="replaceable">host</em> <span class="token property">-u</span> <em class="replaceable">user</em> <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> ******</code></pre> </div> <p> <em class="replaceable"> <code> host </code> </em> and <em class="replaceable"> <code> user </code> </em> represent the host name where your MySQL server is running and the user name of your MySQL account. Substitute appropriate values for your setup. The <code class="literal"> **** </code> represents your password; enter it when <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> displays the <code class="literal"> Enter password: </code> prompt. </p> <p> If that works, you should see some introductory information followed by a <code class="literal"> mysql> </code> prompt: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa46609857"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-h</span> <em class="replaceable">host</em> <span class="token property">-u</span> <em class="replaceable">user</em> <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> ****** Welcome to the MySQL monitor<span class="token punctuation">.</span> Commands end with <span class="token punctuation">;</span> or \g<span class="token punctuation">.</span> Your MySQL connection id is 25338 to server version<span class="token punctuation">:</span> 8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>3-standard Type <span class="token atrule">'help;'</span> or <span class="token atrule">'\h'</span> for help<span class="token punctuation">.</span> Type <span class="token atrule">'\c'</span> to clear the buffer<span class="token punctuation">.</span> <span class="token prompt">mysql></span></code></pre> </div> <p> The <code class="literal"> mysql> </code> prompt tells you that <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> is ready for you to enter SQL statements. </p> <p> If you are logging in on the same machine that MySQL is running on, you can omit the host, and simply use the following: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa58352605"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> <em class="replaceable">user</em> <span class="token property">-p</span></code></pre> </div> <p> If, when you attempt to log in, you get an error message such as <span class="errortext"> ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2) </span> , it means that the MySQL server daemon (Unix) or service (Windows) is not running. Consult the administrator or see the section of <a class="xref" href="installing.html" title="Chapter 2 Installing MySQL"> Chapter 2, <i> Installing MySQL </i> </a> that is appropriate to your operating system. </p> <p> For help with other problems often encountered when trying to log in, see <a class="xref" href="common-errors.html" title="B.3.2 Common Errors When Using MySQL Programs"> Section B.3.2, “Common Errors When Using MySQL Programs” </a> . </p> <p> Some MySQL installations permit users to connect as the anonymous (unnamed) user to the server running on the local host. If this is the case on your machine, you should be able to connect to that server by invoking <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> without any options: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa74607461"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span></code></pre> </div> <p> After you have connected successfully, you can disconnect any time by typing <code class="literal"> QUIT </code> (or <code class="literal"> \q </code> ) at the <code class="literal"> mysql> </code> prompt: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa35101348"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> QUIT Bye</code></pre> </div> <p> On Unix, you can also disconnect by pressing Control+D. </p> <p> Most examples in the following sections assume that you are connected to the server. They indicate this by the <code class="literal"> mysql> </code> prompt. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/optimizing-queries-myisam.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="optimizing-queries-myisam"> </a> 10.6.1 Optimizing MyISAM Queries </h3> </div> </div> </div> <p> Some general tips for speeding up queries on <code class="literal"> MyISAM </code> tables: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> To help MySQL better optimize queries, use <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> or run <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --analyze </strong> </span> </a> on a table after it has been loaded with data. This updates a value for each index part that indicates the average number of rows that have the same value. (For unique indexes, this is always 1.) MySQL uses this to decide which index to choose when you join two tables based on a nonconstant expression. You can check the result from the table analysis by using <code class="literal"> SHOW INDEX FROM <em class="replaceable"> <code> tbl_name </code> </em> </code> and examining the <code class="literal"> Cardinality </code> value. <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --description --verbose </strong> </span> </a> shows index distribution information. </p> </li> <li class="listitem"> <p> To sort an index and data according to an index, use <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --sort-index --sort-records=1 </strong> </span> </a> (assuming that you want to sort on index 1). This is a good way to make queries faster if you have a unique index from which you want to read all rows in order according to the index. The first time you sort a large table this way, it may take a long time. </p> </li> <li class="listitem"> <p> Try to avoid complex <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> queries on <code class="literal"> MyISAM </code> tables that are updated frequently, to avoid problems with table locking that occur due to contention between readers and writers. </p> </li> <li class="listitem"> <p> <code class="literal"> MyISAM </code> supports concurrent inserts: If a table has no free blocks in the middle of the data file, you can <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> new rows into it at the same time that other threads are reading from the table. If it is important to be able to do this, consider using the table in ways that avoid deleting rows. Another possibility is to run <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> to defragment the table after you have deleted a lot of rows from it. This behavior is altered by setting the <a class="link" href="server-system-variables.html#sysvar_concurrent_insert"> <code class="literal"> concurrent_insert </code> </a> variable. You can force new rows to be appended (and therefore permit concurrent inserts), even in tables that have deleted rows. See <a class="xref" href="concurrent-inserts.html" title="10.11.3 Concurrent Inserts"> Section 10.11.3, “Concurrent Inserts” </a> . </p> </li> <li class="listitem"> <p> For <code class="literal"> MyISAM </code> tables that change frequently, try to avoid all variable-length columns ( <a class="link" href="char.html" title="13.3.2 The CHAR and VARCHAR Types"> <code class="literal"> VARCHAR </code> </a> , <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> , and <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> TEXT </code> </a> ). The table uses dynamic row format if it includes even a single variable-length column. See <a class="xref" href="storage-engines.html" title="Chapter 18 Alternative Storage Engines"> Chapter 18, <i> Alternative Storage Engines </i> </a> . </p> </li> <li class="listitem"> <p> It is normally not useful to split a table into different tables just because the rows become large. In accessing a row, the biggest performance hit is the disk seek needed to find the first byte of the row. After finding the data, most modern disks can read the entire row fast enough for most applications. The only cases where splitting up a table makes an appreciable difference is if it is a <code class="literal"> MyISAM </code> table using dynamic row format that you can change to a fixed row size, or if you very often need to scan the table but do not need most of the columns. See <a class="xref" href="storage-engines.html" title="Chapter 18 Alternative Storage Engines"> Chapter 18, <i> Alternative Storage Engines </i> </a> . </p> </li> <li class="listitem"> <p> Use <code class="literal"> ALTER TABLE ... ORDER BY <em class="replaceable"> <code> expr1 </code> </em> , <em class="replaceable"> <code> expr2 </code> </em> , ... </code> if you usually retrieve rows in <code class="literal"> <em class="replaceable"> <code> expr1 </code> </em> , <em class="replaceable"> <code> expr2 </code> </em> , ... </code> order. By using this option after extensive changes to the table, you may be able to get higher performance. </p> </li> <li class="listitem"> <p> If you often need to calculate results such as counts based on information from a lot of rows, it may be preferable to introduce a new table and update the counter in real time. An update of the following form is very fast: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa29818268"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> <em class="replaceable">tbl_name</em> <span class="token keyword">SET</span> <em class="replaceable">count_col</em><span class="token operator">=</span><em class="replaceable">count_col</em><span class="token operator">+</span><span class="token number">1</span> <span class="token keyword">WHERE</span> <em class="replaceable">key_col</em><span class="token operator">=</span><em class="replaceable">constant</em><span class="token punctuation">;</span></code></pre> </div> <p> This is very important when you use MySQL storage engines such as <code class="literal"> MyISAM </code> that has only table-level locking (multiple readers with single writers). This also gives better performance with most database systems, because the row locking manager in this case has less to do. </p> </li> <li class="listitem"> <p> Use <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> periodically to avoid fragmentation with dynamic-format <code class="literal"> MyISAM </code> tables. See <a class="xref" href="myisam-table-formats.html" title="18.2.3 MyISAM Table Storage Formats"> Section 18.2.3, “MyISAM Table Storage Formats” </a> . </p> </li> <li class="listitem"> <p> Declaring a <code class="literal"> MyISAM </code> table with the <code class="literal"> DELAY_KEY_WRITE=1 </code> table option makes index updates faster because they are not flushed to disk until the table is closed. The downside is that if something kills the server while such a table is open, you must ensure that the table is okay by running the server with the <a class="link" href="server-system-variables.html#sysvar_myisam_recover_options"> <code class="literal"> myisam_recover_options </code> </a> system variable set, or by running <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> before restarting the server. (However, even in this case, you should not lose anything by using <code class="literal"> DELAY_KEY_WRITE </code> , because the key information can always be generated from the data rows.) </p> </li> <li class="listitem"> <p> Strings are automatically prefix- and end-space compressed in <code class="literal"> MyISAM </code> indexes. See <a class="xref" href="create-index.html" title="15.1.15 CREATE INDEX Statement"> Section 15.1.15, “CREATE INDEX Statement” </a> . </p> </li> <li class="listitem"> <p> You can increase performance by caching queries or answers in your application and then executing many inserts or updates together. Locking the table during this operation ensures that the index cache is only flushed once after all updates. </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/error-log-components.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="error-log-components"> </a> 7.5.3 Error Log Components </h3> </div> </div> </div> <p> This section describes the characteristics of individual error log components. For general information about configuring error logging, see <a class="xref" href="error-log.html" title="7.4.2 The Error Log"> Section 7.4.2, “The Error Log” </a> . </p> <p> A log component can be a filter or a sink: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A filter processes log events, to add, remove, or modify event fields, or to delete events entirely. The resulting events pass to the next log component in the list of enabled components. </p> </li> <li class="listitem"> <p> A sink is a destination (writer) for log events. Typically, a sink processes log events into log messages that have a particular format and writes these messages to its associated output, such as a file or the system log. A sink may also write to the Performance Schema <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table; see <a class="xref" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> Section 29.12.22.2, “The error_log Table” </a> . Events pass unmodified to the next log component in the list of enabled components (that is, although a sink formats events to produce output messages, it does not modify events as they pass internally to the next component). </p> </li> </ul> </div> <p> The <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> system variable lists the enabled log components. Components not named in the list are disabled. <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> also implicitly loads error log components if they are not already loaded. For more information, see <a class="xref" href="error-log-configuration.html" title="7.4.2.1 Error Log Configuration"> Section 7.4.2.1, “Error Log Configuration” </a> . </p> <p> The following sections describe individual log components, grouped by component type: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="error-log-components.html#error-log-filter-components" title="Filter Error Log Components"> Filter Error Log Components </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-components.html#error-log-sink-components" title="Sink Error Log Components"> Sink Error Log Components </a> </p> </li> </ul> </div> <p> Component descriptions include these types of information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The component name and intended purpose. </p> </li> <li class="listitem"> <p> Whether the component is built in or must be loaded. For a loadable component, the description specifies the URN to use if explicitly loading or unloading the component with the <a class="link" href="install-component.html" title="15.7.4.3 INSTALL COMPONENT Statement"> <code class="literal"> INSTALL COMPONENT </code> </a> and <a class="link" href="uninstall-component.html" title="15.7.4.5 UNINSTALL COMPONENT Statement"> <code class="literal"> UNINSTALL COMPONENT </code> </a> statements. Implicitly loading error log components requires only the component name. For more information, see <a class="xref" href="error-log-configuration.html" title="7.4.2.1 Error Log Configuration"> Section 7.4.2.1, “Error Log Configuration” </a> . </p> </li> <li class="listitem"> <p> Whether the component can be listed multiple times in the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value. </p> </li> <li class="listitem"> <p> For a sink component, the destination to which the component writes output. </p> </li> <li class="listitem"> <p> For a sink component, whether it supports an interface to the Performance Schema <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table. </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="error-log-filter-components"> </a> Filter Error Log Components </h4> </div> </div> </div> <p> Error log filter components implement filtering of error log events. If no filter component is enabled, no filtering occurs. </p> <p> Any enabled filter component affects log events only for components listed later in the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value. In particular, for any log sink component listed in <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> earlier than any filter component, no log event filtering occurs. </p> <h5> <a name="idm46045257269152"> </a> The log_filter_internal Component </h5> <a class="indexterm" name="idm46045257268480"> </a> <a class="indexterm" name="idm46045257267392"> </a> <a class="indexterm" name="idm46045257265904"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements filtering based on log event priority and error code, in combination with the <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> <code class="literal"> log_error_verbosity </code> </a> and <a class="link" href="server-system-variables.html#sysvar_log_error_suppression_list"> <code class="literal"> log_error_suppression_list </code> </a> system variables. See <a class="xref" href="error-log-priority-based-filtering.html" title="7.4.2.5 Priority-Based Error Log Filtering (log_filter_internal)"> Section 7.4.2.5, “Priority-Based Error Log Filtering (log_filter_internal)” </a> . </p> </li> <li class="listitem"> <p> URN: This component is built in and need not be loaded. </p> </li> <li class="listitem"> <p> Multiple uses permitted: No. </p> </li> </ul> </div> <p> If <code class="literal"> log_filter_internal </code> is disabled, <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> <code class="literal"> log_error_verbosity </code> </a> and <a class="link" href="server-system-variables.html#sysvar_log_error_suppression_list"> <code class="literal"> log_error_suppression_list </code> </a> have no effect. </p> <h5> <a name="idm46045257254448"> </a> The log_filter_dragnet Component </h5> <a class="indexterm" name="idm46045257253728"> </a> <a class="indexterm" name="idm46045257252640"> </a> <a class="indexterm" name="idm46045257251152"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements filtering based on the rules defined by the <a class="link" href="server-system-variables.html#sysvar_dragnet.log_error_filter_rules"> <code class="literal"> dragnet.log_error_filter_rules </code> </a> system variable setting. See <a class="xref" href="error-log-rule-based-filtering.html" title="7.4.2.6 Rule-Based Error Log Filtering (log_filter_dragnet)"> Section 7.4.2.6, “Rule-Based Error Log Filtering (log_filter_dragnet)” </a> . </p> </li> <li class="listitem"> <p> URN: <code class="literal"> file://component_log_filter_dragnet </code> </p> </li> <li class="listitem"> <p> Multiple uses permitted: No. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="error-log-sink-components"> </a> Sink Error Log Components </h4> </div> </div> </div> <p> Error log sink components are writers that implement error log output. If no sink component is enabled, no log output occurs. </p> <p> Some sink component descriptions refer to the default error log destination. This is the console or a file and is indicated by the value of the <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> system variable, determined as described in <a class="xref" href="error-log-destination-configuration.html" title="7.4.2.2 Default Error Log Destination Configuration"> Section 7.4.2.2, “Default Error Log Destination Configuration” </a> . </p> <h5> <a name="idm46045257239616"> </a> The log_sink_internal Component </h5> <a class="indexterm" name="idm46045257238944"> </a> <a class="indexterm" name="idm46045257237856"> </a> <a class="indexterm" name="idm46045257236368"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements traditional error log message output format. </p> </li> <li class="listitem"> <p> URN: This component is built in and need not be loaded. </p> </li> <li class="listitem"> <p> Multiple uses permitted: No. </p> </li> <li class="listitem"> <p> Output destination: Writes to the default error log destination. </p> </li> <li class="listitem"> <p> Performance Schema support: Writes to the <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table. Provides a parser for reading error log files created by previous server instances. </p> </li> </ul> </div> <h5> <a name="idm46045257228768"> </a> The log_sink_json Component </h5> <a class="indexterm" name="idm46045257228096"> </a> <a class="indexterm" name="idm46045257227008"> </a> <a class="indexterm" name="idm46045257225520"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements JSON-format error logging. See <a class="xref" href="error-log-json.html" title="7.4.2.7 Error Logging in JSON Format"> Section 7.4.2.7, “Error Logging in JSON Format” </a> . </p> </li> <li class="listitem"> <p> URN: <code class="literal"> file://component_log_sink_json </code> </p> </li> <li class="listitem"> <p> Multiple uses permitted: Yes. </p> </li> <li class="listitem"> <p> Output destination: This sink determines its output destination based on the default error log destination, which is given by the <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> system variable: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> names a file, the sink bases output file naming on that file name, plus a numbered <code class="filename"> . <em class="replaceable"> <code> NN </code> </em> .json </code> suffix, with <em class="replaceable"> <code> NN </code> </em> starting at 00. For example, if <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> is <em class="replaceable"> <code> file_name </code> </em> , successive instances of <code class="literal"> log_sink_json </code> named in the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value write to <code class="filename"> <em class="replaceable"> <code> file_name </code> </em> .00.json </code> , <code class="filename"> <em class="replaceable"> <code> file_name </code> </em> .01.json </code> , and so forth. </p> </li> <li class="listitem"> <p> If <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> is <code class="literal"> stderr </code> , the sink writes to the console. If <code class="literal"> log_sink_json </code> is named multiple times in the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value, they all write to the console, which is likely not useful. </p> </li> </ul> </div> </li> <li class="listitem"> <p> Performance Schema support: Writes to the <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table. Provides a parser for reading error log files created by previous server instances. </p> </li> </ul> </div> <h5> <a name="idm46045257200480"> </a> The log_sink_syseventlog Component </h5> <a class="indexterm" name="idm46045257199808"> </a> <a class="indexterm" name="idm46045257198720"> </a> <a class="indexterm" name="idm46045257197232"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements error logging to the system log. This is the Event Log on Windows, and <code class="literal"> syslog </code> on Unix and Unix-like systems. See <a class="xref" href="error-log-syslog.html" title="7.4.2.8 Error Logging to the System Log"> Section 7.4.2.8, “Error Logging to the System Log” </a> . </p> </li> <li class="listitem"> <p> URN: <code class="literal"> file://component_log_sink_syseventlog </code> </p> </li> <li class="listitem"> <p> Multiple uses permitted: No. </p> </li> <li class="listitem"> <p> Output destination: Writes to the system log. Does not use the default error log destination. </p> </li> <li class="listitem"> <p> Performance Schema support: Does not write to the <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table. Does not provide a parser for reading error log files created by previous server instances. </p> </li> </ul> </div> <h5> <a name="idm46045257187472"> </a> The log_sink_test Component </h5> <a class="indexterm" name="idm46045257186800"> </a> <a class="indexterm" name="idm46045257185712"> </a> <a class="indexterm" name="idm46045257184224"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Intended for internal use in writing test cases, not for production use. </p> </li> <li class="listitem"> <p> URN: <code class="literal"> file://component_log_sink_test </code> </p> </li> </ul> </div> <p> Sink properties such as whether multiple uses are permitted and the output destination are not specified for <code class="literal"> log_sink_test </code> because, as mentioned, it is for internal use. As such, its behavior is subject to change at any time. </p> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/downgrading.html	<div id="docs-body"> <div class="chapter"> <div class="titlepage"> <div> <div> <h1 class="title"> <a name="downgrading"> </a> Chapter 4 Downgrading MySQL </h1> </div> </div> </div> <a class="indexterm" name="idm46045325743728"> </a> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Notes </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Make sure you understand <a class="link" href="mysql-releases.html" title="1.3 MySQL Releases: Innovation and LTS"> the MySQL release model </a> for MySQL long-term support (LTS) and Innovation releases before proceeding with a downgrade. </p> </li> <li class="listitem"> <p> A replication topology is downgraded by following the rolling downgrade scheme described at <a class="xref" href="replication-upgrade.html" title="19.5.3 Upgrading or Downgrading a Replication Topology"> Section 19.5.3, “Upgrading or Downgrading a Replication Topology” </a> , which uses one of the supported single-server methods for each individual server downgrade. </p> </li> <li class="listitem"> <p> Monthly Rapid Updates (MRUs) and hot fixes also count as releases in this documentation. </p> </li> </ul> </div> </div> <div class="table"> <a name="mysqld-downgrade-paths"> </a> <p class="title"> <b> Table 4.1 Downgrade Paths for MySQL Server </b> </p> <div class="table-contents"> <table width="1062"> <colgroup> <col width="25%"/> <col width="15%"/> <col width="30%"/> <col width="30%"/> </colgroup> <thead> <tr> <th scope="col"> Downgrade Path </th> <th scope="col"> Path Examples </th> <th scope="col"> Supported Downgrade Methods </th> <th scope="col"> Notes </th> </tr> </thead> <tbody> <tr> <th scope="row"> Within an LTS series </th> <td> <p> 8.4.y LTS to 8.4.x LTS </p> </td> <td> In-place, logical dump and load, MySQL Clone, or by using replication </td> <td> </td> </tr> <tr> <th scope="row"> From an LTS or Bugfix series to the previous LTS or Bugfix series </th> <td> 8.4.x LTS to 8.0.y </td> <td> Logical dump and load or by using replication </td> <td> Only supported for rollback purposes (that is, if no new server functionality has been applied to the data) </td> </tr> <tr> <th scope="row"> From an LTS or Bugfix series to an Innovation series <span class="emphasis"> <em> after the previous LTS series </em> </span> </th> <td> 8.4.x LTS to 8.3.0 Innovation </td> <td> Logical dump and load or by using replication </td> <td> Only supported for rollback purposes (that is, if no new server functionality has been applied to the data) </td> </tr> <tr> <th scope="row"> From within an Innovation series </th> <td> 9.1 to 9.0 </td> <td> Logical dump and load or by using replication </td> <td> Only supported for rollback purposes (that is, if no new server functionality has been applied to the data) </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> <p> Downgrading to MySQL 5.7 or earlier is not supported. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/large-page-support.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="large-page-support"> </a> 10.12.3.3 Enabling Large Page Support </h4> </div> </div> </div> <a class="indexterm" name="idm46045222150512"> </a> <p> Some hardware and operating system architectures support memory pages greater than the default (usually 4KB). The actual implementation of this support depends on the underlying hardware and operating system. Applications that perform a lot of memory accesses may obtain performance improvements by using large pages due to reduced Translation Lookaside Buffer (TLB) misses. </p> <p> In MySQL, large pages can be used by <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> , to allocate memory for its buffer pool and additional memory pool. </p> <p> Standard use of large pages in MySQL attempts to use the largest size supported, up to 4MB. Under Solaris, a <span class="quote"> “ <span class="quote"> super large pages </span> ” </span> feature enables uses of pages up to 256MB. This feature is available for recent SPARC platforms. It can be enabled or disabled by using the <a class="link" href="server-options.html#option_mysqld_super-large-pages"> <code class="option"> --super-large-pages </code> </a> or <a class="link" href="server-options.html#option_mysqld_super-large-pages"> <code class="option"> --skip-super-large-pages </code> </a> option. </p> <p> MySQL also supports the Linux implementation of large page support (which is called HugeTLB in Linux). </p> <p> Before large pages can be used on Linux, the kernel must be enabled to support them and it is necessary to configure the HugeTLB memory pool. For reference, the HugeTBL API is documented in the <code class="filename"> Documentation/vm/hugetlbpage.txt </code> file of your Linux sources. </p> <p> The kernels for some recent systems such as Red Hat Enterprise Linux may have the large pages feature enabled by default. To check whether this is true for your kernel, use the following command and look for output lines containing <span class="quote"> “ <span class="quote"> huge </span> ” </span> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa90271592"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">grep</span> <span class="token property">-i</span> huge /proc/meminfo AnonHugePages<span class="token punctuation">:</span> 2658304 kB ShmemHugePages<span class="token punctuation">:</span> 0 kB HugePages_Total<span class="token punctuation">:</span> 0 HugePages_Free<span class="token punctuation">:</span> 0 HugePages_Rsvd<span class="token punctuation">:</span> 0 HugePages_Surp<span class="token punctuation">:</span> 0 Hugepagesize<span class="token punctuation">:</span> 2048 kB Hugetlb<span class="token punctuation">:</span> 0 kB</code></pre> </div> <p> The nonempty command output indicates that large page support is present, but the zero values indicate that no pages are configured for use. </p> <p> If your kernel needs to be reconfigured to support large pages, consult the <code class="filename"> hugetlbpage.txt </code> file for instructions. </p> <p> Assuming that your Linux kernel has large page support enabled, configure it for use by MySQL using the following steps: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Determine the number of large pages needed. This is the size of the InnoDB buffer pool divided by the large page size, which we can calculate as <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> / <code class="literal"> Hugepagesize </code> . Assuming the default value for the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> (128MB) and using the <code class="literal"> Hugepagesize </code> value obtained from <code class="filename"> /proc/meminfo </code> (2MB), this is 128MB / 2MB, or 64 Huge Pages. We call this value <em class="replaceable"> <code> P </code> </em> . </p> </li> <li class="listitem"> <p> As system root, open the file <code class="filename"> /etc/sysctl.conf </code> in a text editor, and add the line shown here, where <em class="replaceable"> <code> P </code> </em> is the number of large pages obtained in the previous step: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa61463335"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">vm.nr_hugepages</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">P</em></span></code></pre> </div> <p> Using the actual value obtained previously, the additional line should look like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa3147095"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">vm.nr_hugepages</span><span class="token attr-value"><span class="token punctuation">=</span>66</span></code></pre> </div> <p> Save the updated file. </p> </li> <li class="listitem"> <p> As system root, run the following command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa31987450"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">$<span class="token operator">></span> sudo sysctl <span class="token operator">-</span>p</code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> On some systems the large pages file may be named slightly differently; for example, some distributions call it <code class="filename"> nr_hugepages </code> . In the event <span class="command"> <strong> sysctl </strong> </span> returns an error relating to the file name, check the name of the corresponding file in <code class="filename"> /proc/sys/vm </code> and use that instead. </p> </div> <p> To verify the large page configuration, check <code class="filename"> /proc/meminfo </code> again as described previously. Now you should see some additional nonzero values in the output, similar to this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa19754463"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">grep</span> <span class="token property">-i</span> huge /proc/meminfo AnonHugePages<span class="token punctuation">:</span> 2686976 kB ShmemHugePages<span class="token punctuation">:</span> 0 kB HugePages_Total<span class="token punctuation">:</span> 233 HugePages_Free<span class="token punctuation">:</span> 233 HugePages_Rsvd<span class="token punctuation">:</span> 0 HugePages_Surp<span class="token punctuation">:</span> 0 Hugepagesize<span class="token punctuation">:</span> 2048 kB Hugetlb<span class="token punctuation">:</span> 477184 kB</code></pre> </div> </li> <li class="listitem"> <p> Optionally, you may wish to compact the Linux VM. You can do this using a sequence of commands, possibly in a script file, similar to what is shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-bash"><div class="docs-select-all right" id="sa57947087"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-bash"><span class="token function">sync</span> <span class="token function">sync</span> <span class="token function">sync</span> <span class="token keyword">echo</span> 3 <span class="token operator">></span> /proc/sys/vm/drop_caches <span class="token keyword">echo</span> 1 <span class="token operator">></span> /proc/sys/vm/compact_memory</code></pre> </div> <p> See your operating platform documentation for more information about how to do this. </p> </li> <li class="listitem"> <p> Check any configuration files such as <code class="filename"> my.cnf </code> used by the server, and make sure that <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> is set larger than the huge page size. The default for this variable is 128M. </p> </li> <li class="listitem"> <p> Large page support in the MySQL server is disabled by default. To enable it, start the server with <a class="link" href="server-options.html#option_mysqld_large-pages"> <code class="option"> --large-pages </code> </a> . You can also do so by adding the following line to the <code class="literal"> [mysqld] </code> section of the server <code class="filename"> my.cnf </code> file: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa62367466"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">large-pages</span><span class="token attr-value"><span class="token punctuation">=</span>ON</span></code></pre> </div> <p> With this option enabled, <code class="literal"> InnoDB </code> uses large pages automatically for its buffer pool and additional memory pool. If <code class="literal"> InnoDB </code> cannot do this, it falls back to use of traditional memory and writes a warning to the error log: <span class="errortext"> Warning: Using conventional memory pool </span> . </p> </li> </ol> </div> <p> You can verify that MySQL is now using large pages by checking <code class="filename"> /proc/meminfo </code> again after restarting <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> , like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa57815047"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">grep</span> <span class="token property">-i</span> huge /proc/meminfo AnonHugePages<span class="token punctuation">:</span> 2516992 kB ShmemHugePages<span class="token punctuation">:</span> 0 kB HugePages_Total<span class="token punctuation">:</span> 233 HugePages_Free<span class="token punctuation">:</span> 222 HugePages_Rsvd<span class="token punctuation">:</span> 55 HugePages_Surp<span class="token punctuation">:</span> 0 Hugepagesize<span class="token punctuation">:</span> 2048 kB Hugetlb<span class="token punctuation">:</span> 477184 kB</code></pre> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-table-distribution-status.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-ndbinfo-table-distribution-status"> </a> 25.6.17.57 The ndbinfo table_distribution_status Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045087785536"> </a> <p> The <code class="literal"> table_distribution_status </code> table provides information about the progress of table distribution for <code class="literal"> NDB </code> tables. </p> <p> The <code class="literal"> table_distribution_status </code> table contains the following columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> node_id </code> </p> <p> Node id </p> </li> <li class="listitem"> <p> <code class="literal"> table_id </code> </p> <p> Table ID </p> </li> <li class="listitem"> <p> <code class="literal"> tab_copy_status </code> </p> <p> Status of copying of table distribution data to disk; one of <code class="literal"> IDLE </code> , <code class="literal"> SR_PHASE1_READ_PAGES </code> , <code class="literal"> SR_PHASE2_READ_TABLE </code> , <code class="literal"> SR_PHASE3_COPY_TABLE </code> , <code class="literal"> REMOVE_NODE </code> , <code class="literal"> LCP_READ_TABLE </code> , <code class="literal"> COPY_TAB_REQ </code> , <code class="literal"> COPY_NODE_STATE </code> , <code class="literal"> ADD_TABLE_COORDINATOR </code> , <code class="literal"> ADD_TABLE_PARTICIPANT </code> , <code class="literal"> INVALIDATE_NODE_LCP </code> , <code class="literal"> ALTER_TABLE </code> , <code class="literal"> COPY_TO_SAVE </code> , or <code class="literal"> GET_TABINFO </code> </p> </li> <li class="listitem"> <p> <code class="literal"> tab_update_status </code> </p> <p> Status of updating of table distribution data; one of <code class="literal"> IDLE </code> , <code class="literal"> LOCAL_CHECKPOINT </code> , <code class="literal"> LOCAL_CHECKPOINT_QUEUED </code> , <code class="literal"> REMOVE_NODE </code> , <code class="literal"> COPY_TAB_REQ </code> , <code class="literal"> ADD_TABLE_MASTER </code> , <code class="literal"> ADD_TABLE_SLAVE </code> , <code class="literal"> INVALIDATE_NODE_LCP </code> , or <code class="literal"> CALLBACK </code> </p> </li> <li class="listitem"> <p> <code class="literal"> tab_lcp_status </code> </p> <p> Status of table LCP; one of <code class="literal"> ACTIVE </code> (waiting for local checkpoint to be performed), <code class="literal"> WRITING_TO_FILE </code> (checkpoint performed but not yet written to disk), or <code class="literal"> COMPLETED </code> (checkpoint performed and persisted to disk) </p> </li> <li class="listitem"> <p> <code class="literal"> tab_status </code> </p> <p> Table internal status; one of <code class="literal"> ACTIVE </code> (table exists), <code class="literal"> CREATING </code> (table is being created), or <code class="literal"> DROPPING </code> (table is being dropped) </p> </li> <li class="listitem"> <p> <code class="literal"> tab_storage </code> </p> <p> Table recoverability; one of <code class="literal"> NORMAL </code> (fully recoverable with redo logging and checkpointing), <code class="literal"> NOLOGGING </code> (recoverable from node crash, empty following cluster crash), or <code class="literal"> TEMPORARY </code> (not recoverable) </p> </li> <li class="listitem"> <p> <code class="literal"> tab_partitions </code> </p> <p> Number of partitions in table </p> </li> <li class="listitem"> <p> <code class="literal"> tab_fragments </code> </p> <p> Number of fragments in table; normally same as <code class="literal"> tab_partitions </code> ; for fully replicated tables equal to <code class="literal"> tab_partitions * [number of node groups] </code> </p> </li> <li class="listitem"> <p> <code class="literal"> current_scan_count </code> </p> <p> Current number of active scans </p> </li> <li class="listitem"> <p> <code class="literal"> scan_count_wait </code> </p> <p> Current number of scans waiting to be performed before <code class="literal"> ALTER TABLE </code> can complete. </p> </li> <li class="listitem"> <p> <code class="literal"> is_reorg_ongoing </code> </p> <p> Whether the table is currently being reorganized (1 if true) </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-information-schema-tables.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysql-cluster-information-schema-tables"> </a> 25.6.18 INFORMATION_SCHEMA Tables for NDB Cluster </h3> </div> </div> </div> <p> Two <a class="link" href="information-schema.html" title="Chapter 28 INFORMATION_SCHEMA Tables"> <code class="literal"> INFORMATION_SCHEMA </code> </a> tables provide information that is of particular use when managing an NDB Cluster. The <a class="link" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table"> <code class="literal"> FILES </code> </a> table provides information about NDB Cluster Disk Data files (see <a class="xref" href="mysql-cluster-disk-data-objects.html" title="25.6.11.1 NDB Cluster Disk Data Objects"> Section 25.6.11.1, “NDB Cluster Disk Data Objects” </a> ). The <a class="link" href="information-schema-ndb-transid-mysql-connection-map-table.html" title="28.3.18 The INFORMATION_SCHEMA ndb_transid_mysql_connection_map Table"> <code class="literal"> ndb_transid_mysql_connection_map </code> </a> table provides a mapping between transactions, transaction coordinators, and API nodes. </p> <p> Additional statistical and other data about NDB Cluster transactions, operations, threads, blocks, and other aspects of performance can be obtained from the tables in the <a class="link" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> <code class="literal"> ndbinfo </code> </a> database. For information about these tables, see <a class="xref" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> Section 25.6.17, “ndbinfo: The NDB Cluster Information Database” </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/dynindex-is.html	<div id="docs-body"> <div class="index"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="dynindex-is"> </a> INFORMATION_SCHEMA Index </h2> </div> </div> </div> <p> <a name="is-index-top"> </a> <a class="link" href="dynindex-is.html#is-index-A" title="A"> A </a> \| <a class="link" href="dynindex-is.html#is-index-C" title="C"> C </a> \| <a class="link" href="dynindex-is.html#is-index-E" title="E"> E </a> \| <a class="link" href="dynindex-is.html#is-index-F" title="F"> F </a> \| <a class="link" href="dynindex-is.html#is-index-I" title="I"> I </a> \| <a class="link" href="dynindex-is.html#is-index-K" title="K"> K </a> \| <a class="link" href="dynindex-is.html#is-index-M" title="M"> M </a> \| <a class="link" href="dynindex-is.html#is-index-N" title="N"> N </a> \| <a class="link" href="dynindex-is.html#is-index-O" title="O"> O </a> \| <a class="link" href="dynindex-is.html#is-index-P" title="P"> P </a> \| <a class="link" href="dynindex-is.html#is-index-R" title="R"> R </a> \| <a class="link" href="dynindex-is.html#is-index-S" title="S"> S </a> \| <a class="link" href="dynindex-is.html#is-index-T" title="T"> T </a> \| <a class="link" href="dynindex-is.html#is-index-U" title="U"> U </a> \| <a class="link" href="dynindex-is.html#is-index-V" title="V"> V </a> </p> <div class="indexdiv"> <a name="is-index-A"> </a> <h3 class="title"> A </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ADMINISTRABLE_ROLE_AUTHORIZATIONS </h3> <dl> <dt> <a class="xref" href="information-schema-administrable-role-authorizations-table.html" title="28.3.2 The INFORMATION_SCHEMA ADMINISTRABLE_ROLE_AUTHORIZATIONS Table"> Section 28.3.2, “The INFORMATION_SCHEMA ADMINISTRABLE_ROLE_AUTHORIZATIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> APPLICABLE_ROLES </h3> <dl> <dt> <a class="xref" href="information-schema-applicable-roles-table.html" title="28.3.3 The INFORMATION_SCHEMA APPLICABLE_ROLES Table"> Section 28.3.3, “The INFORMATION_SCHEMA APPLICABLE_ROLES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-C"> </a> <h3 class="title"> C </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> CHARACTER_SETS </h3> <dl> <dt> <a class="xref" href="charset-introducer.html" title="12.3.8 Character Set Introducers"> Section 12.3.8, “Character Set Introducers” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-mysql.html" title="12.2 Character Sets and Collations in MySQL"> Section 12.2, “Character Sets and Collations in MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-literal.html" title="12.3.6 Character String Literal Character Set and Collation"> Section 12.3.6, “Character String Literal Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-column.html" title="12.3.5 Column Character Set and Collation"> Section 12.3.5, “Column Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-database.html" title="12.3.3 Database Character Set and Collation"> Section 12.3.3, “Database Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-character-set.html" title="15.7.7.4 SHOW CHARACTER SET Statement"> Section 15.7.7.4, “SHOW CHARACTER SET Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-charsets.html" title="12.10 Supported Character Sets and Collations"> Section 12.10, “Supported Character Sets and Collations” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-table.html" title="12.3.4 Table Character Set and Collation"> Section 12.3.4, “Table Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-character-sets-table.html" title="28.3.4 The INFORMATION_SCHEMA CHARACTER_SETS Table"> Section 28.3.4, “The INFORMATION_SCHEMA CHARACTER_SETS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> CHECK_CONSTRAINTS </h3> <dl> <dt> <a class="xref" href="create-table-check-constraints.html" title="15.1.20.6 CHECK Constraints"> Section 15.1.20.6, “CHECK Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-check-constraints-table.html" title="28.3.5 The INFORMATION_SCHEMA CHECK_CONSTRAINTS Table"> Section 28.3.5, “The INFORMATION_SCHEMA CHECK_CONSTRAINTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLLATION_CHARACTER_SET_APPLICABILITY </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-optimization.html" title="10.2.3 Optimizing INFORMATION_SCHEMA Queries"> Section 10.2.3, “Optimizing INFORMATION_SCHEMA Queries” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-collation-character-set-applicability-table.html" title="28.3.7 The INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY Table"> Section 28.3.7, “The INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLLATIONS </h3> <dl> <dt> <a class="xref" href="charset-configuration.html" title="12.15 Character Set Configuration"> Section 12.15, “Character Set Configuration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-mysql.html" title="12.2 Character Sets and Collations in MySQL"> Section 12.2, “Character Sets and Collations in MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="adding-collation-choosing-id.html" title="12.14.2 Choosing a Collation ID"> Section 12.14.2, “Choosing a Collation ID” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-collation.html" title="15.7.7.5 SHOW COLLATION Statement"> Section 15.7.7.5, “SHOW COLLATION Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-binary-collations.html" title="12.8.5 The binary Collation Compared to _bin Collations"> Section 12.8.5, “The binary Collation Compared to _bin Collations” </a> </dt> <dd> </dd> <dt> <a class="xref" href="char.html" title="13.3.2 The CHAR and VARCHAR Types"> Section 13.3.2, “The CHAR and VARCHAR Types” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-collations-table.html" title="28.3.6 The INFORMATION_SCHEMA COLLATIONS Table"> Section 28.3.6, “The INFORMATION_SCHEMA COLLATIONS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-unicode-sets.html" title="12.10.1 Unicode Character Sets"> Section 12.10.1, “Unicode Character Sets” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLUMN_PRIVILEGES </h3> <dl> <dt> <a class="xref" href="information-schema-column-privileges-table.html" title="28.3.10 The INFORMATION_SCHEMA COLUMN_PRIVILEGES Table"> Section 28.3.10, “The INFORMATION_SCHEMA COLUMN_PRIVILEGES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLUMN_STATISTICS </h3> <dl> <dt> <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-column-statistics-table.html" title="28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table"> Section 28.3.11, “The INFORMATION_SCHEMA COLUMN_STATISTICS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLUMNS </h3> <dl> <dt> <a class="xref" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> Section 15.1.20, “CREATE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-gipks.html" title="15.1.20.11 Generated Invisible Primary Keys"> Section 15.1.20.11, “Generated Invisible Primary Keys” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-introduction.html" title="28.1 Introduction"> Section 28.1, “Introduction” </a> </dt> <dd> </dd> <dt> <a class="xref" href="invisible-columns.html" title="15.1.20.10 Invisible Columns"> Section 15.1.20.10, “Invisible Columns” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-columns.html" title="15.7.7.6 SHOW COLUMNS Statement"> Section 15.7.7.6, “SHOW COLUMNS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> Section 28.3.8, “The INFORMATION_SCHEMA COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table"> Section 28.4.2, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table"> Section 28.4.3, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-pool-stats-table.html" title="28.4.4 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table"> Section 28.4.4, “The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cached-indexes-table.html" title="28.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table"> Section 28.4.5, “The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-table.html" title="28.4.6 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables"> Section 28.4.6, “The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> Section 28.4.8, “The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmpmem-table.html" title="28.4.7 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables"> Section 28.4.7, “The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-columns-table.html" title="28.4.9 The INFORMATION_SCHEMA INNODB_COLUMNS Table"> Section 28.4.9, “The INFORMATION_SCHEMA INNODB_COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-datafiles-table.html" title="28.4.10 The INFORMATION_SCHEMA INNODB_DATAFILES Table"> Section 28.4.10, “The INFORMATION_SCHEMA INNODB_DATAFILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-fields-table.html" title="28.4.11 The INFORMATION_SCHEMA INNODB_FIELDS Table"> Section 28.4.11, “The INFORMATION_SCHEMA INNODB_FIELDS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-foreign-table.html" title="28.4.12 The INFORMATION_SCHEMA INNODB_FOREIGN Table"> Section 28.4.12, “The INFORMATION_SCHEMA INNODB_FOREIGN Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-foreign-cols-table.html" title="28.4.13 The INFORMATION_SCHEMA INNODB_FOREIGN_COLS Table"> Section 28.4.13, “The INFORMATION_SCHEMA INNODB_FOREIGN_COLS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> Section 28.4.14, “The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-config-table.html" title="28.4.15 The INFORMATION_SCHEMA INNODB_FT_CONFIG Table"> Section 28.4.15, “The INFORMATION_SCHEMA INNODB_FT_CONFIG Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-default-stopword-table.html" title="28.4.16 The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table"> Section 28.4.16, “The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-deleted-table.html" title="28.4.17 The INFORMATION_SCHEMA INNODB_FT_DELETED Table"> Section 28.4.17, “The INFORMATION_SCHEMA INNODB_FT_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-index-cache-table.html" title="28.4.18 The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table"> Section 28.4.18, “The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-index-table-table.html" title="28.4.19 The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table"> Section 28.4.19, “The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-indexes-table.html" title="28.4.20 The INFORMATION_SCHEMA INNODB_INDEXES Table"> Section 28.4.20, “The INFORMATION_SCHEMA INNODB_INDEXES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> Section 28.4.21, “The INFORMATION_SCHEMA INNODB_METRICS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-session-temp-tablespaces-table.html" title="28.4.22 The INFORMATION_SCHEMA INNODB_SESSION_TEMP_TABLESPACES Table"> Section 28.4.22, “The INFORMATION_SCHEMA INNODB_SESSION_TEMP_TABLESPACES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tables-table.html" title="28.4.23 The INFORMATION_SCHEMA INNODB_TABLES Table"> Section 28.4.23, “The INFORMATION_SCHEMA INNODB_TABLES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-table.html" title="28.4.24 The INFORMATION_SCHEMA INNODB_TABLESPACES Table"> Section 28.4.24, “The INFORMATION_SCHEMA INNODB_TABLESPACES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> Section 28.4.25, “The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablestats-table.html" title="28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View"> Section 28.4.26, “The INFORMATION_SCHEMA INNODB_TABLESTATS View” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-temp-table-info-table.html" title="28.4.27 The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table"> Section 28.4.27, “The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-trx-table.html" title="28.4.28 The INFORMATION_SCHEMA INNODB_TRX Table"> Section 28.4.28, “The INFORMATION_SCHEMA INNODB_TRX Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-virtual-table.html" title="28.4.29 The INFORMATION_SCHEMA INNODB_VIRTUAL Table"> Section 28.4.29, “The INFORMATION_SCHEMA INNODB_VIRTUAL Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-st-geometry-columns-table.html" title="28.3.35 The INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS Table"> Section 28.3.35, “The INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="upgrade-binary-package.html" title="3.7 Upgrading MySQL Binary or Package-based Installations on Unix/Linux"> Section 3.7, “Upgrading MySQL Binary or Package-based Installations on Unix/Linux” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLUMNS_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="information-schema-columns-extensions-table.html" title="28.3.9 The INFORMATION_SCHEMA COLUMNS_EXTENSIONS Table"> Section 28.3.9, “The INFORMATION_SCHEMA COLUMNS_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS </h3> <dl> <dt> <a class="xref" href="connection-control-installation.html" title="8.4.2.1 Connection-Control Plugin Installation"> Section 8.4.2.1, “Connection-Control Plugin Installation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="connection-control-variables.html" title="8.4.2.2 Connection-Control System and Status Variables"> Section 8.4.2.2, “Connection-Control System and Status Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="connection-control.html" title="8.4.2 The Connection-Control Plugins"> Section 8.4.2, “The Connection-Control Plugins” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table"> Section 28.6.2, “The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-E"> </a> <h3 class="title"> E </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ENABLED_ROLES </h3> <dl> <dt> <a class="xref" href="information-schema-enabled-roles-table.html" title="28.3.12 The INFORMATION_SCHEMA ENABLED_ROLES Table"> Section 28.3.12, “The INFORMATION_SCHEMA ENABLED_ROLES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ENGINES </h3> <dl> <dt> <a class="xref" href="performance-schema-quick-start.html" title="29.1 Performance Schema Quick Start"> Section 29.1, “Performance Schema Quick Start” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-sql-statements.html" title="25.6.20 Quick Reference: NDB Cluster SQL Statements"> Section 25.6.20, “Quick Reference: NDB Cluster SQL Statements” </a> </dt> <dd> </dd> <dt> <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-engines.html" title="15.7.7.17 SHOW ENGINES Statement"> Section 15.7.7.17, “SHOW ENGINES Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-engines-table.html" title="28.3.13 The INFORMATION_SCHEMA ENGINES Table"> Section 28.3.13, “The INFORMATION_SCHEMA ENGINES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-check-availability.html" title="17.1.3 Verifying that InnoDB is the Default Storage Engine"> Section 17.1.3, “Verifying that InnoDB is the Default Storage Engine” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> EVENTS </h3> <dl> <dt> <a class="xref" href="replication-howto-additionalslaves.html" title="19.1.2.8 Adding Replicas to a Replication Environment"> Section 19.1.2.8, “Adding Replicas to a Replication Environment” </a> </dt> <dd> </dd> <dt> <a class="xref" href="events-metadata.html" title="27.4.4 Event Metadata"> Section 27.4.4, “Event Metadata” </a> </dt> <dd> </dd> <dt> <a class="xref" href="events-configuration.html" title="27.4.2 Event Scheduler Configuration"> Section 27.4.2, “Event Scheduler Configuration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="replication-features-invoked.html" title="19.5.1.16 Replication of Invoked Features"> Section 19.5.1.16, “Replication of Invoked Features” </a> </dt> <dd> </dd> <dt> <a class="xref" href="stored-program-restrictions.html" title="27.8 Restrictions on Stored Programs"> Section 27.8, “Restrictions on Stored Programs” </a> </dt> <dd> </dd> <dt> <a class="xref" href="replication-setup-replicas.html#replication-howto-existingdata" title="19.1.2.6.2 Setting Up Replication with Existing Data"> Section 19.1.2.6.2, “Setting Up Replication with Existing Data” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-events.html" title="15.7.7.19 SHOW EVENTS Statement"> Section 15.7.7.19, “SHOW EVENTS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="events-privileges.html" title="27.4.6 The Event Scheduler and MySQL Privileges"> Section 27.4.6, “The Event Scheduler and MySQL Privileges” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-events-table.html" title="28.3.14 The INFORMATION_SCHEMA EVENTS Table"> Section 28.3.14, “The INFORMATION_SCHEMA EVENTS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-F"> </a> <h3 class="title"> F </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> FILES </h3> <dl> <dt> <a class="xref" href="alter-logfile-group.html" title="15.1.6 ALTER LOGFILE GROUP Statement"> Section 15.1.6, “ALTER LOGFILE GROUP Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement"> Section 15.1.10, “ALTER TABLESPACE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="clone-plugin-remote.html" title="7.6.7.3 Cloning Remote Data"> Section 7.6.7.3, “Cloning Remote Data” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-logfile-group.html" title="15.1.16 CREATE LOGFILE GROUP Statement"> Section 15.1.16, “CREATE LOGFILE GROUP Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> Section 15.1.21, “CREATE TABLESPACE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-information-schema-tables.html" title="25.6.18 INFORMATION_SCHEMA Tables for NDB Cluster"> Section 25.6.18, “INFORMATION_SCHEMA Tables for NDB Cluster” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-moving-data-files-offline.html" title="17.6.3.6 Moving Tablespace Files While the Server is Offline"> Section 17.6.3.6, “Moving Tablespace Files While the Server is Offline” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-disk-data-objects.html" title="25.6.11.1 NDB Cluster Disk Data Objects"> Section 25.6.11.1, “NDB Cluster Disk Data Objects” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-disk-data-storage-requirements.html" title="25.6.11.2 NDB Cluster Disk Data Storage Requirements"> Section 25.6.11.2, “NDB Cluster Disk Data Storage Requirements” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-programs-ndb-desc.html" title="25.5.9 ndb_desc — Describe NDB Tables"> Section 25.5.9, “ndb_desc — Describe NDB Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> Section 25.6.17, “ndbinfo: The NDB Cluster Information Database” </a> </dt> <dd> </dd> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-files-table.html" title="17.15.8 Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES"> Section 17.15.8, “Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-temporary-tablespace.html" title="17.6.3.5 Temporary Tablespaces"> Section 17.6.3.5, “Temporary Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table"> Section 28.3.15, “The INFORMATION_SCHEMA FILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-datafiles-table.html" title="28.4.10 The INFORMATION_SCHEMA INNODB_DATAFILES Table"> Section 28.4.10, “The INFORMATION_SCHEMA INNODB_DATAFILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-table.html" title="28.4.24 The INFORMATION_SCHEMA INNODB_TABLESPACES Table"> Section 28.4.24, “The INFORMATION_SCHEMA INNODB_TABLESPACES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-dict-obj-info.html" title="25.6.17.25 The ndbinfo dict_obj_info Table"> Section 25.6.17.25, “The ndbinfo dict_obj_info Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-dict-obj-tree.html" title="25.6.17.26 The ndbinfo dict_obj_tree Table"> Section 25.6.17.26, “The ndbinfo dict_obj_tree Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-logbuffers.html" title="25.6.17.43 The ndbinfo logbuffers Table"> Section 25.6.17.43, “The ndbinfo logbuffers Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-logspaces.html" title="25.6.17.44 The ndbinfo logspaces Table"> Section 25.6.17.44, “The ndbinfo logspaces Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-I"> </a> <h3 class="title"> I </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA </h3> <dl> <dt> <a class="xref" href="data-dictionary-schema.html" title="16.1 Data Dictionary Schema"> Section 16.1, “Data Dictionary Schema” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-information-schema-tables.html" title="25.6.18 INFORMATION_SCHEMA Tables for NDB Cluster"> Section 25.6.18, “INFORMATION_SCHEMA Tables for NDB Cluster” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema.html" title="17.15 InnoDB INFORMATION_SCHEMA Tables"> Section 17.15, “InnoDB INFORMATION_SCHEMA Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary.html" title="Chapter 16 MySQL Data Dictionary"> Chapter 16, <i> MySQL Data Dictionary </i> </a> </dt> <dd> </dd> <dt> <a class="xref" href="glossary.html" title="MySQL Glossary"> MySQL Glossary </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-security-mysql-privileges.html" title="25.6.21.2 NDB Cluster and MySQL Privileges"> Section 25.6.21.2, “NDB Cluster and MySQL Privileges” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-online-ddl-operations.html" title="17.12.1 Online DDL Operations"> Section 17.12.1, “Online DDL Operations” </a> </dt> <dd> </dd> <dt> <a class="xref" href="reserved-accounts.html" title="8.2.9 Reserved Accounts"> Section 8.2.9, “Reserved Accounts” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-directory.html" title="7.2 The MySQL Data Directory"> Section 7.2, “The MySQL Data Directory” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-unicode-utf8.html" title="12.9.3 The utf8 Character Set (Deprecated alias for utf8mb3)"> Section 12.9.3, “The utf8 Character Set (Deprecated alias for utf8mb3)” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-schema-usage.html" title="30.2 Using the sys Schema"> Section 30.2, “Using the sys Schema” </a> </dt> <dd> </dd> <dt> <a class="xref" href="upgrading-what-is-upgraded.html" title="3.4 What the MySQL Upgrade Process Upgrades"> Section 3.4, “What the MySQL Upgrade Process Upgrades” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.CHARACTER_SETS </h3> <dl> <dt> <a class="xref" href="faqs-cjk.html" title="A.11 MySQL 8.4 FAQ: MySQL Chinese, Japanese, and Korean Character Sets"> Section A.11, “MySQL 8.4 FAQ: MySQL Chinese, Japanese, and Korean Character Sets” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.COLUMN_STATISTICS </h3> <dl> <dt> <a class="xref" href="controlling-optimizer.html" title="10.9 Controlling the Query Optimizer"> Section 10.9, “Controlling the Query Optimizer” </a> </dt> <dd> </dd> <dt> <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.COLUMNS </h3> <dl> <dt> <a class="xref" href="mysql-cluster-programs-ndb-index-stat.html" title="25.5.14 ndb_index_stat — NDB Index Statistics Utility"> Section 25.5.14, “ndb_index_stat — NDB Index Statistics Utility” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-quick-start.html" title="29.1 Performance Schema Quick Start"> Section 29.1, “Performance Schema Quick Start” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.EVENTS </h3> <dl> <dt> <a class="xref" href="replication-features-invoked.html" title="19.5.1.16 Replication of Invoked Features"> Section 19.5.1.16, “Replication of Invoked Features” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.FILES </h3> <dl> <dt> <a class="xref" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> Section 15.1.21, “CREATE TABLESPACE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-dict-obj-tree.html" title="25.6.17.26 The ndbinfo dict_obj_tree Table"> Section 25.6.17.26, “The ndbinfo dict_obj_tree Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_CMP </h3> <dl> <dt> <a class="xref" href="glossary.html" title="MySQL Glossary"> MySQL Glossary </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning.html" title="17.9.1.3 Tuning Compression for InnoDB Tables"> Section 17.9.1.3, “Tuning Compression for InnoDB Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_CMP_PER_INDEX </h3> <dl> <dt> <a class="xref" href="innodb-compression-tuning.html" title="17.9.1.3 Tuning Compression for InnoDB Tables"> Section 17.9.1.3, “Tuning Compression for InnoDB Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_CMPMEM </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_TABLES </h3> <dl> <dt> <a class="xref" href="partitioning-management-exchange.html" title="26.3.3 Exchanging Partitions and Subpartitions with Tables"> Section 26.3.3, “Exchanging Partitions and Subpartitions with Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_TABLESPACES </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_TABLESTATS </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.OPTIMIZER_TRACE </h3> <dl> <dt> <a class="xref" href="optimizer-tracing.html" title="10.15 Tracing the Optimizer"> Section 10.15, “Tracing the Optimizer” </a> </dt> <dd> </dd> <dt> <a class="xref" href="optimizer-tracing-typical-usage.html" title="10.15.1 Typical Usage"> Section 10.15.1, “Typical Usage” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.PARTITIONS </h3> <dl> <dt> <a class="xref" href="partitioning-handling-nulls.html" title="26.2.7 How MySQL Partitioning Handles NULL"> Section 26.2.7, “How MySQL Partitioning Handles NULL” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.PROCESSLIST </h3> <dl> <dt> <a class="xref" href="information-schema-processlist-table.html" title="28.3.23 The INFORMATION_SCHEMA PROCESSLIST Table"> Section 28.3.23, “The INFORMATION_SCHEMA PROCESSLIST Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> information_schema.processlist </h3> <dl> <dt> <a class="xref" href="server-status-variables.html" title="7.1.10 Server Status Variables"> Section 7.1.10, “Server Status Variables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.ROUTINES </h3> <dl> <dt> <a class="xref" href="faqs-stored-procs.html" title="A.4 MySQL 8.4 FAQ: Stored Procedures and Functions"> Section A.4, “MySQL 8.4 FAQ: Stored Procedures and Functions” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.STATISTICS </h3> <dl> <dt> <a class="xref" href="mysql-cluster-programs-ndb-index-stat.html" title="25.5.14 ndb_index_stat — NDB Index Statistics Utility"> Section 25.5.14, “ndb_index_stat — NDB Index Statistics Utility” </a> </dt> <dd> </dd> <dt> <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.TABLES </h3> <dl> <dt> <a class="xref" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> Section 17.13, “InnoDB Data-at-Rest Encryption” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.TRIGGERS </h3> <dl> <dt> <a class="xref" href="faqs-triggers.html" title="A.5 MySQL 8.4 FAQ: Triggers"> Section A.5, “MySQL 8.4 FAQ: Triggers” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_BUFFER_PAGE </h3> <dl> <dt> <a class="xref" href="innodb-change-buffer.html" title="17.5.2 Change Buffer"> Section 17.5.2, “Change Buffer” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-buffer-pool-tables.html" title="17.15.5 InnoDB INFORMATION_SCHEMA Buffer Pool Tables"> Section 17.15.5, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-schema-prerequisites.html" title="30.1 Prerequisites for Using the sys Schema"> Section 30.1, “Prerequisites for Using the sys Schema” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table"> Section 28.4.2, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table"> Section 28.4.3, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-innodb-buffer-stats-by-schema.html" title="30.4.3.7 The innodb_buffer_stats_by_schema and x$innodb_buffer_stats_by_schema Views"> Section 30.4.3.7, “The innodb_buffer_stats_by_schema and x$innodb_buffer_stats_by_schema Views” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-innodb-buffer-stats-by-table.html" title="30.4.3.8 The innodb_buffer_stats_by_table and x$innodb_buffer_stats_by_table Views"> Section 30.4.3.8, “The innodb_buffer_stats_by_table and x$innodb_buffer_stats_by_table Views” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_BUFFER_PAGE_LRU </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-buffer-pool-tables.html" title="17.15.5 InnoDB INFORMATION_SCHEMA Buffer Pool Tables"> Section 17.15.5, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table"> Section 28.4.3, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_BUFFER_POOL_STATS </h3> <dl> <dt> <a class="xref" href="innodb-buffer-pool.html" title="17.5.1 Buffer Pool"> Section 17.5.1, “Buffer Pool” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-buffer-pool-tables.html" title="17.15.5 InnoDB INFORMATION_SCHEMA Buffer Pool Tables"> Section 17.15.5, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-pool-stats-table.html" title="28.4.4 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table"> Section 28.4.4, “The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CACHED_INDEXES </h3> <dl> <dt> <a class="xref" href="information-schema-innodb-cached-indexes-table.html" title="28.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table"> Section 28.4.5, “The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMP </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-compression-tables.html" title="17.15.1 InnoDB INFORMATION_SCHEMA Tables about Compression"> Section 17.15.1, “InnoDB INFORMATION_SCHEMA Tables about Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmp.html" title="17.15.1.1 INNODB_CMP and INNODB_CMP_RESET"> Section 17.15.1.1, “INNODB_CMP and INNODB_CMP_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmpmem.html" title="17.15.1.2 INNODB_CMPMEM and INNODB_CMPMEM_RESET"> Section 17.15.1.2, “INNODB_CMPMEM and INNODB_CMPMEM_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning-monitoring.html" title="17.9.1.4 Monitoring InnoDB Table Compression at Runtime"> Section 17.9.1.4, “Monitoring InnoDB Table Compression at Runtime” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-table.html" title="28.4.6 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables"> Section 28.4.6, “The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning.html" title="17.9.1.3 Tuning Compression for InnoDB Tables"> Section 17.9.1.3, “Tuning Compression for InnoDB Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMP_PER_INDEX </h3> <dl> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning-monitoring.html" title="17.9.1.4 Monitoring InnoDB Table Compression at Runtime"> Section 17.9.1.4, “Monitoring InnoDB Table Compression at Runtime” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> Section 28.4.8, “The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning.html" title="17.9.1.3 Tuning Compression for InnoDB Tables"> Section 17.9.1.3, “Tuning Compression for InnoDB Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMP_PER_INDEX_RESET </h3> <dl> <dt> <a class="xref" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> Section 28.4.8, “The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMP_RESET </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-compression-tables.html" title="17.15.1 InnoDB INFORMATION_SCHEMA Tables about Compression"> Section 17.15.1, “InnoDB INFORMATION_SCHEMA Tables about Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmp.html" title="17.15.1.1 INNODB_CMP and INNODB_CMP_RESET"> Section 17.15.1.1, “INNODB_CMP and INNODB_CMP_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmpmem.html" title="17.15.1.2 INNODB_CMPMEM and INNODB_CMPMEM_RESET"> Section 17.15.1.2, “INNODB_CMPMEM and INNODB_CMPMEM_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-table.html" title="28.4.6 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables"> Section 28.4.6, “The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMPMEM </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-compression-tables.html" title="17.15.1 InnoDB INFORMATION_SCHEMA Tables about Compression"> Section 17.15.1, “InnoDB INFORMATION_SCHEMA Tables about Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmpmem.html" title="17.15.1.2 INNODB_CMPMEM and INNODB_CMPMEM_RESET"> Section 17.15.1.2, “INNODB_CMPMEM and INNODB_CMPMEM_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmpmem-table.html" title="28.4.7 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables"> Section 28.4.7, “The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMPMEM_RESET </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-compression-tables.html" title="17.15.1 InnoDB INFORMATION_SCHEMA Tables about Compression"> Section 17.15.1, “InnoDB INFORMATION_SCHEMA Tables about Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmpmem.html" title="17.15.1.2 INNODB_CMPMEM and INNODB_CMPMEM_RESET"> Section 17.15.1.2, “INNODB_CMPMEM and INNODB_CMPMEM_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmpmem-table.html" title="28.4.7 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables"> Section 28.4.7, “The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_COLUMNS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-columns-table.html" title="28.4.9 The INFORMATION_SCHEMA INNODB_COLUMNS Table"> Section 28.4.9, “The INFORMATION_SCHEMA INNODB_COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-virtual-table.html" title="28.4.29 The INFORMATION_SCHEMA INNODB_VIRTUAL Table"> Section 28.4.29, “The INFORMATION_SCHEMA INNODB_VIRTUAL Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_DATAFILES </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-files-table.html" title="17.15.8 Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES"> Section 17.15.8, “Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table"> Section 28.3.15, “The INFORMATION_SCHEMA FILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-datafiles-table.html" title="28.4.10 The INFORMATION_SCHEMA INNODB_DATAFILES Table"> Section 28.4.10, “The INFORMATION_SCHEMA INNODB_DATAFILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> Section 28.4.25, “The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FIELDS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-fields-table.html" title="28.4.11 The INFORMATION_SCHEMA INNODB_FIELDS Table"> Section 28.4.11, “The INFORMATION_SCHEMA INNODB_FIELDS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FOREIGN </h3> <dl> <dt> <a class="xref" href="constraint-foreign-key.html" title="1.7.3.2 FOREIGN KEY Constraints"> Section 1.7.3.2, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-foreign-keys.html" title="15.1.20.5 FOREIGN KEY Constraints"> Section 15.1.20.5, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-foreign-table.html" title="28.4.12 The INFORMATION_SCHEMA INNODB_FOREIGN Table"> Section 28.4.12, “The INFORMATION_SCHEMA INNODB_FOREIGN Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FOREIGN_COLS </h3> <dl> <dt> <a class="xref" href="constraint-foreign-key.html" title="1.7.3.2 FOREIGN KEY Constraints"> Section 1.7.3.2, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-foreign-keys.html" title="15.1.20.5 FOREIGN KEY Constraints"> Section 15.1.20.5, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-foreign-cols-table.html" title="28.4.13 The INFORMATION_SCHEMA INNODB_FOREIGN_COLS Table"> Section 28.4.13, “The INFORMATION_SCHEMA INNODB_FOREIGN_COLS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_BEING_DELETED </h3> <dl> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> Section 28.4.14, “The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_CONFIG </h3> <dl> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-config-table.html" title="28.4.15 The INFORMATION_SCHEMA INNODB_FT_CONFIG Table"> Section 28.4.15, “The INFORMATION_SCHEMA INNODB_FT_CONFIG Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_DEFAULT_STOPWORD </h3> <dl> <dt> <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-default-stopword-table.html" title="28.4.16 The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table"> Section 28.4.16, “The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_DELETED </h3> <dl> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> Section 28.4.14, “The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-deleted-table.html" title="28.4.17 The INFORMATION_SCHEMA INNODB_FT_DELETED Table"> Section 28.4.17, “The INFORMATION_SCHEMA INNODB_FT_DELETED Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_INDEX_CACHE </h3> <dl> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="fulltext-search-mecab.html" title="14.9.9 MeCab Full-Text Parser Plugin"> Section 14.9.9, “MeCab Full-Text Parser Plugin” </a> </dt> <dd> </dd> <dt> <a class="xref" href="fulltext-search-ngram.html" title="14.9.8 ngram Full-Text Parser"> Section 14.9.8, “ngram Full-Text Parser” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-index-cache-table.html" title="28.4.18 The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table"> Section 28.4.18, “The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_INDEX_TABLE </h3> <dl> <dt> <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> Section 28.4.14, “The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-deleted-table.html" title="28.4.17 The INFORMATION_SCHEMA INNODB_FT_DELETED Table"> Section 28.4.17, “The INFORMATION_SCHEMA INNODB_FT_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-index-table-table.html" title="28.4.19 The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table"> Section 28.4.19, “The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_INDEXES </h3> <dl> <dt> <a class="xref" href="index-page-merge-threshold.html" title="17.8.11 Configuring the Merge Threshold for Index Pages"> Section 17.8.11, “Configuring the Merge Threshold for Index Pages” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cached-indexes-table.html" title="28.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table"> Section 28.4.5, “The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-indexes-table.html" title="28.4.20 The INFORMATION_SCHEMA INNODB_INDEXES Table"> Section 28.4.20, “The INFORMATION_SCHEMA INNODB_INDEXES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_METRICS </h3> <dl> <dt> <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-change-buffer.html" title="17.5.2 Change Buffer"> Section 17.5.2, “Change Buffer” </a> </dt> <dd> </dd> <dt> <a class="xref" href="index-page-merge-threshold.html" title="17.8.11 Configuring the Merge Threshold for Index Pages"> Section 17.8.11, “Configuring the Merge Threshold for Index Pages” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="glossary.html" title="MySQL Glossary"> MySQL Glossary </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> Section 28.4.21, “The INFORMATION_SCHEMA INNODB_METRICS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-metrics.html" title="30.4.3.21 The metrics View"> Section 30.4.3.21, “The metrics View” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-transaction-scheduling.html" title="17.7.6 Transaction Scheduling"> Section 17.7.6, “Transaction Scheduling” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_SESSION_TEMP_TABLESPACES </h3> <dl> <dt> <a class="xref" href="innodb-temporary-tablespace.html" title="17.6.3.5 Temporary Tablespaces"> Section 17.6.3.5, “Temporary Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-session-temp-tablespaces-table.html" title="28.4.22 The INFORMATION_SCHEMA INNODB_SESSION_TEMP_TABLESPACES Table"> Section 28.4.22, “The INFORMATION_SCHEMA INNODB_SESSION_TEMP_TABLESPACES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TABLES </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-row-format.html" title="17.10 InnoDB Row Formats"> Section 17.10, “InnoDB Row Formats” </a> </dt> <dd> </dd> <dt> <a class="xref" href="identifier-mapping.html" title="11.2.4 Mapping of Identifiers to File Names"> Section 11.2.4, “Mapping of Identifiers to File Names” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cached-indexes-table.html" title="28.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table"> Section 28.4.5, “The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tables-table.html" title="28.4.23 The INFORMATION_SCHEMA INNODB_TABLES Table"> Section 28.4.23, “The INFORMATION_SCHEMA INNODB_TABLES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TABLESPACES </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> Section 17.13, “InnoDB Data-at-Rest Encryption” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-page-compression.html" title="17.9.2 InnoDB Page Compression"> Section 17.9.2, “InnoDB Page Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-files-table.html" title="17.15.8 Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES"> Section 17.15.8, “Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement"> Section 15.7.7.38, “SHOW TABLE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-tablespace-autoextend-size.html" title="17.6.3.9 Tablespace AUTOEXTEND_SIZE Configuration"> Section 17.6.3.9, “Tablespace AUTOEXTEND_SIZE Configuration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table"> Section 28.3.15, “The INFORMATION_SCHEMA FILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-table.html" title="28.4.24 The INFORMATION_SCHEMA INNODB_TABLESPACES Table"> Section 28.4.24, “The INFORMATION_SCHEMA INNODB_TABLESPACES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> Section 28.4.25, “The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> Section 28.3.38, “The INFORMATION_SCHEMA TABLES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TABLESPACES_BRIEF </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> Section 28.4.25, “The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TABLESTATS </h3> <dl> <dt> <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablestats-table.html" title="28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View"> Section 28.4.26, “The INFORMATION_SCHEMA INNODB_TABLESTATS View” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TEMP_TABLE_INFO </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-temp-table-info.html" title="17.15.7 InnoDB INFORMATION_SCHEMA Temporary Table Info Table"> Section 17.15.7, “InnoDB INFORMATION_SCHEMA Temporary Table Info Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-temporary-tablespace.html" title="17.6.3.5 Temporary Tablespaces"> Section 17.6.3.5, “Temporary Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-temp-table-info-table.html" title="28.4.27 The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table"> Section 28.4.27, “The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TRX </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-transactions.html" title="17.15.2 InnoDB INFORMATION_SCHEMA Transaction and Locking Information"> Section 17.15.2, “InnoDB INFORMATION_SCHEMA Transaction and Locking Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-understanding-innodb-locking.html" title="17.15.2.2 InnoDB Lock and Lock-Wait Information"> Section 17.15.2.2, “InnoDB Lock and Lock-Wait Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-internal-data.html" title="17.15.2.3 Persistence and Consistency of InnoDB Transaction and Locking Information"> Section 17.15.2.3, “Persistence and Consistency of InnoDB Transaction and Locking Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-data-locks-table.html" title="29.12.13.1 The data_locks Table"> Section 29.12.13.1, “The data_locks Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-trx-table.html" title="28.4.28 The INFORMATION_SCHEMA INNODB_TRX Table"> Section 28.4.28, “The INFORMATION_SCHEMA INNODB_TRX Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-transaction-scheduling.html" title="17.7.6 Transaction Scheduling"> Section 17.7.6, “Transaction Scheduling” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples.html" title="17.15.2.1 Using InnoDB Transaction and Locking Information"> Section 17.15.2.1, “Using InnoDB Transaction and Locking Information” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_VIRTUAL </h3> <dl> <dt> <a class="xref" href="information-schema-innodb-virtual-table.html" title="28.4.29 The INFORMATION_SCHEMA INNODB_VIRTUAL Table"> Section 28.4.29, “The INFORMATION_SCHEMA INNODB_VIRTUAL Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-K"> </a> <h3 class="title"> K </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> KEY_COLUMN_USAGE </h3> <dl> <dt> <a class="xref" href="constraint-foreign-key.html" title="1.7.3.2 FOREIGN KEY Constraints"> Section 1.7.3.2, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-foreign-keys.html" title="15.1.20.5 FOREIGN KEY Constraints"> Section 15.1.20.5, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-key-column-usage-table.html" title="28.3.16 The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table"> Section 28.3.16, “The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> KEYWORDS </h3> <dl> <dt> <a class="xref" href="information-schema-keywords-table.html" title="28.3.17 The INFORMATION_SCHEMA KEYWORDS Table"> Section 28.3.17, “The INFORMATION_SCHEMA KEYWORDS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-M"> </a> <h3 class="title"> M </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> MYSQL_FIREWALL_USERS </h3> <dl> <dt> <a class="xref" href="firewall-reference.html" title="8.4.7.4 MySQL Enterprise Firewall Reference"> Section 8.4.7.4, “MySQL Enterprise Firewall Reference” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-mysql-firewall-users-table.html" title="28.7.2 The INFORMATION_SCHEMA MYSQL_FIREWALL_USERS Table"> Section 28.7.2, “The INFORMATION_SCHEMA MYSQL_FIREWALL_USERS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="firewall-usage.html" title="8.4.7.3 Using MySQL Enterprise Firewall"> Section 8.4.7.3, “Using MySQL Enterprise Firewall” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> MYSQL_FIREWALL_WHITELIST </h3> <dl> <dt> <a class="xref" href="firewall-reference.html" title="8.4.7.4 MySQL Enterprise Firewall Reference"> Section 8.4.7.4, “MySQL Enterprise Firewall Reference” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-mysql-firewall-whitelist-table.html" title="28.7.3 The INFORMATION_SCHEMA MYSQL_FIREWALL_WHITELIST Table"> Section 28.7.3, “The INFORMATION_SCHEMA MYSQL_FIREWALL_WHITELIST Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-N"> </a> <h3 class="title"> N </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> NDB_TRANSID_MYSQL_CONNECTION_MAP </h3> <dl> <dt> <a class="xref" href="mysql-cluster-ndbinfo-server-operations.html" title="25.6.17.55 The ndbinfo server_operations Table"> Section 25.6.17.55, “The ndbinfo server_operations Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-server-transactions.html" title="25.6.17.56 The ndbinfo server_transactions Table"> Section 25.6.17.56, “The ndbinfo server_transactions Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ndb_transid_mysql_connection_map </h3> <dl> <dt> <a class="xref" href="mysql-cluster-information-schema-tables.html" title="25.6.18 INFORMATION_SCHEMA Tables for NDB Cluster"> Section 25.6.18, “INFORMATION_SCHEMA Tables for NDB Cluster” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-options-variables.html#mysql-cluster-program-options-mysqld" title="25.4.3.9.1 MySQL Server Options for NDB Cluster"> Section 25.4.3.9.1, “MySQL Server Options for NDB Cluster” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> Section 25.6.17, “ndbinfo: The NDB Cluster Information Database” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-O"> </a> <h3 class="title"> O </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> OPTIMIZER_TRACE </h3> <dl> <dt> <a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization"> Section 10.2.1.2, “Range Optimization” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-optimizer-trace-table.html" title="28.3.19 The INFORMATION_SCHEMA OPTIMIZER_TRACE Table"> Section 28.3.19, “The INFORMATION_SCHEMA OPTIMIZER_TRACE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="tuning-trace-purging.html" title="10.15.4 Tuning Trace Purging"> Section 10.15.4, “Tuning Trace Purging” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-P"> </a> <h3 class="title"> P </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PARAMETERS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="faqs-stored-procs.html" title="A.4 MySQL 8.4 FAQ: Stored Procedures and Functions"> Section A.4, “MySQL 8.4 FAQ: Stored Procedures and Functions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-procedure-status.html" title="15.7.7.30 SHOW PROCEDURE STATUS Statement"> Section 15.7.7.30, “SHOW PROCEDURE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-parameters-table.html" title="28.3.20 The INFORMATION_SCHEMA PARAMETERS Table"> Section 28.3.20, “The INFORMATION_SCHEMA PARAMETERS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-routines-table.html" title="28.3.30 The INFORMATION_SCHEMA ROUTINES Table"> Section 28.3.30, “The INFORMATION_SCHEMA ROUTINES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PARTITIONS </h3> <dl> <dt> <a class="xref" href="partitioning-management-exchange.html" title="26.3.3 Exchanging Partitions and Subpartitions with Tables"> Section 26.3.3, “Exchanging Partitions and Subpartitions with Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning-handling-nulls.html" title="26.2.7 How MySQL Partitioning Handles NULL"> Section 26.2.7, “How MySQL Partitioning Handles NULL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning-key.html" title="26.2.5 KEY Partitioning"> Section 26.2.5, “KEY Partitioning” </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning-info.html" title="26.3.5 Obtaining Information About Partitions"> Section 26.3.5, “Obtaining Information About Partitions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning.html" title="Chapter 26 Partitioning"> Chapter 26, <i> Partitioning </i> </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning-columns-range.html" title="26.2.3.1 RANGE COLUMNS partitioning"> Section 26.2.3.1, “RANGE COLUMNS partitioning” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement"> Section 15.7.7.38, “SHOW TABLE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-partitions-table.html" title="28.3.21 The INFORMATION_SCHEMA PARTITIONS Table"> Section 28.3.21, “The INFORMATION_SCHEMA PARTITIONS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> Section 28.3.38, “The INFORMATION_SCHEMA TABLES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PLUGINS </h3> <dl> <dt> <a class="xref" href="clone-plugin-remote.html" title="7.6.7.3 Cloning Remote Data"> Section 7.6.7.3, “Cloning Remote Data” </a> </dt> <dd> </dd> <dt> <a class="xref" href="connection-control-installation.html" title="8.4.2.1 Connection-Control Plugin Installation"> Section 8.4.2.1, “Connection-Control Plugin Installation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> Section 15.7.4.4, “INSTALL PLUGIN Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="plugin-loading.html" title="7.6.1 Installing and Uninstalling Plugins"> Section 7.6.1, “Installing and Uninstalling Plugins” </a> </dt> <dd> </dd> <dt> <a class="xref" href="ddl-rewriter-installation.html" title="7.6.5.1 Installing or Uninstalling ddl_rewriter"> Section 7.6.5.1, “Installing or Uninstalling ddl_rewriter” </a> </dt> <dd> </dd> <dt> <a class="xref" href="audit-log-installation.html" title="8.4.5.2 Installing or Uninstalling MySQL Enterprise Audit"> Section 8.4.5.2, “Installing or Uninstalling MySQL Enterprise Audit” </a> </dt> <dd> </dd> <dt> <a class="xref" href="replication-semisync-installation.html" title="19.4.10.1 Installing Semisynchronous Replication"> Section 19.4.10.1, “Installing Semisynchronous Replication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="clone-plugin-installation.html" title="7.6.7.1 Installing the Clone Plugin"> Section 7.6.7.1, “Installing the Clone Plugin” </a> </dt> <dd> </dd> <dt> <a class="xref" href="kerberos-pluggable-authentication.html" title="8.4.1.8 Kerberos Pluggable Authentication"> Section 8.4.1.8, “Kerberos Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="keyring-metadata.html" title="8.4.4.14 Keyring Metadata"> Section 8.4.4.14, “Keyring Metadata” </a> </dt> <dd> </dd> <dt> <a class="xref" href="keyring-plugin-installation.html" title="8.4.4.3 Keyring Plugin Installation"> Section 8.4.4.3, “Keyring Plugin Installation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="ldap-pluggable-authentication.html" title="8.4.1.7 LDAP Pluggable Authentication"> Section 8.4.1.7, “LDAP Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="no-login-pluggable-authentication.html" title="8.4.1.9 No-Login Pluggable Authentication"> Section 8.4.1.9, “No-Login Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="obtaining-plugin-information.html" title="7.6.2 Obtaining Server Plugin Information"> Section 7.6.2, “Obtaining Server Plugin Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="pam-pluggable-authentication.html" title="8.4.1.5 PAM Pluggable Authentication"> Section 8.4.1.5, “PAM Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-sql-statements.html" title="25.6.20 Quick Reference: NDB Cluster SQL Statements"> Section 25.6.20, “Quick Reference: NDB Cluster SQL Statements” </a> </dt> <dd> </dd> <dt> <a class="xref" href="server-options.html" title="7.1.7 Server Command Options"> Section 7.1.7, “Server Command Options” </a> </dt> <dd> </dd> <dt> <a class="xref" href="socket-pluggable-authentication.html" title="8.4.1.10 Socket Peer-Credential Pluggable Authentication"> Section 8.4.1.10, “Socket Peer-Credential Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="test-pluggable-authentication.html" title="8.4.1.12 Test Pluggable Authentication"> Section 8.4.1.12, “Test Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-plugins-table.html" title="28.3.22 The INFORMATION_SCHEMA PLUGINS Table"> Section 28.3.22, “The INFORMATION_SCHEMA PLUGINS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="thread-pool-installation.html" title="7.6.3.2 Thread Pool Installation"> Section 7.6.3.2, “Thread Pool Installation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="webauthn-pluggable-authentication.html" title="8.4.1.11 WebAuthn Pluggable Authentication"> Section 8.4.1.11, “WebAuthn Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="windows-pluggable-authentication.html" title="8.4.1.6 Windows Pluggable Authentication"> Section 8.4.1.6, “Windows Pluggable Authentication” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PROCESSLIST </h3> <dl> <dt> <a class="xref" href="processlist-access.html" title="10.14.1 Accessing the Process List"> Section 10.14.1, “Accessing the Process List” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-functions.html" title="14.15 Information Functions"> Section 14.15, “Information Functions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="kill.html" title="15.7.8.4 KILL Statement"> Section 15.7.8.4, “KILL Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="explain-for-connection.html" title="10.8.4 Obtaining Execution Plan Information for a Named Connection"> Section 10.8.4, “Obtaining Execution Plan Information for a Named Connection” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-instrument-naming.html" title="29.6 Performance Schema Instrument Naming Conventions"> Section 29.6, “Performance Schema Instrument Naming Conventions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-replication-tables.html" title="29.12.11 Performance Schema Replication Tables"> Section 29.12.11, “Performance Schema Replication Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-stage-tables.html" title="29.12.5 Performance Schema Stage Event Tables"> Section 29.12.5, “Performance Schema Stage Event Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-internal-data.html" title="17.15.2.3 Persistence and Consistency of InnoDB Transaction and Locking Information"> Section 17.15.2.3, “Persistence and Consistency of InnoDB Transaction and Locking Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement"> Section 15.7.7.31, “SHOW PROCESSLIST Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="clone-plugin-stop.html" title="7.6.7.11 Stopping a Cloning Operation"> Section 7.6.7.11, “Stopping a Cloning Operation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> Section 29.12.22.2, “The error_log Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-trx-table.html" title="28.4.28 The INFORMATION_SCHEMA INNODB_TRX Table"> Section 28.4.28, “The INFORMATION_SCHEMA INNODB_TRX Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-processlist-table.html" title="28.3.23 The INFORMATION_SCHEMA PROCESSLIST Table"> Section 28.3.23, “The INFORMATION_SCHEMA PROCESSLIST Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-processlist.html" title="30.4.3.22 The processlist and x$processlist Views"> Section 30.4.3.22, “The processlist and x$processlist Views” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-processlist-table.html" title="29.12.22.7 The processlist Table"> Section 29.12.22.7, “The processlist Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-threads-table.html" title="29.12.22.8 The threads Table"> Section 29.12.22.8, “The threads Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples.html" title="17.15.2.1 Using InnoDB Transaction and Locking Information"> Section 17.15.2.1, “Using InnoDB Transaction and Locking Information” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PROFILING </h3> <dl> <dt> <a class="xref" href="show-profile.html" title="15.7.7.32 SHOW PROFILE Statement"> Section 15.7.7.32, “SHOW PROFILE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-profiling-table.html" title="28.3.24 The INFORMATION_SCHEMA PROFILING Table"> Section 28.3.24, “The INFORMATION_SCHEMA PROFILING Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-R"> </a> <h3 class="title"> R </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> REFERENTIAL_CONSTRAINTS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-referential-constraints-table.html" title="28.3.25 The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table"> Section 28.3.25, “The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> RESOURCE_GROUPS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="resource-groups.html" title="7.1.16 Resource Groups"> Section 7.1.16, “Resource Groups” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-resource-groups-table.html" title="28.3.26 The INFORMATION_SCHEMA RESOURCE_GROUPS Table"> Section 28.3.26, “The INFORMATION_SCHEMA RESOURCE_GROUPS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ROLE_COLUMN_GRANTS </h3> <dl> <dt> <a class="xref" href="information-schema-role-column-grants-table.html" title="28.3.27 The INFORMATION_SCHEMA ROLE_COLUMN_GRANTS Table"> Section 28.3.27, “The INFORMATION_SCHEMA ROLE_COLUMN_GRANTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ROLE_ROUTINE_GRANTS </h3> <dl> <dt> <a class="xref" href="information-schema-role-routine-grants-table.html" title="28.3.28 The INFORMATION_SCHEMA ROLE_ROUTINE_GRANTS Table"> Section 28.3.28, “The INFORMATION_SCHEMA ROLE_ROUTINE_GRANTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ROLE_TABLE_GRANTS </h3> <dl> <dt> <a class="xref" href="information-schema-role-table-grants-table.html" title="28.3.29 The INFORMATION_SCHEMA ROLE_TABLE_GRANTS Table"> Section 28.3.29, “The INFORMATION_SCHEMA ROLE_TABLE_GRANTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ROUTINES </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-introduction.html" title="28.1 Introduction"> Section 28.1, “Introduction” </a> </dt> <dd> </dd> <dt> <a class="xref" href="faqs-stored-procs.html" title="A.4 MySQL 8.4 FAQ: Stored Procedures and Functions"> Section A.4, “MySQL 8.4 FAQ: Stored Procedures and Functions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-procedure-status.html" title="15.7.7.30 SHOW PROCEDURE STATUS Statement"> Section 15.7.7.30, “SHOW PROCEDURE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="stored-objects-security.html" title="27.6 Stored Object Access Control"> Section 27.6, “Stored Object Access Control” </a> </dt> <dd> </dd> <dt> <a class="xref" href="stored-routines-metadata.html" title="27.2.3 Stored Routine Metadata"> Section 27.2.3, “Stored Routine Metadata” </a> </dt> <dd> </dd> <dt> <a class="xref" href="stored-routines-privileges.html" title="27.2.2 Stored Routines and MySQL Privileges"> Section 27.2.2, “Stored Routines and MySQL Privileges” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-routines-table.html" title="28.3.30 The INFORMATION_SCHEMA ROUTINES Table"> Section 28.3.30, “The INFORMATION_SCHEMA ROUTINES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-S"> </a> <h3 class="title"> S </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> SCHEMA_PRIVILEGES </h3> <dl> <dt> <a class="xref" href="information-schema-schema-privileges-table.html" title="28.3.33 The INFORMATION_SCHEMA SCHEMA_PRIVILEGES Table"> Section 28.3.33, “The INFORMATION_SCHEMA SCHEMA_PRIVILEGES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> SCHEMATA </h3> <dl> <dt> <a class="xref" href="charset-database.html" title="12.3.3 Database Character Set and Collation"> Section 12.3.3, “Database Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="grant-tables.html" title="8.2.3 Grant Tables"> Section 8.2.3, “Grant Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> Section 17.13, “InnoDB Data-at-Rest Encryption” </a> </dt> <dd> </dd> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-databases.html" title="15.7.7.15 SHOW DATABASES Statement"> Section 15.7.7.15, “SHOW DATABASES Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-schemata-table.html" title="28.3.31 The INFORMATION_SCHEMA SCHEMATA Table"> Section 28.3.31, “The INFORMATION_SCHEMA SCHEMATA Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-schemata-extensions-table.html" title="28.3.32 The INFORMATION_SCHEMA SCHEMATA_EXTENSIONS Table"> Section 28.3.32, “The INFORMATION_SCHEMA SCHEMATA_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> SCHEMATA_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="alter-database.html" title="15.1.2 ALTER DATABASE Statement"> Section 15.1.2, “ALTER DATABASE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-schemata-table.html" title="28.3.31 The INFORMATION_SCHEMA SCHEMATA Table"> Section 28.3.31, “The INFORMATION_SCHEMA SCHEMATA Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-schemata-extensions-table.html" title="28.3.32 The INFORMATION_SCHEMA SCHEMATA_EXTENSIONS Table"> Section 28.3.32, “The INFORMATION_SCHEMA SCHEMATA_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ST_GEOMETRY_COLUMNS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> Section 28.3.8, “The INFORMATION_SCHEMA COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-st-geometry-columns-table.html" title="28.3.35 The INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS Table"> Section 28.3.35, “The INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ST_SPATIAL_REFERENCE_SYSTEMS </h3> <dl> <dt> <a class="xref" href="create-spatial-reference-system.html" title="15.1.19 CREATE SPATIAL REFERENCE SYSTEM Statement"> Section 15.1.19, “CREATE SPATIAL REFERENCE SYSTEM Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="spatial-reference-systems.html" title="13.4.5 Spatial Reference System Support"> Section 13.4.5, “Spatial Reference System Support” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-st-spatial-reference-systems-table.html" title="28.3.36 The INFORMATION_SCHEMA ST_SPATIAL_REFERENCE_SYSTEMS Table"> Section 28.3.36, “The INFORMATION_SCHEMA ST_SPATIAL_REFERENCE_SYSTEMS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ST_UNITS_OF_MEASURE </h3> <dl> <dt> <a class="xref" href="gis-linestring-property-functions.html" title="14.16.7.3 LineString and MultiLineString Property Functions"> Section 14.16.7.3, “LineString and MultiLineString Property Functions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="spatial-relation-functions-object-shapes.html" title="14.16.9.1 Spatial Relation Functions That Use Object Shapes"> Section 14.16.9.1, “Spatial Relation Functions That Use Object Shapes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-st-units-of-measure-table.html" title="28.3.37 The INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table"> Section 28.3.37, “The INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> STATISTICS </h3> <dl> <dt> <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-usage-differences.html" title="16.7 Data Dictionary Usage Differences"> Section 16.7, “Data Dictionary Usage Differences” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-gipks.html" title="15.1.20.11 Generated Invisible Primary Keys"> Section 15.1.20.11, “Generated Invisible Primary Keys” </a> </dt> <dd> </dd> <dt> <a class="xref" href="index-hints.html" title="10.9.4 Index Hints"> Section 10.9.4, “Index Hints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-introduction.html" title="28.1 Introduction"> Section 28.1, “Introduction” </a> </dt> <dd> </dd> <dt> <a class="xref" href="invisible-indexes.html" title="10.3.12 Invisible Indexes"> Section 10.3.12, “Invisible Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-index.html" title="15.7.7.23 SHOW INDEX Statement"> Section 15.7.7.23, “SHOW INDEX Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table"> Section 28.3.34, “The INFORMATION_SCHEMA STATISTICS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-T"> </a> <h3 class="title"> T </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLE_CONSTRAINTS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-online-ddl-operations.html" title="17.12.1 Online DDL Operations"> Section 17.12.1, “Online DDL Operations” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-referential-constraints-table.html" title="28.3.25 The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table"> Section 28.3.25, “The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-table-constraints-table.html" title="28.3.41 The INFORMATION_SCHEMA TABLE_CONSTRAINTS Table"> Section 28.3.41, “The INFORMATION_SCHEMA TABLE_CONSTRAINTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLE_CONSTRAINTS_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="information-schema-table-constraints-extensions-table.html" title="28.3.42 The INFORMATION_SCHEMA TABLE_CONSTRAINTS_EXTENSIONS Table"> Section 28.3.42, “The INFORMATION_SCHEMA TABLE_CONSTRAINTS_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLE_PRIVILEGES </h3> <dl> <dt> <a class="xref" href="information-schema-table-privileges-table.html" title="28.3.43 The INFORMATION_SCHEMA TABLE_PRIVILEGES Table"> Section 28.3.43, “The INFORMATION_SCHEMA TABLE_PRIVILEGES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLES </h3> <dl> <dt> <a class="xref" href="mysql-cluster-online-add-node-example.html" title="25.6.7.3 Adding NDB Cluster Data Nodes Online: Detailed Example"> Section 25.6.7.3, “Adding NDB Cluster Data Nodes Online: Detailed Example” </a> </dt> <dd> </dd> <dt> <a class="xref" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> Section 15.1.9, “ALTER TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> Section 15.1.20, “CREATE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-usage-differences.html" title="16.7 Data Dictionary Usage Differences"> Section 16.7, “Data Dictionary Usage Differences” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-page-compression.html" title="17.9.2 InnoDB Page Compression"> Section 17.9.2, “InnoDB Page Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-introduction.html" title="28.1 Introduction"> Section 28.1, “Introduction” </a> </dt> <dd> </dd> <dt> <a class="xref" href="identifier-mapping.html" title="11.2.4 Mapping of Identifiers to File Names"> Section 11.2.4, “Mapping of Identifiers to File Names” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-options-variables.html#mysql-cluster-system-variables" title="25.4.3.9.2 NDB Cluster System Variables"> Section 25.4.3.9.2, “NDB Cluster System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-file-removal.html" title="16.2 Removal of File-based Metadata Storage"> Section 16.2, “Removal of File-based Metadata Storage” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-ndb-comment-options.html" title="15.1.20.12 Setting NDB Comment Options"> Section 15.1.20.12, “Setting NDB Comment Options” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement"> Section 15.7.7.38, “SHOW TABLE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> Section 15.7.7.39, “SHOW TABLES Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> Section 30.4.4.2, “The diagnostics() Procedure” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> Section 28.3.38, “The INFORMATION_SCHEMA TABLES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> Section 30.4.2.1, “The sys_config Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="thread-pool-installation.html" title="7.6.3.2 Thread Pool Installation"> Section 7.6.3.2, “Thread Pool Installation” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLES_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="information-schema-tables-extensions-table.html" title="28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table"> Section 28.3.39, “The INFORMATION_SCHEMA TABLES_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLESPACES_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="information-schema-tablespaces-extensions-table.html" title="28.3.40 The INFORMATION_SCHEMA TABLESPACES_EXTENSIONS Table"> Section 28.3.40, “The INFORMATION_SCHEMA TABLESPACES_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TP_THREAD_GROUP_STATE </h3> <dl> <dt> <a class="xref" href="thread-pool-information-schema-tables.html" title="28.5 INFORMATION_SCHEMA Thread Pool Tables"> Section 28.5, “INFORMATION_SCHEMA Thread Pool Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TP_THREAD_GROUP_STATS </h3> <dl> <dt> <a class="xref" href="thread-pool-information-schema-tables.html" title="28.5 INFORMATION_SCHEMA Thread Pool Tables"> Section 28.5, “INFORMATION_SCHEMA Thread Pool Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TP_THREAD_STATE </h3> <dl> <dt> <a class="xref" href="thread-pool-information-schema-tables.html" title="28.5 INFORMATION_SCHEMA Thread Pool Tables"> Section 28.5, “INFORMATION_SCHEMA Thread Pool Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TRIGGERS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="upgrade-prerequisites.html" title="3.6 Preparing Your Installation for Upgrade"> Section 3.6, “Preparing Your Installation for Upgrade” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-create-trigger.html" title="15.7.7.12 SHOW CREATE TRIGGER Statement"> Section 15.7.7.12, “SHOW CREATE TRIGGER Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-triggers.html" title="15.7.7.40 SHOW TRIGGERS Statement"> Section 15.7.7.40, “SHOW TRIGGERS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-triggers-table.html" title="28.3.44 The INFORMATION_SCHEMA TRIGGERS Table"> Section 28.3.44, “The INFORMATION_SCHEMA TRIGGERS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="trigger-metadata.html" title="27.3.2 Trigger Metadata"> Section 27.3.2, “Trigger Metadata” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-U"> </a> <h3 class="title"> U </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> USER_ATTRIBUTES </h3> <dl> <dt> <a class="xref" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> Section 15.7.1.1, “ALTER USER Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> Section 15.7.1.3, “CREATE USER Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="grant-tables.html" title="8.2.3 Grant Tables"> Section 8.2.3, “Grant Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-user-attributes-table.html" title="28.3.45 The INFORMATION_SCHEMA USER_ATTRIBUTES Table"> Section 28.3.45, “The INFORMATION_SCHEMA USER_ATTRIBUTES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> USER_PRIVILEGES </h3> <dl> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-user-privileges-table.html" title="28.3.46 The INFORMATION_SCHEMA USER_PRIVILEGES Table"> Section 28.3.46, “The INFORMATION_SCHEMA USER_PRIVILEGES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-V"> </a> <h3 class="title"> V </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> VIEW_ROUTINE_USAGE </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-view-routine-usage-table.html" title="28.3.48 The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table"> Section 28.3.48, “The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> VIEW_TABLE_USAGE </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-view-table-usage-table.html" title="28.3.49 The INFORMATION_SCHEMA VIEW_TABLE_USAGE Table"> Section 28.3.49, “The INFORMATION_SCHEMA VIEW_TABLE_USAGE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> VIEWS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="upgrade-prerequisites.html" title="3.6 Preparing Your Installation for Upgrade"> Section 3.6, “Preparing Your Installation for Upgrade” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-create-view.html" title="15.7.7.14 SHOW CREATE VIEW Statement"> Section 15.7.7.14, “SHOW CREATE VIEW Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-views-table.html" title="28.3.47 The INFORMATION_SCHEMA VIEWS Table"> Section 28.3.47, “The INFORMATION_SCHEMA VIEWS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="view-updatability.html" title="27.5.3 Updatable and Insertable Views"> Section 27.5.3, “Updatable and Insertable Views” </a> </dt> <dd> </dd> <dt> <a class="xref" href="view-metadata.html" title="27.5.5 View Metadata"> Section 27.5.5, “View Metadata” </a> </dt> <dd> </dd> </dl> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/innodb-buffer-pool-flushing.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="innodb-buffer-pool-flushing"> </a> 17.8.3.5 Configuring Buffer Pool Flushing </h4> </div> </div> </div> <a class="indexterm" name="idm46045163057584"> </a> <a class="indexterm" name="idm46045163056512"> </a> <p> <code class="literal"> InnoDB </code> performs certain tasks in the background, including flushing of dirty pages from the buffer pool. Dirty pages are those that have been modified but are not yet written to the data files on disk. </p> <p> Buffer pool flushing is performed by page cleaner threads. The number of page cleaner threads is controlled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> <code class="literal"> innodb_page_cleaners </code> </a> variable, which has a default value set to the same value as <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . </p> <p> Buffer pool flushing is initiated when the percentage of dirty pages reaches the low water mark value defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> variable. The default low water mark is 10% of buffer pool pages. A <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> value of 0 disables this early flushing behaviour. </p> <p> The purpose of the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> threshold is to control the percentage dirty pages in the buffer pool and to prevent the amount of dirty pages from reaching the threshold defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> variable, which has a default value of 90. <code class="literal"> InnoDB </code> aggressively flushes buffer pool pages if the percentage of dirty pages in the buffer pool reaches the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> threshold. </p> <p> When configuring <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> , the value should always be lower than the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> value. </p> <p> Additional variables permit fine-tuning of buffer pool flushing behavior: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> variable defines whether flushing a page from the buffer pool also flushes other dirty pages in the same extent. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> The default setting of 0 disables <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> . Dirty pages in the same extent are not flushed. This setting is recommended for non-rotational storage (SSD) devices where seek time is not a significant factor. </p> </li> <li class="listitem"> <p> A setting of 1 flushes contiguous dirty pages in the same extent. </p> </li> <li class="listitem"> <p> A setting of 2 flushes dirty pages in the same extent. </p> </li> </ul> </div> <p> When table data is stored on a traditional <a class="link" href="glossary.html#glos_hdd" title="HDD"> HDD </a> storage device, flushing neighbor pages in one operation reduces I/O overhead (primarily for disk seek operations) compared to flushing individual pages at different times. For table data stored on <a class="link" href="glossary.html#glos_ssd" title="SSD"> SSD </a> , seek time is not a significant factor and you can disable this setting to spread out write operations. </p> </li> <li class="listitem"> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> variable specifies, per buffer pool instance, how far down the buffer pool LRU list the page cleaner thread scans looking for dirty pages to flush. This is a background operation performed by a page cleaner thread once per second. </p> <p> A setting smaller than the default is generally suitable for most workloads. A value that is significantly higher than necessary may impact performance. Only consider increasing the value if you have spare I/O capacity under a typical workload. Conversely, if a write-intensive workload saturates your I/O capacity, decrease the value, especially in the case of a large buffer pool. </p> <p> When tuning <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> , start with a low value and configure the setting upward with the goal of rarely seeing zero free pages. Also, consider adjusting <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> when changing the number of buffer pool instances, since <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> defines the amount of work performed by the page cleaner thread each second. </p> </li> </ul> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> variables are primarily intended for write-intensive workloads. With heavy DML activity, flushing can fall behind if it is not aggressive enough, or disk writes can saturate I/O capacity if flushing is too aggressive. The ideal settings depend on your workload, data access patterns, and storage configuration (for example, whether data is stored on HDD or SSD devices). </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="innodb-adaptive-flushing"> </a> Adaptive Flushing </h5> </div> </div> </div> <p> <code class="literal"> InnoDB </code> uses an adaptive flushing algorithm to dynamically adjust the rate of flushing based on the speed of redo log generation and the current rate of flushing. The intent is to smooth overall performance by ensuring that flushing activity keeps pace with the current workload. Automatically adjusting the flushing rate helps avoid sudden dips in throughput that can occur when bursts of I/O activity due to buffer pool flushing affects the I/O capacity available for ordinary read and write activity. </p> <p> Sharp checkpoints, which are typically associated with write-intensive workloads that generate a lot of redo entries, can cause a sudden change in throughput, for example. A sharp checkpoint occurs when <code class="literal"> InnoDB </code> wants to reuse a portion of a log file. Before doing so, all dirty pages with redo entries in that portion of the log file must be flushed. If log files become full, a sharp checkpoint occurs, causing a temporary reduction in throughput. This scenario can occur even if <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> threshold is not reached. </p> <p> The adaptive flushing algorithm helps avoid such scenarios by tracking the number of dirty pages in the buffer pool and the rate at which redo log records are being generated. Based on this information, it decides how many dirty pages to flush from the buffer pool each second, which permits it to manage sudden changes in workload. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> <code class="literal"> innodb_adaptive_flushing_lwm </code> </a> variable defines a low water mark for redo log capacity. When that threshold is crossed, adaptive flushing is enabled, even if the <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> <code class="literal"> innodb_adaptive_flushing </code> </a> variable is disabled. </p> <p> Internal benchmarking has shown that the algorithm not only maintains throughput over time, but can also improve overall throughput significantly. However, adaptive flushing can affect the I/O pattern of a workload significantly and may not be appropriate in all cases. It gives the most benefit when the redo log is in danger of filling up. If adaptive flushing is not appropriate to the characteristics of your workload, you can disable it. Adaptive flushing controlled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> <code class="literal"> innodb_adaptive_flushing </code> </a> variable, which is enabled by default. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> <code class="literal"> innodb_flushing_avg_loops </code> </a> defines the number of iterations that <code class="literal"> InnoDB </code> keeps the previously calculated snapshot of the flushing state, controlling how quickly adaptive flushing responds to foreground workload changes. A high <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> <code class="literal"> innodb_flushing_avg_loops </code> </a> value means that <code class="literal"> InnoDB </code> keeps the previously calculated snapshot longer, so adaptive flushing responds more slowly. When setting a high value it is important to ensure that redo log utilization does not reach 75% (the hardcoded limit at which asynchronous flushing starts), and that the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> threshold keeps the number of dirty pages to a level that is appropriate for the workload. </p> <p> Systems with consistent workloads, a large log file size ( <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> ), and small spikes that do not reach 75% log space utilization should use a high <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> <code class="literal"> innodb_flushing_avg_loops </code> </a> value to keep flushing as smooth as possible. For systems with extreme load spikes or log files that do not provide a lot of space, a smaller value allows flushing to closely track workload changes, and helps to avoid reaching 75% log space utilization. </p> <p> Be aware that if flushing falls behind, the rate of buffer pool flushing can exceed the I/O capacity available to <code class="literal"> InnoDB </code> , as defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> setting. The <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> value defines an upper limit on I/O capacity in such situations, so that a spike in I/O activity does not consume the entire I/O capacity of the server. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> setting is applicable to all buffer pool instances. When dirty pages are flushed, I/O capacity is divided equally among buffer pool instances. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="innodb-limit-flushing-rate"> </a> Limiting Buffer Flushing During Idle Periods </h5> </div> </div> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> <code class="literal"> innodb_idle_flush_pct </code> </a> variable limits the rate of buffer pool flushing during idle periods, which are periods of time that database pages are not modified. Its value is interpreted as a percentage of <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> (which defines the number of I/O operations per second available to <code class="literal"> InnoDB </code> ). The default value is 100, or 100 percent of the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> . To limit flushing during idle periods, set <code class="literal"> innodb_idle_flush_pct </code> to less than 100. </p> <p> Limiting page flushing during idle periods can help extend the life of solid state storage devices. Side effects of limiting page flushing during idle periods may include a longer shutdown time following a lengthy idle period, and a longer recovery period should a server failure occur. </p> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/innodb-parameters.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="innodb-parameters"> </a> 17.14 InnoDB Startup Options and System Variables </h2> </div> </div> </div> <a class="indexterm" name="idm46045159103408"> </a> <a class="indexterm" name="idm46045159101984"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="innodb-parameters.html#innodb-parameters-startup" title="InnoDB Startup Options"> InnoDB Startup Options </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="innodb-parameters.html#innodb-parameters-sysvars" title="InnoDB System Variables"> InnoDB System Variables </a> </p> </li> </ul> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> System variables that are true or false can be enabled at server startup by naming them, or disabled by using a <code class="literal"> --skip- </code> prefix. For example, to enable or disable the <code class="literal"> InnoDB </code> adaptive hash index, you can use <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="option"> --innodb-adaptive-hash-index </code> </a> or <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="option"> --skip-innodb-adaptive-hash-index </code> </a> on the command line, or <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="literal"> innodb_adaptive_hash_index </code> </a> or <code class="literal"> skip_innodb_adaptive_hash_index </code> in an option file. </p> </li> <li class="listitem"> <p> Some variable descriptions refer to <span class="quote"> “ <span class="quote"> enabling </span> ” </span> or <span class="quote"> “ <span class="quote"> disabling </span> ” </span> a variable. These variables can be enabled with the <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement by setting them to <code class="literal"> ON </code> or <code class="literal"> 1 </code> , or disabled by setting them to <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . Boolean variables can be set at startup to the values <code class="literal"> ON </code> , <code class="literal"> TRUE </code> , <code class="literal"> OFF </code> , and <code class="literal"> FALSE </code> (not case-sensitive), as well as <code class="literal"> 1 </code> and <code class="literal"> 0 </code> . See <a class="xref" href="option-modifiers.html" title="6.2.2.4 Program Option Modifiers"> Section 6.2.2.4, “Program Option Modifiers” </a> . </p> </li> <li class="listitem"> <p> System variables that take a numeric value can be specified as <code class="option"> -- <em class="replaceable"> <code> var_name </code> </em> = <em class="replaceable"> <code> value </code> </em> </code> on the command line or as <code class="literal"> <em class="replaceable"> <code> var_name </code> </em> = <em class="replaceable"> <code> value </code> </em> </code> in option files. </p> </li> <li class="listitem"> <p> Many system variables can be changed at runtime (see <a class="xref" href="dynamic-system-variables.html" title="7.1.9.2 Dynamic System Variables"> Section 7.1.9.2, “Dynamic System Variables” </a> ). </p> </li> <li class="listitem"> <p> For information about <code class="literal"> GLOBAL </code> and <code class="literal"> SESSION </code> variable scope modifiers, refer to the <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement documentation. </p> </li> <li class="listitem"> <p> Certain options control the locations and layout of the <code class="literal"> InnoDB </code> data files. <a class="xref" href="innodb-init-startup-configuration.html" title="17.8.1 InnoDB Startup Configuration"> Section 17.8.1, “InnoDB Startup Configuration” </a> explains how to use these options. </p> </li> <li class="listitem"> <p> Some options, which you might not use initially, help tune <code class="literal"> InnoDB </code> performance characteristics based on machine capacity and database <a class="link" href="glossary.html#glos_workload" title="workload"> workload </a> . </p> </li> <li class="listitem"> <p> For more information on specifying options and system variables, see <a class="xref" href="program-options.html" title="6.2.2 Specifying Program Options"> Section 6.2.2, “Specifying Program Options” </a> . </p> </li> </ul> </div> <div class="table"> <a name="idm46045159065744"> </a> <p class="title"> <b> Table 17.23 InnoDB Option and Variable Reference </b> </p> <div class="table-contents"> <table frame="box" rules="all" summary="Reference for InnoDB command-line options and system variables."> <colgroup> <col style="width: 20%"/> <col style="width: 15%"/> <col style="width: 15%"/> <col style="width: 15%"/> <col style="width: 15%"/> <col style="width: 15%"/> <col style="width: 15%"/> </colgroup> <thead> <tr> <th scope="col"> Name </th> <th scope="col"> Cmd-Line </th> <th scope="col"> Option File </th> <th scope="col"> System Var </th> <th scope="col"> Status Var </th> <th scope="col"> Var Scope </th> <th scope="col"> Dynamic </th> </tr> </thead> <tbody> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_foreign_key_checks"> foreign_key_checks </a> </th> <td> </td> <td> </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> innodb_adaptive_flushing </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> innodb_adaptive_flushing_lwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> innodb_adaptive_hash_index </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index_parts"> innodb_adaptive_hash_index_parts </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> innodb_adaptive_max_sleep_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> innodb_autoextend_increment </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode"> innodb_autoinc_lock_mode </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> innodb_background_drop_list_empty </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_data"> Innodb_buffer_pool_bytes_data </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_dirty"> Innodb_buffer_pool_bytes_dirty </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> innodb_buffer_pool_chunk_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_debug"> innodb_buffer_pool_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> innodb_buffer_pool_dump_at_shutdown </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> innodb_buffer_pool_dump_now </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> innodb_buffer_pool_dump_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_dump_status"> Innodb_buffer_pool_dump_status </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_filename"> innodb_buffer_pool_filename </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> innodb_buffer_pool_in_core_file </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> innodb_buffer_pool_instances </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> innodb_buffer_pool_load_abort </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> innodb_buffer_pool_load_at_startup </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> innodb_buffer_pool_load_now </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_load_status"> Innodb_buffer_pool_load_status </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_data"> Innodb_buffer_pool_pages_data </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_dirty"> Innodb_buffer_pool_pages_dirty </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_flushed"> Innodb_buffer_pool_pages_flushed </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_free"> Innodb_buffer_pool_pages_free </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_latched"> Innodb_buffer_pool_pages_latched </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_misc"> Innodb_buffer_pool_pages_misc </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_total"> Innodb_buffer_pool_pages_total </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead"> Innodb_buffer_pool_read_ahead </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_evicted"> Innodb_buffer_pool_read_ahead_evicted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_rnd"> Innodb_buffer_pool_read_ahead_rnd </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_requests"> Innodb_buffer_pool_read_requests </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_reads"> Innodb_buffer_pool_reads </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status"> Innodb_buffer_pool_resize_status </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> innodb_buffer_pool_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_wait_free"> Innodb_buffer_pool_wait_free </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_write_requests"> Innodb_buffer_pool_write_requests </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffer_max_size"> innodb_change_buffer_max_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering"> innodb_change_buffering </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering_debug"> innodb_change_buffering_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checkpoint_disabled"> innodb_checkpoint_disabled </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> innodb_checksum_algorithm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_cmp_per_index_enabled"> innodb_cmp_per_index_enabled </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> innodb_commit_concurrency </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compress_debug"> innodb_compress_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> innodb_compression_failure_threshold_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_level"> innodb_compression_level </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> innodb_compression_pad_pct_max </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> innodb_concurrency_tickets </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> innodb_data_file_path </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_fsyncs"> Innodb_data_fsyncs </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> innodb_data_home_dir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_fsyncs"> Innodb_data_pending_fsyncs </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_reads"> Innodb_data_pending_reads </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_writes"> Innodb_data_pending_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_read"> Innodb_data_read </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_reads"> Innodb_data_reads </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_writes"> Innodb_data_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_written"> Innodb_data_written </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_pages_written"> Innodb_dblwr_pages_written </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_writes"> Innodb_dblwr_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> innodb_ddl_buffer_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Session </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_log_crash_reset_debug"> innodb_ddl_log_crash_reset_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> innodb_ddl_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Session </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> innodb_deadlock_detect </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> innodb_dedicated_server </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> innodb_default_row_format </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> innodb_directories </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_disable_sort_file_cache"> innodb_disable_sort_file_cache </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> innodb_doublewrite </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_batch_size"> innodb_doublewrite_batch_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_dir"> innodb_doublewrite_dir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_files"> innodb_doublewrite_files </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> innodb_doublewrite_pages </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> innodb_fast_shutdown </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> innodb_fil_make_page_dirty_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> innodb_file_per_table </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> innodb_fill_factor </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> innodb_flush_log_at_timeout </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> innodb_flush_log_at_trx_commit </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> innodb_flush_method </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> innodb_flush_neighbors </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> innodb_flush_sync </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> innodb_flushing_avg_loops </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_load_corrupted"> innodb_force_load_corrupted </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> innodb_force_recovery </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> innodb_fsync_threshold </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_aux_table"> innodb_ft_aux_table </a> </th> <td> </td> <td> </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> innodb_ft_cache_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_diag_print"> innodb_ft_enable_diag_print </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> innodb_ft_enable_stopword </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_max_token_size"> innodb_ft_max_token_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_min_token_size"> innodb_ft_min_token_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_num_word_optimize"> innodb_ft_num_word_optimize </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> innodb_ft_result_cache_limit </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> innodb_ft_server_stopword_table </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_sort_pll_degree"> innodb_ft_sort_pll_degree </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> innodb_ft_total_cache_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> innodb_ft_user_stopword_table </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_have_atomic_builtins"> Innodb_have_atomic_builtins </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> innodb_idle_flush_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> innodb_io_capacity </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> innodb_io_capacity_max </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_limit_optimistic_insert_debug"> innodb_limit_optimistic_insert_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> innodb_lock_wait_timeout </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> innodb_log_buffer_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_fuzzy_now"> innodb_log_checkpoint_fuzzy_now </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_now"> innodb_log_checkpoint_now </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> innodb_log_checksums </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> innodb_log_compressed_pages </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> innodb_log_file_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> innodb_log_files_in_group </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> innodb_log_group_home_dir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_abs_lwm"> innodb_log_spin_cpu_abs_lwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> innodb_log_spin_cpu_pct_hwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_wait_for_flush_spin_hwm"> innodb_log_wait_for_flush_spin_hwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_waits"> Innodb_log_waits </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> innodb_log_write_ahead_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_write_requests"> Innodb_log_write_requests </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_writer_threads"> innodb_log_writer_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_writes"> Innodb_log_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> innodb_lru_scan_depth </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> innodb_max_dirty_pages_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> innodb_max_dirty_pages_pct_lwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> innodb_max_purge_lag </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> innodb_max_purge_lag_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> innodb_max_undo_log_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_merge_threshold_set_all_debug"> innodb_merge_threshold_set_all_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> innodb_monitor_disable </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> innodb_monitor_enable </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> innodb_monitor_reset </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset_all"> innodb_monitor_reset_all </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_num_open_files"> Innodb_num_open_files </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> innodb_numa_interleave </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> innodb_old_blocks_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> innodb_old_blocks_time </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> innodb_online_alter_log_max_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> innodb_open_files </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_optimize_fulltext_only"> innodb_optimize_fulltext_only </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_fsyncs"> Innodb_os_log_fsyncs </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_fsyncs"> Innodb_os_log_pending_fsyncs </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_writes"> Innodb_os_log_pending_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_written"> Innodb_os_log_written </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> innodb_page_cleaners </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_page_size"> Innodb_page_size </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> innodb_page_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_created"> Innodb_pages_created </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_read"> Innodb_pages_read </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_written"> Innodb_pages_written </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> innodb_parallel_read_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Session </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_all_deadlocks"> innodb_print_all_deadlocks </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_ddl_logs"> innodb_print_ddl_logs </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> innodb_purge_batch_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> innodb_purge_rseg_truncate_frequency </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> innodb_purge_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_random_read_ahead"> innodb_random_read_ahead </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> innodb_read_ahead_threshold </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> innodb_read_io_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> innodb_read_only </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_archive_dirs"> innodb_redo_log_archive_dirs </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> innodb_redo_log_capacity </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_capacity_resized"> Innodb_redo_log_capacity_resized </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_checkpoint_lsn"> Innodb_redo_log_checkpoint_lsn </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_current_lsn"> Innodb_redo_log_current_lsn </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_enabled"> Innodb_redo_log_enabled </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_encrypt"> innodb_redo_log_encrypt </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_flushed_to_disk_lsn"> Innodb_redo_log_flushed_to_disk_lsn </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_logical_size"> Innodb_redo_log_logical_size </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_physical_size"> Innodb_redo_log_physical_size </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_read_only"> Innodb_redo_log_read_only </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_resize_status"> Innodb_redo_log_resize_status </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_uuid"> Innodb_redo_log_uuid </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_replication_delay"> innodb_replication_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> innodb_rollback_on_timeout </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> innodb_rollback_segments </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_current_waits"> Innodb_row_lock_current_waits </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time"> Innodb_row_lock_time </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_avg"> Innodb_row_lock_time_avg </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_max"> Innodb_row_lock_time_max </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_waits"> Innodb_row_lock_waits </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_deleted"> Innodb_rows_deleted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_inserted"> Innodb_rows_inserted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_read"> Innodb_rows_read </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_updated"> Innodb_rows_updated </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> innodb_saved_page_number_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> innodb_segment_reserve_factor </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> innodb_sort_buffer_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_delay"> innodb_spin_wait_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> innodb_spin_wait_pause_multiplier </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_auto_recalc"> innodb_stats_auto_recalc </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> innodb_stats_include_delete_marked </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> innodb_stats_method </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> innodb_stats_on_metadata </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> innodb_stats_persistent </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> innodb_stats_persistent_sample_pages </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> innodb_stats_transient_sample_pages </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#option_mysqld_innodb-status-file"> innodb-status-file </a> </th> <td> Yes </td> <td> Yes </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output"> innodb_status_output </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> innodb_status_output_locks </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> innodb_strict_mode </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_array_size"> innodb_sync_array_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_debug"> innodb_sync_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_spin_loops"> innodb_sync_spin_loops </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_deleted"> Innodb_system_rows_deleted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_inserted"> Innodb_system_rows_inserted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_read"> Innodb_system_rows_read </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_updated"> Innodb_system_rows_updated </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> innodb_table_locks </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> innodb_temp_data_file_path </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_tablespaces_dir"> innodb_temp_tablespaces_dir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> innodb_thread_concurrency </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> innodb_thread_sleep_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> innodb_tmpdir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_truncated_status_writes"> Innodb_truncated_status_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_purge_view_update_only_debug"> innodb_trx_purge_view_update_only_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_rseg_n_slots_debug"> innodb_trx_rseg_n_slots_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> innodb_undo_directory </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_encrypt"> innodb_undo_log_encrypt </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> innodb_undo_log_truncate </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> innodb_undo_tablespaces </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_active"> Innodb_undo_tablespaces_active </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_explicit"> Innodb_undo_tablespaces_explicit </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_implicit"> Innodb_undo_tablespaces_implicit </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_total"> Innodb_undo_tablespaces_total </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> innodb_use_fdatasync </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_native_aio"> innodb_use_native_aio </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_validate_tablespace_paths"> innodb_validate_tablespace_paths </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_version"> innodb_version </a> </th> <td> </td> <td> </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> innodb_write_io_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_unique_checks"> unique_checks </a> </th> <td> </td> <td> </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th scope="col" style="width: 312.094px;"> Name </th> <th scope="col" style="width: 64.875px;"> Cmd-Line </th> <th scope="col" style="width: 73.3594px;"> Option File </th> <th scope="col" style="width: 75.0938px;"> System Var </th> <th scope="col" style="width: 70.75px;"> Status Var </th> <th scope="col" style="width: 72.5156px;"> Var Scope </th> <th scope="col" style="width: 69.3125px;"> Dynamic </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> <h3> <a name="innodb-parameters-startup"> </a> InnoDB Startup Options </h3> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_mysqld_innodb-dedicated-server"> </a> <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> </p> <a class="indexterm" name="idm46045157426144"> </a> <a class="indexterm" name="idm46045157424640"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb-dedicated-server"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-dedicated-server[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> innodb_dedicated_server </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> When this option is set by starting the server with <code class="option"> --innodb-dedicated-server </code> or <code class="option"> --innodb-dedicated-server=ON </code> , either on the command line or in a <code class="filename"> my.cnf </code> file, <code class="literal"> InnoDB </code> automatically calculates and sets the values of the following variables: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> </p> </li> </ul> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> In older versions of MySQL 8.0, <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> were also set by <code class="option"> --innodb-dedicated-server </code> . <code class="literal"> innodb_log_file_size </code> and <code class="literal"> innodb_log_files_in_group </code> have since been deprecated, and superseded by <code class="literal"> innodb_redo_log_capacity </code> . See <a class="xref" href="innodb-redo-log.html" title="17.6.5 Redo Log"> Section 17.6.5, “Redo Log” </a> . </p> <p> In MySQL 8.0, <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> was also set automatically by this option, but in MySQL 8.4, this is no longer the case. </p> </div> <p> You should consider using <code class="option"> --innodb-dedicated-server </code> only if the MySQL instance resides on a dedicated server where it can use all available system resources. Using this option is not recommended if the MySQL instance shares system resources with other applications. </p> <p> It is strongly recommended that you read <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> , before using this option in production. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_innodb-status-file"> </a> <a class="link" href="innodb-parameters.html#option_mysqld_innodb-status-file"> <code class="option"> --innodb-status-file </code> </a> </p> <a class="indexterm" name="idm46045157383008"> </a> <a class="indexterm" name="idm46045157381552"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb-status-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-status-file[={OFF\|ON}] </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> The <code class="option"> --innodb-status-file </code> startup option controls whether <code class="literal"> InnoDB </code> creates a file named <code class="filename"> innodb_status. <em class="replaceable"> <code> pid </code> </em> </code> in the data directory and writes <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output to it every 15 seconds, approximately. </p> <p> The <code class="filename"> innodb_status. <em class="replaceable"> <code> pid </code> </em> </code> file is not created by default. To create it, start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> with the <code class="option"> --innodb-status-file </code> option. <code class="literal"> InnoDB </code> removes the file when the server is shut down normally. If an abnormal shutdown occurs, the status file may have to be removed manually. </p> <p> The <code class="option"> --innodb-status-file </code> option is intended for temporary use, as <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output generation can affect performance, and the <code class="filename"> innodb_status. <em class="replaceable"> <code> pid </code> </em> </code> file can become quite large over time. </p> <p> For related information, see <a class="xref" href="innodb-enabling-monitors.html" title="17.17.2 Enabling InnoDB Monitors"> Section 17.17.2, “Enabling InnoDB Monitors” </a> . </p> </li> </ul> </div> <h3> <a name="innodb-parameters-sysvars"> </a> InnoDB System Variables </h3> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_flushing"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> <code class="literal"> innodb_adaptive_flushing </code> </a> </p> <a class="indexterm" name="idm46045157353568"> </a> <a class="indexterm" name="idm46045157352464"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_flushing"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-flushing[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> innodb_adaptive_flushing </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045157330800"> </a> <p> Specifies whether to dynamically adjust the rate of flushing <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> in the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> based on the workload. Adjusting the flush rate dynamically is intended to avoid bursts of I/O activity. This setting is enabled by default. See <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> for more information. For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_flushing_lwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> <code class="literal"> innodb_adaptive_flushing_lwm </code> </a> </p> <a class="indexterm" name="idm46045157322784"> </a> <a class="indexterm" name="idm46045157321680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_flushing_lwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-flushing-lwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> innodb_adaptive_flushing_lwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 70 </code> </td> </tr> </tbody> </table> </div> <p> Defines the low water mark representing percentage of <a class="link" href="glossary.html#glos_redo_log" title="redo log"> redo log </a> capacity at which <a class="link" href="glossary.html#glos_adaptive_flushing" title="adaptive flushing"> adaptive flushing </a> is enabled. For more information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_hash_index"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="literal"> innodb_adaptive_hash_index </code> </a> </p> <a class="indexterm" name="idm46045157289600"> </a> <a class="indexterm" name="idm46045157288496"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_hash_index"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-hash-index[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> innodb_adaptive_hash_index </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Whether the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_adaptive_hash_index" title="adaptive hash index"> adaptive hash index </a> is enabled or disabled. It may be desirable, depending on your workload, to dynamically enable or disable <a class="link" href="glossary.html#glos_adaptive_hash_index" title="adaptive hash index"> adaptive hash indexing </a> to improve query performance. Because the adaptive hash index may not be useful for all workloads, conduct benchmarks with it both enabled and disabled, using realistic workloads. See <a class="xref" href="innodb-adaptive-hash.html" title="17.5.3 Adaptive Hash Index"> Section 17.5.3, “Adaptive Hash Index” </a> for details. </p> <p> This variable is disabled by default. You can modify this parameter using the <code class="literal"> SET GLOBAL </code> statement, without restarting the server. Changing the setting at runtime requires privileges sufficient to set global system variables. See <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> . You can also use <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="option"> --innodb-adaptive-hash-index </code> </a> at server startup to enable it. </p> <p> Disabling the adaptive hash index empties the hash table immediately. Normal operations can continue while the hash table is emptied, and executing queries that were using the hash table access the index B-trees directly instead. When the adaptive hash index is re-enabled, the hash table is populated again during normal operation. </p> <p> Before MySQL 8.4, this option was enabled by default. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_hash_index_parts"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index_parts"> <code class="literal"> innodb_adaptive_hash_index_parts </code> </a> </p> <a class="indexterm" name="idm46045157256064"> </a> <a class="indexterm" name="idm46045157254960"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_hash_index_parts"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-hash-index-parts=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index_parts"> innodb_adaptive_hash_index_parts </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 8 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 512 </code> </td> </tr> </tbody> </table> </div> <p> Partitions the adaptive hash index search system. Each index is bound to a specific partition, with each partition protected by a separate latch. </p> <p> The adaptive hash index search system is partitioned into 8 parts by default. The maximum setting is 512. </p> <p> For related information, see <a class="xref" href="innodb-adaptive-hash.html" title="17.5.3 Adaptive Hash Index"> Section 17.5.3, “Adaptive Hash Index” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_max_sleep_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> <code class="literal"> innodb_adaptive_max_sleep_delay </code> </a> </p> <a class="indexterm" name="idm46045157223728"> </a> <a class="indexterm" name="idm46045157222624"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_max_sleep_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-max-sleep-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> innodb_adaptive_max_sleep_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 150000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000000 </code> </td> </tr> <tr> <th> Unit </th> <td> microseconds </td> </tr> </tbody> </table> </div> <p> Permits <code class="literal"> InnoDB </code> to automatically adjust the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> up or down according to the current workload. Any nonzero value enables automated, dynamic adjustment of the <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> value, up to the maximum value specified in the <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> <code class="literal"> innodb_adaptive_max_sleep_delay </code> </a> option. The value represents the number of microseconds. This option can be useful in busy systems, with greater than 16 <code class="literal"> InnoDB </code> threads. (In practice, it is most valuable for MySQL systems with hundreds or thousands of simultaneous connections.) </p> <p> For more information, see <a class="xref" href="innodb-performance-thread_concurrency.html" title="17.8.4 Configuring Thread Concurrency for InnoDB"> Section 17.8.4, “Configuring Thread Concurrency for InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_autoextend_increment"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> <code class="literal"> innodb_autoextend_increment </code> </a> </p> <a class="indexterm" name="idm46045157184176"> </a> <a class="indexterm" name="idm46045157183072"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_autoextend_increment"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-autoextend-increment=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> innodb_autoextend_increment </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 64 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> <tr> <th> Unit </th> <td> megabytes </td> </tr> </tbody> </table> </div> <p> The increment size (in megabytes) for extending the size of an auto-extending <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> file when it becomes full. The default value is 64. For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-data-file-configuration" title="System Tablespace Data File Configuration"> System Tablespace Data File Configuration </a> , and <a class="xref" href="innodb-system-tablespace.html#innodb-resize-system-tablespace" title="Resizing the System Tablespace"> Resizing the System Tablespace </a> . </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> <code class="literal"> innodb_autoextend_increment </code> </a> setting does not affect <a class="link" href="glossary.html#glos_file_per_table" title="file-per-table"> file-per-table </a> tablespace files or <a class="link" href="glossary.html#glos_general_tablespace" title="general tablespace"> general tablespace </a> files. These files are auto-extending regardless of the <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> <code class="literal"> innodb_autoextend_increment </code> </a> setting. The initial extensions are by small amounts, after which extensions occur in increments of 4MB. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_autoinc_lock_mode"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode"> <code class="literal"> innodb_autoinc_lock_mode </code> </a> </p> <a class="indexterm" name="idm46045157143568"> </a> <a class="indexterm" name="idm46045157142464"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_autoinc_lock_mode"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-autoinc-lock-mode=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode"> innodb_autoinc_lock_mode </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 0 </code> </p> <p class="valid-value"> <code class="literal"> 1 </code> </p> <p class="valid-value"> <code class="literal"> 2 </code> </p> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="glossary.html#glos_lock_mode" title="lock mode"> lock mode </a> to use for generating <a class="link" href="glossary.html#glos_auto_increment" title="auto-increment"> auto-increment </a> values. Permissible values are 0, 1, or 2, for traditional, consecutive, or interleaved, respectively. </p> <p> The default setting is 2 (interleaved), for compatibility with row-based replication. </p> <p> For the characteristics of each lock mode, see <a class="xref" href="innodb-auto-increment-handling.html#innodb-auto-increment-lock-modes" title="InnoDB AUTO_INCREMENT Lock Modes"> InnoDB AUTO_INCREMENT Lock Modes </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_background_drop_list_empty"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> <code class="literal"> innodb_background_drop_list_empty </code> </a> </p> <a class="indexterm" name="idm46045157109440"> </a> <a class="indexterm" name="idm46045157108400"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_background_drop_list_empty"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-background-drop-list-empty[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> innodb_background_drop_list_empty </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enabling the <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> <code class="literal"> innodb_background_drop_list_empty </code> </a> debug option helps avoid test case failures by delaying table creation until the background drop list is empty. For example, if test case A places table <code class="literal"> t1 </code> on the background drop list, test case B waits until the background drop list is empty before creating table <code class="literal"> t1 </code> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_chunk_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> </p> <a class="indexterm" name="idm46045157080768"> </a> <a class="indexterm" name="idm46045157079664"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_chunk_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-chunk-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> innodb_buffer_pool_chunk_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 134217728 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1048576 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> innodb_buffer_pool_size / innodb_buffer_pool_instances </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> defines the chunk size for <code class="literal"> InnoDB </code> buffer pool resizing operations. </p> <p> To avoid copying all buffer pool pages during resizing operations, the operation is performed in <span class="quote"> “ <span class="quote"> chunks </span> ” </span> . By default, <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> is 128MB (134217728 bytes). The number of pages contained in a chunk depends on the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> . <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> can be increased or decreased in units of 1MB (1048576 bytes). </p> <p> The following conditions apply when altering the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> value: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> is larger than the current buffer pool size when the buffer pool is initialized, <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> is truncated to <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> / <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . </p> </li> <li class="listitem"> <p> Buffer pool size must always be equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . If you alter <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> is automatically rounded to a value that is equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . The adjustment occurs when the buffer pool is initialized. </p> </li> </ul> </div> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> Care should be taken when changing <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> , as changing this value can automatically increase the size of the buffer pool. Before changing <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> , calculate its effect on <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> to ensure that the resulting buffer pool size is acceptable. </p> </div> <p> To avoid potential performance issues, the number of chunks ( <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> / <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> ) should not exceed 1000. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> variable is dynamic, which permits resizing the buffer pool while the server is online. However, the buffer pool size must be equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> , and changing either of those variable settings requires restarting the server. </p> <p> See <a class="xref" href="innodb-buffer-pool-resize.html" title="17.8.3.1 Configuring InnoDB Buffer Pool Size"> Section 17.8.3.1, “Configuring InnoDB Buffer Pool Size” </a> for more information. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_debug"> <code class="literal"> innodb_buffer_pool_debug </code> </a> </p> <a class="indexterm" name="idm46045157009264"> </a> <a class="indexterm" name="idm46045157008176"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-debug[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_debug"> innodb_buffer_pool_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enabling this option permits multiple buffer pool instances when the buffer pool is less than 1GB in size, ignoring the 1GB minimum buffer pool size constraint imposed on <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . The <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_debug"> <code class="literal"> innodb_buffer_pool_debug </code> </a> option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_dump_at_shutdown"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> </p> <a class="indexterm" name="idm46045156979072"> </a> <a class="indexterm" name="idm46045156978032"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_dump_at_shutdown"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-dump-at-shutdown[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> innodb_buffer_pool_dump_at_shutdown </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies whether to record the pages cached in the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> when the MySQL server is shut down, to shorten the <a class="link" href="glossary.html#glos_warm_up" title="warm up"> warmup </a> process at the next restart. Typically used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> . The <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> <code class="literal"> innodb_buffer_pool_dump_pct </code> </a> option defines the percentage of most recently used buffer pool pages to dump. </p> <p> Both <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> are enabled by default. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_dump_now"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> <code class="literal"> innodb_buffer_pool_dump_now </code> </a> </p> <a class="indexterm" name="idm46045156943904"> </a> <a class="indexterm" name="idm46045156942800"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_dump_now"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-dump-now[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> innodb_buffer_pool_dump_now </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Immediately makes a record of pages cached in the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> . Typically used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> <code class="literal"> innodb_buffer_pool_load_now </code> </a> . </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> <code class="literal"> innodb_buffer_pool_dump_now </code> </a> triggers the recording action but does not alter the variable setting, which always remains <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . To view buffer pool dump status after triggering a dump, query the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_dump_status"> <code class="literal"> Innodb_buffer_pool_dump_status </code> </a> variable. </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> <code class="literal"> innodb_buffer_pool_dump_now </code> </a> triggers the dump action but does not alter the variable setting, which always remains <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . To view buffer pool dump status after triggering a dump, query the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_dump_status"> <code class="literal"> Innodb_buffer_pool_dump_status </code> </a> variable. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_dump_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> <code class="literal"> innodb_buffer_pool_dump_pct </code> </a> </p> <a class="indexterm" name="idm46045156905040"> </a> <a class="indexterm" name="idm46045156903936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_dump_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-dump-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> innodb_buffer_pool_dump_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 25 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the percentage of the most recently used pages for each buffer pool to read out and dump. The range is 1 to 100. The default value is 25. For example, if there are 4 buffer pools with 100 pages each, and <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> <code class="literal"> innodb_buffer_pool_dump_pct </code> </a> is set to 25, the 25 most recently used pages from each buffer pool are dumped. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_filename"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_filename"> <code class="literal"> innodb_buffer_pool_filename </code> </a> </p> <a class="indexterm" name="idm46045156872896"> </a> <a class="indexterm" name="idm46045156871792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_filename"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-filename=file_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_filename"> innodb_buffer_pool_filename </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ib_buffer_pool </code> </td> </tr> </tbody> </table> </div> <p> Specifies the name of the file that holds the list of tablespace IDs and page IDs produced by <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> or <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> <code class="literal"> innodb_buffer_pool_dump_now </code> </a> . Tablespace IDs and page IDs are saved in the following format: <code class="literal"> space, page_id </code> . By default, the file is named <code class="filename"> ib_buffer_pool </code> and is located in the <code class="literal"> InnoDB </code> data directory. A non-default location must be specified relative to the data directory. </p> <p> A file name can be specified at runtime, using a <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa45697009"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> innodb_buffer_pool_filename<span class="token operator">=</span><span class="token string"><em class="replaceable">'file_name'</em></span><span class="token punctuation">;</span></code></pre> </div> <p> You can also specify a file name at startup, in a startup string or MySQL configuration file. When specifying a file name at startup, the file must exist or <code class="literal"> InnoDB </code> returns a startup error indicating that there is no such file or directory. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_in_core_file"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> <code class="literal"> innodb_buffer_pool_in_core_file </code> </a> </p> <a class="indexterm" name="idm46045156836512"> </a> <a class="indexterm" name="idm46045156835408"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_in_core_file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-in-core-file[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> innodb_buffer_pool_in_core_file </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Disabling (default) the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> <code class="literal"> innodb_buffer_pool_in_core_file </code> </a> variable reduces the size of core files by excluding <code class="literal"> InnoDB </code> buffer pool pages. </p> <p> To use this variable, the <a class="link" href="server-system-variables.html#sysvar_core_file"> <code class="literal"> core_file </code> </a> variable must be enabled, and to disable this option the operating system must support the <code class="literal"> MADV_DONTDUMP </code> non-POSIX extension to <code class="literal"> madvise() </code> , which is supported in Linux 3.4 and later. For more information, see <a class="xref" href="innodb-buffer-pool-in-core-file.html" title="17.8.3.7 Excluding or Including Buffer Pool Pages from Core Files"> Section 17.8.3.7, “Excluding or Including Buffer Pool Pages from Core Files” </a> . </p> <p> This is disabled by default on systems that support <code class="literal"> MADV_DONTDUMP </code> , which is typically only Linux and not macOS or Windows. </p> <p> Before MySQL 8.4, this option was enabled by default. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_instances"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> </p> <a class="indexterm" name="idm46045156802944"> </a> <a class="indexterm" name="idm46045156801840"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_instances"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-instances=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> innodb_buffer_pool_instances </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> see description </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> The number of regions that the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> is divided into. For systems with buffer pools in the multi-gigabyte range, dividing the buffer pool into separate instances can improve concurrency, by reducing contention as different threads read and write to cached pages. Each page that is stored in or read from the buffer pool is assigned to one of the buffer pool instances randomly, using a hashing function. Each buffer pool manages its own free lists, <a class="link" href="glossary.html#glos_flush_list" title="flush list"> flush lists </a> , <a class="link" href="glossary.html#glos_lru" title="LRU"> LRUs </a> , and all other data structures connected to a buffer pool, and is protected by its own buffer pool <a class="link" href="glossary.html#glos_mutex" title="mutex"> mutex </a> . </p> <p> The total buffer pool size is divided among all the buffer pools. For best efficiency, specify a combination of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> so that each buffer pool instance is at least 1GB. </p> <p> If <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> <= 1 GiB, then the default <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> value is 1. </p> <p> If <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> > 1 GiB, then the default <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> value is the minimum value from the following two calculated hints, within a range of 1-64: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Buffer pool hint: calculated as 1/2 of ( <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> / <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> ) </p> </li> <li class="listitem"> <p> CPU hint: calculated as 1/4 of available logical processors </p> </li> </ul> </div> <p> For related information, see <a class="xref" href="innodb-buffer-pool-resize.html" title="17.8.3.1 Configuring InnoDB Buffer Pool Size"> Section 17.8.3.1, “Configuring InnoDB Buffer Pool Size” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_load_abort"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> <code class="literal"> innodb_buffer_pool_load_abort </code> </a> </p> <a class="indexterm" name="idm46045156752416"> </a> <a class="indexterm" name="idm46045156751312"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_load_abort"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-load-abort[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> innodb_buffer_pool_load_abort </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Interrupts the process of restoring <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> contents triggered by <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> or <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> <code class="literal"> innodb_buffer_pool_load_now </code> </a> . </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> <code class="literal"> innodb_buffer_pool_load_abort </code> </a> triggers the abort action but does not alter the variable setting, which always remains <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . To view buffer pool load status after triggering an abort action, query the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_load_status"> <code class="literal"> Innodb_buffer_pool_load_status </code> </a> variable. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_load_at_startup"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> </p> <a class="indexterm" name="idm46045156716688"> </a> <a class="indexterm" name="idm46045156715648"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_load_at_startup"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-load-at-startup[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> innodb_buffer_pool_load_at_startup </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies that, on MySQL server startup, the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> is automatically <a class="link" href="glossary.html#glos_warm_up" title="warm up"> warmed up </a> by loading the same pages it held at an earlier time. Typically used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> . </p> <p> Both <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> are enabled by default. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_load_now"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> <code class="literal"> innodb_buffer_pool_load_now </code> </a> </p> <a class="indexterm" name="idm46045156682928"> </a> <a class="indexterm" name="idm46045156681824"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_load_now"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-load-now[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> innodb_buffer_pool_load_now </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Immediately <a class="link" href="glossary.html#glos_warm_up" title="warm up"> warms up </a> the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> by loading data pages without waiting for a server restart. Can be useful to bring cache memory back to a known state during benchmarking or to ready the MySQL server to resume its normal workload after running queries for reports or maintenance. </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> <code class="literal"> innodb_buffer_pool_load_now </code> </a> triggers the load action but does not alter the variable setting, which always remains <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . To view buffer pool load progress after triggering a load, query the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_load_status"> <code class="literal"> Innodb_buffer_pool_load_status </code> </a> variable. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> </p> <a class="indexterm" name="idm46045156648848"> </a> <a class="indexterm" name="idm46045156647808"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> innodb_buffer_pool_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 134217728 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 5242880 </code> </td> </tr> <tr> <th> Maximum Value (64-bit platforms) </th> <td> <code class="literal"> 264-1 </code> </td> </tr> <tr> <th> Maximum Value (32-bit platforms) </th> <td> <code class="literal"> 232-1 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> The size in bytes of the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> , the memory area where <code class="literal"> InnoDB </code> caches table and index data. The default value is 134217728 bytes (128MB). The maximum value depends on the CPU architecture; the maximum is 4294967295 (2 <sup> 32 </sup> -1) on 32-bit systems and 18446744073709551615 (2 <sup> 64 </sup> -1) on 64-bit systems. On 32-bit systems, the CPU architecture and operating system may impose a lower practical maximum size than the stated maximum. When the size of the buffer pool is greater than 1GB, setting <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> to a value greater than 1 can improve the scalability on a busy server. </p> <p> A larger buffer pool requires less disk I/O to access the same table data more than once. On a dedicated database server, you might set the buffer pool size to 80% of the machine's physical memory size. Be aware of the following potential issues when configuring buffer pool size, and be prepared to scale back the size of the buffer pool if necessary. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Competition for physical memory can cause paging in the operating system. </p> </li> <li class="listitem"> <p> <code class="literal"> InnoDB </code> reserves additional memory for buffers and control structures, so that the total allocated space is approximately 10% greater than the specified buffer pool size. </p> </li> <li class="listitem"> <p> Address space for the buffer pool must be contiguous, which can be an issue on Windows systems with DLLs that load at specific addresses. </p> </li> <li class="listitem"> <p> The time to initialize the buffer pool is roughly proportional to its size. On instances with large buffer pools, initialization time might be significant. To reduce the initialization period, you can save the buffer pool state at server shutdown and restore it at server startup. See <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> </ul> </div> <p> When you increase or decrease buffer pool size, the operation is performed in chunks. Chunk size is defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> variable, which has a default of 128 MB. </p> <p> Buffer pool size must always be equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . If you alter the buffer pool size to a value that is not equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> , buffer pool size is automatically adjusted to a value that is equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> can be set dynamically, which allows you to resize the buffer pool without restarting the server. The <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status"> <code class="literal"> Innodb_buffer_pool_resize_status </code> </a> status variable reports the status of online buffer pool resizing operations. See <a class="xref" href="innodb-buffer-pool-resize.html" title="17.8.3.1 Configuring InnoDB Buffer Pool Size"> Section 17.8.3.1, “Configuring InnoDB Buffer Pool Size” </a> for more information. </p> <p> If the server is started with <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> , the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> is set automatically if it is not explicitly defined. For more information, see <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_change_buffer_max_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffer_max_size"> <code class="literal"> innodb_change_buffer_max_size </code> </a> </p> <a class="indexterm" name="idm46045156585376"> </a> <a class="indexterm" name="idm46045156584272"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_change_buffer_max_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-change-buffer-max-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffer_max_size"> innodb_change_buffer_max_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 25 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 50 </code> </td> </tr> </tbody> </table> </div> <p> Maximum size for the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_change_buffer" title="change buffer"> change buffer </a> , as a percentage of the total size of the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> . You might increase this value for a MySQL server with heavy insert, update, and delete activity, or decrease it for a MySQL server with unchanging data used for reporting. For more information, see <a class="xref" href="innodb-change-buffer.html" title="17.5.2 Change Buffer"> Section 17.5.2, “Change Buffer” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_change_buffering"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering"> <code class="literal"> innodb_change_buffering </code> </a> </p> <a class="indexterm" name="idm46045156550784"> </a> <a class="indexterm" name="idm46045156549744"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_change_buffering"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-change-buffering=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering"> innodb_change_buffering </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> none </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> none </code> </p> <p class="valid-value"> <code class="literal"> inserts </code> </p> <p class="valid-value"> <code class="literal"> deletes </code> </p> <p class="valid-value"> <code class="literal"> changes </code> </p> <p class="valid-value"> <code class="literal"> purges </code> </p> <p class="valid-value"> <code class="literal"> all </code> </p> </td> </tr> </tbody> </table> </div> <p> Whether <code class="literal"> InnoDB </code> performs <a class="link" href="glossary.html#glos_change_buffering" title="change buffering"> change buffering </a> , an optimization that delays write operations to secondary indexes so that the I/O operations can be performed sequentially. Permitted values are described in the following table. Values may also be specified numerically. </p> <div class="table"> <a name="innodb-change-buffer-permitted-values"> </a> <p class="title"> <b> Table 17.24 Permitted Values for innodb_change_buffering </b> </p> <div class="table-contents"> <table summary="Permitted values for the innodb_chansge_buffering variable. The first column defines the value. The second column describes the option effect."> <colgroup> <col style="width: 20%"/> <col style="width: 20%"/> <col style="width: 60%"/> </colgroup> <thead> <tr> <th scope="col"> Value </th> <th scope="col"> Numeric Value </th> <th scope="col"> Description </th> </tr> </thead> <tbody> <tr> <th scope="row"> <code class="literal"> none </code> </th> <td> <code class="literal"> 0 </code> </td> <td> Default. Do not buffer any operations. </td> </tr> <tr> <th scope="row"> <code class="literal"> inserts </code> </th> <td> <code class="literal"> 1 </code> </td> <td> Buffer insert operations. </td> </tr> <tr> <th scope="row"> <code class="literal"> deletes </code> </th> <td> <code class="literal"> 2 </code> </td> <td> Buffer delete marking operations; strictly speaking, the writes that mark index records for later deletion during a purge operation. </td> </tr> <tr> <th scope="row"> <code class="literal"> changes </code> </th> <td> <code class="literal"> 3 </code> </td> <td> Buffer inserts and delete-marking operations. </td> </tr> <tr> <th scope="row"> <code class="literal"> purges </code> </th> <td> <code class="literal"> 4 </code> </td> <td> Buffer the physical deletion operations that happen in the background. </td> </tr> <tr> <th scope="row"> <code class="literal"> all </code> </th> <td> <code class="literal"> 5 </code> </td> <td> Buffer inserts, delete-marking operations, and purges. </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> <p> Before MySQL 8.4, the default value was <code class="literal"> all </code> . </p> <p> For more information, see <a class="xref" href="innodb-change-buffer.html" title="17.5.2 Change Buffer"> Section 17.5.2, “Change Buffer” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_change_buffering_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering_debug"> <code class="literal"> innodb_change_buffering_debug </code> </a> </p> <a class="indexterm" name="idm46045156479408"> </a> <a class="indexterm" name="idm46045156478320"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_change_buffering_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-change-buffering-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering_debug"> innodb_change_buffering_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2 </code> </td> </tr> </tbody> </table> </div> <p> Sets a debug flag for <code class="literal"> InnoDB </code> change buffering. A value of 1 forces all changes to the change buffer. A value of 2 causes an unexpected exit at merge. A default value of 0 indicates that the change buffering debug flag is not set. This option is only available when debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_checkpoint_disabled"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_checkpoint_disabled"> <code class="literal"> innodb_checkpoint_disabled </code> </a> </p> <a class="indexterm" name="idm46045156446208"> </a> <a class="indexterm" name="idm46045156445104"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_checkpoint_disabled"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-checkpoint-disabled[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checkpoint_disabled"> innodb_checkpoint_disabled </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> This is a debug option that is only intended for expert debugging use. It disables checkpoints so that a deliberate server exit always initiates <code class="literal"> InnoDB </code> recovery. It should only be enabled for a short interval, typically before running DML operations that write redo log entries that would require recovery following a server exit. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_checksum_algorithm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> <code class="literal"> innodb_checksum_algorithm </code> </a> </p> <a class="indexterm" name="idm46045156417712"> </a> <a class="indexterm" name="idm46045156416608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_checksum_algorithm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-checksum-algorithm=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> innodb_checksum_algorithm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> crc32 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> crc32 </code> </p> <p class="valid-value"> <code class="literal"> strict_crc32 </code> </p> <p class="valid-value"> <code class="literal"> innodb </code> </p> <p class="valid-value"> <code class="literal"> strict_innodb </code> </p> <p class="valid-value"> <code class="literal"> none </code> </p> <p class="valid-value"> <code class="literal"> strict_none </code> </p> </td> </tr> </tbody> </table> </div> <p> Specifies how to generate and verify the <a class="link" href="glossary.html#glos_checksum" title="checksum"> checksum </a> stored in the disk blocks of <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_tablespace" title="tablespace"> tablespaces </a> . The default value for <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> <code class="literal"> innodb_checksum_algorithm </code> </a> is <code class="literal"> crc32 </code> . </p> <p> The value <code class="literal"> innodb </code> is backward-compatible with earlier versions of MySQL. The value <code class="literal"> crc32 </code> uses an algorithm that is faster to compute the checksum for every modified block, and to check the checksums for each disk read. It scans blocks 64 bits at a time, which is faster than the <code class="literal"> innodb </code> checksum algorithm, which scans blocks 8 bits at a time. The value <code class="literal"> none </code> writes a constant value in the checksum field rather than computing a value based on the block data. The blocks in a tablespace can use a mix of old, new, and no checksum values, being updated gradually as the data is modified; once blocks in a tablespace are modified to use the <code class="literal"> crc32 </code> algorithm, the associated tables cannot be read by earlier versions of MySQL. </p> <p> The strict form of a checksum algorithm reports an error if it encounters a valid but non-matching checksum value in a tablespace. It is recommended that you only use strict settings in a new instance, to set up tablespaces for the first time. Strict settings are somewhat faster, because they do not need to compute all checksum values during disk reads. </p> <p> The following table shows the difference between the <code class="literal"> none </code> , <code class="literal"> innodb </code> , and <code class="literal"> crc32 </code> option values, and their strict counterparts. <code class="literal"> none </code> , <code class="literal"> innodb </code> , and <code class="literal"> crc32 </code> write the specified type of checksum value into each data block, but for compatibility accept other checksum values when verifying a block during a read operation. Strict settings also accept valid checksum values but print an error message when a valid non-matching checksum value is encountered. Using the strict form can make verification faster if all <code class="literal"> InnoDB </code> data files in an instance are created under an identical <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> <code class="literal"> innodb_checksum_algorithm </code> </a> value. </p> <div class="table"> <a name="innodb-checksum-algorithm-values"> </a> <p class="title"> <b> Table 17.25 Permitted innodb_checksum_algorithm Values </b> </p> <div class="table-contents"> <table summary="Permitted values for the innodb_checksum_algorithm variable. The first column defines the checksum value. The second column describes the generated checksum. The third column describes compatible checksums."> <colgroup> <col style="width: 20%"/> <col style="width: 40%"/> <col style="width: 40%"/> </colgroup> <thead> <tr> <th scope="col"> Value </th> <th scope="col"> Generated checksum (when writing) </th> <th scope="col"> Permitted checksums (when reading) </th> </tr> </thead> <tbody> <tr> <th scope="row"> none </th> <td> A constant number. </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . </td> </tr> <tr> <th scope="row"> innodb </th> <td> A checksum calculated in software, using the original algorithm from <code class="literal"> InnoDB </code> . </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . </td> </tr> <tr> <th scope="row"> crc32 </th> <td> A checksum calculated using the <code class="literal"> crc32 </code> algorithm, possibly done with a hardware assist. </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . </td> </tr> <tr> <th scope="row"> strict_none </th> <td> A constant number </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . <code class="literal"> InnoDB </code> prints an error message if a valid but non-matching checksum is encountered. </td> </tr> <tr> <th scope="row"> strict_innodb </th> <td> A checksum calculated in software, using the original algorithm from <code class="literal"> InnoDB </code> . </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . <code class="literal"> InnoDB </code> prints an error message if a valid but non-matching checksum is encountered. </td> </tr> <tr> <th scope="row"> strict_crc32 </th> <td> A checksum calculated using the <code class="literal"> crc32 </code> algorithm, possibly done with a hardware assist. </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . <code class="literal"> InnoDB </code> prints an error message if a valid but non-matching checksum is encountered. </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> </li> <li class="listitem"> <p> <a name="sysvar_innodb_cmp_per_index_enabled"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_cmp_per_index_enabled"> <code class="literal"> innodb_cmp_per_index_enabled </code> </a> </p> <a class="indexterm" name="idm46045156319904"> </a> <a class="indexterm" name="idm46045156318800"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_cmp_per_index_enabled"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-cmp-per-index-enabled[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_cmp_per_index_enabled"> innodb_cmp_per_index_enabled </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables per-index compression-related statistics in the Information Schema <a class="link" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> <code class="literal"> INNODB_CMP_PER_INDEX </code> </a> table. Because these statistics can be expensive to gather, only enable this option on development, test, or replica instances during performance tuning related to <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_compression" title="compression"> compressed </a> tables. </p> <p> For more information, see <a class="xref" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> Section 28.4.8, “The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables” </a> , and <a class="xref" href="innodb-compression-tuning-monitoring.html" title="17.9.1.4 Monitoring InnoDB Table Compression at Runtime"> Section 17.9.1.4, “Monitoring InnoDB Table Compression at Runtime” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_commit_concurrency"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> <code class="literal"> innodb_commit_concurrency </code> </a> </p> <a class="indexterm" name="idm46045156289232"> </a> <a class="indexterm" name="idm46045156288128"> </a> <a class="indexterm" name="idm46045156286624"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_commit_concurrency"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-commit-concurrency=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> innodb_commit_concurrency </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> </tbody> </table> </div> <p> The number of <a class="link" href="glossary.html#glos_thread" title="thread"> threads </a> that can <a class="link" href="glossary.html#glos_commit" title="commit"> commit </a> at the same time. A value of 0 (the default) permits any number of <a class="link" href="glossary.html#glos_transaction" title="transaction"> transactions </a> to commit simultaneously. </p> <p> The value of <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> <code class="literal"> innodb_commit_concurrency </code> </a> cannot be changed at runtime from zero to nonzero or vice versa. The value can be changed from one nonzero value to another. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_compress_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_compress_debug"> <code class="literal"> innodb_compress_debug </code> </a> </p> <a class="indexterm" name="idm46045156252688"> </a> <a class="indexterm" name="idm46045156251616"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_compress_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-compress-debug=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compress_debug"> innodb_compress_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> none </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> none </code> </p> <p class="valid-value"> <code class="literal"> zlib </code> </p> <p class="valid-value"> <code class="literal"> lz4 </code> </p> <p class="valid-value"> <code class="literal"> lz4hc </code> </p> </td> </tr> </tbody> </table> </div> <p> Compresses all tables using a specified compression algorithm without having to define a <code class="literal"> COMPRESSION </code> attribute for each table. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> <p> For related information, see <a class="xref" href="innodb-page-compression.html" title="17.9.2 InnoDB Page Compression"> Section 17.9.2, “InnoDB Page Compression” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_compression_failure_threshold_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> <code class="literal"> innodb_compression_failure_threshold_pct </code> </a> </p> <a class="indexterm" name="idm46045156217632"> </a> <a class="indexterm" name="idm46045156216512"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_compression_failure_threshold_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-compression-failure-threshold-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> innodb_compression_failure_threshold_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Defines the compression failure rate threshold for a table, as a percentage, at which point MySQL begins adding padding within <a class="link" href="glossary.html#glos_compression" title="compression"> compressed </a> pages to avoid expensive <a class="link" href="glossary.html#glos_compression_failure" title="compression failure"> compression failures </a> . When this threshold is passed, MySQL begins to leave additional free space within each new compressed page, dynamically adjusting the amount of free space up to the percentage of page size specified by <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> <code class="literal"> innodb_compression_pad_pct_max </code> </a> . A value of zero disables the mechanism that monitors compression efficiency and dynamically adjusts the padding amount. </p> <p> For more information, see <a class="xref" href="innodb-performance-compression-oltp.html" title="17.9.1.6 Compression for OLTP Workloads"> Section 17.9.1.6, “Compression for OLTP Workloads” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_compression_level"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_level"> <code class="literal"> innodb_compression_level </code> </a> </p> <a class="indexterm" name="idm46045156182336"> </a> <a class="indexterm" name="idm46045156181232"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_compression_level"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-compression-level=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_level"> innodb_compression_level </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 6 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 9 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the level of zlib compression to use for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_compression" title="compression"> compressed </a> tables and indexes. A higher value lets you fit more data onto a storage device, at the expense of more CPU overhead during compression. A lower value lets you reduce CPU overhead when storage space is not critical, or you expect the data is not especially compressible. </p> <p> For more information, see <a class="xref" href="innodb-performance-compression-oltp.html" title="17.9.1.6 Compression for OLTP Workloads"> Section 17.9.1.6, “Compression for OLTP Workloads” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_compression_pad_pct_max"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> <code class="literal"> innodb_compression_pad_pct_max </code> </a> </p> <a class="indexterm" name="idm46045156148784"> </a> <a class="indexterm" name="idm46045156147680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_compression_pad_pct_max"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-compression-pad-pct-max=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> innodb_compression_pad_pct_max </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 75 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the maximum percentage that can be reserved as free space within each compressed <a class="link" href="glossary.html#glos_page" title="page"> page </a> , allowing room to reorganize the data and modification log within the page when a <a class="link" href="glossary.html#glos_compression" title="compression"> compressed </a> table or index is updated and the data might be recompressed. Only applies when <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> <code class="literal"> innodb_compression_failure_threshold_pct </code> </a> is set to a nonzero value, and the rate of <a class="link" href="glossary.html#glos_compression_failure" title="compression failure"> compression failures </a> passes the cutoff point. </p> <p> For more information, see <a class="xref" href="innodb-performance-compression-oltp.html" title="17.9.1.6 Compression for OLTP Workloads"> Section 17.9.1.6, “Compression for OLTP Workloads” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_concurrency_tickets"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> </p> <a class="indexterm" name="idm46045156112896"> </a> <a class="indexterm" name="idm46045156111792"> </a> <a class="indexterm" name="idm46045156110288"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_concurrency_tickets"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-concurrency-tickets=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> innodb_concurrency_tickets </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Determines the number of <a class="link" href="glossary.html#glos_thread" title="thread"> threads </a> that can enter <code class="literal"> InnoDB </code> concurrently. A thread is placed in a queue when it tries to enter <code class="literal"> InnoDB </code> if the number of threads has already reached the concurrency limit. When a thread is permitted to enter <code class="literal"> InnoDB </code> , it is given a number of <span class="quote"> “ <span class="quote"> tickets </span> ” </span> equal to the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> , and the thread can enter and leave <code class="literal"> InnoDB </code> freely until it has used up its tickets. After that point, the thread again becomes subject to the concurrency check (and possible queuing) the next time it tries to enter <code class="literal"> InnoDB </code> . The default value is 5000. </p> <p> With a small <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value, small transactions that only need to process a few rows compete fairly with larger transactions that process many rows. The disadvantage of a small <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value is that large transactions must loop through the queue many times before they can complete, which extends the amount of time required to complete their task. </p> <p> With a large <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value, large transactions spend less time waiting for a position at the end of the queue (controlled by <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> ) and more time retrieving rows. Large transactions also require fewer trips through the queue to complete their task. The disadvantage of a large <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value is that too many large transactions running at the same time can starve smaller transactions by making them wait a longer time before executing. </p> <p> With a nonzero <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> value, you may need to adjust the <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value up or down to find the optimal balance between larger and smaller transactions. The <code class="literal"> SHOW ENGINE INNODB STATUS </code> report shows the number of tickets remaining for an executing transaction in its current pass through the queue. This data may also be obtained from the <code class="literal"> TRX_CONCURRENCY_TICKETS </code> column of the Information Schema <a class="link" href="information-schema-innodb-trx-table.html" title="28.4.28 The INFORMATION_SCHEMA INNODB_TRX Table"> <code class="literal"> INNODB_TRX </code> </a> table. </p> <p> For more information, see <a class="xref" href="innodb-performance-thread_concurrency.html" title="17.8.4 Configuring Thread Concurrency for InnoDB"> Section 17.8.4, “Configuring Thread Concurrency for InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_data_file_path"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> </p> <a class="indexterm" name="idm46045156058832"> </a> <a class="indexterm" name="idm46045156057792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_data_file_path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-data-file-path=file_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> innodb_data_file_path </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ibdata1:12M:autoextend </code> </td> </tr> </tbody> </table> </div> <p> Defines the name, size, and attributes of <code class="literal"> InnoDB </code> system tablespace data files. If you do not specify a value for <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> , the default behavior is to create a single auto-extending data file, slightly larger than 12MB, named <code class="filename"> ibdata1 </code> . </p> <p> The full syntax for a data file specification includes the file name, file size, <code class="literal"> autoextend </code> attribute, and <code class="literal"> max </code> attribute: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa64702669"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none"><em class="replaceable">file_name</em>:<em class="replaceable">file_size</em>[:autoextend[:max:<em class="replaceable">max_file_size</em>]]</code></pre> </div> <p> File sizes are specified in kilobytes, megabytes, or gigabytes by appending <code class="literal"> K </code> , <code class="literal"> M </code> or <code class="literal"> G </code> to the size value. If specifying the data file size in kilobytes, do so in multiples of 1024. Otherwise, KB values are rounded to nearest megabyte (MB) boundary. The sum of file sizes must be, at a minimum, slightly larger than 12MB. </p> <p> For additional configuration information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-data-file-configuration" title="System Tablespace Data File Configuration"> System Tablespace Data File Configuration </a> . For resizing instructions, see <a class="xref" href="innodb-system-tablespace.html#innodb-resize-system-tablespace" title="Resizing the System Tablespace"> Resizing the System Tablespace </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_data_home_dir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> </p> <a class="indexterm" name="idm46045156021632"> </a> <a class="indexterm" name="idm46045156020592"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_data_home_dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-data-home-dir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> innodb_data_home_dir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> </tbody> </table> </div> <p> The common part of the directory path for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> data files. The default value is the MySQL <code class="filename"> data </code> directory. The setting is concatenated with the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> setting, unless that setting is defined with an absolute path. </p> <p> A trailing slash is required when specifying a value for <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> . For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa58117203"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">innodb_data_home_dir</span> <span class="token attr-value"><span class="token punctuation">=</span> /path/to/myibdata/</span></code></pre> </div> <p> This setting does not affect the location of <a class="link" href="glossary.html#glos_file_per_table" title="file-per-table"> file-per-table </a> tablespaces. </p> <p> For related information, see <a class="xref" href="innodb-init-startup-configuration.html" title="17.8.1 InnoDB Startup Configuration"> Section 17.8.1, “InnoDB Startup Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ddl_buffer_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> <code class="literal"> innodb_ddl_buffer_size </code> </a> </p> <a class="indexterm" name="idm46045155989552"> </a> <a class="indexterm" name="idm46045155988512"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ddl_buffer_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ddl-buffer-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> innodb_ddl_buffer_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1048576 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 65536 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Defines the maximum buffer size for DDL operations. The default setting is 1048576 bytes (approximately 1 MB). Applies to online DDL operations that create or rebuild secondary indexes. See <a class="xref" href="online-ddl-memory-management.html" title="17.12.4 Online DDL Memory Management"> Section 17.12.4, “Online DDL Memory Management” </a> . The maximum buffer size per DDL thread is the maximum buffer size divided by the number of DDL threads ( <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> <code class="literal"> innodb_ddl_buffer_size </code> </a> / <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> <code class="literal"> innodb_ddl_threads </code> </a> ). </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ddl_log_crash_reset_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_log_crash_reset_debug"> <code class="literal"> innodb_ddl_log_crash_reset_debug </code> </a> </p> <a class="indexterm" name="idm46045155953408"> </a> <a class="indexterm" name="idm46045155952304"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ddl_log_crash_reset_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ddl-log-crash-reset-debug[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_log_crash_reset_debug"> innodb_ddl_log_crash_reset_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enable this debug option to reset DDL log crash injection counters to 1. This option is only available when debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ddl_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> <code class="literal"> innodb_ddl_threads </code> </a> </p> <a class="indexterm" name="idm46045155925920"> </a> <a class="indexterm" name="idm46045155924880"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ddl_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ddl-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> innodb_ddl_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> Defines the maximum number of parallel threads for the sort and build phases of index creation. Applies to online DDL operations that create or rebuild secondary indexes. For related information, see <a class="xref" href="online-ddl-parallel-thread-configuration.html" title="17.12.5 Configuring Parallel Threads for Online DDL Operations"> Section 17.12.5, “Configuring Parallel Threads for Online DDL Operations” </a> , and <a class="xref" href="online-ddl-memory-management.html" title="17.12.4 Online DDL Memory Management"> Section 17.12.4, “Online DDL Memory Management” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_deadlock_detect"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> <code class="literal"> innodb_deadlock_detect </code> </a> </p> <a class="indexterm" name="idm46045155893696"> </a> <a class="indexterm" name="idm46045155892656"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_deadlock_detect"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-deadlock-detect[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> innodb_deadlock_detect </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> This option is used to disable deadlock detection. On high concurrency systems, deadlock detection can cause a slowdown when numerous threads wait for the same lock. At times, it may be more efficient to disable deadlock detection and rely on the <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> setting for transaction rollback when a deadlock occurs. </p> <p> For related information, see <a class="xref" href="innodb-deadlock-detection.html" title="17.7.5.2 Deadlock Detection"> Section 17.7.5.2, “Deadlock Detection” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_default_row_format"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> </p> <a class="indexterm" name="idm46045155865408"> </a> <a class="indexterm" name="idm46045155864304"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_default_row_format"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-default-row-format=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> innodb_default_row_format </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> DYNAMIC </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> REDUNDANT </code> </p> <p class="valid-value"> <code class="literal"> COMPACT </code> </p> <p class="valid-value"> <code class="literal"> DYNAMIC </code> </p> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> option defines the default row format for <code class="literal"> InnoDB </code> tables and user-created temporary tables. The default setting is <code class="literal"> DYNAMIC </code> . Other permitted values are <code class="literal"> COMPACT </code> and <code class="literal"> REDUNDANT </code> . The <code class="literal"> COMPRESSED </code> row format, which is not supported for use in the <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> , cannot be defined as the default. </p> <p> Newly created tables use the row format defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> when a <code class="literal"> ROW_FORMAT </code> option is not specified explicitly or when <code class="literal"> ROW_FORMAT=DEFAULT </code> is used. </p> <p> When a <code class="literal"> ROW_FORMAT </code> option is not specified explicitly or when <code class="literal"> ROW_FORMAT=DEFAULT </code> is used, any operation that rebuilds a table also silently changes the row format of the table to the format defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> . For more information, see <a class="xref" href="innodb-row-format.html#innodb-row-format-defining" title="Defining the Row Format of a Table"> Defining the Row Format of a Table </a> . </p> <p> Internal <code class="literal"> InnoDB </code> temporary tables created by the server to process queries use the <code class="literal"> DYNAMIC </code> row format, regardless of the <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> setting. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_directories"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> </p> <a class="indexterm" name="idm46045155818432"> </a> <a class="indexterm" name="idm46045155817392"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_directories"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-directories=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> innodb_directories </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> Defines directories to scan at startup for tablespace files. This option is used when moving or restoring tablespace files to a new location while the server is offline. It is also used to specify directories of tablespace files created using an absolute path or that reside outside of the data directory. </p> <p> Tablespace discovery during crash recovery relies on the <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> setting to identify tablespaces referenced in the redo logs. For more information, see <a class="xref" href="innodb-recovery.html#innodb-recovery-tablespace-discovery" title="Tablespace Discovery During Crash Recovery"> Tablespace Discovery During Crash Recovery </a> . </p> <p> The default value is NULL, but directories defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> , and <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="literal"> datadir </code> </a> are always appended to the <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> argument value when <code class="literal"> InnoDB </code> builds a list of directories to scan at startup. These directories are appended regardless of whether an <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> setting is specified explicitly. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> may be specified as an option in a startup command or in a MySQL option file. Quotes surround the argument value because otherwise some command interpreters interpret semicolon ( <code class="literal"> ; </code> ) as a special character. (For example, Unix shells treat it as a command terminator.) </p> <p> Startup command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa21029187"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld <span class="token constant">--innodb-directories</span>=<span class="token atrule">"<em class="replaceable">directory_path_1</em>;<em class="replaceable">directory_path_2</em>"</span></code></pre> </div> <p> MySQL option file: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa50695958"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">innodb_directories</span><span class="token attr-value"><span class="token punctuation">=</span>"<em class="replaceable">directory_path_1</em>;<em class="replaceable">directory_path_2</em>"</span></code></pre> </div> <p> Wildcard expressions cannot be used to specify directories. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> scan also traverses the subdirectories of specified directories. Duplicate directories and subdirectories are discarded from the list of directories to be scanned. </p> <p> For more information, see <a class="xref" href="innodb-moving-data-files-offline.html" title="17.6.3.6 Moving Tablespace Files While the Server is Offline"> Section 17.6.3.6, “Moving Tablespace Files While the Server is Offline” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_disable_sort_file_cache"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_disable_sort_file_cache"> <code class="literal"> innodb_disable_sort_file_cache </code> </a> </p> <a class="indexterm" name="idm46045155771600"> </a> <a class="indexterm" name="idm46045155770496"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_disable_sort_file_cache"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-disable-sort-file-cache[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_disable_sort_file_cache"> innodb_disable_sort_file_cache </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Disables the operating system file system cache for merge-sort temporary files. The effect is to open such files with the equivalent of <code class="literal"> O_DIRECT </code> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> </p> <a class="indexterm" name="idm46045155745008"> </a> <a class="indexterm" name="idm46045155743968"> </a> <a class="indexterm" name="idm46045155742480"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> innodb_doublewrite </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> ON </code> </p> <p class="valid-value"> <code class="literal"> OFF </code> </p> <p class="valid-value"> <code class="literal"> DETECT_AND_RECOVER </code> </p> <p class="valid-value"> <code class="literal"> DETECT_ONLY </code> </p> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> variable controls doublewrite buffering. Doublewrite buffering is enabled by default in most cases. </p> <p> You can set <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> to <code class="literal"> ON </code> or <code class="literal"> OFF </code> when starting the server to enable or disable doublewrite buffering, respectively. <code class="literal"> DETECT_AND_RECOVER </code> is the same as <code class="literal"> ON </code> . With this setting, except that the doublewrite buffer is fully enabled, with database page content written to the doublewrite buffer where it is accessed during recovery to fix incomplete page writes. With <code class="literal"> DETECT_ONLY </code> , only metadata is written to the doublewrite buffer. Database page content is not written to the doublewrite buffer, and recovery does not use the doublewrite buffer to fix incomplete page writes. This lightweight setting is intended for detecting incomplete page writes only. </p> <p> MySQL supports dynamic changes to the <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> setting that enables the doublewrite buffer, between <code class="literal"> ON </code> , <code class="literal"> DETECT_AND_RECOVER </code> , and <code class="literal"> DETECT_ONLY </code> . MySQL does not support dynamic changes between a setting that enables the doublewrite buffer and <code class="literal"> OFF </code> or vice versa. </p> <p> If the doublewrite buffer is located on a Fusion-io device that supports atomic writes, the doublewrite buffer is automatically disabled and data file writes are performed using Fusion-io atomic writes instead. However, be aware that the <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> setting is global. When the doublewrite buffer is disabled, it is disabled for all data files including those that do not reside on Fusion-io hardware. This feature is only supported on Fusion-io hardware and is only enabled for Fusion-io NVMFS on Linux. To take full advantage of this feature, an <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> setting of <code class="literal"> O_DIRECT </code> is recommended. </p> <p> For related information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite_batch_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_batch_size"> <code class="literal"> innodb_doublewrite_batch_size </code> </a> </p> <a class="indexterm" name="idm46045155695328"> </a> <a class="indexterm" name="idm46045155694240"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite_batch_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite-batch-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_batch_size"> innodb_doublewrite_batch_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 256 </code> </td> </tr> </tbody> </table> </div> <p> This variable was intended to represent the number of doublewrite pages to write in a batch. This functionality was replaced by <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> <code class="literal"> innodb_doublewrite_pages </code> </a> . </p> <p> For more information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite_dir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_dir"> <code class="literal"> innodb_doublewrite_dir </code> </a> </p> <a class="indexterm" name="idm46045155662208"> </a> <a class="indexterm" name="idm46045155661136"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite_dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite-dir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_dir"> innodb_doublewrite_dir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> </tbody> </table> </div> <p> Defines the directory for doublewrite files. If no directory is specified, doublewrite files are created in the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> directory, which defaults to the data directory if unspecified. </p> <p> For more information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite_files"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_files"> <code class="literal"> innodb_doublewrite_files </code> </a> </p> <a class="indexterm" name="idm46045155636448"> </a> <a class="indexterm" name="idm46045155635360"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite_files"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite-files=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_files"> innodb_doublewrite_files </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 256 </code> </td> </tr> </tbody> </table> </div> <p> Defines the number of doublewrite files. By default, two doublewrite files are created for each buffer pool instance. </p> <p> At a minimum, there are two doublewrite files. The maximum number of doublewrite files is two times the number of buffer pool instances. (The number of buffer pool instances is controlled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> variable.) </p> <p> For more information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite_pages"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> <code class="literal"> innodb_doublewrite_pages </code> </a> </p> <a class="indexterm" name="idm46045155602752"> </a> <a class="indexterm" name="idm46045155601664"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite_pages"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite-pages=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> innodb_doublewrite_pages </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 128 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 512 </code> </td> </tr> </tbody> </table> </div> <p> Defines the maximum number of doublewrite pages per thread for a batch write. If no value is specified, <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> <code class="literal"> innodb_doublewrite_pages </code> </a> defaults to 128. </p> <p> Before MySQL 8.4, the default value was the <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> value, which is 4 by default. </p> <p> For more information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_extend_and_initialize"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_extend_and_initialize"> <code class="literal"> innodb_extend_and_initialize </code> </a> </p> <a class="indexterm" name="idm46045155567952"> </a> <a class="indexterm" name="idm46045155566848"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_extend_and_initialize"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb=extend-and-initialize[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_extend_and_initialize"> innodb_extend_and_initialize </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Controls how space is allocated to file-per-table and general tablespaces on Linux systems. </p> <p> When enabled, <code class="literal"> InnoDB </code> writes NULLs to newly allocated pages. When disabled, space is allocated using <code class="literal"> posix_fallocate() </code> calls, which reserve space without physically writing NULLs. </p> <p> For more information, see <a class="xref" href="innodb-optimize-tablespace-page-allocation.html" title="17.6.3.8 Optimizing Tablespace Space Allocation on Linux"> Section 17.6.3.8, “Optimizing Tablespace Space Allocation on Linux” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_fast_shutdown"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> <code class="literal"> innodb_fast_shutdown </code> </a> </p> <a class="indexterm" name="idm46045155538784"> </a> <a class="indexterm" name="idm46045155537744"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_fast_shutdown"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-fast-shutdown=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> innodb_fast_shutdown </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 0 </code> </p> <p class="valid-value"> <code class="literal"> 1 </code> </p> <p class="valid-value"> <code class="literal"> 2 </code> </p> </td> </tr> </tbody> </table> </div> <p> The <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_shutdown" title="shutdown"> shutdown </a> mode. If the value is 0, <code class="literal"> InnoDB </code> does a <a class="link" href="glossary.html#glos_slow_shutdown" title="slow shutdown"> slow shutdown </a> , a full <a class="link" href="glossary.html#glos_purge" title="purge"> purge </a> and a change buffer merge before shutting down. If the value is 1 (the default), <code class="literal"> InnoDB </code> skips these operations at shutdown, a process known as a <a class="link" href="glossary.html#glos_fast_shutdown" title="fast shutdown"> fast shutdown </a> . If the value is 2, <code class="literal"> InnoDB </code> flushes its logs and shuts down cold, as if MySQL had crashed; no committed transactions are lost, but the <a class="link" href="glossary.html#glos_crash_recovery" title="crash recovery"> crash recovery </a> operation makes the next startup take longer. </p> <p> The slow shutdown can take minutes, or even hours in extreme cases where substantial amounts of data are still buffered. Use the slow shutdown technique before upgrading or downgrading between MySQL major releases, so that all data files are fully prepared in case the upgrade process updates the file format. </p> <p> Use <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> <code class="literal"> innodb_fast_shutdown=2 </code> </a> in emergency or troubleshooting situations, to get the absolute fastest shutdown if data is at risk of corruption. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_fil_make_page_dirty_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> </p> <a class="indexterm" name="idm46045155498544"> </a> <a class="indexterm" name="idm46045155497456"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_fil_make_page_dirty_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-fil-make-page-dirty-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> innodb_fil_make_page_dirty_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 232-1 </code> </td> </tr> </tbody> </table> </div> <p> By default, setting <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> to the ID of a tablespace immediately dirties the first page of the tablespace. If <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> <code class="literal"> innodb_saved_page_number_debug </code> </a> is set to a non-default value, setting <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> dirties the specified page. The <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_file_per_table"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> </p> <a class="indexterm" name="idm46045155460928"> </a> <a class="indexterm" name="idm46045155459888"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_file_per_table"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-file-per-table[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> innodb_file_per_table </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> When <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> is enabled, tables are created in file-per-table tablespaces by default. When disabled, tables are created in the system tablespace by default. For information about file-per-table tablespaces, see <a class="xref" href="innodb-file-per-table-tablespaces.html" title="17.6.3.2 File-Per-Table Tablespaces"> Section 17.6.3.2, “File-Per-Table Tablespaces” </a> . For information about the <code class="literal"> InnoDB </code> system tablespace, see <a class="xref" href="innodb-system-tablespace.html" title="17.6.3.1 The System Tablespace"> Section 17.6.3.1, “The System Tablespace” </a> . </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> variable can be configured at runtime using a <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET GLOBAL </code> </a> statement, specified on the command line at startup, or specified in an option file. Configuration at runtime requires privileges sufficient to set global system variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ) and immediately affects the operation of all connections. </p> <p> When a table that resides in a file-per-table tablespace is truncated or dropped, the freed space is returned to the operating system. Truncating or dropping a table that resides in the system tablespace only frees space in the system tablespace. Freed space in the system tablespace can be used again for <code class="literal"> InnoDB </code> data but is not returned to the operating system, as system tablespace data files never shrink. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per-table </code> </a> setting does not affect the creation of temporary tables; temporary tables are created in session temporary tablespaces. See <a class="xref" href="innodb-temporary-tablespace.html" title="17.6.3.5 Temporary Tablespaces"> Section 17.6.3.5, “Temporary Tablespaces” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_fill_factor"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> </p> <a class="indexterm" name="idm46045155423488"> </a> <a class="indexterm" name="idm46045155422448"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_fill_factor"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-fill-factor=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> innodb_fill_factor </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> <code class="literal"> InnoDB </code> performs a bulk load when creating or rebuilding indexes. This method of index creation is known as a <span class="quote"> “ <span class="quote"> sorted index build </span> ” </span> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> defines the percentage of space on each B-tree page that is filled during a sorted index build, with the remaining space reserved for future index growth. For example, setting <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> to 80 reserves 20 percent of the space on each B-tree page for future index growth. Actual percentages may vary. The <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> setting is interpreted as a hint rather than a hard limit. </p> <p> An <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> setting of 100 leaves 1/16 of the space in clustered index pages free for future index growth. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> applies to both B-tree leaf and non-leaf pages. It does not apply to external pages used for <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> TEXT </code> </a> or <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> entries. </p> <p> For more information, see <a class="xref" href="sorted-index-builds.html" title="17.6.2.3 Sorted Index Builds"> Section 17.6.2.3, “Sorted Index Builds” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_log_at_timeout"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> <code class="literal"> innodb_flush_log_at_timeout </code> </a> </p> <a class="indexterm" name="idm46045155379456"> </a> <a class="indexterm" name="idm46045155378352"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_log_at_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-log-at-timeout=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> innodb_flush_log_at_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2700 </code> </td> </tr> <tr> <th> Unit </th> <td> seconds </td> </tr> </tbody> </table> </div> <p> Write and flush the logs every <em class="replaceable"> <code> N </code> </em> seconds. <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> <code class="literal"> innodb_flush_log_at_timeout </code> </a> allows the timeout period between flushes to be increased in order to reduce flushing and avoid impacting performance of binary log group commit. The default setting for <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> <code class="literal"> innodb_flush_log_at_timeout </code> </a> is once per second. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_log_at_trx_commit"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit </code> </a> </p> <a class="indexterm" name="idm46045155343632"> </a> <a class="indexterm" name="idm46045155342528"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_log_at_trx_commit"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-log-at-trx-commit=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> innodb_flush_log_at_trx_commit </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 0 </code> </p> <p class="valid-value"> <code class="literal"> 1 </code> </p> <p class="valid-value"> <code class="literal"> 2 </code> </p> </td> </tr> </tbody> </table> </div> <p> Controls the balance between strict <a class="link" href="glossary.html#glos_acid" title="ACID"> ACID </a> compliance for <a class="link" href="glossary.html#glos_commit" title="commit"> commit </a> operations and higher performance that is possible when commit-related I/O operations are rearranged and done in batches. You can achieve better performance by changing the default value but then you can lose transactions in a crash. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> The default setting of 1 is required for full ACID compliance. Logs are written and flushed to disk at each transaction commit. </p> </li> <li class="listitem"> <p> With a setting of 0, logs are written and flushed to disk once per second. Transactions for which logs have not been flushed can be lost in a crash. </p> </li> <li class="listitem"> <p> With a setting of 2, logs are written after each transaction commit and flushed to disk once per second. Transactions for which logs have not been flushed can be lost in a crash. </p> </li> <li class="listitem"> <p> For settings 0 and 2, once-per-second flushing is not 100% guaranteed. Flushing may occur more frequently due to DDL changes and other internal <code class="literal"> InnoDB </code> activities that cause logs to be flushed independently of the <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit </code> </a> setting, and sometimes less frequently due to scheduling issues. If logs are flushed once per second, up to one second of transactions can be lost in a crash. If logs are flushed more or less frequently than once per second, the amount of transactions that can be lost varies accordingly. </p> </li> <li class="listitem"> <p> Log flushing frequency is controlled by <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> <code class="literal"> innodb_flush_log_at_timeout </code> </a> , which allows you to set log flushing frequency to <em class="replaceable"> <code> N </code> </em> seconds (where <em class="replaceable"> <code> N </code> </em> is <code class="literal"> 1 ... 2700 </code> , with a default value of 1). However, any unexpected <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process exit can erase up to <em class="replaceable"> <code> N </code> </em> seconds of transactions. </p> </li> <li class="listitem"> <p> DDL changes and other internal <code class="literal"> InnoDB </code> activities flush the log independently of the <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit </code> </a> setting. </p> </li> <li class="listitem"> <p> <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_crash_recovery" title="crash recovery"> crash recovery </a> works regardless of the <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit </code> </a> setting. Transactions are either applied entirely or erased entirely. </p> </li> </ul> </div> <p> For durability and consistency in a replication setup that uses <code class="literal"> InnoDB </code> with transactions: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If binary logging is enabled, set <code class="literal"> sync_binlog=1 </code> . </p> </li> <li class="listitem"> <p> Always set <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit=1 </code> </a> . </p> </li> </ul> </div> <p> For information on the combination of settings on a replica that is most resilient to unexpected halts, see <a class="xref" href="replication-solutions-unexpected-replica-halt.html" title="19.4.2 Handling an Unexpected Halt of a Replica"> Section 19.4.2, “Handling an Unexpected Halt of a Replica” </a> . </p> <div class="caution" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Caution </div> <p> Many operating systems and some disk hardware fool the flush-to-disk operation. They may tell <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> that the flush has taken place, even though it has not. In this case, the durability of transactions is not guaranteed even with the recommended settings, and in the worst case, a power outage can corrupt <code class="literal"> InnoDB </code> data. Using a battery-backed disk cache in the SCSI disk controller or in the disk itself speeds up file flushes, and makes the operation safer. You can also try to disable the caching of disk writes in hardware caches. </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_method"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> </p> <a class="indexterm" name="idm46045155282368"> </a> <a class="indexterm" name="idm46045155281328"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_method"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-method=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> innodb_flush_method </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value (Unix) </th> <td> <code class="literal"> O_DIRECT if supported, otherwise fsync </code> </td> </tr> <tr> <th> Default Value (Windows) </th> <td> <code class="literal"> unbuffered </code> </td> </tr> <tr> <th> Valid Values (Unix) </th> <td> <p class="valid-value"> <code class="literal"> fsync </code> </p> <p class="valid-value"> <code class="literal"> O_DSYNC </code> </p> <p class="valid-value"> <code class="literal"> littlesync </code> </p> <p class="valid-value"> <code class="literal"> nosync </code> </p> <p class="valid-value"> <code class="literal"> O_DIRECT </code> </p> <p class="valid-value"> <code class="literal"> O_DIRECT_NO_FSYNC </code> </p> </td> </tr> <tr> <th> Valid Values (Windows) </th> <td> <p class="valid-value"> <code class="literal"> unbuffered </code> </p> <p class="valid-value"> <code class="literal"> normal </code> </p> </td> </tr> </tbody> </table> </div> <p> Defines the method used to <a class="link" href="glossary.html#glos_flush" title="flush"> flush </a> data to <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_data_files" title="data files"> data files </a> and <a class="link" href="glossary.html#glos_log_file" title="log file"> log files </a> , which can affect I/O throughput. </p> <p> On Unix-like systems, the default value is <code class="literal"> O_DIRECT </code> if supported otherwise defaults to <code class="literal"> fsync </code> . On Windows, the default value is <code class="literal"> unbuffered </code> . </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> options for Unix-like systems include: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> fsync </code> or <code class="literal"> 0 </code> : <code class="literal"> InnoDB </code> uses the <code class="literal"> fsync() </code> system call to flush both the data and log files. </p> </li> <li class="listitem"> <p> <code class="literal"> O_DSYNC </code> or <code class="literal"> 1 </code> : <code class="literal"> InnoDB </code> uses <code class="literal"> O_SYNC </code> to open and flush the log files, and <code class="literal"> fsync() </code> to flush the data files. <code class="literal"> InnoDB </code> does not use <code class="literal"> O_DSYNC </code> directly because there have been problems with it on many varieties of Unix. </p> </li> <li class="listitem"> <p> <code class="literal"> littlesync </code> or <code class="literal"> 2 </code> : This option is used for internal performance testing and is currently unsupported. Use at your own risk. </p> </li> <li class="listitem"> <p> <code class="literal"> nosync </code> or <code class="literal"> 3 </code> : This option is used for internal performance testing and is currently unsupported. Use at your own risk. </p> </li> <li class="listitem"> <p> <code class="literal"> O_DIRECT </code> or <code class="literal"> 4 </code> : <code class="literal"> InnoDB </code> uses <code class="literal"> O_DIRECT </code> (or <code class="literal"> directio() </code> on Solaris) to open the data files, and uses <code class="literal"> fsync() </code> to flush both the data and log files. This option is available on some GNU/Linux versions, FreeBSD, and Solaris. </p> </li> <li class="listitem"> <p> <code class="literal"> O_DIRECT_NO_FSYNC </code> : <code class="literal"> InnoDB </code> uses <code class="literal"> O_DIRECT </code> during flushing I/O, but skips the <code class="literal"> fsync() </code> system call after each write operation. </p> <p> MySQL calls <code class="literal"> fsync() </code> after creating a new file, after increasing file size, and after closing a file, to ensure that file system metadata changes are synchronized. The <code class="literal"> fsync() </code> system call is still skipped after each write operation. </p> <p> Data loss is possible if redo log files and data files reside on different storage devices, and an unexpected exit occurs before data file writes are flushed from a device cache that is not battery-backed. If you use or intend to use different storage devices for redo log files and data files, and your data files reside on a device with a cache that is not battery-backed, use <code class="literal"> O_DIRECT </code> instead. </p> </li> </ul> </div> <p> On platforms that support <code class="literal"> fdatasync() </code> system calls, the <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> variable permits <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> options that use <code class="literal"> fsync() </code> to use <code class="literal"> fdatasync() </code> instead. An <code class="literal"> fdatasync() </code> system call does not flush changes to file metadata unless required for subsequent data retrieval, providing a potential performance benefit. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> options for Windows systems include: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> unbuffered </code> or <code class="literal"> 0 </code> : <code class="literal"> InnoDB </code> uses non-buffered I/O. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Running MySQL server on a 4K sector hard drive on Windows is not supported with <code class="literal"> unbuffered </code> . The workaround is to use <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method=normal </code> </a> . </p> </div> </li> <li class="listitem"> <p> <code class="literal"> normal </code> or <code class="literal"> 1 </code> : <code class="literal"> InnoDB </code> uses buffered I/O. </p> </li> </ul> </div> <p> How each setting affects performance depends on hardware configuration and workload. Benchmark your particular configuration to decide which setting to use, or whether to keep the default setting. Examine the <a class="link" href="server-status-variables.html#statvar_Innodb_data_fsyncs"> <code class="literal"> Innodb_data_fsyncs </code> </a> status variable to see the overall number of <code class="literal"> fsync() </code> calls (or <code class="literal"> fdatasync() </code> calls if <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> is enabled) for each setting. The mix of read and write operations in your workload can affect how a setting performs. For example, on a system with a hardware RAID controller and battery-backed write cache, <code class="literal"> O_DIRECT </code> can help to avoid double buffering between the <code class="literal"> InnoDB </code> buffer pool and the operating system file system cache. On some systems where <code class="literal"> InnoDB </code> data and log files are located on a SAN, the default value or <code class="literal"> O_DSYNC </code> might be faster for a read-heavy workload with mostly <code class="literal"> SELECT </code> statements. Always test this parameter with hardware and workload that reflect your production environment. For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_neighbors"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> </p> <a class="indexterm" name="idm46045155180336"> </a> <a class="indexterm" name="idm46045155179296"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_neighbors"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-neighbors=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> innodb_flush_neighbors </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 0 </code> </p> <p class="valid-value"> <code class="literal"> 1 </code> </p> <p class="valid-value"> <code class="literal"> 2 </code> </p> </td> </tr> </tbody> </table> </div> <p> Specifies whether <a class="link" href="glossary.html#glos_flush" title="flush"> flushing </a> a page from the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> also flushes other <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> in the same <a class="link" href="glossary.html#glos_extent" title="extent"> extent </a> . </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> A setting of 0 disables <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> . Dirty pages in the same extent are not flushed. </p> </li> <li class="listitem"> <p> A setting of 1 flushes contiguous dirty pages in the same extent. </p> </li> <li class="listitem"> <p> A setting of 2 flushes dirty pages in the same extent. </p> </li> </ul> </div> <p> When the table data is stored on a traditional <a class="link" href="glossary.html#glos_hdd" title="HDD"> HDD </a> storage device, flushing such <a class="link" href="glossary.html#glos_neighbor_page" title="neighbor page"> neighbor pages </a> in one operation reduces I/O overhead (primarily for disk seek operations) compared to flushing individual pages at different times. For table data stored on <a class="link" href="glossary.html#glos_ssd" title="SSD"> SSD </a> , seek time is not a significant factor and you can set this option to 0 to spread out write operations. For related information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_sync"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> </p> <a class="indexterm" name="idm46045155137568"> </a> <a class="indexterm" name="idm46045155136528"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_sync"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-sync[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> innodb_flush_sync </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> variable, which is enabled by default, causes the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> settings to be ignored during bursts of I/O activity that occur at <a class="link" href="glossary.html#glos_checkpoint" title="checkpoint"> checkpoints </a> . To adhere to the I/O rate defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> , disable <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> . </p> <p> For information about configuring the <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> variable, see <a class="xref" href="innodb-configuring-io-capacity.html" title="17.8.7 Configuring InnoDB I/O Capacity"> Section 17.8.7, “Configuring InnoDB I/O Capacity” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flushing_avg_loops"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> <code class="literal"> innodb_flushing_avg_loops </code> </a> </p> <a class="indexterm" name="idm46045155100960"> </a> <a class="indexterm" name="idm46045155099856"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flushing_avg_loops"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flushing-avg-loops=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> innodb_flushing_avg_loops </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 30 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> </tbody> </table> </div> <p> Number of iterations for which <code class="literal"> InnoDB </code> keeps the previously calculated snapshot of the flushing state, controlling how quickly <a class="link" href="glossary.html#glos_adaptive_flushing" title="adaptive flushing"> adaptive flushing </a> responds to changing <a class="link" href="glossary.html#glos_workload" title="workload"> workloads </a> . Increasing the value makes the rate of <a class="link" href="glossary.html#glos_flush" title="flush"> flush </a> operations change smoothly and gradually as the workload changes. Decreasing the value makes adaptive flushing adjust quickly to workload changes, which can cause spikes in flushing activity if the workload increases and decreases suddenly. </p> <p> For related information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_force_load_corrupted"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_load_corrupted"> <code class="literal"> innodb_force_load_corrupted </code> </a> </p> <a class="indexterm" name="idm46045155065568"> </a> <a class="indexterm" name="idm46045155064464"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_force_load_corrupted"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-force-load-corrupted[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_load_corrupted"> innodb_force_load_corrupted </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Permits <code class="literal"> InnoDB </code> to load tables at startup that are marked as corrupted. Use only during troubleshooting, to recover data that is otherwise inaccessible. When troubleshooting is complete, disable this setting and restart the server. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_force_recovery"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> <code class="literal"> innodb_force_recovery </code> </a> </p> <a class="indexterm" name="idm46045155038864"> </a> <a class="indexterm" name="idm46045155037824"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_force_recovery"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-force-recovery=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> innodb_force_recovery </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 6 </code> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="glossary.html#glos_crash_recovery" title="crash recovery"> crash recovery </a> mode, typically only changed in serious troubleshooting situations. Possible values are from 0 to 6. For the meanings of these values and important information about <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> <code class="literal"> innodb_force_recovery </code> </a> , see <a class="xref" href="forcing-innodb-recovery.html" title="17.20.3 Forcing InnoDB Recovery"> Section 17.20.3, “Forcing InnoDB Recovery” </a> . </p> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> Only set this variable to a value greater than 0 in an emergency situation so that you can start <code class="literal"> InnoDB </code> and dump your tables. As a safety measure, <code class="literal"> InnoDB </code> prevents <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , or <a class="link" href="delete.html" title="15.2.2 DELETE Statement"> <code class="literal"> DELETE </code> </a> operations when <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> <code class="literal"> innodb_force_recovery </code> </a> is greater than 0. An <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> <code class="literal"> innodb_force_recovery </code> </a> setting of 4 or greater places <code class="literal"> InnoDB </code> into read-only mode. </p> <p> These restrictions may cause replication administration commands to fail with an error, as replication stores the replica status logs in <code class="literal"> InnoDB </code> tables. </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_fsync_threshold"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> <code class="literal"> innodb_fsync_threshold </code> </a> </p> <a class="indexterm" name="idm46045154994720"> </a> <a class="indexterm" name="idm46045154993680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_fsync_threshold"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-fsync-threshold=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> innodb_fsync_threshold </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 264-1 </code> </td> </tr> </tbody> </table> </div> <p> By default, when <code class="literal"> InnoDB </code> creates a new data file, such as a new log file or tablespace file, the file is fully written to the operating system cache before it is flushed to disk, which can cause a large amount of disk write activity to occur at once. To force smaller, periodic flushes of data from the operating system cache, you can use the <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> <code class="literal"> innodb_fsync_threshold </code> </a> variable to define a threshold value, in bytes. When the byte threshold is reached, the contents of the operating system cache are flushed to disk. The default value of 0 forces the default behavior, which is to flush data to disk only after a file is fully written to the cache. </p> <p> Specifying a threshold to force smaller, periodic flushes may be beneficial in cases where multiple MySQL instances use the same storage devices. For example, creating a new MySQL instance and its associated data files could cause large surges of disk write activity, impeding the performance of other MySQL instances that use the same storage devices. Configuring a threshold helps avoid such surges in write activity. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_aux_table"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_aux_table"> <code class="literal"> innodb_ft_aux_table </code> </a> </p> <a class="indexterm" name="idm46045154960656"> </a> <a class="indexterm" name="idm46045154959616"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_aux_table"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_aux_table"> innodb_ft_aux_table </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> </tbody> </table> </div> <p> Specifies the qualified name of an <code class="literal"> InnoDB </code> table containing a <code class="literal"> FULLTEXT </code> index. This variable is intended for diagnostic purposes and can only be set at runtime. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa51050869"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> innodb_ft_aux_table <span class="token operator">=</span> <span class="token string">'test/t1'</span><span class="token punctuation">;</span></code></pre> </div> <p> After you set this variable to a name in the format <code class="literal"> <em class="replaceable"> <code> db_name </code> </em> / <em class="replaceable"> <code> table_name </code> </em> </code> , the <code class="literal"> INFORMATION_SCHEMA </code> tables <a class="link" href="information-schema-innodb-ft-index-table-table.html" title="28.4.19 The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table"> <code class="literal"> INNODB_FT_INDEX_TABLE </code> </a> , <a class="link" href="information-schema-innodb-ft-index-cache-table.html" title="28.4.18 The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table"> <code class="literal"> INNODB_FT_INDEX_CACHE </code> </a> , <a class="link" href="information-schema-innodb-ft-config-table.html" title="28.4.15 The INFORMATION_SCHEMA INNODB_FT_CONFIG Table"> <code class="literal"> INNODB_FT_CONFIG </code> </a> , <a class="link" href="information-schema-innodb-ft-deleted-table.html" title="28.4.17 The INFORMATION_SCHEMA INNODB_FT_DELETED Table"> <code class="literal"> INNODB_FT_DELETED </code> </a> , and <a class="link" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> <code class="literal"> INNODB_FT_BEING_DELETED </code> </a> show information about the search index for the specified table. </p> <p> For more information, see <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_cache_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> <code class="literal"> innodb_ft_cache_size </code> </a> </p> <a class="indexterm" name="idm46045154927184"> </a> <a class="indexterm" name="idm46045154926144"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_cache_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-cache-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> innodb_ft_cache_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 8000000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1600000 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 80000000 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> The memory allocated, in bytes, for the <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> search index cache, which holds a parsed document in memory while creating an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index. Index inserts and updates are only committed to disk when the <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> <code class="literal"> innodb_ft_cache_size </code> </a> size limit is reached. <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> <code class="literal"> innodb_ft_cache_size </code> </a> defines the cache size on a per table basis. To set a global limit for all tables, see <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> <code class="literal"> innodb_ft_total_cache_size </code> </a> . </p> <p> For more information, see <a class="xref" href="innodb-fulltext-index.html#innodb-fulltext-index-cache" title="InnoDB Full-Text Index Cache"> InnoDB Full-Text Index Cache </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_enable_diag_print"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_diag_print"> <code class="literal"> innodb_ft_enable_diag_print </code> </a> </p> <a class="indexterm" name="idm46045154886528"> </a> <a class="indexterm" name="idm46045154885424"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_enable_diag_print"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-enable-diag-print[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_diag_print"> innodb_ft_enable_diag_print </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Whether to enable additional full-text search (FTS) diagnostic output. This option is primarily intended for advanced FTS debugging and is not of interest to most users. Output is printed to the error log and includes information such as: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> FTS index sync progress (when the FTS cache limit is reached). For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa84819959"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">FTS SYNC for table test<span class="token punctuation">,</span> deleted count<span class="token punctuation">:</span> 100 size<span class="token punctuation">:</span> 10000 bytes SYNC words<span class="token punctuation">:</span> 100</code></pre> </div> </li> <li class="listitem"> <p> FTS optimize progress. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa19082731"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">FTS start optimize test FTS_OPTIMIZE<span class="token punctuation">:</span> optimize <span class="token atrule">"mysql"</span> FTS_OPTIMIZE<span class="token punctuation">:</span> processed <span class="token atrule">"mysql"</span></code></pre> </div> </li> <li class="listitem"> <p> FTS index build progress. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa92060829"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">Number of doc processed<span class="token punctuation">:</span> 1000</code></pre> </div> </li> <li class="listitem"> <p> For FTS queries, the query parsing tree, word weight, query processing time, and memory usage are printed. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa44572851"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">FTS Search Processing time<span class="token punctuation">:</span> 1 secs<span class="token punctuation">:</span> 100 millisec<span class="token punctuation">:</span> row<span class="token punctuation">(</span>s<span class="token punctuation">)</span> 10000 Full Search Memory<span class="token punctuation">:</span> 245666 <span class="token punctuation">(</span>bytes<span class="token punctuation">)</span><span class="token punctuation">,</span> Row<span class="token punctuation">:</span> 10000</code></pre> </div> </li> </ul> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_enable_stopword"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> <code class="literal"> innodb_ft_enable_stopword </code> </a> </p> <a class="indexterm" name="idm46045154852544"> </a> <a class="indexterm" name="idm46045154851440"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_enable_stopword"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-enable-stopword[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> innodb_ft_enable_stopword </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies that a set of <a class="link" href="glossary.html#glos_stopword" title="stopword"> stopwords </a> is associated with an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index at the time the index is created. If the <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> option is set, the stopwords are taken from that table. Else, if the <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> option is set, the stopwords are taken from that table. Otherwise, a built-in set of default stopwords is used. </p> <p> For more information, see <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_max_token_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_max_token_size"> <code class="literal"> innodb_ft_max_token_size </code> </a> </p> <a class="indexterm" name="idm46045154820528"> </a> <a class="indexterm" name="idm46045154819424"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_max_token_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-max-token-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_max_token_size"> innodb_ft_max_token_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 84 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 84 </code> </td> </tr> </tbody> </table> </div> <p> Maximum character length of words that are stored in an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index. Setting a limit on this value reduces the size of the index, thus speeding up queries, by omitting long keywords or arbitrary collections of letters that are not real words and are not likely to be search terms. </p> <p> For more information, see <a class="xref" href="fulltext-fine-tuning.html" title="14.9.6 Fine-Tuning MySQL Full-Text Search"> Section 14.9.6, “Fine-Tuning MySQL Full-Text Search” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_min_token_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_min_token_size"> <code class="literal"> innodb_ft_min_token_size </code> </a> </p> <a class="indexterm" name="idm46045154787184"> </a> <a class="indexterm" name="idm46045154786080"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_min_token_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-min-token-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_min_token_size"> innodb_ft_min_token_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 3 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 16 </code> </td> </tr> </tbody> </table> </div> <p> Minimum length of words that are stored in an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index. Increasing this value reduces the size of the index, thus speeding up queries, by omitting common words that are unlikely to be significant in a search context, such as the English words <span class="quote"> “ <span class="quote"> a </span> ” </span> and <span class="quote"> “ <span class="quote"> to </span> ” </span> . For content using a CJK (Chinese, Japanese, Korean) character set, specify a value of 1. </p> <p> For more information, see <a class="xref" href="fulltext-fine-tuning.html" title="14.9.6 Fine-Tuning MySQL Full-Text Search"> Section 14.9.6, “Fine-Tuning MySQL Full-Text Search” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_num_word_optimize"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_num_word_optimize"> <code class="literal"> innodb_ft_num_word_optimize </code> </a> </p> <a class="indexterm" name="idm46045154752960"> </a> <a class="indexterm" name="idm46045154751856"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_num_word_optimize"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-num-word-optimize=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_num_word_optimize"> innodb_ft_num_word_optimize </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> </tbody> </table> </div> <p> Number of words to process during each <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> operation on an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index. Because a bulk insert or update operation to a table containing a full-text search index could require substantial index maintenance to incorporate all changes, you might do a series of <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> statements, each picking up where the last left off. </p> <p> For more information, see <a class="xref" href="fulltext-fine-tuning.html" title="14.9.6 Fine-Tuning MySQL Full-Text Search"> Section 14.9.6, “Fine-Tuning MySQL Full-Text Search” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_result_cache_limit"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> <code class="literal"> innodb_ft_result_cache_limit </code> </a> </p> <a class="indexterm" name="idm46045154717008"> </a> <a class="indexterm" name="idm46045154715904"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_result_cache_limit"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-result-cache-limit=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> innodb_ft_result_cache_limit </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2000000000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1000000 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 232-1 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> The <code class="literal"> InnoDB </code> full-text search query result cache limit (defined in bytes) per full-text search query or per thread. Intermediate and final <code class="literal"> InnoDB </code> full-text search query results are handled in memory. Use <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> <code class="literal"> innodb_ft_result_cache_limit </code> </a> to place a size limit on the full-text search query result cache to avoid excessive memory consumption in case of very large <code class="literal"> InnoDB </code> full-text search query results (millions or hundreds of millions of rows, for example). Memory is allocated as required when a full-text search query is processed. If the result cache size limit is reached, an error is returned indicating that the query exceeds the maximum allowed memory. </p> <p> The maximum value of <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> <code class="literal"> innodb_ft_result_cache_limit </code> </a> for all platform types and bit sizes is 232-1. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_server_stopword_table"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> </p> <a class="indexterm" name="idm46045154678464"> </a> <a class="indexterm" name="idm46045154677360"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_server_stopword_table"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-server-stopword-table=db_name/table_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> innodb_ft_server_stopword_table </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> This option is used to specify your own <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index stopword list for all <code class="literal"> InnoDB </code> tables. To configure your own stopword list for a specific <code class="literal"> InnoDB </code> table, use <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> . </p> <p> Set <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> to the name of the table containing a list of stopwords, in the format <code class="literal"> <em class="replaceable"> <code> db_name </code> </em> / <em class="replaceable"> <code> table_name </code> </em> </code> . </p> <p> The stopword table must exist before you configure <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> . <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> <code class="literal"> innodb_ft_enable_stopword </code> </a> must be enabled and <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> option must be configured before you create the <code class="literal"> FULLTEXT </code> index. </p> <p> The stopword table must be an <code class="literal"> InnoDB </code> table, containing a single <code class="literal"> VARCHAR </code> column named <code class="literal"> value </code> . </p> <p> For more information, see <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_sort_pll_degree"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_sort_pll_degree"> <code class="literal"> innodb_ft_sort_pll_degree </code> </a> </p> <a class="indexterm" name="idm46045154636544"> </a> <a class="indexterm" name="idm46045154635440"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_sort_pll_degree"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-sort-pll-degree=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_sort_pll_degree"> innodb_ft_sort_pll_degree </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 16 </code> </td> </tr> </tbody> </table> </div> <p> Number of threads used in parallel to index and tokenize text in an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index when building a <a class="link" href="glossary.html#glos_search_index" title="search index"> search index </a> . </p> <p> For related information, see <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> , and <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> <code class="literal"> innodb_sort_buffer_size </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_total_cache_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> <code class="literal"> innodb_ft_total_cache_size </code> </a> </p> <a class="indexterm" name="idm46045154601200"> </a> <a class="indexterm" name="idm46045154600096"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_total_cache_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-total-cache-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> innodb_ft_total_cache_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 640000000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 32000000 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1600000000 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> The total memory allocated, in bytes, for the <code class="literal"> InnoDB </code> full-text search index cache for all tables. Creating numerous tables, each with a <code class="literal"> FULLTEXT </code> search index, could consume a significant portion of available memory. <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> <code class="literal"> innodb_ft_total_cache_size </code> </a> defines a global memory limit for all full-text search indexes to help avoid excessive memory consumption. If the global limit is reached by an index operation, a forced sync is triggered. </p> <p> For more information, see <a class="xref" href="innodb-fulltext-index.html#innodb-fulltext-index-cache" title="InnoDB Full-Text Index Cache"> InnoDB Full-Text Index Cache </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_user_stopword_table"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> </p> <a class="indexterm" name="idm46045154564224"> </a> <a class="indexterm" name="idm46045154563120"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_user_stopword_table"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-user-stopword-table=db_name/table_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> innodb_ft_user_stopword_table </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> This option is used to specify your own <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index stopword list on a specific table. To configure your own stopword list for all <code class="literal"> InnoDB </code> tables, use <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> . </p> <p> Set <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> to the name of the table containing a list of stopwords, in the format <code class="literal"> <em class="replaceable"> <code> db_name </code> </em> / <em class="replaceable"> <code> table_name </code> </em> </code> . </p> <p> The stopword table must exist before you configure <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> . <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> <code class="literal"> innodb_ft_enable_stopword </code> </a> must be enabled and <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> must be configured before you create the <code class="literal"> FULLTEXT </code> index. </p> <p> The stopword table must be an <code class="literal"> InnoDB </code> table, containing a single <code class="literal"> VARCHAR </code> column named <code class="literal"> value </code> . </p> <p> For more information, see <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_idle_flush_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> <code class="literal"> innodb_idle_flush_pct </code> </a> </p> <a class="indexterm" name="idm46045154522976"> </a> <a class="indexterm" name="idm46045154521936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_idle_flush_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-idle-flush-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> innodb_idle_flush_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Limits page flushing when <code class="literal"> InnoDB </code> is idle. The <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> <code class="literal"> innodb_idle_flush_pct </code> </a> value is a percentage of the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> setting, which defines the number of I/O operations per second available to <code class="literal"> InnoDB </code> . For more information, see <a class="xref" href="innodb-buffer-pool-flushing.html#innodb-limit-flushing-rate" title="Limiting Buffer Flushing During Idle Periods"> Limiting Buffer Flushing During Idle Periods </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_io_capacity"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> </p> <a class="indexterm" name="idm46045154487648"> </a> <a class="indexterm" name="idm46045154486608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_io_capacity"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-io-capacity=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> innodb_io_capacity </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Maximum Value (64-bit platforms, 8.4.0) </th> <td> <code class="literal"> 264-1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 232-1 </code> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> variable defines the number of I/O operations per second (IOPS) available to <code class="literal"> InnoDB </code> background tasks, such as <a class="link" href="glossary.html#glos_flush" title="flush"> flushing </a> pages from the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> and merging data from the <a class="link" href="glossary.html#glos_change_buffer" title="change buffer"> change buffer </a> . </p> <p> For information about configuring the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> variable, see <a class="xref" href="innodb-configuring-io-capacity.html" title="17.8.7 Configuring InnoDB I/O Capacity"> Section 17.8.7, “Configuring InnoDB I/O Capacity” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_io_capacity_max"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> </p> <a class="indexterm" name="idm46045154447648"> </a> <a class="indexterm" name="idm46045154446608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_io_capacity_max"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-io-capacity-max=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> innodb_io_capacity_max </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 * innodb_io_capacity </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 232-1 </code> </td> </tr> </tbody> </table> </div> <p> If flushing activity falls behind, <code class="literal"> InnoDB </code> can flush more aggressively, at a higher rate of I/O operations per second (IOPS) than defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> variable. The <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> variable defines a maximum number of IOPS performed by <code class="literal"> InnoDB </code> background tasks in such situations. This option does not control <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> behavior. </p> <p> The default value is twice the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> . </p> <p> For information about configuring the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> variable, see <a class="xref" href="innodb-configuring-io-capacity.html" title="17.8.7 Configuring InnoDB I/O Capacity"> Section 17.8.7, “Configuring InnoDB I/O Capacity” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_limit_optimistic_insert_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_limit_optimistic_insert_debug"> <code class="literal"> innodb_limit_optimistic_insert_debug </code> </a> </p> <a class="indexterm" name="idm46045154407360"> </a> <a class="indexterm" name="idm46045154406272"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_limit_optimistic_insert_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-limit-optimistic-insert-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_limit_optimistic_insert_debug"> innodb_limit_optimistic_insert_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 232-1 </code> </td> </tr> </tbody> </table> </div> <p> Limits the number of records per <a class="link" href="glossary.html#glos_b_tree" title="B-tree"> B-tree </a> page. A default value of 0 means that no limit is imposed. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_lock_wait_timeout"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> </p> <a class="indexterm" name="idm46045154374192"> </a> <a class="indexterm" name="idm46045154373088"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_lock_wait_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-lock-wait-timeout=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> innodb_lock_wait_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1073741824 </code> </td> </tr> <tr> <th> Unit </th> <td> seconds </td> </tr> </tbody> </table> </div> <p> The length of time in seconds an <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_transaction" title="transaction"> transaction </a> waits for a <a class="link" href="glossary.html#glos_row_lock" title="row lock"> row lock </a> before giving up. The default value is 50 seconds. A transaction that tries to access a row that is locked by another <code class="literal"> InnoDB </code> transaction waits at most this many seconds for write access to the row before issuing the following error: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa55581655"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token output">ERROR 1205 (HY000)<span class="token punctuation">:</span> Lock wait timeout exceeded; try restarting transaction</span></code></pre> </div> <p> When a lock wait timeout occurs, the current statement is <a class="link" href="glossary.html#glos_rollback" title="rollback"> rolled back </a> (not the entire transaction). To have the entire transaction roll back, start the server with the <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> <code class="option"> --innodb-rollback-on-timeout </code> </a> option. See also <a class="xref" href="innodb-error-handling.html" title="17.20.5 InnoDB Error Handling"> Section 17.20.5, “InnoDB Error Handling” </a> . </p> <p> You might decrease this value for highly interactive applications or <a class="link" href="glossary.html#glos_oltp" title="OLTP"> OLTP </a> systems, to display user feedback quickly or put the update into a queue for processing later. You might increase this value for long-running back-end operations, such as a transform step in a data warehouse that waits for other large insert or update operations to finish. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> applies to <code class="literal"> InnoDB </code> row locks. A MySQL <a class="link" href="glossary.html#glos_table_lock" title="table lock"> table lock </a> does not happen inside <code class="literal"> InnoDB </code> and this timeout does not apply to waits for table locks. </p> <p> The lock wait timeout value does not apply to <a class="link" href="glossary.html#glos_deadlock" title="deadlock"> deadlocks </a> when <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> <code class="literal"> innodb_deadlock_detect </code> </a> is enabled (the default) because <code class="literal"> InnoDB </code> detects deadlocks immediately and rolls back one of the deadlocked transactions. When <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> <code class="literal"> innodb_deadlock_detect </code> </a> is disabled, <code class="literal"> InnoDB </code> relies on <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> for transaction rollback when a deadlock occurs. See <a class="xref" href="innodb-deadlock-detection.html" title="17.7.5.2 Deadlock Detection"> Section 17.7.5.2, “Deadlock Detection” </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> can be set at runtime with the <code class="literal"> SET GLOBAL </code> or <code class="literal"> SET SESSION </code> statement. Changing the <code class="literal"> GLOBAL </code> setting requires privileges sufficient to set global system variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ) and affects the operation of all clients that subsequently connect. Any client can change the <code class="literal"> SESSION </code> setting for <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> , which affects only that client. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_buffer_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> <code class="literal"> innodb_log_buffer_size </code> </a> </p> <a class="indexterm" name="idm46045154314160"> </a> <a class="indexterm" name="idm46045154313120"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_buffer_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-buffer-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> innodb_log_buffer_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 67108864 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1048576 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> The size in bytes of the buffer that <code class="literal"> InnoDB </code> uses to write to the <a class="link" href="glossary.html#glos_log_file" title="log file"> log files </a> on disk. The default is 64MB. A large <a class="link" href="glossary.html#glos_log_buffer" title="log buffer"> log buffer </a> enables large <a class="link" href="glossary.html#glos_transaction" title="transaction"> transactions </a> to run without the need to write the log to disk before the transactions <a class="link" href="glossary.html#glos_commit" title="commit"> commit </a> . Thus, if you have transactions that update, insert, or delete many rows, making the log buffer larger saves disk I/O. For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-memory-configuration" title="Memory Configuration"> Memory Configuration </a> , and <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_checkpoint_fuzzy_now"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_fuzzy_now"> <code class="literal"> innodb_log_checkpoint_fuzzy_now </code> </a> </p> <a class="indexterm" name="idm46045154277120"> </a> <a class="indexterm" name="idm46045154276016"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_checkpoint_fuzzy_now"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-checkpoint-fuzzy-now[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_fuzzy_now"> innodb_log_checkpoint_fuzzy_now </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enable this debug option to force <code class="literal"> InnoDB </code> to write a fuzzy checkpoint. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_checkpoint_now"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_now"> <code class="literal"> innodb_log_checkpoint_now </code> </a> </p> <a class="indexterm" name="idm46045154248896"> </a> <a class="indexterm" name="idm46045154247792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_checkpoint_now"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-checkpoint-now[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_now"> innodb_log_checkpoint_now </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enable this debug option to force <code class="literal"> InnoDB </code> to write a checkpoint. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_checksums"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> <code class="literal"> innodb_log_checksums </code> </a> </p> <a class="indexterm" name="idm46045154220672"> </a> <a class="indexterm" name="idm46045154219632"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_checksums"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-checksums[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> innodb_log_checksums </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Enables or disables checksums for redo log pages. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> <code class="literal"> innodb_log_checksums=ON </code> </a> enables the <code class="literal"> CRC-32C </code> checksum algorithm for redo log pages. When <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> <code class="literal"> innodb_log_checksums </code> </a> is disabled, the contents of the redo log page checksum field are ignored. </p> <p> Checksums on the redo log header page and redo log checkpoint pages are never disabled. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_compressed_pages"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> <code class="literal"> innodb_log_compressed_pages </code> </a> </p> <a class="indexterm" name="idm46045154190768"> </a> <a class="indexterm" name="idm46045154189664"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_compressed_pages"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-compressed-pages[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> innodb_log_compressed_pages </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies whether images of <a class="link" href="glossary.html#glos_compression" title="compression"> re-compressed </a> <a class="link" href="glossary.html#glos_page" title="page"> pages </a> are written to the <a class="link" href="glossary.html#glos_redo_log" title="redo log"> redo log </a> . Re-compression may occur when changes are made to compressed data. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> <code class="literal"> innodb_log_compressed_pages </code> </a> is enabled by default to prevent corruption that could occur if a different version of the <code class="literal"> zlib </code> compression algorithm is used during recovery. If you are certain that the <code class="literal"> zlib </code> version is not subject to change, you can disable <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> <code class="literal"> innodb_log_compressed_pages </code> </a> to reduce redo log generation for workloads that modify compressed data. </p> <p> To measure the effect of enabling or disabling <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> <code class="literal"> innodb_log_compressed_pages </code> </a> , compare redo log generation for both settings under the same workload. Options for measuring redo log generation include observing the <code class="literal"> Log sequence number </code> (LSN) in the <code class="literal"> LOG </code> section of <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output, or monitoring <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_written"> <code class="literal"> Innodb_os_log_written </code> </a> status for the number of bytes written to the redo log files. </p> <p> For related information, see <a class="xref" href="innodb-performance-compression-oltp.html" title="17.9.1.6 Compression for OLTP Workloads"> Section 17.9.1.6, “Compression for OLTP Workloads” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_file_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> </p> <a class="indexterm" name="idm46045154150720"> </a> <a class="indexterm" name="idm46045154149680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_file_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-file-size=# </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> innodb_log_file_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50331648 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 4194304 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 512GB / innodb_log_files_in_group </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> have been superseded by <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> ; see <a class="xref" href="innodb-redo-log.html" title="17.6.5 Redo Log"> Section 17.6.5, “Redo Log” </a> . </p> </div> <p> The size in bytes of each <a class="link" href="glossary.html#glos_log_file" title="log file"> log file </a> in a <a class="link" href="glossary.html#glos_log_group" title="log group"> log group </a> . The combined size of log files ( <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> ) cannot exceed a maximum value that is slightly less than 512GB. A pair of 255 GB log files, for example, approaches the limit but does not exceed it. The default value is 48MB. </p> <p> Generally, the combined size of the log files should be large enough that the server can smooth out peaks and troughs in workload activity, which often means that there is enough redo log space to handle more than an hour of write activity. The larger the value, the less checkpoint flush activity is required in the buffer pool, saving disk I/O. Larger log files also make <a class="link" href="glossary.html#glos_crash_recovery" title="crash recovery"> crash recovery </a> slower. </p> <p> The minimum <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> is 4MB. </p> <p> For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-log-file-configuration" title="Redo Log Configuration"> Redo Log Configuration </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> <p> If the server is started with <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> , the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> is set automatically if it is not explicitly defined. For more information, see <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_files_in_group"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> </p> <a class="indexterm" name="idm46045154097488"> </a> <a class="indexterm" name="idm46045154096384"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_files_in_group"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-files-in-group=# </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> innodb_log_files_in_group </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> have been superseded by <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> ; see <a class="xref" href="innodb-redo-log.html" title="17.6.5 Redo Log"> Section 17.6.5, “Redo Log” </a> . </p> </div> <p> The number of <a class="link" href="glossary.html#glos_log_file" title="log file"> log files </a> in the <a class="link" href="glossary.html#glos_log_group" title="log group"> log group </a> . <code class="literal"> InnoDB </code> writes to the files in a circular fashion. The default (and recommended) value is 2. The location of the files is specified by <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> <code class="literal"> innodb_log_group_home_dir </code> </a> . The combined size of log files ( <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> ) can be up to 512GB. </p> <p> For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-log-file-configuration" title="Redo Log Configuration"> Redo Log Configuration </a> . </p> <p> If the server is started with <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> , the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> is set automatically if it is not explicitly defined. For more information, see <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_group_home_dir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> <code class="literal"> innodb_log_group_home_dir </code> </a> </p> <a class="indexterm" name="idm46045154048576"> </a> <a class="indexterm" name="idm46045154047472"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_group_home_dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-group-home-dir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> innodb_log_group_home_dir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> </tbody> </table> </div> <p> The directory path to the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_redo_log" title="redo log"> redo log </a> files. </p> <p> For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-log-file-configuration" title="Redo Log Configuration"> Redo Log Configuration </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_spin_cpu_abs_lwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_abs_lwm"> <code class="literal"> innodb_log_spin_cpu_abs_lwm </code> </a> </p> <a class="indexterm" name="idm46045154022624"> </a> <a class="indexterm" name="idm46045154021520"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_spin_cpu_abs_lwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-spin-cpu-abs-lwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_abs_lwm"> innodb_log_spin_cpu_abs_lwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 80 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Defines the minimum amount of CPU usage below which user threads no longer spin while waiting for flushed redo. The value is expressed as a sum of CPU core usage. For example, The default value of 80 is 80% of a single CPU core. On a system with a multi-core processor, a value of 150 represents 100% usage of one CPU core plus 50% usage of a second CPU core. </p> <p> For related information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_spin_cpu_pct_hwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> <code class="literal"> innodb_log_spin_cpu_pct_hwm </code> </a> </p> <a class="indexterm" name="idm46045153990512"> </a> <a class="indexterm" name="idm46045153989408"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_spin_cpu_pct_hwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-spin-cpu-pct-hwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> innodb_log_spin_cpu_pct_hwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Defines the maximum amount of CPU usage above which user threads no longer spin while waiting for flushed redo. The value is expressed as a percentage of the combined total processing power of all CPU cores. The default value is 50%. For example, 100% usage of two CPU cores is 50% of the combined CPU processing power on a server with four CPU cores. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> <code class="literal"> innodb_log_spin_cpu_pct_hwm </code> </a> variable respects processor affinity. For example, if a server has 48 cores but the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process is pinned to only four CPU cores, the other 44 CPU cores are ignored. </p> <p> For related information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_wait_for_flush_spin_hwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_wait_for_flush_spin_hwm"> <code class="literal"> innodb_log_wait_for_flush_spin_hwm </code> </a> </p> <a class="indexterm" name="idm46045153955184"> </a> <a class="indexterm" name="idm46045153954144"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_wait_for_flush_spin_hwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-wait-for-flush-spin-hwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_wait_for_flush_spin_hwm"> innodb_log_wait_for_flush_spin_hwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 400 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value (64-bit platforms, 8.4.0) </th> <td> <code class="literal"> 264-1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 232-1 </code> </td> </tr> <tr> <th> Unit </th> <td> microseconds </td> </tr> </tbody> </table> </div> <p> Defines the maximum average log flush time beyond which user threads no longer spin while waiting for flushed redo. The default value is 400 microseconds. </p> <p> For related information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_write_ahead_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> </p> <a class="indexterm" name="idm46045153918832"> </a> <a class="indexterm" name="idm46045153917728"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_write_ahead_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-write-ahead-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> innodb_log_write_ahead_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 8192 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 512 (log file block size) </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> Equal to innodb_page_size </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Defines the write-ahead block size for the redo log, in bytes. To avoid <span class="quote"> “ <span class="quote"> read-on-write </span> ” </span> , set <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> to match the operating system or file system cache block size. The default setting is 8192 bytes. Read-on-write occurs when redo log blocks are not entirely cached to the operating system or file system due to a mismatch between write-ahead block size for the redo log and operating system or file system cache block size. </p> <p> Valid values for <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> are multiples of the <code class="literal"> InnoDB </code> log file block size (2 <sup> n </sup> ). The minimum value is the <code class="literal"> InnoDB </code> log file block size (512). Write-ahead does not occur when the minimum value is specified. The maximum value is equal to the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value. If you specify a value for <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> that is larger than the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value, the <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> setting is truncated to the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value. </p> <p> Setting the <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> value too low in relation to the operating system or file system cache block size results in <span class="quote"> “ <span class="quote"> read-on-write </span> ” </span> . Setting the value too high may have a slight impact on <code class="literal"> fsync </code> performance for log file writes due to several blocks being written at once. </p> <p> For related information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_writer_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_writer_threads"> <code class="literal"> innodb_log_writer_threads </code> </a> </p> <a class="indexterm" name="idm46045153869616"> </a> <a class="indexterm" name="idm46045153868512"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_writer_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-writer-threads[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_writer_threads"> innodb_log_writer_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Enables dedicated log writer threads for writing redo log records from the log buffer to the system buffers and flushing the system buffers to the redo log files. Dedicated log writer threads can improve performance on high-concurrency systems, but for low-concurrency systems, disabling dedicated log writer threads provides better performance. </p> <p> For more information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_lru_scan_depth"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> </p> <a class="indexterm" name="idm46045153842352"> </a> <a class="indexterm" name="idm46045153841312"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_lru_scan_depth"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-lru-scan-depth=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> innodb_lru_scan_depth </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1024 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Maximum Value (64-bit platforms, 8.4.0) </th> <td> <code class="literal"> 264-1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 232-1 </code> </td> </tr> </tbody> </table> </div> <p> A parameter that influences the algorithms and heuristics for the <a class="link" href="glossary.html#glos_flush" title="flush"> flush </a> operation for the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> . Primarily of interest to performance experts tuning I/O-intensive workloads. It specifies, per buffer pool instance, how far down the buffer pool LRU page list the page cleaner thread scans looking for <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> to flush. This is a background operation performed once per second. </p> <p> A setting smaller than the default is generally suitable for most workloads. A value that is much higher than necessary may impact performance. Only consider increasing the value if you have spare I/O capacity under a typical workload. Conversely, if a write-intensive workload saturates your I/O capacity, decrease the value, especially in the case of a large buffer pool. </p> <p> When tuning <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> , start with a low value and configure the setting upward with the goal of rarely seeing zero free pages. Also, consider adjusting <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> when changing the number of buffer pool instances, since <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> defines the amount of work performed by the page cleaner thread each second. </p> <p> For related information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_dirty_pages_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> </p> <a class="indexterm" name="idm46045153797312"> </a> <a class="indexterm" name="idm46045153796208"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_dirty_pages_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-dirty-pages-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> innodb_max_dirty_pages_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 90 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 99.999 </code> </td> </tr> </tbody> </table> </div> <p> <code class="literal"> InnoDB </code> tries to <a class="link" href="glossary.html#glos_flush" title="flush"> flush </a> data from the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> so that the percentage of <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> does not exceed this value. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> setting establishes a target for flushing activity. It does not affect the rate of flushing. For information about managing the rate of flushing, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> <p> For related information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_dirty_pages_pct_lwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> </p> <a class="indexterm" name="idm46045153758256"> </a> <a class="indexterm" name="idm46045153757152"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_dirty_pages_pct_lwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-dirty-pages-pct-lwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> innodb_max_dirty_pages_pct_lwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 99.999 </code> </td> </tr> </tbody> </table> </div> <p> Defines a low water mark representing the percentage of <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> at which preflushing is enabled to control the dirty page ratio. A value of 0 disables the pre-flushing behavior entirely. The configured value should always be lower than the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> value. For more information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_purge_lag"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> <code class="literal"> innodb_max_purge_lag </code> </a> </p> <a class="indexterm" name="idm46045153724560"> </a> <a class="indexterm" name="idm46045153723520"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_purge_lag"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-purge-lag=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> innodb_max_purge_lag </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Defines the desired maximum purge lag. If this value is exceeded, a delay is imposed on <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , and <a class="link" href="delete.html" title="15.2.2 DELETE Statement"> <code class="literal"> DELETE </code> </a> operations to allow time for purge to catch up. The default value is 0, which means there is no maximum purge lag and no delay. </p> <p> For more information, see <a class="xref" href="innodb-purge-configuration.html" title="17.8.9 Purge Configuration"> Section 17.8.9, “Purge Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_purge_lag_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> <code class="literal"> innodb_max_purge_lag_delay </code> </a> </p> <a class="indexterm" name="idm46045153689040"> </a> <a class="indexterm" name="idm46045153687936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_purge_lag_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-purge-lag-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> innodb_max_purge_lag_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 10000000 </code> </td> </tr> <tr> <th> Unit </th> <td> microseconds </td> </tr> </tbody> </table> </div> <p> Specifies the maximum delay in microseconds for the delay imposed when the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> <code class="literal"> innodb_max_purge_lag </code> </a> threshold is exceeded. The specified <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> <code class="literal"> innodb_max_purge_lag_delay </code> </a> value is an upper limit on the delay period calculated by the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> <code class="literal"> innodb_max_purge_lag </code> </a> formula. </p> <p> For more information, see <a class="xref" href="innodb-purge-configuration.html" title="17.8.9 Purge Configuration"> Section 17.8.9, “Purge Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_undo_log_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> <code class="literal"> innodb_max_undo_log_size </code> </a> </p> <a class="indexterm" name="idm46045153651280"> </a> <a class="indexterm" name="idm46045153650176"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_undo_log_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-undo-log-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> innodb_max_undo_log_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1073741824 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 10485760 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 264-1 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Defines a threshold size for undo tablespaces. If an undo tablespace exceeds the threshold, it can be marked for truncation when <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> <code class="literal"> innodb_undo_log_truncate </code> </a> is enabled. The default value is 1073741824 bytes (1024 MiB). </p> <p> For more information, see <a class="xref" href="innodb-undo-tablespaces.html#truncate-undo-tablespace" title="Truncating Undo Tablespaces"> Truncating Undo Tablespaces </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_merge_threshold_set_all_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_merge_threshold_set_all_debug"> <code class="literal"> innodb_merge_threshold_set_all_debug </code> </a> </p> <a class="indexterm" name="idm46045153615856"> </a> <a class="indexterm" name="idm46045153614768"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_merge_threshold_set_all_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-merge-threshold-set-all-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_merge_threshold_set_all_debug"> innodb_merge_threshold_set_all_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 50 </code> </td> </tr> </tbody> </table> </div> <p> Defines a page-full percentage value for index pages that overrides the current <code class="literal"> MERGE_THRESHOLD </code> setting for all indexes that are currently in the dictionary cache. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. For related information, see <a class="xref" href="index-page-merge-threshold.html" title="17.8.11 Configuring the Merge Threshold for Index Pages"> Section 17.8.11, “Configuring the Merge Threshold for Index Pages” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_monitor_disable"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> <code class="literal"> innodb_monitor_disable </code> </a> </p> <a class="indexterm" name="idm46045153582000"> </a> <a class="indexterm" name="idm46045153580960"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_monitor_disable"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-monitor-disable={counter\|module\|pattern\|all} </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> innodb_monitor_disable </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> </tbody> </table> </div> <p> This variable acts as a switch, disabling <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_metrics_counter" title="metrics counter"> metrics counters </a> . Counter data may be queried using the Information Schema <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> <code class="literal"> INNODB_METRICS </code> </a> table. For usage information, see <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> <code class="literal"> innodb_monitor_disable='latch' </code> </a> disables statistics collection for <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB MUTEX </code> </a> . For more information, see <a class="xref" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> Section 15.7.7.16, “SHOW ENGINE Statement” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_monitor_enable"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> <code class="literal"> innodb_monitor_enable </code> </a> </p> <a class="indexterm" name="idm46045153551408"> </a> <a class="indexterm" name="idm46045153550368"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_monitor_enable"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-monitor-enable={counter\|module\|pattern\|all} </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> innodb_monitor_enable </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> </tbody> </table> </div> <p> This variable acts as a switch, enabling <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_metrics_counter" title="metrics counter"> metrics counters </a> . Counter data may be queried using the Information Schema <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> <code class="literal"> INNODB_METRICS </code> </a> table. For usage information, see <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> . </p> <p> </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> <code class="literal"> innodb_monitor_enable='latch' </code> </a> enables statistics collection for <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB MUTEX </code> </a> . For more information, see <a class="xref" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> Section 15.7.7.16, “SHOW ENGINE Statement” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_monitor_reset"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> <code class="literal"> innodb_monitor_reset </code> </a> </p> <a class="indexterm" name="idm46045153520688"> </a> <a class="indexterm" name="idm46045153519648"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_monitor_reset"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-monitor-reset={counter\|module\|pattern\|all} </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> innodb_monitor_reset </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> counter </code> </p> <p class="valid-value"> <code class="literal"> module </code> </p> <p class="valid-value"> <code class="literal"> pattern </code> </p> <p class="valid-value"> <code class="literal"> all </code> </p> </td> </tr> </tbody> </table> </div> <p> This variable acts as a switch, resetting the count value for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_metrics_counter" title="metrics counter"> metrics counters </a> to zero. Counter data may be queried using the Information Schema <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> <code class="literal"> INNODB_METRICS </code> </a> table. For usage information, see <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> <code class="literal"> innodb_monitor_reset='latch' </code> </a> resets statistics reported by <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB MUTEX </code> </a> . For more information, see <a class="xref" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> Section 15.7.7.16, “SHOW ENGINE Statement” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_monitor_reset_all"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset_all"> <code class="literal"> innodb_monitor_reset_all </code> </a> </p> <a class="indexterm" name="idm46045153482096"> </a> <a class="indexterm" name="idm46045153480992"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_monitor_reset_all"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-monitor-reset-all={counter\|module\|pattern\|all} </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset_all"> innodb_monitor_reset_all </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> counter </code> </p> <p class="valid-value"> <code class="literal"> module </code> </p> <p class="valid-value"> <code class="literal"> pattern </code> </p> <p class="valid-value"> <code class="literal"> all </code> </p> </td> </tr> </tbody> </table> </div> <p> This variable acts as a switch, resetting all values (minimum, maximum, and so on) for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_metrics_counter" title="metrics counter"> metrics counters </a> . Counter data may be queried using the Information Schema <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> <code class="literal"> INNODB_METRICS </code> </a> table. For usage information, see <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_numa_interleave"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> <code class="literal"> innodb_numa_interleave </code> </a> </p> <a class="indexterm" name="idm46045153446976"> </a> <a class="indexterm" name="idm46045153445936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_numa_interleave"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-numa-interleave[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> innodb_numa_interleave </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Enables the NUMA interleave memory policy for allocation of the <code class="literal"> InnoDB </code> buffer pool. When <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> <code class="literal"> innodb_numa_interleave </code> </a> is enabled, the NUMA memory policy is set to <code class="literal"> MPOL_INTERLEAVE </code> for the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process. After the <code class="literal"> InnoDB </code> buffer pool is allocated, the NUMA memory policy is set back to <code class="literal"> MPOL_DEFAULT </code> . For the <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> <code class="literal"> innodb_numa_interleave </code> </a> option to be available, MySQL must be compiled on a NUMA-enabled Linux system. The default value is <code class="literal"> ON </code> if the system supports it, otherwise it defaults to <code class="literal"> OFF </code> . </p> <p> <span class="command"> <strong> CMake </strong> </span> sets the default <a class="link" href="source-configuration-options.html#option_cmake_with_numa"> <code class="option"> WITH_NUMA </code> </a> value based on whether the current platform has <code class="literal"> NUMA </code> support. For more information, see <a class="xref" href="source-configuration-options.html" title="2.8.7 MySQL Source-Configuration Options"> Section 2.8.7, “MySQL Source-Configuration Options” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_old_blocks_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> <code class="literal"> innodb_old_blocks_pct </code> </a> </p> <a class="indexterm" name="idm46045153409360"> </a> <a class="indexterm" name="idm46045153408320"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_old_blocks_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-old-blocks-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> innodb_old_blocks_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 37 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 95 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the approximate percentage of the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> used for the old block <a class="link" href="glossary.html#glos_sublist" title="sublist"> sublist </a> . The range of values is 5 to 95. The default value is 37 (that is, 3/8 of the pool). Often used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> <code class="literal"> innodb_old_blocks_time </code> </a> . </p> <p> For more information, see <a class="xref" href="innodb-performance-midpoint_insertion.html" title="17.8.3.3 Making the Buffer Pool Scan Resistant"> Section 17.8.3.3, “Making the Buffer Pool Scan Resistant” </a> . For information about buffer pool management, the <a class="link" href="glossary.html#glos_lru" title="LRU"> LRU </a> algorithm, and <a class="link" href="glossary.html#glos_eviction" title="eviction"> eviction </a> policies, see <a class="xref" href="innodb-buffer-pool.html" title="17.5.1 Buffer Pool"> Section 17.5.1, “Buffer Pool” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_old_blocks_time"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> <code class="literal"> innodb_old_blocks_time </code> </a> </p> <a class="indexterm" name="idm46045153371456"> </a> <a class="indexterm" name="idm46045153370416"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_old_blocks_time"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-old-blocks-time=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> innodb_old_blocks_time </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 232-1 </code> </td> </tr> <tr> <th> Unit </th> <td> milliseconds </td> </tr> </tbody> </table> </div> <p> Non-zero values protect against the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> being filled by data that is referenced only for a brief period, such as during a <a class="link" href="glossary.html#glos_full_table_scan" title="full table scan"> full table scan </a> . Increasing this value offers more protection against full table scans interfering with data cached in the buffer pool. </p> <p> Specifies how long in milliseconds a block inserted into the old <a class="link" href="glossary.html#glos_sublist" title="sublist"> sublist </a> must stay there after its first access before it can be moved to the new sublist. If the value is 0, a block inserted into the old sublist moves immediately to the new sublist the first time it is accessed, no matter how soon after insertion the access occurs. If the value is greater than 0, blocks remain in the old sublist until an access occurs at least that many milliseconds after the first access. For example, a value of 1000 causes blocks to stay in the old sublist for 1 second after the first access before they become eligible to move to the new sublist. </p> <p> The default value is 1000. </p> <p> This variable is often used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> <code class="literal"> innodb_old_blocks_pct </code> </a> . For more information, see <a class="xref" href="innodb-performance-midpoint_insertion.html" title="17.8.3.3 Making the Buffer Pool Scan Resistant"> Section 17.8.3.3, “Making the Buffer Pool Scan Resistant” </a> . For information about buffer pool management, the <a class="link" href="glossary.html#glos_lru" title="LRU"> LRU </a> algorithm, and <a class="link" href="glossary.html#glos_eviction" title="eviction"> eviction </a> policies, see <a class="xref" href="innodb-buffer-pool.html" title="17.5.1 Buffer Pool"> Section 17.5.1, “Buffer Pool” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_online_alter_log_max_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> <code class="literal"> innodb_online_alter_log_max_size </code> </a> </p> <a class="indexterm" name="idm46045153329728"> </a> <a class="indexterm" name="idm46045153328624"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_online_alter_log_max_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-online-alter-log-max-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> innodb_online_alter_log_max_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 134217728 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 65536 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2*64-1 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Specifies an upper limit in bytes on the size of the temporary log files used during <a class="link" href="glossary.html#glos_online_ddl" title="online DDL"> online DDL </a> operations for <code class="literal"> InnoDB </code> tables. There is one such log file for each index being created or table being altered. This log file stores data inserted, updated, or deleted in the table during the DDL operation. The temporary log file is extended when needed by the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> <code class="literal"> innodb_sort_buffer_size </code> </a> , up to the maximum specified by <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> <code class="literal"> innodb_online_alter_log_max_size </code> </a> . If a temporary log file exceeds the upper size limit, the <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operation fails and all uncommitted concurrent DML operations are rolled back. Thus, a large value for this option allows more DML to happen during an online DDL operation, but also extends the period of time at the end of the DDL operation when the table is locked to apply the data from the log. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_open_files"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> </p> <a class="indexterm" name="idm46045153290896"> </a> <a class="indexterm" name="idm46045153289856"> </a> <a class="indexterm" name="idm46045153288368"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_open_files"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-open-files=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> innodb_open_files </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> -1 </code> (signifies autosizing; do not assign this literal value) </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2147483647 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the maximum number of files that <code class="literal"> InnoDB </code> can have open at one time. The minimum value is 10. If <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> is disabled, the default value is 300; otherwise, the default value is 300 or the <a class="link" href="server-system-variables.html#sysvar_table_open_cache"> <code class="literal"> table_open_cache </code> </a> setting, whichever is higher. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> limit can be set at runtime using a <code class="literal"> SELECT innodb_set_open_files_limit( <em class="replaceable"> <code> N </code> </em> ) </code> statement, where <em class="replaceable"> <code> N </code> </em> is the desired <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> limit; for example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa50026232"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> innodb_set_open_files_limit<span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> The statement executes a stored procedure that sets the new limit. If the procedure is successful, it returns the value of the newly set limit; otherwise, a failure message is returned. </p> <p> It is not permitted to set <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> using a <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement. To set <code class="literal"> innodb_open_files </code> at runtime, use the <code class="literal"> SELECT innodb_set_open_files_limit( <em class="replaceable"> <code> N </code> </em> ) </code> statement described above. </p> <p> Setting <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files=default </code> </a> is not supported. Only integer values are permitted. </p> <p> To prevent non-LRU managed files from consuming the entire <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> limit, non-LRU managed files are limited to 90 percent of this limit, which reserves 10 percent of it for LRU managed files. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_optimize_fulltext_only"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_optimize_fulltext_only"> <code class="literal"> innodb_optimize_fulltext_only </code> </a> </p> <a class="indexterm" name="idm46045153239056"> </a> <a class="indexterm" name="idm46045153237952"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_optimize_fulltext_only"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-optimize-fulltext-only[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_optimize_fulltext_only"> innodb_optimize_fulltext_only </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Changes the way <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> operates on <code class="literal"> InnoDB </code> tables. Intended to be enabled temporarily, during maintenance operations for <code class="literal"> InnoDB </code> tables with <code class="literal"> FULLTEXT </code> indexes. </p> <p> By default, <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> reorganizes data in the <a class="link" href="glossary.html#glos_clustered_index" title="clustered index"> clustered index </a> of the table. When this option is enabled, <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> skips the reorganization of table data, and instead processes newly added, deleted, and updated token data for <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> indexes. For more information, see <a class="xref" href="fulltext-fine-tuning.html#fulltext-optimize" title="Optimizing InnoDB Full-Text Indexes"> Optimizing InnoDB Full-Text Indexes </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_page_cleaners"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> <code class="literal"> innodb_page_cleaners </code> </a> </p> <a class="indexterm" name="idm46045153203808"> </a> <a class="indexterm" name="idm46045153202768"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_page_cleaners"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-page-cleaners=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> innodb_page_cleaners </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> innodb_buffer_pool_instances </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> The number of page cleaner threads that flush dirty pages from buffer pool instances. Page cleaner threads perform flush list and LRU flushing. When there are multiple page cleaner threads, buffer pool flushing tasks for each buffer pool instance are dispatched to idle page cleaner threads. The <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> <code class="literal"> innodb_page_cleaners </code> </a> default value is set to the same value as <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . If the specified number of page cleaner threads exceeds the number of buffer pool instances, then <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> <code class="literal"> innodb_page_cleaners </code> </a> is automatically set to the same value as <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . </p> <p> If your workload is write-IO bound when flushing dirty pages from buffer pool instances to data files, and if your system hardware has available capacity, increasing the number of page cleaner threads may help improve write-IO throughput. </p> <p> Multithreaded page cleaner support extends to shutdown and recovery phases. </p> <p> The <code class="literal"> setpriority() </code> system call is used on Linux platforms where it is supported, and where the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> execution user is authorized to give <code class="literal"> page_cleaner </code> threads priority over other MySQL and <code class="literal"> InnoDB </code> threads to help page flushing keep pace with the current workload. <code class="literal"> setpriority() </code> support is indicated by this <code class="literal"> InnoDB </code> startup message: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa59335561"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token punctuation">[</span>Note<span class="token punctuation">]</span> InnoDB<span class="token punctuation">:</span> If the mysqld execution user is authorized<span class="token punctuation">,</span> page cleaner thread priority can be changed<span class="token punctuation">.</span> See the man page of setpriority<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span></code></pre> </div> <p> For systems where server startup and shutdown is not managed by systemd, <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> execution user authorization can be configured in <code class="filename"> /etc/security/limits.conf </code> . For example, if <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> is run under the <code class="literal"> mysql </code> user, you can authorize the <code class="literal"> mysql </code> user by adding these lines to <code class="filename"> /etc/security/limits.conf </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa42253882"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini">mysql hard nice -20 mysql soft nice -20</code></pre> </div> <p> For systemd managed systems, the same can be achieved by specifying <code class="literal"> LimitNICE=-20 </code> in a localized systemd configuration file. For example, create a file named <code class="filename"> override.conf </code> in <code class="filename"> /etc/systemd/system/mysqld.service.d/override.conf </code> and add this entry: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa78683224"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[Service]</span> <span class="token constant">LimitNICE</span><span class="token attr-value"><span class="token punctuation">=</span>-20</span></code></pre> </div> <p> After creating or changing <code class="filename"> override.conf </code> , reload the systemd configuration, then tell systemd to restart the MySQL service: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa91362659"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini">systemctl daemon-reload systemctl restart mysqld <span class="token comment" spellcheck="true"># RPM platforms</span> systemctl restart mysql <span class="token comment" spellcheck="true"># Debian platforms</span></code></pre> </div> <p> For more information about using a localized systemd configuration file, see <a class="xref" href="using-systemd.html#systemd-mysql-configuration" title="Configuring systemd for MySQL"> Configuring systemd for MySQL </a> . </p> <p> After authorizing the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> execution user, use the <span class="command"> <strong> cat </strong> </span> command to verify the configured <code class="literal"> Nice </code> limits for the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa80479455"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">cat</span> /proc/<em class="replaceable">mysqld_pid</em>/limits \| grep nice Max nice priority 18446744073709551596 18446744073709551596</code></pre> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_page_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> </p> <a class="indexterm" name="idm46045153139920"> </a> <a class="indexterm" name="idm46045153138832"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_page_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-page-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> innodb_page_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 16384 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 4096 </code> </p> <p class="valid-value"> <code class="literal"> 8192 </code> </p> <p class="valid-value"> <code class="literal"> 16384 </code> </p> <p class="valid-value"> <code class="literal"> 32768 </code> </p> <p class="valid-value"> <code class="literal"> 65536 </code> </p> </td> </tr> </tbody> </table> </div> <p> Specifies the <a class="link" href="glossary.html#glos_page_size" title="page size"> page size </a> for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_tablespace" title="tablespace"> tablespaces </a> . Values can be specified in bytes or kilobytes. For example, a 16 kilobyte page size value can be specified as 16384, 16KB, or 16k. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> can only be configured prior to initializing the MySQL instance and cannot be changed afterward. If no value is specified, the instance is initialized using the default page size. See <a class="xref" href="innodb-init-startup-configuration.html" title="17.8.1 InnoDB Startup Configuration"> Section 17.8.1, “InnoDB Startup Configuration” </a> . </p> <p> For both 32KB and 64KB page sizes, the maximum row length is approximately 16000 bytes. <code class="literal"> ROW_FORMAT=COMPRESSED </code> is not supported when <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> is set to 32KB or 64KB. For <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size=32KB </code> </a> , extent size is 2MB. For <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size=64KB </code> </a> , extent size is 4MB. <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> <code class="literal"> innodb_log_buffer_size </code> </a> should be set to at least 16MB (the default is 64MB) when using 32KB or 64KB page sizes. </p> <p> The default 16KB page size or larger is appropriate for a wide range of <a class="link" href="glossary.html#glos_workload" title="workload"> workloads </a> , particularly for queries involving table scans and DML operations involving bulk updates. Smaller page sizes might be more efficient for <a class="link" href="glossary.html#glos_oltp" title="OLTP"> OLTP </a> workloads involving many small writes, where contention can be an issue when single pages contain many rows. Smaller pages might also be efficient with <a class="link" href="glossary.html#glos_ssd" title="SSD"> SSD </a> storage devices, which typically use small block sizes. Keeping the <code class="literal"> InnoDB </code> page size close to the storage device block size minimizes the amount of unchanged data that is rewritten to disk. </p> <p> The minimum file size for the first system tablespace data file ( <code class="literal"> ibdata1 </code> ) differs depending on the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value. See the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> option description for more information. </p> <p> A MySQL instance using a particular <code class="literal"> InnoDB </code> page size cannot use data files or log files from an instance that uses a different page size. </p> <p> For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_parallel_read_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> <code class="literal"> innodb_parallel_read_threads </code> </a> </p> <a class="indexterm" name="idm46045153085744"> </a> <a class="indexterm" name="idm46045153084640"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_parallel_read_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-parallel-read-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> innodb_parallel_read_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> (available logical processors / 8), min of 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 256 </code> </td> </tr> </tbody> </table> </div> <p> Defines the number of threads that can be used for parallel clustered index reads. Parallel scanning of partitions is also supported. Parallel read threads can improve <a class="link" href="check-table.html" title="15.7.3.2 CHECK TABLE Statement"> <code class="literal"> CHECK TABLE </code> </a> performance. <code class="literal"> InnoDB </code> reads the clustered index twice during a <a class="link" href="check-table.html" title="15.7.3.2 CHECK TABLE Statement"> <code class="literal"> CHECK TABLE </code> </a> operation. The second read can be performed in parallel. This feature does not apply to secondary index scans. The <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> <code class="literal"> innodb_parallel_read_threads </code> </a> session variable must be set to a value greater than 1 for parallel clustered index reads to occur. The actual number of threads used to perform a parallel clustered index read is determined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> <code class="literal"> innodb_parallel_read_threads </code> </a> setting or the number of index subtrees to scan, whichever is smaller. The pages read into the buffer pool during the scan are kept at the tail of the buffer pool LRU list so that they can be discarded quickly when free buffer pool pages are required. </p> <p> The maximum number of parallel read threads (256) is the total number of threads for all client connections. If the thread limit is reached, connections fall back to using a single thread. The default value is calculated by the number of available logical processors on the system divided by 8, with a minimum default value of 4. </p> <p> Before MySQL 8.4, the default value was always 4. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_print_all_deadlocks"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_all_deadlocks"> <code class="literal"> innodb_print_all_deadlocks </code> </a> </p> <a class="indexterm" name="idm46045153047264"> </a> <a class="indexterm" name="idm46045153046160"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_print_all_deadlocks"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-print-all-deadlocks[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_all_deadlocks"> innodb_print_all_deadlocks </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045153024448"> </a> <p> When this option is enabled, information about all <a class="link" href="glossary.html#glos_deadlock" title="deadlock"> deadlocks </a> in <code class="literal"> InnoDB </code> user transactions is recorded in the <code class="literal"> mysqld </code> <a class="link" href="error-log.html" title="7.4.2 The Error Log"> error log </a> . Otherwise, you see information about only the last deadlock, using the <code class="literal"> SHOW ENGINE INNODB STATUS </code> statement. An occasional <code class="literal"> InnoDB </code> deadlock is not necessarily an issue, because <code class="literal"> InnoDB </code> detects the condition immediately and rolls back one of the transactions automatically. You might use this option to troubleshoot why deadlocks are occurring if an application does not have appropriate error-handling logic to detect the rollback and retry its operation. A large number of deadlocks might indicate the need to restructure transactions that issue <a class="link" href="glossary.html#glos_dml" title="DML"> DML </a> or <code class="literal"> SELECT ... FOR UPDATE </code> statements for multiple tables, so that each transaction accesses the tables in the same order, thus avoiding the deadlock condition. </p> <p> For related information, see <a class="xref" href="innodb-deadlocks.html" title="17.7.5 Deadlocks in InnoDB"> Section 17.7.5, “Deadlocks in InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_print_ddl_logs"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_ddl_logs"> <code class="literal"> innodb_print_ddl_logs </code> </a> </p> <a class="indexterm" name="idm46045153011760"> </a> <a class="indexterm" name="idm46045153010720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_print_ddl_logs"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-print-ddl-logs[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_ddl_logs"> innodb_print_ddl_logs </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enabling this option causes MySQL to write DDL logs to <code class="literal"> stderr </code> . For more information, see <a class="xref" href="atomic-ddl.html#atomic-ddl-view-logs" title="Viewing DDL Logs"> Viewing DDL Logs </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_purge_batch_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> </p> <a class="indexterm" name="idm46045152984688"> </a> <a class="indexterm" name="idm46045152983648"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_purge_batch_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-purge-batch-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> innodb_purge_batch_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 300 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 5000 </code> </td> </tr> </tbody> </table> </div> <p> Defines the number of undo log pages that purge parses and processes in one batch from the <a class="link" href="glossary.html#glos_history_list" title="history list"> history list </a> . In a multithreaded purge configuration, the coordinator purge thread divides <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> by <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> <code class="literal"> innodb_purge_threads </code> </a> and assigns that number of pages to each purge thread. The <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> variable also defines the number of undo log pages that purge frees after every 128 iterations through the undo logs. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> option is intended for advanced performance tuning in combination with the <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> <code class="literal"> innodb_purge_threads </code> </a> setting. Most users need not change <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> from its default value. </p> <p> For related information, see <a class="xref" href="innodb-purge-configuration.html" title="17.8.9 Purge Configuration"> Section 17.8.9, “Purge Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_purge_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> <code class="literal"> innodb_purge_threads </code> </a> </p> <a class="indexterm" name="idm46045152943488"> </a> <a class="indexterm" name="idm46045152942448"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_purge_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-purge-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> innodb_purge_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 if # of available logical processors is <= 16; otherwise 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 32 </code> </td> </tr> </tbody> </table> </div> <p> The number of background threads devoted to the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_purge" title="purge"> purge </a> operation. Increasing the value creates additional purge threads, which can improve efficiency on systems where <a class="link" href="glossary.html#glos_dml" title="DML"> DML </a> operations are performed on multiple tables. </p> <p> For related information, see <a class="xref" href="innodb-purge-configuration.html" title="17.8.9 Purge Configuration"> Section 17.8.9, “Purge Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_purge_rseg_truncate_frequency"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> <code class="literal"> innodb_purge_rseg_truncate_frequency </code> </a> </p> <a class="indexterm" name="idm46045152909168"> </a> <a class="indexterm" name="idm46045152908128"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_purge_rseg_truncate_frequency"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-purge-rseg-truncate-frequency=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> innodb_purge_rseg_truncate_frequency </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 128 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 128 </code> </td> </tr> </tbody> </table> </div> <p> Defines the frequency with which the purge system frees rollback segments in terms of the number of times that purge is invoked. An undo tablespace cannot be truncated until its rollback segments are freed. Normally, the purge system frees rollback segments once every 128 times that purge is invoked. The default value is 128. Reducing this value increases the frequency with which the purge thread frees rollback segments. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> <code class="literal"> innodb_purge_rseg_truncate_frequency </code> </a> is intended for use with <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> <code class="literal"> innodb_undo_log_truncate </code> </a> . For more information, see <a class="xref" href="innodb-undo-tablespaces.html#truncate-undo-tablespace" title="Truncating Undo Tablespaces"> Truncating Undo Tablespaces </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_random_read_ahead"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_random_read_ahead"> <code class="literal"> innodb_random_read_ahead </code> </a> </p> <a class="indexterm" name="idm46045152874432"> </a> <a class="indexterm" name="idm46045152873328"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_random_read_ahead"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-random-read-ahead[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_random_read_ahead"> innodb_random_read_ahead </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables the random <a class="link" href="glossary.html#glos_read_ahead" title="read-ahead"> read-ahead </a> technique for optimizing <code class="literal"> InnoDB </code> I/O. </p> <p> For details about performance considerations for different types of read-ahead requests, see <a class="xref" href="innodb-performance-read_ahead.html" title="17.8.3.4 Configuring InnoDB Buffer Pool Prefetching (Read-Ahead)"> Section 17.8.3.4, “Configuring InnoDB Buffer Pool Prefetching (Read-Ahead)” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_read_ahead_threshold"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> <code class="literal"> innodb_read_ahead_threshold </code> </a> </p> <a class="indexterm" name="idm46045309042080"> </a> <a class="indexterm" name="idm46045309041040"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_read_ahead_threshold"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-read-ahead-threshold=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> innodb_read_ahead_threshold </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 56 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> Controls the sensitivity of linear <a class="link" href="glossary.html#glos_read_ahead" title="read-ahead"> read-ahead </a> that <code class="literal"> InnoDB </code> uses to prefetch pages into the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> . If <code class="literal"> InnoDB </code> reads at least <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> <code class="literal"> innodb_read_ahead_threshold </code> </a> pages sequentially from an <a class="link" href="glossary.html#glos_extent" title="extent"> extent </a> (64 pages), it initiates an asynchronous read for the entire following extent. The permissible range of values is 0 to 64. A value of 0 disables read-ahead. For the default of 56, <code class="literal"> InnoDB </code> must read at least 56 pages sequentially from an extent to initiate an asynchronous read for the following extent. </p> <p> Knowing how many pages are read through the read-ahead mechanism, and how many of these pages are evicted from the buffer pool without ever being accessed, can be useful when fine-tuning the <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> <code class="literal"> innodb_read_ahead_threshold </code> </a> setting. <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output displays counter information from the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead"> <code class="literal"> Innodb_buffer_pool_read_ahead </code> </a> and <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_evicted"> <code class="literal"> Innodb_buffer_pool_read_ahead_evicted </code> </a> global status variables, which report the number of pages brought into the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> by read-ahead requests, and the number of such pages <a class="link" href="glossary.html#glos_eviction" title="eviction"> evicted </a> from the buffer pool without ever being accessed, respectively. The status variables report global values since the last server restart. </p> <p> <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> also shows the rate at which the read-ahead pages are read and the rate at which such pages are evicted without being accessed. The per-second averages are based on the statistics collected since the last invocation of <code class="literal"> SHOW ENGINE INNODB STATUS </code> and are displayed in the <code class="literal"> BUFFER POOL AND MEMORY </code> section of the <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output. </p> <p> For more information, see <a class="xref" href="innodb-performance-read_ahead.html" title="17.8.3.4 Configuring InnoDB Buffer Pool Prefetching (Read-Ahead)"> Section 17.8.3.4, “Configuring InnoDB Buffer Pool Prefetching (Read-Ahead)” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_read_io_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> <code class="literal"> innodb_read_io_threads </code> </a> </p> <a class="indexterm" name="idm46045308991376"> </a> <a class="indexterm" name="idm46045308990336"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_read_io_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-read-io-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> innodb_read_io_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> (available logical processors / 2), min of 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> The number of I/O threads for read operations in <code class="literal"> InnoDB </code> . Its counterpart for write threads is <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> . For more information, see <a class="xref" href="innodb-performance-multiple_io_threads.html" title="17.8.5 Configuring the Number of Background InnoDB I/O Threads"> Section 17.8.5, “Configuring the Number of Background InnoDB I/O Threads” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . The default value is the number of available logical processors on the system divided by 2, with a minimum default value of 4. </p> <p> Before MySQL 8.4, the default value was always 4. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> On Linux systems, running multiple MySQL servers (typically more than 12) with default settings for <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> <code class="literal"> innodb_read_io_threads </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> , and the Linux <code class="literal"> aio-max-nr </code> setting can exceed system limits. Ideally, increase the <code class="literal"> aio-max-nr </code> setting; as a workaround, you might reduce the settings for one or both of the MySQL variables. </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_read_only"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> <code class="literal"> innodb_read_only </code> </a> </p> <a class="indexterm" name="idm46045308952064"> </a> <a class="indexterm" name="idm46045308950976"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_read_only"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-read-only[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> innodb_read_only </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Starts <code class="literal"> InnoDB </code> in read-only mode. For distributing database applications or data sets on read-only media. Can also be used in data warehouses to share the same data directory between multiple instances. For more information, see <a class="xref" href="innodb-read-only-instance.html" title="17.8.2 Configuring InnoDB for Read-Only Operation"> Section 17.8.2, “Configuring InnoDB for Read-Only Operation” </a> . </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> <code class="literal"> innodb_read_only </code> </a> prevents creating and dropping tables for all storage engines, and not only <code class="literal"> InnoDB </code> . Table creation and drop operations for any storage engine modify data dictionary tables in the <code class="literal"> mysql </code> system database, but those tables use the <code class="literal"> InnoDB </code> storage engine and cannot be modified when <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> <code class="literal"> innodb_read_only </code> </a> is enabled. The same principle applies to other table operations that require modifying data dictionary tables. Examples: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If the <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> <code class="literal"> innodb_read_only </code> </a> system variable is enabled, <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> may fail because it cannot update statistics tables in the data dictionary, which use <code class="literal"> InnoDB </code> . For <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> operations that update the key distribution, failure may occur even if the operation updates the table itself (for example, if it is a <code class="literal"> MyISAM </code> table). To obtain the updated distribution statistics, set <a class="link" href="server-system-variables.html#sysvar_information_schema_stats_expiry"> <code class="literal"> information_schema_stats_expiry=0 </code> </a> . </p> </li> <li class="listitem"> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE <em class="replaceable"> <code> tbl_name </code> </em> ENGINE= <em class="replaceable"> <code> engine_name </code> </em> </code> </a> fails because it updates the storage engine designation, which is stored in the data dictionary. </p> </li> </ul> </div> <p> In addition, other tables in the <code class="literal"> mysql </code> system database use the <code class="literal"> InnoDB </code> storage engine. Making those tables read-only results in restrictions on operations that modify them. Examples: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Account-management statements such as <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> and <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> fail because the grant tables use <code class="literal"> InnoDB </code> . </p> </li> <li class="listitem"> <p> The <a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> <code class="literal"> INSTALL PLUGIN </code> </a> and <a class="link" href="uninstall-plugin.html" title="15.7.4.6 UNINSTALL PLUGIN Statement"> <code class="literal"> UNINSTALL PLUGIN </code> </a> plugin-management statements fail because the <code class="literal"> mysql.plugin </code> system table uses <code class="literal"> InnoDB </code> . </p> </li> <li class="listitem"> <p> The <a class="link" href="create-function-loadable.html" title="15.7.4.1 CREATE FUNCTION Statement for Loadable Functions"> <code class="literal"> CREATE FUNCTION </code> </a> and <a class="link" href="drop-function-loadable.html" title="15.7.4.2 DROP FUNCTION Statement for Loadable Functions"> <code class="literal"> DROP FUNCTION </code> </a> loadable function-management statements fail because the <code class="literal"> mysql.func </code> system table uses <code class="literal"> InnoDB </code> . </p> </li> </ul> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_redo_log_archive_dirs"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_archive_dirs"> <code class="literal"> innodb_redo_log_archive_dirs </code> </a> </p> <a class="indexterm" name="idm46045152799920"> </a> <a class="indexterm" name="idm46045152798912"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_redo_log_archive_dirs"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-redo-log-archive-dirs </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_archive_dirs"> innodb_redo_log_archive_dirs </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> Defines labeled directories where redo log archive files can be created. You can define multiple labeled directories in a semicolon-separated list. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa2846136"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">innodb_redo_log_archive_dirs</span><span class="token attr-value"><span class="token punctuation">=</span>'label1:/backups1;label2:/backups2'</span></code></pre> </div> <p> A label can be any string of characters, with the exception of colons (:), which are not permitted. An empty label is also permitted, but the colon (:) is still required in this case. </p> <p> A path must be specified, and the directory must exist. The path can contain colons (':'), but semicolons (;) are not permitted. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_redo_log_capacity"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> </p> <a class="indexterm" name="idm46045152773584"> </a> <a class="indexterm" name="idm46045152772576"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_redo_log_capacity"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-redo-log-capacity=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> innodb_redo_log_capacity </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 104857600 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 8388608 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 549755813888 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Defines the amount of disk space occupied by redo log files. </p> <p> <code class="literal"> innodb_redo_log_capacity </code> supercedes the <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> variables, which are both ignored if <code class="literal"> innodb_redo_log_capacity </code> is defined. </p> <p> If <code class="literal"> innodb_redo_log_capacity </code> is not defined, and if neither <code class="literal"> innodb_log_file_size </code> or <code class="literal"> innodb_log_files_in_group </code> are defined, then the default <code class="literal"> innodb_redo_log_capacity </code> value is used. </p> <p> If <code class="literal"> innodb_redo_log_capacity </code> is not defined, and if <code class="literal"> innodb_log_file_size </code> and/or <code class="literal"> innodb_log_files_in_group </code> is defined, then the InnoDB redo log capacity is calculated as <span class="emphasis"> <em> (innodb_log_files_in_group innodb_log_file_size) </em> </span> . This calculation does not modify the unused <code class="literal"> innodb_redo_log_capacity </code> setting's value. </p> <p> The <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_capacity_resized"> <code class="literal"> Innodb_redo_log_capacity_resized </code> </a> server status variable indicates the total redo log capacity for all redo log files. </p> <p> If the server is started with <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> , the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> is set automatically if it is not explicitly defined. For more information, see <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> . </p> <p> For more information, see <a class="xref" href="innodb-redo-log.html" title="17.6.5 Redo Log"> Section 17.6.5, “Redo Log” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_redo_log_encrypt"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_encrypt"> <code class="literal"> innodb_redo_log_encrypt </code> </a> </p> <a class="indexterm" name="idm46045152727616"> </a> <a class="indexterm" name="idm46045152726608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_redo_log_encrypt"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-redo-log-encrypt[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_encrypt"> innodb_redo_log_encrypt </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Controls encryption of redo log data for tables encrypted using the <code class="literal"> InnoDB </code> <a class="link" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> data-at-rest encryption feature </a> . Encryption of redo log data is disabled by default. For more information, see <a class="xref" href="innodb-data-encryption.html#innodb-data-encryption-redo-log" title="Redo Log Encryption"> Redo Log Encryption </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_replication_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_replication_delay"> <code class="literal"> innodb_replication_delay </code> </a> </p> <a class="indexterm" name="idm46045152701680"> </a> <a class="indexterm" name="idm46045152700672"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_replication_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-replication-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_replication_delay"> innodb_replication_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> <tr> <th> Unit </th> <td> milliseconds </td> </tr> </tbody> </table> </div> <p> The replication thread delay in milliseconds on a replica server if <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> is reached. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_rollback_on_timeout"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> <code class="literal"> innodb_rollback_on_timeout </code> </a> </p> <a class="indexterm" name="idm46045152669920"> </a> <a class="indexterm" name="idm46045152668912"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_rollback_on_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-rollback-on-timeout[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> innodb_rollback_on_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_rollback" title="rollback"> rolls back </a> only the last statement on a transaction timeout by default. If <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> <code class="option"> --innodb-rollback-on-timeout </code> </a> is specified, a transaction timeout causes <code class="literal"> InnoDB </code> to abort and roll back the entire transaction. </p> <p> For more information, see <a class="xref" href="innodb-error-handling.html" title="17.20.5 InnoDB Error Handling"> Section 17.20.5, “InnoDB Error Handling” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_rollback_segments"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> <code class="literal"> innodb_rollback_segments </code> </a> </p> <a class="indexterm" name="idm46045152642192"> </a> <a class="indexterm" name="idm46045152641184"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_rollback_segments"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-rollback-segments=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> innodb_rollback_segments </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 128 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 128 </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> <code class="literal"> innodb_rollback_segments </code> </a> defines the number of <a class="link" href="glossary.html#glos_rollback_segment" title="rollback segment"> rollback segments </a> allocated to each undo tablespace and the global temporary tablespace for transactions that generate undo records. The number of transactions that each rollback segment supports depends on the <code class="literal"> InnoDB </code> page size and the number of undo logs assigned to each transaction. For more information, see <a class="xref" href="innodb-undo-logs.html" title="17.6.6 Undo Logs"> Section 17.6.6, “Undo Logs” </a> . </p> <p> For related information, see <a class="xref" href="innodb-multi-versioning.html" title="17.3 InnoDB Multi-Versioning"> Section 17.3, “InnoDB Multi-Versioning” </a> . For information about undo tablespaces, see <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_saved_page_number_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> <code class="literal"> innodb_saved_page_number_debug </code> </a> </p> <a class="indexterm" name="idm46045152608944"> </a> <a class="indexterm" name="idm46045152607936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_saved_page_number_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-saved-page-number-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> innodb_saved_page_number_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> </tbody> </table> </div> <p> Saves a page number. Setting the <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> option dirties the page defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> <code class="literal"> innodb_saved_page_number_debug </code> </a> . The <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> <code class="literal"> innodb_saved_page_number_debug </code> </a> option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_segment_reserve_factor"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> <code class="literal"> innodb_segment_reserve_factor </code> </a> </p> <a class="indexterm" name="idm46045152575728"> </a> <a class="indexterm" name="idm46045152574720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_segment_reserve_factor"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-segment-reserve-factor=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> innodb_segment_reserve_factor </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 12.5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0.03 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 40 </code> </td> </tr> </tbody> </table> </div> <p> Defines the percentage of tablespace file segment pages reserved as empty pages. The setting is applicable to file-per-table and general tablespaces. The <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> <code class="literal"> innodb_segment_reserve_factor </code> </a> default setting is 12.5 percent, which is the same percentage of pages reserved in previous MySQL releases. </p> <p> For more information, see <a class="xref" href="innodb-file-space.html#innodb-config-reserved-file-segment-pages" title="Configuring the Percentage of Reserved File Segment Pages"> Configuring the Percentage of Reserved File Segment Pages </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_sort_buffer_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> <code class="literal"> innodb_sort_buffer_size </code> </a> </p> <a class="indexterm" name="idm46045152544816"> </a> <a class="indexterm" name="idm46045152543808"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_sort_buffer_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-sort-buffer-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> innodb_sort_buffer_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1048576 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 65536 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 67108864 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> This variable defines the amount by which the temporary log file is extended when recording concurrent DML during an <a class="link" href="glossary.html#glos_online_ddl" title="online DDL"> online DDL </a> operation, and the size of the temporary log file read buffer and write buffer. </p> <p> For more information, see <a class="xref" href="innodb-online-ddl-space-requirements.html" title="17.12.3 Online DDL Space Requirements"> Section 17.12.3, “Online DDL Space Requirements” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_spin_wait_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_delay"> <code class="literal"> innodb_spin_wait_delay </code> </a> </p> <a class="indexterm" name="idm46045152512368"> </a> <a class="indexterm" name="idm46045152511360"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_spin_wait_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-spin-wait-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_delay"> innodb_spin_wait_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 6 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> </tbody> </table> </div> <p> The maximum delay between polls for a <a class="link" href="glossary.html#glos_spin" title="spin"> spin </a> lock. The low-level implementation of this mechanism varies depending on the combination of hardware and operating system, so the delay does not correspond to a fixed time interval. </p> <p> Can be used in combination with the <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> <code class="literal"> innodb_spin_wait_pause_multiplier </code> </a> variable for greater control over the duration of spin-lock polling delays. </p> <p> For more information, see <a class="xref" href="innodb-performance-spin_lock_polling.html" title="17.8.8 Configuring Spin Lock Polling"> Section 17.8.8, “Configuring Spin Lock Polling” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_spin_wait_pause_multiplier"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> <code class="literal"> innodb_spin_wait_pause_multiplier </code> </a> </p> <a class="indexterm" name="idm46045152480288"> </a> <a class="indexterm" name="idm46045152479280"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_spin_wait_pause_multiplier"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-spin-wait-pause-multiplier=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> innodb_spin_wait_pause_multiplier </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Defines a multiplier value used to determine the number of PAUSE instructions in spin-wait loops that occur when a thread waits to acquire a mutex or rw-lock. </p> <p> For more information, see <a class="xref" href="innodb-performance-spin_lock_polling.html" title="17.8.8 Configuring Spin Lock Polling"> Section 17.8.8, “Configuring Spin Lock Polling” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_auto_recalc"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_auto_recalc"> <code class="literal"> innodb_stats_auto_recalc </code> </a> </p> <a class="indexterm" name="idm46045152450528"> </a> <a class="indexterm" name="idm46045152449520"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_auto_recalc"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-auto-recalc[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_auto_recalc"> innodb_stats_auto_recalc </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Causes <code class="literal"> InnoDB </code> to automatically recalculate <a class="link" href="glossary.html#glos_persistent_statistics" title="persistent statistics"> persistent statistics </a> after the data in a table is changed substantially. The threshold value is 10% of the rows in the table. This setting applies to tables created when the <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> option is enabled. Automatic statistics recalculation may also be configured by specifying <code class="literal"> STATS_AUTO_RECALC=1 </code> in a <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> or <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statement. The amount of data sampled to produce the statistics is controlled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> variable. </p> <p> For more information, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_include_delete_marked"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> <code class="literal"> innodb_stats_include_delete_marked </code> </a> </p> <a class="indexterm" name="idm46045152419360"> </a> <a class="indexterm" name="idm46045152418352"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_include_delete_marked"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-include-delete-marked[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> innodb_stats_include_delete_marked </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> By default, <code class="literal"> InnoDB </code> reads uncommitted data when calculating statistics. In the case of an uncommitted transaction that deletes rows from a table, <code class="literal"> InnoDB </code> excludes records that are delete-marked when calculating row estimates and index statistics, which can lead to non-optimal execution plans for other transactions that are operating on the table concurrently using a transaction isolation level other than <a class="link" href="innodb-transaction-isolation-levels.html#isolevel_read-uncommitted"> <code class="literal"> READ UNCOMMITTED </code> </a> . To avoid this scenario, <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> <code class="literal"> innodb_stats_include_delete_marked </code> </a> can be enabled to ensure that <code class="literal"> InnoDB </code> includes delete-marked records when calculating persistent optimizer statistics. </p> <p> When <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> <code class="literal"> innodb_stats_include_delete_marked </code> </a> is enabled, <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> considers delete-marked records when recalculating statistics. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> <code class="literal"> innodb_stats_include_delete_marked </code> </a> is a global setting that affects all <code class="literal"> InnoDB </code> tables. It is only applicable to persistent optimizer statistics. </p> <p> For related information, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_method"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> </p> <a class="indexterm" name="idm46045152385456"> </a> <a class="indexterm" name="idm46045152384448"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_method"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-method=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> innodb_stats_method </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> nulls_equal </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> nulls_equal </code> </p> <p class="valid-value"> <code class="literal"> nulls_unequal </code> </p> <p class="valid-value"> <code class="literal"> nulls_ignored </code> </p> </td> </tr> </tbody> </table> </div> <p> How the server treats <code class="literal"> NULL </code> values when collecting <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> about the distribution of index values for <code class="literal"> InnoDB </code> tables. Permitted values are <code class="literal"> nulls_equal </code> , <code class="literal"> nulls_unequal </code> , and <code class="literal"> nulls_ignored </code> . For <code class="literal"> nulls_equal </code> , all <code class="literal"> NULL </code> index values are considered equal and form a single value group with a size equal to the number of <code class="literal"> NULL </code> values. For <code class="literal"> nulls_unequal </code> , <code class="literal"> NULL </code> values are considered unequal, and each <code class="literal"> NULL </code> forms a distinct value group of size 1. For <code class="literal"> nulls_ignored </code> , <code class="literal"> NULL </code> values are ignored. </p> <p> The method used to generate table statistics influences how the optimizer chooses indexes for query execution, as described in <a class="xref" href="index-statistics.html" title="10.3.8 InnoDB and MyISAM Index Statistics Collection"> Section 10.3.8, “InnoDB and MyISAM Index Statistics Collection” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_on_metadata"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> <code class="literal"> innodb_stats_on_metadata </code> </a> </p> <a class="indexterm" name="idm46045152346944"> </a> <a class="indexterm" name="idm46045152345936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_on_metadata"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-on-metadata[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> innodb_stats_on_metadata </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> This option only applies when optimizer <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> are configured to be non-persistent. Optimizer statistics are not persisted to disk when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is disabled or when individual tables are created or altered with <code class="literal"> STATS_PERSISTENT=0 </code> . For more information, see <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> . </p> <p> When <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> <code class="literal"> innodb_stats_on_metadata </code> </a> is enabled, <code class="literal"> InnoDB </code> updates non-persistent <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> when metadata statements such as <a class="link" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement"> <code class="literal"> SHOW TABLE STATUS </code> </a> or when accessing the Information Schema <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> or <a class="link" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table"> <code class="literal"> STATISTICS </code> </a> tables. (These updates are similar to what happens for <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> .) When disabled, <code class="literal"> InnoDB </code> does not update statistics during these operations. Leaving the setting disabled can improve access speed for schemas that have a large number of tables or indexes. It can also improve the stability of <a class="link" href="glossary.html#glos_query_execution_plan" title="query execution plan"> execution plans </a> for queries that involve <code class="literal"> InnoDB </code> tables. </p> <p> To change the setting, issue the statement <code class="literal"> SET GLOBAL innodb_stats_on_metadata= <em class="replaceable"> <code> mode </code> </em> </code> , where <code class="literal"> <em class="replaceable"> <code> mode </code> </em> </code> is either <code class="literal"> ON </code> or <code class="literal"> OFF </code> (or <code class="literal"> 1 </code> or <code class="literal"> 0 </code> ). Changing the setting requires privileges sufficient to set global system variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ) and immediately affects the operation of all connections. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_persistent"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> </p> <a class="indexterm" name="idm46045152305872"> </a> <a class="indexterm" name="idm46045152304864"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_persistent"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-persistent[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> innodb_stats_persistent </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies whether <code class="literal"> InnoDB </code> index statistics are persisted to disk. Otherwise, statistics may be recalculated frequently which can lead to variations in <a class="link" href="glossary.html#glos_query_execution_plan" title="query execution plan"> query execution plans </a> . This setting is stored with each table when the table is created. You can set <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> at the global level before creating a table, or use the <code class="literal"> STATS_PERSISTENT </code> clause of the <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> and <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements to override the system-wide setting and configure persistent statistics for individual tables. </p> <p> For more information, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_persistent_sample_pages"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> </p> <a class="indexterm" name="idm46045152275648"> </a> <a class="indexterm" name="idm46045152274640"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_persistent_sample_pages"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-persistent-sample-pages=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> innodb_stats_persistent_sample_pages </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 20 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 18446744073709551615 </code> </td> </tr> </tbody> </table> </div> <p> The number of index <a class="link" href="glossary.html#glos_page" title="page"> pages </a> to sample when estimating <a class="link" href="glossary.html#glos_cardinality" title="cardinality"> cardinality </a> and other <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> for an indexed column, such as those calculated by <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> . Increasing the value improves the accuracy of index statistics, which can improve the <a class="link" href="glossary.html#glos_query_execution_plan" title="query execution plan"> query execution plan </a> , at the expense of increased I/O during the execution of <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> for an <code class="literal"> InnoDB </code> table. For more information, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Setting a high value for <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> could result in lengthy <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> execution time. To estimate the number of database pages accessed by <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> , see <a class="xref" href="innodb-analyze-table-complexity.html" title="17.8.10.3 Estimating ANALYZE TABLE Complexity for InnoDB Tables"> Section 17.8.10.3, “Estimating ANALYZE TABLE Complexity for InnoDB Tables” </a> . </p> </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> only applies when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is enabled for a table; when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is disabled, <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> <code class="literal"> innodb_stats_transient_sample_pages </code> </a> applies instead. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_transient_sample_pages"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> <code class="literal"> innodb_stats_transient_sample_pages </code> </a> </p> <a class="indexterm" name="idm46045152232384"> </a> <a class="indexterm" name="idm46045152231376"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_transient_sample_pages"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-transient-sample-pages=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> innodb_stats_transient_sample_pages </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 8 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 18446744073709551615 </code> </td> </tr> </tbody> </table> </div> <p> The number of index <a class="link" href="glossary.html#glos_page" title="page"> pages </a> to sample when estimating <a class="link" href="glossary.html#glos_cardinality" title="cardinality"> cardinality </a> and other <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> for an indexed column, such as those calculated by <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> . The default value is 8. Increasing the value improves the accuracy of index statistics, which can improve the <a class="link" href="glossary.html#glos_query_execution_plan" title="query execution plan"> query execution plan </a> , at the expense of increased I/O when opening an <code class="literal"> InnoDB </code> table or recalculating statistics. For more information, see <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Setting a high value for <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> <code class="literal"> innodb_stats_transient_sample_pages </code> </a> could result in lengthy <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> execution time. To estimate the number of database pages accessed by <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> , see <a class="xref" href="innodb-analyze-table-complexity.html" title="17.8.10.3 Estimating ANALYZE TABLE Complexity for InnoDB Tables"> Section 17.8.10.3, “Estimating ANALYZE TABLE Complexity for InnoDB Tables” </a> . </p> </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> <code class="literal"> innodb_stats_transient_sample_pages </code> </a> only applies when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is disabled for a table; when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is enabled, <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> applies instead. Takes the place of <code class="literal"> innodb_stats_sample_pages </code> that was removed in MySQL 8.0. For more information, see <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_status_output"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output"> <code class="literal"> innodb_status_output </code> </a> </p> <a class="indexterm" name="idm46045152188688"> </a> <a class="indexterm" name="idm46045152187680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_status_output"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-status-output[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output"> innodb_status_output </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables or disables periodic output for the standard <code class="literal"> InnoDB </code> Monitor. Also used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> <code class="literal"> innodb_status_output_locks </code> </a> to enable or disable periodic output for the <code class="literal"> InnoDB </code> Lock Monitor. For more information, see <a class="xref" href="innodb-enabling-monitors.html" title="17.17.2 Enabling InnoDB Monitors"> Section 17.17.2, “Enabling InnoDB Monitors” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_status_output_locks"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> <code class="literal"> innodb_status_output_locks </code> </a> </p> <a class="indexterm" name="idm46045152161728"> </a> <a class="indexterm" name="idm46045152160720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_status_output_locks"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-status-output-locks[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> innodb_status_output_locks </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables or disables the <code class="literal"> InnoDB </code> Lock Monitor. When enabled, the <code class="literal"> InnoDB </code> Lock Monitor prints additional information about locks in <code class="literal"> SHOW ENGINE INNODB STATUS </code> output and in periodic output printed to the MySQL error log. Periodic output for the <code class="literal"> InnoDB </code> Lock Monitor is printed as part of the standard <code class="literal"> InnoDB </code> Monitor output. The standard <code class="literal"> InnoDB </code> Monitor must therefore be enabled for the <code class="literal"> InnoDB </code> Lock Monitor to print data to the MySQL error log periodically. For more information, see <a class="xref" href="innodb-enabling-monitors.html" title="17.17.2 Enabling InnoDB Monitors"> Section 17.17.2, “Enabling InnoDB Monitors” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_strict_mode"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> </p> <a class="indexterm" name="idm46045152132448"> </a> <a class="indexterm" name="idm46045152131440"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_strict_mode"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-strict-mode[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> innodb_strict_mode </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> When <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> is enabled, <code class="literal"> InnoDB </code> returns errors rather than warnings when checking for invalid or incompatible table options. </p> <p> It checks that <code class="literal"> KEY_BLOCK_SIZE </code> , <code class="literal"> ROW_FORMAT </code> , <code class="literal"> DATA DIRECTORY </code> , <code class="literal"> TEMPORARY </code> , and <code class="literal"> TABLESPACE </code> options are compatible with each other and other settings. </p> <p> <code class="literal"> innodb_strict_mode=ON </code> also enables a row size check when creating or altering a table, to prevent <code class="literal"> INSERT </code> or <code class="literal"> UPDATE </code> from failing due to the record being too large for the selected page size. <code class="literal"> </code> </p> <p> You can enable or disable <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> on the command line when starting <code class="literal"> mysqld </code> , or in a MySQL <a class="link" href="glossary.html#glos_configuration_file" title="configuration file"> configuration file </a> . You can also enable or disable <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> at runtime with the statement <code class="literal"> SET [GLOBAL\|SESSION] innodb_strict_mode= <em class="replaceable"> <code> mode </code> </em> </code> , where <code class="literal"> <em class="replaceable"> <code> mode </code> </em> </code> is either <code class="literal"> ON </code> or <code class="literal"> OFF </code> . Changing the <code class="literal"> GLOBAL </code> setting requires privileges sufficient to set global system variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ) and affects the operation of all clients that subsequently connect. Any client can change the <code class="literal"> SESSION </code> setting for <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> , and the setting affects only that client. </p> <p> Setting the session value of this system variable is a restricted operation. The session user must have privileges sufficient to set restricted session variables. See <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_sync_array_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_array_size"> <code class="literal"> innodb_sync_array_size </code> </a> </p> <a class="indexterm" name="idm46045152089488"> </a> <a class="indexterm" name="idm46045152088480"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_sync_array_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-sync-array-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_array_size"> innodb_sync_array_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1024 </code> </td> </tr> </tbody> </table> </div> <p> Defines the size of the mutex/lock wait array. Increasing the value splits the internal data structure used to coordinate threads, for higher concurrency in workloads with large numbers of waiting threads. This setting must be configured when the MySQL instance is starting up, and cannot be changed afterward. Increasing the value is recommended for workloads that frequently produce a large number of waiting threads, typically greater than 768. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_sync_spin_loops"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_spin_loops"> <code class="literal"> innodb_sync_spin_loops </code> </a> </p> <a class="indexterm" name="idm46045152060256"> </a> <a class="indexterm" name="idm46045152059248"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_sync_spin_loops"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-sync-spin-loops=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_spin_loops"> innodb_sync_spin_loops </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 30 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> The number of times a thread waits for an <code class="literal"> InnoDB </code> mutex to be freed before the thread is suspended. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_sync_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_debug"> <code class="literal"> innodb_sync_debug </code> </a> </p> <a class="indexterm" name="idm46045152030800"> </a> <a class="indexterm" name="idm46045152029792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_sync_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-sync-debug[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_debug"> innodb_sync_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables sync debug checking for the <code class="literal"> InnoDB </code> storage engine. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_table_locks"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> <code class="literal"> innodb_table_locks </code> </a> </p> <a class="indexterm" name="idm46045152004688"> </a> <a class="indexterm" name="idm46045152003680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_table_locks"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-table-locks[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> innodb_table_locks </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> If <a class="link" href="server-system-variables.html#sysvar_autocommit"> <code class="literal"> autocommit = 0 </code> </a> , <code class="literal"> InnoDB </code> honors <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES </code> </a> ; MySQL does not return from <code class="literal"> LOCK TABLES ... WRITE </code> until all other threads have released all their locks to the table. The default value of <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> <code class="literal"> innodb_table_locks </code> </a> is 1, which means that <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES </code> </a> causes InnoDB to lock a table internally if <a class="link" href="server-system-variables.html#sysvar_autocommit"> <code class="literal"> autocommit = 0 </code> </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> <code class="literal"> innodb_table_locks = 0 </code> </a> has no effect for tables locked explicitly with <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES ... WRITE </code> </a> . It does have an effect for tables locked for read or write by <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES ... WRITE </code> </a> implicitly (for example, through triggers) or by <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES ... READ </code> </a> . </p> <p> For related information, see <a class="xref" href="innodb-locking-transaction-model.html" title="17.7 InnoDB Locking and Transaction Model"> Section 17.7, “InnoDB Locking and Transaction Model” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_temp_data_file_path"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> </p> <a class="indexterm" name="idm46045151968816"> </a> <a class="indexterm" name="idm46045151967808"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_temp_data_file_path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-temp-data-file-path=file_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> innodb_temp_data_file_path </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ibtmp1:12M:autoextend </code> </td> </tr> </tbody> </table> </div> <p> Defines the relative path, name, size, and attributes of global temporary tablespace data files. The global temporary tablespace stores rollback segments for changes made to user-created temporary tables. </p> <p> If no value is specified for <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> , the default behavior is to create a single auto-extending data file named <code class="filename"> ibtmp1 </code> in the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> directory. The initial file size is slightly larger than 12MB. </p> <p> The syntax for a global temporary tablespace data file specification includes the file name, file size, and <code class="literal"> autoextend </code> and <code class="literal"> max </code> attributes: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa16657423"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none"><em class="replaceable">file_name</em>:<em class="replaceable">file_size</em>[:autoextend[:max:<em class="replaceable">max_file_size</em>]]</code></pre> </div> <p> The global temporary tablespace data file cannot have the same name as another <code class="literal"> InnoDB </code> data file. Any inability or error creating the global temporary tablespace data file is treated as fatal and server startup is refused. </p> <p> File sizes are specified in KB, MB, or GB by appending <code class="literal"> K </code> , <code class="literal"> M </code> or <code class="literal"> G </code> to the size value. The sum of file sizes must be slightly larger than 12MB. </p> <p> The size limit of individual files is determined by the operating system. File size can be more than 4GB on operating systems that support large files. Use of raw disk partitions for global temporary tablespace data files is not supported. </p> <p> The <code class="literal"> autoextend </code> and <code class="literal"> max </code> attributes can be used only for the data file specified last in the <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> setting. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa43730906"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">innodb_temp_data_file_path</span><span class="token attr-value"><span class="token punctuation">=</span>ibtmp1:50M;ibtmp2:12M:autoextend:max:500M</span></code></pre> </div> <p> The <code class="literal"> autoextend </code> option causes the data file to automatically increase in size when it runs out of free space. The <code class="literal"> autoextend </code> increment is 64MB by default. To modify the increment, change the <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> <code class="literal"> innodb_autoextend_increment </code> </a> variable setting. </p> <p> The directory path for global temporary tablespace data files is formed by concatenating the paths defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> . </p> <p> Before running <code class="literal"> InnoDB </code> in read-only mode, set <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> to a location outside of the data directory. The path must be relative to the data directory. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa54676602"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token constant">--innodb-temp-data-file-path</span><span class="token attr-value"><span class="token punctuation">=</span>../../../tmp/ibtmp1:12M:autoextend</span></code></pre> </div> <p> For more information, see <a class="xref" href="innodb-temporary-tablespace.html#innodb-global-temporary-tablespace" title="Global Temporary Tablespace"> Global Temporary Tablespace </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_temp_tablespaces_dir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_tablespaces_dir"> <code class="literal"> innodb_temp_tablespaces_dir </code> </a> </p> <a class="indexterm" name="idm46045151920192"> </a> <a class="indexterm" name="idm46045151919184"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_temp_tablespaces_dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-temp-tablespaces-dir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_tablespaces_dir"> innodb_temp_tablespaces_dir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> #innodb_temp </code> </td> </tr> </tbody> </table> </div> <p> Defines the location where <code class="literal"> InnoDB </code> creates a pool of session temporary tablespaces at startup. The default location is the <code class="filename"> #innodb_temp </code> directory in the data directory. A fully qualified path or path relative to the data directory is permitted. </p> <p> Session temporary tablespaces always store user-created temporary tables and internal temporary tables created by the optimizer using <code class="literal"> InnoDB </code> . (Previously, the on-disk storage engine for internal temporary tables was determined by the <a class="ulink" href="/doc/refman/8.0/en/server-system-variables.html#sysvar_internal_tmp_disk_storage_engine" target="_top"> <code class="literal"> internal_tmp_disk_storage_engine </code> </a> system variable, which is no longer supported. See <a class="xref" href="internal-temporary-tables.html#internal-temporary-tables-engines-disk" title="Storage Engine for On-Disk Internal Temporary Tables"> Storage Engine for On-Disk Internal Temporary Tables </a> .) </p> <p> For more information, see <a class="xref" href="innodb-temporary-tablespace.html#innodb-session-temporary-tablespaces" title="Session Temporary Tablespaces"> Session Temporary Tablespaces </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_thread_concurrency"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> </p> <a class="indexterm" name="idm46045151890768"> </a> <a class="indexterm" name="idm46045151889760"> </a> <a class="indexterm" name="idm46045151888368"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_thread_concurrency"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-thread-concurrency=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> innodb_thread_concurrency </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> </tbody> </table> </div> <p> Defines the maximum number of threads permitted inside of <code class="literal"> InnoDB </code> . A value of 0 (the default) is interpreted as infinite concurrency (no limit). This variable is intended for performance tuning on high concurrency systems. </p> <p> <code class="literal"> InnoDB </code> tries to keep the number of threads inside <code class="literal"> InnoDB </code> less than or equal to the <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> limit. Threads waiting for locks are not counted in the number of concurrently executing threads. </p> <p> The correct setting depends on workload and computing environment. Consider setting this variable if your MySQL instance shares CPU resources with other applications or if your workload or number of concurrent users is growing. Test a range of values to determine the setting that provides the best performance. <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> is a dynamic variable, which permits experimenting with different settings on a live test system. If a particular setting performs poorly, you can quickly set <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> back to 0. </p> <p> Use the following guidelines to help find and maintain an appropriate setting: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If the number of concurrent user threads for a workload is consistently small and does not affect performance, set <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency=0 </code> </a> (no limit). </p> </li> <li class="listitem"> <p> If your workload is consistently heavy or occasionally spikes, set an <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> value and adjust it until you find the number of threads that provides the best performance. For example, suppose that your system typically has 40 to 50 users, but periodically the number increases to 60, 70, or more. Through testing, you find that performance remains largely stable with a limit of 80 concurrent users. In this case, set <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> to 80. </p> </li> <li class="listitem"> <p> If you do not want <code class="literal"> InnoDB </code> to use more than a certain number of virtual CPUs for user threads (20 virtual CPUs, for example), set <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> to this number (or possibly lower, depending on performance testing). If your goal is to isolate MySQL from other applications, consider binding the <code class="literal"> mysqld </code> process exclusively to the virtual CPUs. Be aware, however, that exclusive binding can result in non-optimal hardware usage if the <code class="literal"> mysqld </code> process is not consistently busy. In this case, you can bind the <code class="literal"> mysqld </code> process to the virtual CPUs but allow other applications to use some or all of the virtual CPUs. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> From an operating system perspective, using a resource management solution to manage how CPU time is shared among applications may be preferable to binding the <code class="literal"> mysqld </code> process. For example, you could assign 90% of virtual CPU time to a given application while other critical processes <span class="emphasis"> <em> are not </em> </span> running, and scale that value back to 40% when other critical processes <span class="emphasis"> <em> are </em> </span> running. </p> </div> </li> <li class="listitem"> <p> In some cases, the optimal <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> setting can be smaller than the number of virtual CPUs. </p> </li> <li class="listitem"> <p> An <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> value that is too high can cause performance regression due to increased contention on system internals and resources. </p> </li> <li class="listitem"> <p> Monitor and analyze your system regularly. Changes to workload, number of users, or computing environment may require that you adjust the <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> setting. </p> </li> </ul> </div> <p> A value of 0 disables the <code class="literal"> queries inside InnoDB </code> and <code class="literal"> queries in queue </code> counters in the <code class="literal"> ROW OPERATIONS </code> section of <code class="literal"> SHOW ENGINE INNODB STATUS </code> output. </p> <p> For related information, see <a class="xref" href="innodb-performance-thread_concurrency.html" title="17.8.4 Configuring Thread Concurrency for InnoDB"> Section 17.8.4, “Configuring Thread Concurrency for InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_thread_sleep_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> </p> <a class="indexterm" name="idm46045151830448"> </a> <a class="indexterm" name="idm46045151829440"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_thread_sleep_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-thread-sleep-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> innodb_thread_sleep_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000000 </code> </td> </tr> <tr> <th> Unit </th> <td> microseconds </td> </tr> </tbody> </table> </div> <p> How long <code class="literal"> InnoDB </code> threads sleep before joining the <code class="literal"> InnoDB </code> queue, in microseconds. The default value is 10000. A value of 0 disables sleep. You can set <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> <code class="literal"> innodb_adaptive_max_sleep_delay </code> </a> to the highest value you would allow for <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> , and <code class="literal"> InnoDB </code> automatically adjusts <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> up or down depending on current thread-scheduling activity. This dynamic adjustment helps the thread scheduling mechanism to work smoothly during times when the system is lightly loaded or when it is operating near full capacity. </p> <p> For more information, see <a class="xref" href="innodb-performance-thread_concurrency.html" title="17.8.4 Configuring Thread Concurrency for InnoDB"> Section 17.8.4, “Configuring Thread Concurrency for InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_tmpdir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> </p> <a class="indexterm" name="idm46045151793552"> </a> <a class="indexterm" name="idm46045151792544"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_tmpdir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-tmpdir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> innodb_tmpdir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> Used to define an alternate directory for temporary sort files created during online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations that rebuild the table. </p> <p> Online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations that rebuild the table also create an <span class="emphasis"> <em> intermediate </em> </span> table file in the same directory as the original table. The <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> option is not applicable to intermediate table files. </p> <p> A valid value is any directory path other than the MySQL data directory path. If the value is NULL (the default), temporary files are created MySQL temporary directory ( <code class="literal"> $TMPDIR </code> on Unix, <code class="literal"> %TEMP% </code> on Windows, or the directory specified by the <a class="link" href="server-system-variables.html#sysvar_tmpdir"> <code class="literal"> --tmpdir </code> </a> configuration option). If a directory is specified, existence of the directory and permissions are only checked when <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> is configured using a <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement. If a symlink is provided in a directory string, the symlink is resolved and stored as an absolute path. The path should not exceed 512 bytes. An online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operation reports an error if <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> is set to an invalid directory. <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> overrides the MySQL <a class="link" href="server-system-variables.html#sysvar_tmpdir"> <code class="literal"> tmpdir </code> </a> setting but only for online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations. </p> <p> The <code class="literal"> FILE </code> privilege is required to configure <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> . </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> option was introduced to help avoid overflowing a temporary file directory located on a <code class="literal"> tmpfs </code> file system. Such overflows could occur as a result of large temporary sort files created during online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations that rebuild the table. </p> <p> In replication environments, only consider replicating the <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> setting if all servers have the same operating system environment. Otherwise, replicating the <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> setting could result in a replication failure when running online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations that rebuild the table. If server operating environments differ, it is recommended that you configure <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> on each server individually. </p> <p> For more information, see <a class="xref" href="innodb-online-ddl-space-requirements.html" title="17.12.3 Online DDL Space Requirements"> Section 17.12.3, “Online DDL Space Requirements” </a> . For information about online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations, see <a class="xref" href="innodb-online-ddl.html" title="17.12 InnoDB and Online DDL"> Section 17.12, “InnoDB and Online DDL” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_trx_purge_view_update_only_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_purge_view_update_only_debug"> <code class="literal"> innodb_trx_purge_view_update_only_debug </code> </a> </p> <a class="indexterm" name="idm46045151742720"> </a> <a class="indexterm" name="idm46045151741712"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_trx_purge_view_update_only_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-trx-purge-view-update-only-debug[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_purge_view_update_only_debug"> innodb_trx_purge_view_update_only_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Pauses purging of delete-marked records while allowing the purge view to be updated. This option artificially creates a situation in which the purge view is updated but purges have not yet been performed. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_trx_rseg_n_slots_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_rseg_n_slots_debug"> <code class="literal"> innodb_trx_rseg_n_slots_debug </code> </a> </p> <a class="indexterm" name="idm46045151717024"> </a> <a class="indexterm" name="idm46045151716016"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_trx_rseg_n_slots_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-trx-rseg-n-slots-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_rseg_n_slots_debug"> innodb_trx_rseg_n_slots_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1024 </code> </td> </tr> </tbody> </table> </div> <p> Sets a debug flag that limits <code class="literal"> TRX_RSEG_N_SLOTS </code> to a given value for the <code class="literal"> trx_rsegf_undo_find_free </code> function that looks for free slots for undo log segments. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_undo_directory"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> </p> <a class="indexterm" name="idm46045151685552"> </a> <a class="indexterm" name="idm46045151684544"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_undo_directory"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-undo-directory=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> innodb_undo_directory </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> </tbody> </table> </div> <p> The path where <code class="literal"> InnoDB </code> creates undo tablespaces. Typically used to place undo tablespaces on a different storage device. </p> <p> There is no default value (it is NULL). If the <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> variable is undefined, undo tablespaces are created in the data directory. </p> <p> The default undo tablespaces ( <code class="filename"> innodb_undo_001 </code> and <code class="filename"> innodb_undo_002 </code> ) created when the MySQL instance is initialized always reside in the directory defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> variable. </p> <p> Undo tablespaces created using <a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> <code class="literal"> CREATE UNDO TABLESPACE </code> </a> syntax are created in the directory defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> variable if a different path is not specified. </p> <p> For more information, see <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_undo_log_encrypt"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_encrypt"> <code class="literal"> innodb_undo_log_encrypt </code> </a> </p> <a class="indexterm" name="idm46045151655408"> </a> <a class="indexterm" name="idm46045151654400"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_undo_log_encrypt"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-undo-log-encrypt[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_encrypt"> innodb_undo_log_encrypt </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Controls encryption of undo log data for tables encrypted using the <code class="literal"> InnoDB </code> <a class="link" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> data-at-rest encryption feature </a> . Only applies to undo logs that reside in separate <a class="link" href="glossary.html#glos_undo_tablespace" title="undo tablespace"> undo tablespaces </a> . See <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> . Encryption is not supported for undo log data that resides in the system tablespace. For more information, see <a class="xref" href="innodb-data-encryption.html#innodb-data-encryption-undo-log" title="Undo Log Encryption"> Undo Log Encryption </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_undo_log_truncate"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> <code class="literal"> innodb_undo_log_truncate </code> </a> </p> <a class="indexterm" name="idm46045151628224"> </a> <a class="indexterm" name="idm46045151627216"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_undo_log_truncate"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-undo-log-truncate[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> innodb_undo_log_truncate </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> When enabled, undo tablespaces that exceed the threshold value defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> <code class="literal"> innodb_max_undo_log_size </code> </a> are marked for truncation. Only undo tablespaces can be truncated. Truncating undo logs that reside in the system tablespace is not supported. For truncation to occur, there must be at least two undo tablespaces. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> <code class="literal"> innodb_purge_rseg_truncate_frequency </code> </a> variable can be used to expedite truncation of undo tablespaces. </p> <p> For more information, see <a class="xref" href="innodb-undo-tablespaces.html#truncate-undo-tablespace" title="Truncating Undo Tablespaces"> Truncating Undo Tablespaces </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_undo_tablespaces"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> <code class="literal"> innodb_undo_tablespaces </code> </a> </p> <a class="indexterm" name="idm46045151600496"> </a> <a class="indexterm" name="idm46045151599488"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_undo_tablespaces"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-undo-tablespaces=# </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> innodb_undo_tablespaces </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 127 </code> </td> </tr> </tbody> </table> </div> <p> Defines the number of <a class="link" href="glossary.html#glos_undo_tablespace" title="undo tablespace"> undo tablespaces </a> used by <code class="literal"> InnoDB </code> . The default and minimum value is 2. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> <code class="literal"> innodb_undo_tablespaces </code> </a> variable is deprecated; setting it has no effect. You should expect it to be removed in a future MySQL release. </p> </div> <p> For more information, see <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_use_fdatasync"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> </p> <a class="indexterm" name="idm46045151565712"> </a> <a class="indexterm" name="idm46045151564704"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_use_fdatasync"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-use-fdatasync[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> innodb_use_fdatasync </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> On platforms that support <code class="literal"> fdatasync() </code> system calls, having <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> enabled permits using <code class="literal"> fdatasync() </code> instead of <code class="literal"> fsync() </code> system calls for operating system flushes. An <code class="literal"> fdatasync() </code> call does not flush changes to file metadata unless required for subsequent data retrieval, providing a potential performance benefit. </p> <p> A subset of <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> settings such as <code class="literal"> fsync </code> , <code class="literal"> O_DSYNC </code> , and <code class="literal"> O_DIRECT </code> use <code class="literal"> fsync() </code> system calls. The <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> variable is applicable when using those settings. </p> <p> Before MySQL 8.4, this option was disabled by default. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_use_native_aio"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_native_aio"> <code class="literal"> innodb_use_native_aio </code> </a> </p> <a class="indexterm" name="idm46045151532576"> </a> <a class="indexterm" name="idm46045151531568"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_use_native_aio"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-use-native-aio[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_native_aio"> innodb_use_native_aio </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies whether to use the <a class="link" href="glossary.html#glos_asynchronous_io" title="asynchronous I/O"> asynchronous I/O </a> subsystem. This variable cannot be changed while the server is running. Normally, you do not need to configure this option, because it is enabled by default. </p> <p> This feature improves the scalability of heavily I/O-bound systems, which typically show many pending reads/writes in <code class="literal"> SHOW ENGINE INNODB STATUS </code> output. </p> <p> Running with a large number of <code class="literal"> InnoDB </code> I/O threads, and especially running multiple such instances on the same server machine, can exceed capacity limits on Linux systems. In this case, you may receive the following error: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa14581038"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">EAGAIN<span class="token punctuation">:</span> The specified maxevents exceeds the user's limit of available events<span class="token punctuation">.</span></code></pre> </div> <p> You can typically address this error by writing a higher limit to <code class="literal"> /proc/sys/fs/aio-max-nr </code> . </p> <p> However, if a problem with the asynchronous I/O subsystem in the OS prevents <code class="literal"> InnoDB </code> from starting, you can start the server with <a class="link" href="innodb-parameters.html#sysvar_innodb_use_native_aio"> <code class="literal"> innodb_use_native_aio=0 </code> </a> . This option may also be disabled automatically during startup if <code class="literal"> InnoDB </code> detects a potential problem such as a combination of <code class="literal"> tmpdir </code> location, <code class="literal"> tmpfs </code> file system, and Linux kernel that does not support AIO on <code class="literal"> tmpfs </code> . </p> <p> For more information, see <a class="xref" href="innodb-linux-native-aio.html" title="17.8.6 Using Asynchronous I/O on Linux"> Section 17.8.6, “Using Asynchronous I/O on Linux” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_validate_tablespace_paths"> </a> <code class="literal"> innodb_validate_tablespace_paths </code> </p> <a class="indexterm" name="idm46045151497840"> </a> <a class="indexterm" name="idm46045151496832"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_validate_tablespace_paths"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-validate-tablespace-paths[={OFF\|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_validate_tablespace_paths"> innodb_validate_tablespace_paths </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Controls tablespace file path validation. At startup, <code class="literal"> InnoDB </code> validates the paths of known tablespace files against tablespace file paths stored in the data dictionary in case tablespace files have been moved to a different location. The <a class="link" href="innodb-parameters.html#sysvar_innodb_validate_tablespace_paths"> <code class="literal"> innodb_validate_tablespace_paths </code> </a> variable permits disabling tablespace path validation. This feature is intended for environments where tablespaces files are not moved. Disabling path validation improves startup time on systems with a large number of tablespace files. </p> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> Starting the server with tablespace path validation disabled after moving tablespace files can lead to undefined behavior. </p> </div> <p> For more information, see <a class="xref" href="innodb-disabling-tablespace-path-validation.html" title="17.6.3.7 Disabling Tablespace Path Validation"> Section 17.6.3.7, “Disabling Tablespace Path Validation” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_version"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_version"> <code class="literal"> innodb_version </code> </a> </p> <a class="indexterm" name="idm46045151469776"> </a> <a class="indexterm" name="idm46045151468768"> </a> <p> The <code class="literal"> InnoDB </code> version number. This is a legacy variable, the value is the same as the MySQL server <a class="link" href="server-system-variables.html#sysvar_version"> <code class="literal"> version </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_write_io_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> </p> <a class="indexterm" name="idm46045151463248"> </a> <a class="indexterm" name="idm46045151462240"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_write_io_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-write-io-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> innodb_write_io_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> The number of I/O threads for write operations in <code class="literal"> InnoDB </code> . The default value is 4. Its counterpart for read threads is <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> <code class="literal"> innodb_read_io_threads </code> </a> . For more information, see <a class="xref" href="innodb-performance-multiple_io_threads.html" title="17.8.5 Configuring the Number of Background InnoDB I/O Threads"> Section 17.8.5, “Configuring the Number of Background InnoDB I/O Threads” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> On Linux systems, running multiple MySQL servers (typically more than 12) with default settings for <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> <code class="literal"> innodb_read_io_threads </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> , and the Linux <code class="literal"> aio-max-nr </code> setting can exceed system limits. Ideally, increase the <code class="literal"> aio-max-nr </code> setting; as a workaround, you might reduce the settings for one or both of the MySQL variables. </p> </div> <p> Also take into consideration the value of <a class="link" href="replication-options-binary-log.html#sysvar_sync_binlog"> <code class="literal"> sync_binlog </code> </a> , which controls synchronization of the binary log to disk. </p> <p> For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> </ul> </div> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-installation.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="mysql-cluster-installation"> </a> 25.3 NDB Cluster Installation </h2> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="mysql-cluster-install-linux.html"> 25.3.1 Installation of NDB Cluster on Linux </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-windows.html"> 25.3.2 Installing NDB Cluster on Windows </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-configuration.html"> 25.3.3 Initial Configuration of NDB Cluster </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-first-start.html"> 25.3.4 Initial Startup of NDB Cluster </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-example-data.html"> 25.3.5 NDB Cluster Example with Tables and Data </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-shutdown-restart.html"> 25.3.6 Safe Shutdown and Restart of NDB Cluster </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-upgrade-downgrade.html"> 25.3.7 Upgrading and Downgrading NDB Cluster </a> </span> </dt> </dl> </div> <a class="indexterm" name="idm46045123109936"> </a> <a class="indexterm" name="idm46045123108864"> </a> <a class="indexterm" name="idm46045123107792"> </a> <a class="indexterm" name="idm46045123106304"> </a> <a class="indexterm" name="idm46045123105232"> </a> <p> This section describes the basics for planning, installing, configuring, and running an NDB Cluster. Whereas the examples in <a class="xref" href="mysql-cluster-configuration.html" title="25.4 Configuration of NDB Cluster"> Section 25.4, “Configuration of NDB Cluster” </a> provide more in-depth information on a variety of clustering options and configuration, the result of following the guidelines and procedures outlined here should be a usable NDB Cluster which meets the <span class="emphasis"> <em> minimum </em> </span> requirements for availability and safeguarding of data. </p> <p> For information about upgrading or downgrading an NDB Cluster between release versions, see <a class="xref" href="mysql-cluster-upgrade-downgrade.html" title="25.3.7 Upgrading and Downgrading NDB Cluster"> Section 25.3.7, “Upgrading and Downgrading NDB Cluster” </a> . </p> <p> This section covers hardware and software requirements; networking issues; installation of NDB Cluster; basic configuration issues; starting, stopping, and restarting the cluster; loading of a sample database; and performing queries. </p> <p> <b> Assumptions. </b> The following sections make a number of assumptions regarding the cluster's physical and network configuration. These assumptions are discussed in the next few paragraphs. </p> <p> <a name="mysql-cluster-install-nodes-hosts"> </a> <b> Cluster nodes and host computers. </b> The cluster consists of four nodes, each on a separate host computer, and each with a fixed network address on a typical Ethernet network as shown here: </p> <div class="table"> <a name="idm46045123096512"> </a> <p class="title"> <b> Table 25.4 Network addresses of nodes in example cluster </b> </p> <div class="table-contents"> <table> <colgroup> <col style="width: 50%"/> <col style="width: 50%"/> </colgroup> <thead> <tr> <th> Node </th> <th> IP Address </th> </tr> </thead> <tbody> <tr> <td> Management node ( <span class="command"> <strong> mgmd </strong> </span> ) </td> <td> 198.51.100.10 </td> </tr> <tr> <td> SQL node ( <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> ) </td> <td> 198.51.100.20 </td> </tr> <tr> <td> Data node "A" ( <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> ) </td> <td> 198.51.100.30 </td> </tr> <tr> <td> Data node "B" ( <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> ) </td> <td> 198.51.100.40 </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> <p> This setup is also shown in the following diagram: </p> <div class="figure"> <a name="fig-mysql-cluster-multi-computer"> </a> <p class="title"> <b> Figure 25.4 NDB Cluster Multi-Computer Setup </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Most content is described in the surrounding text. The four nodes each connect to a central switch that connects to a network." src="images/multi-comp-1.png" style="width: 100%; max-width: 550px;"/> </div> </div> </div> <br class="figure-break"/> <p> <b> Network addressing. </b> <a class="indexterm" name="idm46045123069952"> </a> <a class="indexterm" name="idm46045123068464"> </a> In the interest of simplicity (and reliability), this <em class="citetitle"> How-To </em> uses only numeric IP addresses. However, if DNS resolution is available on your network, it is possible to use host names in lieu of IP addresses in configuring Cluster. Alternatively, you can use the <code class="filename"> hosts </code> file (typically <code class="filename"> /etc/hosts </code> for Linux and other Unix-like operating systems, <code class="filename"> C:\WINDOWS\system32\drivers\etc\hosts </code> on Windows, or your operating system's equivalent) for providing a means to do host lookup if such is available. </p> <p> <code class="literal"> NDB </code> 8.4 supports IPv6 for connections between all NDB Cluster nodes. </p> <p> <b> Potential hosts file issues. </b> A common problem when trying to use host names for Cluster nodes arises because of the way in which some operating systems (including some Linux distributions) set up the system's own host name in the <code class="filename"> /etc/hosts </code> during installation. Consider two machines with the host names <code class="literal"> ndb1 </code> and <code class="literal"> ndb2 </code> , both in the <code class="literal"> cluster </code> network domain. Red Hat Linux (including some derivatives such as CentOS and Fedora) places the following entries in these machines' <code class="filename"> /etc/hosts </code> files: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa81670398"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># ndb1 /etc/hosts:</span> 127.0.0.1 ndb1.cluster ndb1 localhost.localdomain localhost</code></pre> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa68312983"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># ndb2 /etc/hosts:</span> 127.0.0.1 ndb2.cluster ndb2 localhost.localdomain localhost</code></pre> </div> <p> SUSE Linux (including OpenSUSE) places these entries in the machines' <code class="filename"> /etc/hosts </code> files: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa51699949"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># ndb1 /etc/hosts:</span> 127.0.0.1 localhost 127.0.0.2 ndb1.cluster ndb1</code></pre> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa88610707"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># ndb2 /etc/hosts:</span> 127.0.0.1 localhost 127.0.0.2 ndb2.cluster ndb2</code></pre> </div> <p> In both instances, <code class="literal"> ndb1 </code> routes <code class="literal"> ndb1.cluster </code> to a loopback IP address, but gets a public IP address from DNS for <code class="literal"> ndb2.cluster </code> , while <code class="literal"> ndb2 </code> routes <code class="literal"> ndb2.cluster </code> to a loopback address and obtains a public address for <code class="literal"> ndb1.cluster </code> . The result is that each data node connects to the management server, but cannot tell when any other data nodes have connected, and so the data nodes appear to hang while starting. </p> <div class="caution" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Caution </div> <p> You cannot mix <code class="literal"> localhost </code> and other host names or IP addresses in <code class="filename"> config.ini </code> . For these reasons, the solution in such cases (other than to use IP addresses for <span class="emphasis"> <em> all </em> </span> <code class="filename"> config.ini </code> <code class="literal"> HostName </code> entries) is to remove the fully qualified host names from <code class="filename"> /etc/hosts </code> and use these in <code class="filename"> config.ini </code> for all cluster hosts. </p> </div> <p> <b> Host computer type. </b> Each host computer in our installation scenario is an Intel-based desktop PC running a supported operating system installed to disk in a standard configuration, and running no unnecessary services. The core operating system with standard TCP/IP networking capabilities should be sufficient. Also for the sake of simplicity, we also assume that the file systems on all hosts are set up identically. In the event that they are not, you should adapt these instructions accordingly. </p> <p> <b> Network hardware. </b> Standard 100 Mbps or 1 gigabit Ethernet cards are installed on each machine, along with the proper drivers for the cards, and that all four hosts are connected through a standard-issue Ethernet networking appliance such as a switch. (All machines should use network cards with the same throughput. That is, all four machines in the cluster should have 100 Mbps cards <span class="emphasis"> <em> or </em> </span> all four machines should have 1 Gbps cards.) NDB Cluster works in a 100 Mbps network; however, gigabit Ethernet provides better performance. </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> NDB Cluster is <span class="emphasis"> <em> not </em> </span> intended for use in a network for which throughput is less than 100 Mbps or which experiences a high degree of latency. For this reason (among others), attempting to run an NDB Cluster over a wide area network such as the Internet is not likely to be successful, and is not supported in production. </p> </div> <p> <b> Sample data. </b> We use the <code class="literal"> world </code> database which is available for download from the MySQL website (see <a class="ulink" href="/doc/index-other.html" target="_top"> https://dev.mysql.com/doc/index-other.html </a> ). We assume that each machine has sufficient memory for running the operating system, required NDB Cluster processes, and (on the data nodes) storing the database. </p> <p> For general information about installing MySQL, see <a class="xref" href="installing.html" title="Chapter 2 Installing MySQL"> Chapter 2, <i> Installing MySQL </i> </a> . For information about installation of NDB Cluster on Linux and other Unix-like operating systems, see <a class="xref" href="mysql-cluster-install-linux.html" title="25.3.1 Installation of NDB Cluster on Linux"> Section 25.3.1, “Installation of NDB Cluster on Linux” </a> . For information about installation of NDB Cluster on Windows operating systems, see <a class="xref" href="mysql-cluster-install-windows.html" title="25.3.2 Installing NDB Cluster on Windows"> Section 25.3.2, “Installing NDB Cluster on Windows” </a> . </p> <p> For general information about NDB Cluster hardware, software, and networking requirements, see <a class="xref" href="mysql-cluster-overview-requirements.html" title="25.2.3 NDB Cluster Hardware, Software, and Networking Requirements"> Section 25.2.3, “NDB Cluster Hardware, Software, and Networking Requirements” </a> . </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/innodb-truncate-table-reclaim-space.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="innodb-truncate-table-reclaim-space"> </a> 17.11.5 Reclaiming Disk Space with TRUNCATE TABLE </h3> </div> </div> </div> <p> To reclaim operating system disk space when <a class="link" href="glossary.html#glos_truncate" title="truncate"> truncating </a> an <code class="literal"> InnoDB </code> table, the table must be stored in its own <a class="link" href="glossary.html#glos_ibd_file" title=".ibd file"> .ibd </a> file. For a table to be stored in its own <a class="link" href="glossary.html#glos_ibd_file" title=".ibd file"> .ibd </a> file, <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> must enabled when the table is created. Additionally, there cannot be a <a class="link" href="glossary.html#glos_foreign_key" title="foreign key"> foreign key </a> constraint between the table being truncated and other tables, otherwise the <code class="literal"> TRUNCATE TABLE </code> operation fails. A foreign key constraint between two columns in the same table, however, is permitted. </p> <p> When a table is truncated, it is dropped and re-created in a new <code class="filename"> .ibd </code> file, and the freed space is returned to the operating system. This is in contrast to truncating <code class="literal"> InnoDB </code> tables that are stored within the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> (tables created when <code class="literal"> innodb_file_per_table=OFF </code> ) and tables stored in shared <a class="link" href="glossary.html#glos_general_tablespace" title="general tablespace"> general tablespaces </a> , where only <code class="literal"> InnoDB </code> can use the freed space after the table is truncated. </p> <p> The ability to truncate tables and return disk space to the operating system also means that <a class="link" href="glossary.html#glos_physical_backup" title="physical backup"> physical backups </a> can be smaller. Truncating tables that are stored in the system tablespace (tables created when <code class="literal"> innodb_file_per_table=OFF </code> ) or in a general tablespace leaves blocks of unused space in the tablespace. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/mysqlbinlog-server-id.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysqlbinlog-server-id"> </a> 6.6.9.4 Specifying the mysqlbinlog Server ID </h4> </div> </div> </div> <p> When invoked with the <code class="option"> --read-from-remote-server </code> option, <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects to a MySQL server, specifies a server ID to identify itself, and requests binary log files from the server. You can use <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> to request log files from a server in several ways: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Specify an explicitly named set of files: For each file, <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects and issues a <code class="literal"> Binlog dump </code> command. The server sends the file and disconnects. There is one connection per file. </p> </li> <li class="listitem"> <p> Specify the beginning file and <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_to-last-log"> <code class="option"> --to-last-log </code> </a> : <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects and issues a <code class="literal"> Binlog dump </code> command for all files. The server sends all files and disconnects. </p> </li> <li class="listitem"> <p> Specify the beginning file and <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_stop-never"> <code class="option"> --stop-never </code> </a> (which implies <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_to-last-log"> <code class="option"> --to-last-log </code> </a> ): <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects and issues a <code class="literal"> Binlog dump </code> command for all files. The server sends all files, but does not disconnect after sending the last one. </p> </li> </ul> </div> <p> With <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_read-from-remote-server"> <code class="option"> --read-from-remote-server </code> </a> only, <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects using a server ID of 0, which tells the server to disconnect after sending the last requested log file. </p> <p> With <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_read-from-remote-server"> <code class="option"> --read-from-remote-server </code> </a> and <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_stop-never"> <code class="option"> --stop-never </code> </a> , <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects using a nonzero server ID, so the server does not disconnect after sending the last log file. The server ID is 1 by default, but this can be changed with <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_connection-server-id"> <code class="option"> --connection-server-id </code> </a> . </p> <p> Thus, for the first two ways of requesting files, the server disconnects because <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> specifies a server ID of 0. It does not disconnect if <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_stop-never"> <code class="option"> --stop-never </code> </a> is given because <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> specifies a nonzero server ID. </p> </div> <br/> </div>
https://dev.mysql.com/doc/refman/8.4/en/show-function-status.html	<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="show-function-status"> </a> 15.7.7.21 SHOW FUNCTION STATUS Statement </h4> </div> </div> </div> <a class="indexterm" name="idm46045170329424"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa257780"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SHOW</span> <span class="token keyword">FUNCTION</span> <span class="token keyword">STATUS</span> <span class="token punctuation">[</span><span class="token operator">LIKE</span> <span class="token string">'<em class="replaceable">pattern</em>'</span> <span class="token operator">\|</span> <span class="token keyword">WHERE</span> <em class="replaceable">expr</em><span class="token punctuation">]</span></code></pre> </div> <p> This statement is similar to <a class="link" href="show-procedure-status.html" title="15.7.7.30 SHOW PROCEDURE STATUS Statement"> <code class="literal"> SHOW PROCEDURE STATUS </code> </a> but for stored functions. See <a class="xref" href="show-procedure-status.html" title="15.7.7.30 SHOW PROCEDURE STATUS Statement"> Section 15.7.7.30, “SHOW PROCEDURE STATUS Statement” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/show-tables.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="show-tables"> </a> 15.7.7.39 SHOW TABLES Statement </h4> </div> </div> </div> <a class="indexterm" name="idm46045169128400"> </a> <a class="indexterm" name="idm46045169125632"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa14388240"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SHOW</span> <span class="token punctuation">[</span><span class="token keyword">EXTENDED</span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">FULL</span><span class="token punctuation">]</span> <span class="token keyword">TABLES</span> <span class="token punctuation">[</span>{<span class="token keyword">FROM</span> <span class="token operator">|</span> <span class="token keyword">IN</span>} <em class="replaceable">db_name</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token operator">LIKE</span> <span class="token string">'<em class="replaceable">pattern</em>'</span> <span class="token operator">|</span> <span class="token keyword">WHERE</span> <em class="replaceable">expr</em><span class="token punctuation">]</span></code></pre> </div> <p> <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> lists the non- <code class="literal"> TEMPORARY </code> tables in a given database. You can also get this list using the <a class="link" href="mysqlshow.html" title="6.5.6 mysqlshow — Display Database, Table, and Column Information"> <span class="command"> <strong> mysqlshow <em class="replaceable"> <code> db_name </code> </em> </strong> </span> </a> command. The <a class="link" href="string-comparison-functions.html#operator_like"> <code class="literal"> LIKE </code> </a> clause, if present, indicates which table names to match. The <code class="literal"> WHERE </code> clause can be given to select rows using more general conditions, as discussed in <a class="xref" href="extended-show.html" title="28.8 Extensions to SHOW Statements"> Section 28.8, “Extensions to SHOW Statements” </a> . </p> <p> Matching performed by the <code class="literal"> LIKE </code> clause is dependent on the setting of the <a class="link" href="server-system-variables.html#sysvar_lower_case_table_names"> <code class="literal"> lower_case_table_names </code> </a> system variable. </p> <p> The optional <code class="literal"> EXTENDED </code> modifier causes <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> to list hidden tables created by failed <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements. These temporary tables have names beginning with <code class="literal"> #sql </code> and can be dropped using <a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement"> <code class="literal"> DROP TABLE </code> </a> . </p> <p> This statement also lists any views in the database. The optional <code class="literal"> FULL </code> modifier causes <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> to display a second output column with values of <code class="literal"> BASE TABLE </code> for a table, <code class="literal"> VIEW </code> for a view, or <code class="literal"> SYSTEM VIEW </code> for an <code class="literal"> INFORMATION_SCHEMA </code> table. </p> <p> If you have no privileges for a base table or view, it does not show up in the output from <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> or <a class="link" href="mysqlshow.html" title="6.5.6 mysqlshow — Display Database, Table, and Column Information"> <span class="command"> <strong> mysqlshow db_name </strong> </span> </a> . </p> <p> Table information is also available from the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> table. See <a class="xref" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> Section 28.3.38, “The INFORMATION_SCHEMA TABLES Table” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/sys-schema-prerequisites.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="sys-schema-prerequisites"> </a> 30.1 Prerequisites for Using the sys Schema </h2> </div> </div> </div> <p> Before using the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema, the prerequisites described in this section must be satisfied. </p> <p> Because the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema provides an alternative means of accessing the Performance Schema, the Performance Schema must be enabled for the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema to work. See <a class="xref" href="performance-schema-startup-configuration.html" title="29.3 Performance Schema Startup Configuration"> Section 29.3, “Performance Schema Startup Configuration” </a> . </p> <p> For full access to the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema, a user must have these privileges: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_select"> <code class="literal"> SELECT </code> </a> on all <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> tables and views </p> </li> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_execute"> <code class="literal"> EXECUTE </code> </a> on all <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> stored procedures and functions </p> </li> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_insert"> <code class="literal"> INSERT </code> </a> and <a class="link" href="privileges-provided.html#priv_update"> <code class="literal"> UPDATE </code> </a> for the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table, if changes are to be made to it </p> </li> <li class="listitem"> <p> Additional privileges for certain <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema stored procedures and functions, as noted in their descriptions (for example, the <a class="link" href="sys-ps-setup-save.html" title="30.4.4.14 The ps_setup_save() Procedure"> <code class="literal"> ps_setup_save() </code> </a> procedure) </p> </li> </ul> </div> <p> It is also necessary to have privileges for the objects underlying the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema objects: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_select"> <code class="literal"> SELECT </code> </a> on any Performance Schema tables accessed by <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema objects, and <a class="link" href="privileges-provided.html#priv_update"> <code class="literal"> UPDATE </code> </a> for any tables to be updated using <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema objects </p> </li> <li class="listitem"> <p> <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> for the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table"> <code class="literal"> INNODB_BUFFER_PAGE </code> </a> table </p> </li> </ul> </div> <p> Certain Performance Schema instruments and consumers must be enabled and (for instruments) timed to take full advantage of <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema capabilities: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> All <code class="literal"> wait </code> instruments </p> </li> <li class="listitem"> <p> All <code class="literal"> stage </code> instruments </p> </li> <li class="listitem"> <p> All <code class="literal"> statement </code> instruments </p> </li> <li class="listitem"> <p> <code class="literal"> <em class="replaceable"> <code> xxx </code> </em> _current </code> and <code class="literal"> <em class="replaceable"> <code> xxx </code> </em> _history_long </code> consumers for all events </p> </li> </ul> </div> <p> You can use the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema itself to enable all of the additional instruments and consumers: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa93923863"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_instrument<span class="token punctuation">(</span><span class="token string">'wait'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_instrument<span class="token punctuation">(</span><span class="token string">'stage'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_instrument<span class="token punctuation">(</span><span class="token string">'statement'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_consumer<span class="token punctuation">(</span><span class="token string">'current'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_enable_consumer<span class="token punctuation">(</span><span class="token string">'history_long'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> For many uses of the <code class="literal"> sys </code> schema, the default Performance Schema is sufficient for data collection. Enabling all the instruments and consumers just mentioned has a performance impact, so it is preferable to enable only the additional configuration you need. Also, remember that if you enable additional configuration, you can easily restore the default configuration like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa84602336"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_reset_to_default<span class="token punctuation">(</span><span class="token boolean">TRUE</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/clone-plugin-installation.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="clone-plugin-installation"> </a> 7.6.7.1 Installing the Clone Plugin </h4> </div> </div> </div> <a class="indexterm" name="idm46045255710528"> </a> <a class="indexterm" name="idm46045255709040"> </a> <p> This section describes how to install and configure the clone plugin. For remote cloning operations, the clone plugin must be installed on the donor and recipient MySQL server instances. </p> <p> For general information about installing or uninstalling plugins, see <a class="xref" href="plugin-loading.html" title="7.6.1 Installing and Uninstalling Plugins"> Section 7.6.1, “Installing and Uninstalling Plugins” </a> . </p> <p> To be usable by the server, the plugin library file must be located in the MySQL plugin directory (the directory named by the <a class="link" href="server-system-variables.html#sysvar_plugin_dir"> <code class="literal"> plugin_dir </code> </a> system variable). If necessary, set the value of <a class="link" href="server-system-variables.html#sysvar_plugin_dir"> <code class="literal"> plugin_dir </code> </a> at server startup to tell the server the plugin directory location. </p> <p> The plugin library file base name is <code class="literal"> mysql_clone.so </code> . The file name suffix differs by platform (for example, <code class="filename"> .so </code> for Unix and Unix-like systems, <code class="filename"> .dll </code> for Windows). </p> <p> To load the plugin at server startup, use the <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> --plugin-load-add </code> </a> option to name the library file that contains it. With this plugin-loading method, the option must be given each time the server starts. For example, put these lines in your <code class="filename"> my.cnf </code> file, adjusting the plugin library file name extension for your platform as necessary. (The plugin library file name extension depends on your platform. Common suffixes are <code class="filename"> .so </code> for Unix and Unix-like systems, <code class="filename"> .dll </code> for Windows.) </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa75520758"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">plugin-load-add</span><span class="token attr-value"><span class="token punctuation">=</span>mysql_clone.so</span></code></pre> </div> <p> After modifying <code class="filename"> my.cnf </code> , restart the server to cause the new settings to take effect. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> --plugin-load-add </code> </a> option cannot be used to load the clone plugin when restarting the server during an upgrade from a previous MySQL version. In such cases, attempting to restart the server with <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> plugin-load-add=mysql_clone.so </code> </a> raises the error <span class="errortext"> [ERROR] [MY-013238] [Server] Error installing plugin 'clone': Cannot install during upgrade. </span> To keep this from happening, upgrade the server before attempting to start the server with <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> plugin-load-add=mysql_clone.so </code> </a> . </p> </div> <p> Alternatively, to load the plugin at runtime, use this statement, adjusting the <code class="filename"> .so </code> suffix for your platform as necessary: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa45811432"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSTALL</span> <span class="token keyword">PLUGIN</span> <span class="token keyword">clone</span> <span class="token keyword">SONAME</span> <span class="token string">'mysql_clone.so'</span><span class="token punctuation">;</span></code></pre> </div> <p> <a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> <code class="literal"> INSTALL PLUGIN </code> </a> loads the plugin, and also registers it in the <code class="literal"> mysql.plugins </code> system table to cause the plugin to be loaded for each subsequent normal server startup without the need for <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> --plugin-load-add </code> </a> . </p> <p> To verify plugin installation, examine the Information Schema <a class="link" href="information-schema-plugins-table.html" title="28.3.22 The INFORMATION_SCHEMA PLUGINS Table"> <code class="literal"> PLUGINS </code> </a> table or use the <a class="link" href="show-plugins.html" title="15.7.7.27 SHOW PLUGINS Statement"> <code class="literal"> SHOW PLUGINS </code> </a> statement (see <a class="xref" href="obtaining-plugin-information.html" title="7.6.2 Obtaining Server Plugin Information"> Section 7.6.2, “Obtaining Server Plugin Information” </a> ). For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa7088920"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> PLUGIN_NAME<span class="token punctuation">,</span> PLUGIN_STATUS <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span><span class="token keyword">PLUGINS</span> <span class="token keyword">WHERE</span> PLUGIN_NAME <span class="token operator">=</span> <span class="token string">'clone'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> PLUGIN_NAME <span class="token punctuation">|</span> PLUGIN_STATUS <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> clone <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> If the plugin fails to initialize, check the server error log for clone or plugin-related diagnostic messages. </p> <p> If the plugin has been previously registered with <a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> <code class="literal"> INSTALL PLUGIN </code> </a> or is loaded with <a class="link" href="server-options.html#option_mysqld_plugin-load-add"> <code class="option"> --plugin-load-add </code> </a> , you can use the <code class="option"> --clone </code> option at server startup to control the plugin activation state. For example, to load the plugin at startup and prevent it from being removed at runtime, use these options: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa61299599"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">plugin-load-add</span><span class="token attr-value"><span class="token punctuation">=</span>mysql_clone.so</span> <span class="token constant">clone</span><span class="token attr-value"><span class="token punctuation">=</span>FORCE_PLUS_PERMANENT</span></code></pre> </div> <p> If you want to prevent the server from running without the clone plugin, use <code class="option"> --clone </code> with a value of <code class="literal"> FORCE </code> or <code class="literal"> FORCE_PLUS_PERMANENT </code> to force server startup to fail if the plugin does not initialize successfully. </p> <p> For more information about plugin activation states, see <a class="xref" href="plugin-loading.html#server-plugin-activating" title="Controlling Plugin Activation State"> Controlling Plugin Activation State </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/replication-features-timeout.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-features-timeout"> </a> 19.5.1.32 Replication Retries and Timeouts </h4> </div> </div> </div> <a class="indexterm" name="idm46045135079808"> </a> <a class="indexterm" name="idm46045135078320"> </a> <a class="indexterm" name="idm46045135076832"> </a> <a class="indexterm" name="idm46045135075760"> </a> <p> The global value of the system variable <a class="link" href="replication-options-replica.html#sysvar_replica_transaction_retries"> <code class="literal"> replica_transaction_retries </code> </a> sets the maximum number of times for applier threads on a single-threaded or multithreaded replica to automatically retry failed transactions before stopping. Transactions are automatically retried when the SQL thread fails to execute them because of an <code class="literal"> InnoDB </code> deadlock, or when the transaction's execution time exceeds the <code class="literal"> InnoDB </code> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> value. If a transaction has a non-temporary error that prevents it from succeeding, it is not retried. </p> <p> The default setting for <a class="link" href="replication-options-replica.html#sysvar_replica_transaction_retries"> <code class="literal"> replica_transaction_retries </code> </a> is 10, meaning that a failing transaction with an apparently temporary error is retried 10 times before the applier thread stops. Setting the variable to 0 disables automatic retrying of transactions. On a multithreaded replica, the specified number of transaction retries can take place on all applier threads of all channels. The Performance Schema table <a class="link" href="performance-schema-replication-applier-status-table.html" title="29.12.11.5 The replication_applier_status Table"> <code class="literal"> replication_applier_status </code> </a> shows the total number of transaction retries that took place on each replication channel, in the <code class="literal"> COUNT_TRANSACTIONS_RETRIES </code> column. </p> <p> The process of retrying transactions can cause lag on a replica or on a Group Replication group member, which can be configured as a single-threaded or multithreaded replica. The Performance Schema table <a class="link" href="performance-schema-replication-applier-status-by-worker-table.html" title="29.12.11.7 The replication_applier_status_by_worker Table"> <code class="literal"> replication_applier_status_by_worker </code> </a> shows detailed information on transaction retries by the applier threads on a single-threaded or multithreaded replica. This data includes timestamps showing how long it took the applier thread to apply the last transaction from start to finish (and when the transaction currently in progress was started), and how long this was after the commit on the original source and the immediate source. The data also shows the number of retries for the last transaction and the transaction currently in progress, and enables you to identify the transient errors that caused the transactions to be retried. You can use this information to see whether transaction retries are the cause of replication lag, and investigate the root cause of the failures that led to the retries. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/information-schema-column-statistics-table.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-column-statistics-table"> </a> 28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045080067712"> </a> <p> The <a class="link" href="information-schema-column-statistics-table.html" title="28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table"> <code class="literal"> COLUMN_STATISTICS </code> </a> table provides access to histogram statistics for column values. </p> <p> For information about histogram statistics, see <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> , and <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> . </p> <p> You can see information only for columns for which you have some privilege. </p> <p> The <a class="link" href="information-schema-column-statistics-table.html" title="28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table"> <code class="literal"> COLUMN_STATISTICS </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> SCHEMA_NAME </code> </p> <p> The names of the schema for which the statistics apply. </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_NAME </code> </p> <p> The names of the column for which the statistics apply. </p> </li> <li class="listitem"> <p> <code class="literal"> COLUMN_NAME </code> </p> <p> The names of the column for which the statistics apply. </p> </li> <li class="listitem"> <p> <code class="literal"> HISTOGRAM </code> </p> <p> A <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> object describing the column statistics, stored as a histogram. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/partitioning-limitations-partitioning-keys-unique-keys.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="partitioning-limitations-partitioning-keys-unique-keys"> </a> 26.6.1 Partitioning Keys, Primary Keys, and Unique Keys </h3> </div> </div> </div> <a class="indexterm" name="idm46045082850928"> </a> <a class="indexterm" name="idm46045082849840"> </a> <a class="indexterm" name="idm46045082848352"> </a> <a class="indexterm" name="idm46045082847264"> </a> <a class="indexterm" name="idm46045082845776"> </a> <p> This section discusses the relationship of partitioning keys with primary keys and unique keys. The rule governing this relationship can be expressed as follows: All columns used in the partitioning expression for a partitioned table must be part of every unique key that the table may have. </p> <p> In other words, <span class="emphasis"> <em> every unique key on the table must use every column in the table's partitioning expression </em> </span> . (This also includes the table's primary key, since it is by definition a unique key. This particular case is discussed later in this section.) For example, each of the following table creation statements is invalid: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59193363"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span></code></pre> </div> <p> In each case, the proposed table would have at least one unique key that does not include all columns used in the partitioning expression. </p> <p> Each of the following statements is valid, and represents one way in which the corresponding invalid table creation statement could be made to work: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa6212186"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">,</span> col3<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t2 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col3<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span></code></pre> </div> <p> This example shows the error produced in such cases: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa54203607"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t3 <span class="token punctuation">(</span> <span class="token prompt"> -></span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> col3<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token output">ERROR 1491 (HY000)<span class="token punctuation">:</span> A PRIMARY KEY must include all columns in the table's partitioning function</span></code></pre> </div> <p> The <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> statement fails because both <code class="literal"> col1 </code> and <code class="literal"> col3 </code> are included in the proposed partitioning key, but neither of these columns is part of both of unique keys on the table. This shows one possible fix for the invalid table definition: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa83738260"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t3 <span class="token punctuation">(</span> <span class="token prompt"> -></span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">,</span> col3<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.05 sec)</span></code></pre> </div> <p> In this case, the proposed partitioning key <code class="literal"> col3 </code> is part of both unique keys, and the table creation statement succeeds. </p> <p> The following table cannot be partitioned at all, because there is no way to include in a partitioning key any columns that belong to both unique keys: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa37345684"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t4 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col3<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>col2<span class="token punctuation">,</span> col4<span class="token punctuation">)</span> <span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> Since every primary key is by definition a unique key, this restriction also includes the table's primary key, if it has one. For example, the next two statements are invalid: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa37621533"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t5 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col3<span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t6 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col3<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span> <span class="token function">YEAR</span><span class="token punctuation">(</span>col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span></code></pre> </div> <p> In both cases, the primary key does not include all columns referenced in the partitioning expression. However, both of the next two statements are valid: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa22763384"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t7 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> <span class="token function">YEAR</span><span class="token punctuation">(</span>col2<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t8 <span class="token punctuation">(</span> col1 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col2 <span class="token datatype">DATE</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col3 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> col4 <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col1<span class="token punctuation">,</span> col2<span class="token punctuation">,</span> col4<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>col2<span class="token punctuation">,</span> col1<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>col1 <span class="token operator">+</span> <span class="token function">YEAR</span><span class="token punctuation">(</span>col2<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span></code></pre> </div> <p> If a table has no unique keys—this includes having no primary key—then this restriction does not apply, and you may use any column or columns in the partitioning expression as long as the column type is compatible with the partitioning type. </p> <p> For the same reason, you cannot later add a unique key to a partitioned table unless the key includes all columns used by the table's partitioning expression. Consider the partitioned table created as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78587086"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span><span class="token punctuation">,</span> c2 <span class="token datatype">INT</span><span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">RANGE</span><span class="token punctuation">(</span>c1<span class="token punctuation">)</span> <span class="token punctuation">(</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p0 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p1 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p2 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">30</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> p3 <span class="token keyword">VALUES</span> <span class="token keyword">LESS</span> <span class="token keyword">THAN</span> <span class="token punctuation">(</span><span class="token number">40</span><span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.12 sec)</span></code></pre> </div> <p> It is possible to add a primary key to <code class="literal"> t_no_pk </code> using either of these <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE </code> </a> statements: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa45799369"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token comment" spellcheck="true"># possible PK</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">ADD</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>c1<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.13 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span> <span class="token comment" spellcheck="true"># drop this PK</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">DROP</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.10 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span> <span class="token comment" spellcheck="true"># use another possible PK</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">ADD</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>c1<span class="token punctuation">,</span> c2<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.12 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span> <span class="token comment" spellcheck="true"># drop this PK</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">DROP</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.09 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span></code></pre> </div> <p> However, the next statement fails, because <code class="literal"> c1 </code> is part of the partitioning key, but is not part of the proposed primary key: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa33913564"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token comment" spellcheck="true"># fails with error 1503</span> <span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t_no_pk <span class="token keyword">ADD</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">(</span>c2<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">ERROR 1503 (HY000)<span class="token punctuation">:</span> A PRIMARY KEY must include all columns in the table's partitioning function</span></code></pre> </div> <p> Since <code class="literal"> t_no_pk </code> has only <code class="literal"> c1 </code> in its partitioning expression, attempting to adding a unique key on <code class="literal"> c2 </code> alone fails. However, you can add a unique key that uses both <code class="literal"> c1 </code> and <code class="literal"> c2 </code> . </p> <p> These rules also apply to existing nonpartitioned tables that you wish to partition using <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE ... PARTITION BY </code> </a> . Consider a table <code class="literal"> np_pk </code> created as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa62477395"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> np_pk <span class="token punctuation">(</span> <span class="token prompt"> -></span> id <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">name</span> <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">50</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> added <span class="token datatype">DATE</span><span class="token punctuation">,</span> <span class="token prompt"> -></span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>id<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.08 sec)</span></code></pre> </div> <p> The following <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE </code> </a> statement fails with an error, because the <code class="literal"> added </code> column is not part of any unique key in the table: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa63510578"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> np_pk <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span> <span class="token function">TO_DAYS</span><span class="token punctuation">(</span>added<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token output">ERROR 1503 (HY000)<span class="token punctuation">:</span> A PRIMARY KEY must include all columns in the table's partitioning function</span></code></pre> </div> <p> However, this statement using the <code class="literal"> id </code> column for the partitioning column is valid, as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa76626325"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> np_pk <span class="token prompt"> -></span> <span class="token keyword">PARTITION</span> <span class="token keyword">BY</span> <span class="token keyword">HASH</span><span class="token punctuation">(</span>id<span class="token punctuation">)</span> <span class="token prompt"> -></span> <span class="token keyword">PARTITIONS</span> <span class="token number">4</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.11 sec)</span> <span class="token output">Records: 0 Duplicates: 0 Warnings: 0</span></code></pre> </div> <p> In the case of <code class="literal"> np_pk </code> , the only column that may be used as part of a partitioning expression is <code class="literal"> id </code> ; if you wish to partition this table using any other column or columns in the partitioning expression, you must first modify the table, either by adding the desired column or columns to the primary key, or by dropping the primary key altogether. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-tablestats-table.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-innodb-tablestats-table"> </a> 28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View </h3> </div> </div> </div> <a class="indexterm" name="idm46045076337216"> </a> <p> The <a class="link" href="information-schema-innodb-tablestats-table.html" title="28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View"> <code class="literal"> INNODB_TABLESTATS </code> </a> table provides a view of low-level status information about <code class="literal"> InnoDB </code> tables. This data is used by the MySQL optimizer to calculate which index to use when querying an <code class="literal"> InnoDB </code> table. This information is derived from in-memory data structures rather than data stored on disk. There is no corresponding internal <code class="literal"> InnoDB </code> system table. </p> <p> <code class="literal"> InnoDB </code> tables are represented in this view if they have been opened since the last server restart and have not aged out of the table cache. Tables for which persistent stats are available are always represented in this view. </p> <p> Table statistics are updated only for <a class="link" href="delete.html" title="15.2.2 DELETE Statement"> <code class="literal"> DELETE </code> </a> or <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> operations that modify indexed columns. Statistics are not updated by operations that modify only nonindexed columns. </p> <p> <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> clears table statistics and sets the <code class="literal"> STATS_INITIALIZED </code> column to <code class="literal"> Uninitialized </code> . Statistics are collected again the next time the table is accessed. </p> <p> For related usage information and examples, see <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> . </p> <p> The <a class="link" href="information-schema-innodb-tablestats-table.html" title="28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View"> <code class="literal"> INNODB_TABLESTATS </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> TABLE_ID </code> </p> <p> An identifier representing the table for which statistics are available; the same value as <code class="literal"> INNODB_TABLES.TABLE_ID </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> NAME </code> </p> <p> The name of the table; the same value as <code class="literal"> INNODB_TABLES.NAME </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> STATS_INITIALIZED </code> </p> <p> The value is <code class="literal"> Initialized </code> if the statistics are already collected, <code class="literal"> Uninitialized </code> if not. </p> </li> <li class="listitem"> <p> <code class="literal"> NUM_ROWS </code> </p> <p> The current estimated number of rows in the table. Updated after each DML operation. The value could be imprecise if uncommitted transactions are inserting into or deleting from the table. </p> </li> <li class="listitem"> <p> <code class="literal"> CLUST_INDEX_SIZE </code> </p> <p> The number of pages on disk that store the clustered index, which holds the <code class="literal"> InnoDB </code> table data in primary key order. This value might be null if no statistics are collected yet for the table. </p> </li> <li class="listitem"> <p> <code class="literal"> OTHER_INDEX_SIZE </code> </p> <p> The number of pages on disk that store all secondary indexes for the table. This value might be null if no statistics are collected yet for the table. </p> </li> <li class="listitem"> <p> <code class="literal"> MODIFIED_COUNTER </code> </p> <p> The number of rows modified by DML operations, such as <code class="literal"> INSERT </code> , <code class="literal"> UPDATE </code> , <code class="literal"> DELETE </code> , and also cascade operations from foreign keys. This column is reset each time table statistics are recalculated </p> </li> <li class="listitem"> <p> <code class="literal"> AUTOINC </code> </p> <p> The next number to be issued for any auto-increment-based operation. The rate at which the <code class="literal"> AUTOINC </code> value changes depends on how many times auto-increment numbers have been requested and how many numbers are granted per request. </p> </li> <li class="listitem"> <p> <code class="literal"> REF_COUNT </code> </p> <p> When this counter reaches zero, the table metadata can be evicted from the table cache. </p> </li> </ul> </div> <h4> <a name="idm46045076296080"> </a> Example </h4> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa36130149"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_TABLESTATS <span class="token keyword">where</span> TABLE_ID <span class="token operator">=</span> <span class="token number">71</span>\G <span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> TABLE_ID<span class="token punctuation">:</span> 71 NAME<span class="token punctuation">:</span> test/t1 STATS_INITIALIZED<span class="token punctuation">:</span> Initialized NUM_ROWS<span class="token punctuation">:</span> 1 CLUST_INDEX_SIZE<span class="token punctuation">:</span> 1 OTHER_INDEX_SIZE<span class="token punctuation">:</span> 0 MODIFIED_COUNTER<span class="token punctuation">:</span> 1 AUTOINC<span class="token punctuation">:</span> 0 REF_COUNT<span class="token punctuation">:</span> 1</span></code></pre> </div> <h4> <a name="idm46045076293424"> </a> Notes </h4> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> This table is useful primarily for expert-level performance monitoring, or when developing performance-related extensions for MySQL. </p> </li> <li class="listitem"> <p> You must have the <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> privilege to query this table. </p> </li> <li class="listitem"> <p> Use the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> <code class="literal"> COLUMNS </code> </a> table or the <a class="link" href="show-columns.html" title="15.7.7.6 SHOW COLUMNS Statement"> <code class="literal"> SHOW COLUMNS </code> </a> statement to view additional information about the columns of this table, including data types and default values. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/myisamchk-other-options.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="myisamchk-other-options"> </a> 6.6.4.4 Other myisamchk Options </h4> </div> </div> </div> <p> <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> supports the following options for actions other than table checks and repairs: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_myisamchk_analyze"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_analyze"> <code class="option"> --analyze </code> </a> , <code class="option"> -a </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for analyze"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --analyze </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306872784"> </a> <a class="indexterm" name="idm46045306871296"> </a> <p> Analyze the distribution of key values. This improves join performance by enabling the join optimizer to better choose the order in which to join the tables and which indexes it should use. To obtain information about the key distribution, use a <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --description --verbose <em class="replaceable"> <code> tbl_name </code> </em> </strong> </span> </a> command or the <code class="literal"> SHOW INDEX FROM <em class="replaceable"> <code> tbl_name </code> </em> </code> statement. </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_block-search"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_block-search"> <code class="option"> --block-search= <em class="replaceable"> <code> offset </code> </em> </code> </a> , <code class="option"> -b <em class="replaceable"> <code> offset </code> </em> </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for block-search"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --block-search=offset </code> </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306855760"> </a> <a class="indexterm" name="idm46045306854272"> </a> <p> Find the record that a block at the given offset belongs to. </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_description"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_description"> <code class="option"> --description </code> </a> , <code class="option"> -d </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for description"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --description </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306844240"> </a> <a class="indexterm" name="idm46045306842752"> </a> <p> Print some descriptive information about the table. Specifying the <a class="link" href="myisamchk-general-options.html#option_myisamchk_verbose"> <code class="option"> --verbose </code> </a> option once or twice produces additional information. See <a class="xref" href="myisamchk-table-info.html" title="6.6.4.5 Obtaining Table Information with myisamchk"> Section 6.6.4.5, “Obtaining Table Information with myisamchk” </a> . </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_set-auto-increment"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_set-auto-increment"> <code class="option"> --set-auto-increment[= <em class="replaceable"> <code> value </code> </em> ] </code> </a> , <code class="option"> -A[ <em class="replaceable"> <code> value </code> </em> ] </code> </p> <a class="indexterm" name="idm46045306835552"> </a> <a class="indexterm" name="idm46045306834096"> </a> <p> Force <code class="literal"> AUTO_INCREMENT </code> numbering for new records to start at the given value (or higher, if there are existing records with <code class="literal"> AUTO_INCREMENT </code> values this large). If <em class="replaceable"> <code> value </code> </em> is not specified, <code class="literal"> AUTO_INCREMENT </code> numbers for new records begin with the largest value currently in the table, plus one. </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_sort-index"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_sort-index"> <code class="option"> --sort-index </code> </a> , <code class="option"> -S </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for sort-index"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --sort-index </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306821248"> </a> <a class="indexterm" name="idm46045306819760"> </a> <p> Sort the index tree blocks in high-low order. This optimizes seeks and makes table scans that use indexes faster. </p> </li> <li class="listitem"> <p> <a name="option_myisamchk_sort-records"> </a> <a class="link" href="myisamchk-other-options.html#option_myisamchk_sort-records"> <code class="option"> --sort-records= <em class="replaceable"> <code> N </code> </em> </code> </a> , <code class="option"> -R <em class="replaceable"> <code> N </code> </em> </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for sort-records"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --sort-records=# </code> </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045306806992"> </a> <a class="indexterm" name="idm46045306805504"> </a> <p> Sort records according to a particular index. This makes your data much more localized and may speed up range-based <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> and <code class="literal"> ORDER BY </code> operations that use this index. (The first time you use this option to sort a table, it may be very slow.) To determine a table's index numbers, use <a class="link" href="show-index.html" title="15.7.7.23 SHOW INDEX Statement"> <code class="literal"> SHOW INDEX </code> </a> , which displays a table's indexes in the same order that <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> sees them. Indexes are numbered beginning with 1. </p> <p> If keys are not packed ( <code class="literal"> PACK_KEYS=0 </code> ), they have the same length, so when <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> sorts and moves records, it just overwrites record offsets in the index. If keys are packed ( <code class="literal"> PACK_KEYS=1 </code> ), <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> must unpack key blocks first, then re-create indexes and pack the key blocks again. (In this case, re-creating indexes is faster than updating offsets for each index.) </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/ipv6-local-connections.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="ipv6-local-connections"> </a> 7.1.13.3 Connecting Using the IPv6 Local Host Address </h4> </div> </div> </div> <p> The following procedure shows how to configure MySQL to permit IPv6 connections by clients that connect to the local server using the <code class="literal"> ::1 </code> local host address. The instructions given here assume that your system supports IPv6. </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Start the MySQL server with an appropriate <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> setting to permit it to accept IPv6 connections. For example, put the following lines in the server option file and restart the server: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa17973723"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> *</span></code></pre> </div> <p> Specifying * (or <code class="literal"> :: </code> ) as the value for <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> permits both IPv4 and IPv6 connections on all server host IPv4 and IPv6 interfaces. If you want to bind the server to a specific list of addresses, you can do this by specifying a comma-separated list of values for <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> . This example specifies the local host addresses for both IPv4 and IPv6: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa78913468"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 127.0.0.1,::1</span></code></pre> </div> <p> For more information, see the <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> description in <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> . </p> </li> <li class="listitem"> <p> As an administrator, connect to the server and create an account for a local user who can connect from the <code class="literal"> ::1 </code> local IPv6 host address: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa21333848"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'ipv6user'</span>@<span class="token string">'::1'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'ipv6pass'</span><span class="token punctuation">;</span></code></pre> </div> <p> For the permitted syntax of IPv6 addresses in account names, see <a class="xref" href="account-names.html" title="8.2.4 Specifying Account Names"> Section 8.2.4, “Specifying Account Names” </a> . In addition to the <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> statement, you can issue <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> statements that give specific privileges to the account, although that is not necessary for the remaining steps in this procedure. </p> </li> <li class="listitem"> <p> Invoke the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client to connect to the server using the new account: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa73409060"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-h</span> <span class="token punctuation">:</span><span class="token punctuation">:</span>1 <span class="token property">-u</span> ipv6user <span class="token property">-pipv6pass</span></code></pre> </div> </li> <li class="listitem"> <p> Try some simple statements that show connection information: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa32741677"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">STATUS</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">Connection</span>: ::<span class="token number">1</span> via TCP<span class="token operator">/</span>IP <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">CURRENT_USER</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token variable">@@bind_address</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> CURRENT_USER() <span class="token punctuation">|</span> @@bind_address <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> ipv6user@::1 <span class="token punctuation">|</span> :: <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </li> </ol> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/controlling-query-plan-evaluation.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="controlling-query-plan-evaluation"> </a> 10.9.1 Controlling Query Plan Evaluation </h3> </div> </div> </div> <a class="indexterm" name="idm46045224538752"> </a> <p> The task of the query optimizer is to find an optimal plan for executing an SQL query. Because the difference in performance between <span class="quote"> “ <span class="quote"> good </span> ” </span> and <span class="quote"> “ <span class="quote"> bad </span> ” </span> plans can be orders of magnitude (that is, seconds versus hours or even days), most query optimizers, including that of MySQL, perform a more or less exhaustive search for an optimal plan among all possible query evaluation plans. For join queries, the number of possible plans investigated by the MySQL optimizer grows exponentially with the number of tables referenced in a query. For small numbers of tables (typically less than 7 to 10) this is not a problem. However, when larger queries are submitted, the time spent in query optimization may easily become the major bottleneck in the server's performance. </p> <p> A more flexible method for query optimization enables the user to control how exhaustive the optimizer is in its search for an optimal query evaluation plan. The general idea is that the fewer plans that are investigated by the optimizer, the less time it spends in compiling a query. On the other hand, because the optimizer skips some plans, it may miss finding an optimal plan. </p> <p> The behavior of the optimizer with respect to the number of plans it evaluates can be controlled using two system variables: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The <a class="link" href="server-system-variables.html#sysvar_optimizer_prune_level"> <code class="literal"> optimizer_prune_level </code> </a> variable tells the optimizer to skip certain plans based on estimates of the number of rows accessed for each table. Our experience shows that this kind of <span class="quote"> “ <span class="quote"> educated guess </span> ” </span> rarely misses optimal plans, and may dramatically reduce query compilation times. That is why this option is on ( <code class="literal"> optimizer_prune_level=1 </code> ) by default. However, if you believe that the optimizer missed a better query plan, this option can be switched off ( <code class="literal"> optimizer_prune_level=0 </code> ) with the risk that query compilation may take much longer. Note that, even with the use of this heuristic, the optimizer still explores a roughly exponential number of plans. </p> </li> <li class="listitem"> <p> The <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> variable tells how far into the <span class="quote"> “ <span class="quote"> future </span> ” </span> of each incomplete plan the optimizer should look to evaluate whether it should be expanded further. Smaller values of <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> may result in orders of magnitude smaller query compilation times. For example, queries with 12, 13, or more tables may easily require hours and even days to compile if <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> is close to the number of tables in the query. At the same time, if compiled with <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> equal to 3 or 4, the optimizer may compile in less than a minute for the same query. If you are unsure of what a reasonable value is for <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> <code class="literal"> optimizer_search_depth </code> </a> , this variable can be set to 0 to tell the optimizer to determine the value automatically. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/replication-threads-monitor-worker.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-threads-monitor-worker"> </a> 19.2.3.2 Monitoring Replication Applier Worker Threads </h4> </div> </div> </div> <p> On a multithreaded replica, the Performance Schema tables <a class="link" href="performance-schema-replication-applier-status-by-coordinator-table.html" title="29.12.11.6 The replication_applier_status_by_coordinator Table"> <code class="literal"> replication_applier_status_by_coordinator </code> </a> and <a class="link" href="performance-schema-replication-applier-status-by-worker-table.html" title="29.12.11.7 The replication_applier_status_by_worker Table"> <code class="literal"> replication_applier_status_by_worker </code> </a> show status information for the replica's coordinator thread and applier worker threads respectively. For a replica with multiple channels, the threads for each channel are identified. </p> <p> A multithreaded replica's coordinator thread also prints statistics to the replica's error log on a regular basis if the verbosity setting is set to display informational messages. The statistics are printed depending on the volume of events that the coordinator thread has assigned to applier worker threads, with a maximum frequency of once every 120 seconds. The message lists the following statistics for the relevant replication channel, or the default replication channel (which is not named): </p> <div class="variablelist"> <dl class="variablelist"> <dt> <span class="term"> Seconds elapsed </span> </dt> <dd> <p> The difference in seconds between the current time and the last time this information was printed to the error log. </p> </dd> <dt> <span class="term"> Events assigned </span> </dt> <dd> <p> The total number of events that the coordinator thread has queued to all applier worker threads since the coordinator thread was started. </p> </dd> <dt> <span class="term"> Worker queues filled over overrun level </span> </dt> <dd> <p> The current number of events that are queued to any of the applier worker threads in excess of the overrun level, which is set at 90% of the maximum queue length of 16384 events. If this value is zero, no applier worker threads are operating at the upper limit of their capacity. </p> </dd> <dt> <span class="term"> Waited due to worker queue full </span> </dt> <dd> <p> The number of times that the coordinator thread had to wait to schedule an event because an applier worker thread's queue was full. If this value is zero, no applier worker threads exhausted their capacity. </p> </dd> <dt> <span class="term"> Waited due to the total size </span> </dt> <dd> <p> The number of times that the coordinator thread had to wait to schedule an event because the <a class="link" href="replication-options-replica.html#sysvar_replica_pending_jobs_size_max"> <code class="literal"> replica_pending_jobs_size_max </code> </a> limit had been reached. This system variable sets the maximum amount of memory (in bytes) available to applier worker thread queues holding events not yet applied. If an unusually large event exceeds this size, the transaction is held until all the applier worker threads have empty queues, and then processed. All subsequent transactions are held until the large transaction has been completed. </p> </dd> <dt> <span class="term"> Waited at clock conflicts </span> </dt> <dd> <p> The number of nanoseconds that the coordinator thread had to wait to schedule an event because a transaction that the event depended on had not yet been committed. If <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_type"> <code class="literal"> replica_parallel_type </code> </a> is set to <code class="literal"> DATABASE </code> (rather than <code class="literal"> LOGICAL_CLOCK </code> ), this value is always zero. </p> </dd> <dt> <span class="term"> Waited (count) when workers occupied </span> </dt> <dd> <p> The number of times that the coordinator thread slept for a short period, which it might do in two situations. The first situation is where the coordinator thread assigns an event and finds the applier worker thread's queue is filled beyond the underrun level of 10% of the maximum queue length, in which case it sleeps for a maximum of 1 millisecond. The second situation is where <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_type"> <code class="literal"> replica_parallel_type </code> </a> is set to <code class="literal"> LOGICAL_CLOCK </code> and the coordinator thread needs to assign the first event of a transaction to an applier worker thread's queue, it only does this to a worker with an empty queue, so if no queues are empty, the coordinator thread sleeps until one becomes empty. </p> </dd> <dt> <span class="term"> Waited when workers occupied </span> </dt> <dd> <p> The number of nanoseconds that the coordinator thread slept while waiting for an empty applier worker thread queue (that is, in the second situation described above, where <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_type"> <code class="literal"> replica_parallel_type </code> </a> is set to <code class="literal"> LOGICAL_CLOCK </code> and the first event of a transaction needs to be assigned). </p> </dd> </dl> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/encrypted-connection-protocols-ciphers.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="encrypted-connection-protocols-ciphers"> </a> 8.3.2 Encrypted Connection TLS Protocols and Ciphers </h3> </div> </div> </div> <p> MySQL supports multiple TLS protocols and ciphers, and enables configuring which protocols and ciphers to permit for encrypted connections. It is also possible to determine which protocol and cipher the current session uses. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-supported-protocols" title="Supported TLS Protocols"> Supported TLS Protocols </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-deprecated-protocols" title="Removal of Support for the TLSv1 and TLSv1.1 Protocols"> Removal of Support for the TLSv1 and TLSv1.1 Protocols </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-configuration" title="Connection TLS Protocol Configuration"> Connection TLS Protocol Configuration </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-cipher-configuration" title="Connection Cipher Configuration"> Connection Cipher Configuration </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-negotiation" title="Connection TLS Protocol Negotiation"> Connection TLS Protocol Negotiation </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-monitoring" title="Monitoring Current Client Session TLS Protocol and Cipher"> Monitoring Current Client Session TLS Protocol and Cipher </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-supported-protocols"> </a> Supported TLS Protocols </h4> </div> </div> </div> <p> MySQL 8.4 supports the TLSv1.2 and TLSv1.3 protocols for connections. To use TLSv1.3, both the MySQL server and the client application must be compiled using OpenSSL 1.1.1 or higher. The Group Replication component supports TLSv1.3 from MySQL 8.0.18 (for details, see <a class="xref" href="group-replication-secure-socket-layer-support-ssl.html" title="20.6.2 Securing Group Communication Connections with Secure Socket Layer (SSL)"> Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” </a> ). </p> <p> MySQL 8.4 does not support the old TLSv1 and TLSv1.1 protocols. </p> <p> Permitted TLS protocols can be configured on both the server side and client side to include only a subset of the supported TLS protocols. The configuration on both sides must include at least one protocol in common or connection attempts cannot negotiate a protocol to use. For details, see <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-negotiation" title="Connection TLS Protocol Negotiation"> Connection TLS Protocol Negotiation </a> . </p> <p> The host system may permit only certain TLS protocols, which means that MySQL connections cannot use protocols not allowed by the host even if MySQL itself permits them. Possible workarounds for this issue include the following: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Change the system-wide host configuration to permit additional TLS protocols. Consult your operating system documentation for instructions. For example, your system may have an <code class="literal"> /etc/ssl/openssl.cnf </code> file that contains these lines to restrict TLS protocols to TLSv1.3 or higher: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa45481712"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[system_default_sect]</span> <span class="token constant">MinProtocol</span> <span class="token attr-value"><span class="token punctuation">=</span> TLSv1.3</span></code></pre> </div> <p> Changing the value to a lower protocol version or <code class="literal"> None </code> makes the system more permissive. This workaround has the disadvantage that permitting lower (less secure) protocols may have adverse security consequences. </p> </li> <li class="listitem"> <p> If you cannot or prefer not to change the host system TLS configuration, change MySQL applications to use higher (more secure) TLS protocols that are permitted by the host system. This may not be possible for older versions of MySQL that support only lower protocol versions. For example, TLSv1 is the only supported protocol prior to MySQL 5.6.46, so attempts to connect to a pre-5.6.46 server fail even if the client is from a newer MySQL version that supports higher protocol versions. In such cases, an upgrade to a version of MySQL that supports additional TLS versions may be required. </p> </li> </ul> </div> <div class="variablelist"> <dl class="variablelist"> <dt> <span class="term"> System-wide host configuration </span> </dt> <dd> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If the MySQL configuration permits TLSv1.2, and your host system configuration permits only connections that use TLSv1.2 or higher, you can establish MySQL connections using TLSv1.2 only. </p> </li> <li class="listitem"> <p> Suppose the MySQL configuration permits TLSv1.2, but your host system configuration permits only connections that use TLSv1.3 or higher. If this is the case, you cannot establish MySQL connections at all, because no protocol permitted by MySQL is permitted by the host system. </p> </li> </ul> </div> </dd> </dl> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-deprecated-protocols"> </a> Removal of Support for the TLSv1 and TLSv1.1 Protocols </h4> </div> </div> </div> <p> Support for the TLSv1 and TLSv1.1 connection protocols was deprecated and removed in MySQL 8.0. For background, refer to the IETF memo <a class="ulink" href="https://tools.ietf.org/id/draft-ietf-tls-oldversions-deprecate-02.html" target="_blank"> Deprecating TLSv1.0 and TLSv1.1 </a> . In MySQL 8.4, connections can be made using only the more secure TLSv1.2 and TLSv1.3 protocols. TLSv1.3 requires that both the MySQL server and the client application are compiled with OpenSSL 1.1.1. </p> <p> For more information, see <a class="link" href="faqs-security.html#faq-mysql-tls-versions" title="A.9.7."> Does MySQL 8.4 support TLS 1.0 and 1.1? </a> </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-protocol-configuration"> </a> Connection TLS Protocol Configuration </h4> </div> </div> </div> <p> On the server side, the value of the <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> system variable determines which TLS protocols a MySQL server permits for encrypted connections. The <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> value applies to connections from clients, regular source/replica replication connections where this server instance is the source, Group Replication group communication connections, and Group Replication distributed recovery connections where this server instance is the donor. The administrative connection interface is configured similarly, but uses the <a class="link" href="server-system-variables.html#sysvar_admin_tls_version"> <code class="literal"> admin_tls_version </code> </a> system variable (see <a class="xref" href="administrative-connection-interface.html" title="7.1.12.2 Administrative Connection Management"> Section 7.1.12.2, “Administrative Connection Management” </a> ). This discussion applies to <a class="link" href="server-system-variables.html#sysvar_admin_tls_version"> <code class="literal"> admin_tls_version </code> </a> as well. </p> <p> The <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> value is a list of one or more comma-separated TLS protocol versions, which is not case-sensitive. By default, this variable lists all protocols that are supported by the SSL library used to compile MySQL and by the MySQL Server release. The default settings are therefore as shown in <a class="ulink" href="/doc/refman/8.0/en/encrypted-connection-protocols-ciphers.html#tls-support-defaults" target="_top"> MySQL Server TLS Protocol Default Settings </a> . </p> <p> To determine the value of <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> at runtime, use this statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa76162695"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">GLOBAL</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'tls_version'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Variable_name <span class="token punctuation">|</span> Value <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> tls_version <span class="token punctuation">|</span> TLSv1.2,TLSv1.3 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> To change the value of <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> , set it at server startup. For example, to permit connections that use the TLSv1.2 or TLSv1.3 protocol, but prohibit connections that use any other protocol, use these lines in the server <code class="filename"> my.cnf </code> file: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa50920394"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">tls_version</span><span class="token attr-value"><span class="token punctuation">=</span>TLSv1.2,TLSv1.3</span></code></pre> </div> <p> To be even more restrictive and permit only TLSv1.3 connections, set <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa59766875"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">tls_version</span><span class="token attr-value"><span class="token punctuation">=</span>TLSv1.3</span></code></pre> </div> <p> <code class="literal"> tls_version </code> can be changed at runtime. See <a class="xref" href="using-encrypted-connections.html#using-encrypted-connections-server-side-runtime-configuration" title="Server-Side Runtime Configuration and Monitoring for Encrypted Connections"> Server-Side Runtime Configuration and Monitoring for Encrypted Connections </a> . </p> <p> On the client side, the <a class="link" href="connection-options.html#option_general_tls-version"> <code class="option"> --tls-version </code> </a> option specifies which TLS protocols a client program permits for connections to the server. The format of the option value is the same as for the <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> system variable described previously (a list of one or more comma-separated protocol versions). </p> <p> For source/replica replication connections where this server instance is the replica, the <code class="literal"> SOURCE_TLS_VERSION </code> option for the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement specifies which TLS protocols the replica permits for connections to the source. The format of the option value is the same as for the <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> system variable described previously. See <a class="xref" href="replication-encrypted-connections.html" title="19.3.1 Setting Up Replication to Use Encrypted Connections"> Section 19.3.1, “Setting Up Replication to Use Encrypted Connections” </a> . </p> <p> The protocols that can be specified for <code class="literal"> SOURCE_TLS_VERSION </code> depend on the SSL library. This option is independent of and not affected by the server <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> value. For example, a server that acts as a replica can be configured with <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> set to TLSv1.3 to permit only incoming connections that use TLSv1.3, but also configured with <code class="literal"> SOURCE_TLS_VERSION </code> set to TLSv1.2 to permit only TLSv1.2 for outgoing replica connections to the source. </p> <p> For Group Replication distributed recovery connections where this server instance is the joining member that initiates distributed recovery (that is, the client), the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_version"> <code class="literal"> group_replication_recovery_tls_version </code> </a> system variable specifies which protocols are permitted by the client. Again, this option is independent of and not affected by the server <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> value, which applies when this server instance is the donor. A Group Replication server generally participates in distributed recovery both as a donor and as a joining member over the course of its group membership, so both these system variables should be set. See <a class="xref" href="group-replication-secure-socket-layer-support-ssl.html" title="20.6.2 Securing Group Communication Connections with Secure Socket Layer (SSL)"> Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” </a> . </p> <p> TLS protocol configuration affects which protocol a given connection uses, as described in <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-negotiation" title="Connection TLS Protocol Negotiation"> Connection TLS Protocol Negotiation </a> . </p> <p> Permitted protocols should be chosen such as not to leave <span class="quote"> “ <span class="quote"> holes </span> ” </span> in the list. For example, these server configuration values do not have holes: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa14697150"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">tls_version<span class="token attr-value"><span class="token punctuation">=</span>TLSv1.2,TLSv1.3</span> tls_version<span class="token attr-value"><span class="token punctuation">=</span>TLSv1.3</span></code></pre> </div> <p> The prohibition on holes also applies in other configuration contexts, such as for clients or replicas. </p> <p> Unless you intend to disable encrypted connections, the list of permitted protocols should not be empty. If you set a TLS version parameter to the empty string, encrypted connections cannot be established: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> : The server does not permit encrypted incoming connections. </p> </li> <li class="listitem"> <p> <a class="link" href="connection-options.html#option_general_tls-version"> <code class="option"> --tls-version </code> </a> : The client does not permit encrypted outgoing connections to the server. </p> </li> <li class="listitem"> <p> <code class="literal"> SOURCE_TLS_VERSION </code> : The replica does not permit encrypted outgoing connections to the source. </p> </li> <li class="listitem"> <p> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_version"> <code class="literal"> group_replication_recovery_tls_version </code> </a> : The joining member does not permit encrypted connections to the distributed recovery connection. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-cipher-configuration"> </a> Connection Cipher Configuration </h4> </div> </div> </div> <p> A default set of ciphers applies to encrypted connections, which can be overridden by explicitly configuring the permitted ciphers. During connection establishment, both sides of a connection must permit some cipher in common or the connection fails. Of the permitted ciphers common to both sides, the SSL library chooses the one supported by the provided certificate that has the highest priority. </p> <p> To specify a cipher or ciphers applicable for encrypted connections that use TLSv1.2: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Set the <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> ssl_cipher </code> </a> system variable on the server side, and use the <a class="link" href="connection-options.html#option_general_ssl-cipher"> <code class="option"> --ssl-cipher </code> </a> option for client programs. </p> </li> <li class="listitem"> <p> For regular source/replica replication connections, where this server instance is the source, set the <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> ssl_cipher </code> </a> system variable. Where this server instance is the replica, use the <code class="literal"> SOURCE_SSL_CIPHER </code> option for the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement. See <a class="xref" href="replication-encrypted-connections.html" title="19.3.1 Setting Up Replication to Use Encrypted Connections"> Section 19.3.1, “Setting Up Replication to Use Encrypted Connections” </a> . </p> </li> <li class="listitem"> <p> For a Group Replication group member, for Group Replication group communication connections and also for Group Replication distributed recovery connections where this server instance is the donor, set the <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> ssl_cipher </code> </a> system variable. For Group Replication distributed recovery connections where this server instance is the joining member, use the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_cipher"> <code class="literal"> group_replication_recovery_ssl_cipher </code> </a> system variable. See <a class="xref" href="group-replication-secure-socket-layer-support-ssl.html" title="20.6.2 Securing Group Communication Connections with Secure Socket Layer (SSL)"> Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” </a> . </p> </li> </ul> </div> <p> For encrypted connections that use TLSv1.3, OpenSSL 1.1.1 and higher supports the following ciphersuites, all of which are enabled by default for use with server system variables <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> --tls-ciphersuites </code> </a> or <a class="link" href="server-system-variables.html#sysvar_admin_tls_ciphersuites"> <code class="literal"> --admin-tls-ciphersuites </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa65442314"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">TLS_AES_128_GCM_SHA256 TLS_AES_256_GCM_SHA384 TLS_CHACHA20_POLY1305_SHA256 TLS_AES_128_CCM_SHA256</code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> In MySQL 8.4, use of <code class="literal"> TLS_AES_128_CCM_8_SHA256 </code> with server system variables <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> --tls-ciphersuites </code> </a> or <a class="link" href="server-system-variables.html#sysvar_admin_tls_ciphersuites"> <code class="literal"> --admin-tls-ciphersuites </code> </a> generates a deprecation warning. </p> </div> <p> To configure the permitted TLSv1.3 ciphersuites explicitly, set the following parameters. In each case, the configuration value is a list of zero or more colon-separated ciphersuite names. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> On the server side, use the <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> tls_ciphersuites </code> </a> system variable. If this variable is not set, its default value is <code class="literal"> NULL </code> , which means that the server permits the default set of ciphersuites. If the variable is set to the empty string, no ciphersuites are enabled and encrypted connections cannot be established. </p> </li> <li class="listitem"> <p> On the client side, use the <a class="link" href="connection-options.html#option_general_tls-ciphersuites"> <code class="option"> --tls-ciphersuites </code> </a> option. If this option is not set, the client permits the default set of ciphersuites. If the option is set to the empty string, no ciphersuites are enabled and encrypted connections cannot be established. </p> </li> <li class="listitem"> <p> For regular source/replica replication connections, where this server instance is the source, use the <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> tls_ciphersuites </code> </a> system variable. Where this server instance is the replica, use the <code class="literal"> SOURCE_TLS_CIPHERSUITES </code> option for the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement. See <a class="xref" href="replication-encrypted-connections.html" title="19.3.1 Setting Up Replication to Use Encrypted Connections"> Section 19.3.1, “Setting Up Replication to Use Encrypted Connections” </a> . </p> </li> <li class="listitem"> <p> For a Group Replication group member, for Group Replication group communication connections and also for Group Replication distributed recovery connections where this server instance is the donor, use the <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> <code class="literal"> tls_ciphersuites </code> </a> system variable. For Group Replication distributed recovery connections where this server instance is the joining member, use the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_ciphersuites"> <code class="literal"> group_replication_recovery_tls_ciphersuites </code> </a> system variable. See <a class="xref" href="group-replication-secure-socket-layer-support-ssl.html" title="20.6.2 Securing Group Communication Connections with Secure Socket Layer (SSL)"> Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” </a> . </p> </li> </ul> </div> <p> Ciphersuite support requires that both the MySQL server and the client application be compiled using OpenSSL 1.1.1 or higher. </p> <p> A given cipher may work only with particular TLS protocols, which affects the TLS protocol negotiation process. See <a class="xref" href="encrypted-connection-protocols-ciphers.html#encrypted-connection-protocol-negotiation" title="Connection TLS Protocol Negotiation"> Connection TLS Protocol Negotiation </a> . </p> <p> To determine which ciphers a given server supports, check the session value of the <a class="link" href="server-status-variables.html#statvar_Ssl_cipher_list"> <code class="literal"> Ssl_cipher_list </code> </a> status variable: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa66789796"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SHOW</span> <span class="token keyword">SESSION</span> <span class="token keyword">STATUS</span> <span class="token operator">LIKE</span> <span class="token string">'Ssl_cipher_list'</span><span class="token punctuation">;</span></code></pre> </div> <p> The <a class="link" href="server-status-variables.html#statvar_Ssl_cipher_list"> <code class="literal"> Ssl_cipher_list </code> </a> status variable lists the possible SSL ciphers (empty for non-SSL connections). If MySQL supports TLSv1.3, the value includes the possible TLSv1.3 ciphersuites. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> ECDSA ciphers only work in combination with an SSL certificate that uses ECDSA for the digital signature, and they do not work with certificates that use RSA. MySQL Server’s automatic generation process for SSL certificates does not generate ECDSA signed certificates, it generates only RSA signed certificates. Do not select ECDSA ciphers unless you have an ECDSA certificate available to you. </p> </div> <p> For encrypted connections that use TLS.v1.3, MySQL uses the SSL library default ciphersuite list. </p> <p> For encrypted connections that use TLSv1.2, MySQL passes the following default cipher list to the SSL library when used with the server system variables <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> --ssl-cipher </code> </a> and <a class="link" href="server-system-variables.html#sysvar_admin_ssl_cipher"> <code class="literal"> --admin-ssl-cipher </code> </a> . </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa41336208"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ECDHE-ECDSA-AES128-GCM-SHA256 ECDHE-ECDSA-AES256-GCM-SHA384 ECDHE-RSA-AES128-GCM-SHA256 ECDHE-RSA-AES256-GCM-SHA384 ECDHE-ECDSA-CHACHA20-POLY1305 ECDHE-RSA-CHACHA20-POLY1305 ECDHE-ECDSA-AES256-CCM ECDHE-ECDSA-AES128-CCM DHE-RSA-AES128-GCM-SHA256 DHE-RSA-AES256-GCM-SHA384 DHE-RSA-AES256-CCM DHE-RSA-AES128-CCM DHE-RSA-CHACHA20-POLY1305</code></pre> </div> <p> These cipher restrictions are in place: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The following ciphers are deprecated and produce a warning when used with the server system variables <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> <code class="literal"> --ssl-cipher </code> </a> and <a class="link" href="server-system-variables.html#sysvar_admin_ssl_cipher"> <code class="literal"> --admin-ssl-cipher </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa53845696"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ECDHE-ECDSA-AES128-SHA256 ECDHE-RSA-AES128-SHA256 ECDHE-ECDSA-AES256-SHA384 ECDHE-RSA-AES256-SHA384 DHE-DSS-AES128-GCM-SHA256 DHE-RSA-AES128-SHA256 DHE-DSS-AES128-SHA256 DHE-DSS-AES256-GCM-SHA384 DHE-RSA-AES256-SHA256 DHE-DSS-AES256-SHA256 ECDHE-RSA-AES128-SHA ECDHE-ECDSA-AES128-SHA ECDHE-RSA-AES256-SHA ECDHE-ECDSA-AES256-SHA DHE-DSS-AES128-SHA DHE-RSA-AES128-SHA TLS_DHE_DSS_WITH_AES_256_CBC_SHA DHE-RSA-AES256-SHA AES128-GCM-SHA256 DH-DSS-AES128-GCM-SHA256 ECDH-ECDSA-AES128-GCM-SHA256 AES256-GCM-SHA384 DH-DSS-AES256-GCM-SHA384 ECDH-ECDSA-AES256-GCM-SHA384 AES128-SHA256 DH-DSS-AES128-SHA256 ECDH-ECDSA-AES128-SHA256 AES256-SHA256 DH-DSS-AES256-SHA256 ECDH-ECDSA-AES256-SHA384 AES128-SHA DH-DSS-AES128-SHA ECDH-ECDSA-AES128-SHA AES256-SHA DH-DSS-AES256-SHA ECDH-ECDSA-AES256-SHA DH-RSA-AES128-GCM-SHA256 ECDH-RSA-AES128-GCM-SHA256 DH-RSA-AES256-GCM-SHA384 ECDH-RSA-AES256-GCM-SHA384 DH-RSA-AES128-SHA256 ECDH-RSA-AES128-SHA256 DH-RSA-AES256-SHA256 ECDH-RSA-AES256-SHA384 ECDHE-RSA-AES128-SHA ECDHE-ECDSA-AES128-SHA ECDHE-RSA-AES256-SHA ECDHE-ECDSA-AES256-SHA DHE-DSS-AES128-SHA DHE-RSA-AES128-SHA TLS_DHE_DSS_WITH_AES_256_CBC_SHA DHE-RSA-AES256-SHA AES128-SHA DH-DSS-AES128-SHA ECDH-ECDSA-AES128-SHA AES256-SHA DH-DSS-AES256-SHA ECDH-ECDSA-AES256-SHA DH-RSA-AES128-SHA ECDH-RSA-AES128-SHA DH-RSA-AES256-SHA ECDH-RSA-AES256-SHA DES-CBC3-SHA</code></pre> </div> </li> <li class="listitem"> <p> The following ciphers are permanently restricted: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa44880851"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">!DHE-DSS-DES-CBC3-SHA !DHE-RSA-DES-CBC3-SHA !ECDH-RSA-DES-CBC3-SHA !ECDH-ECDSA-DES-CBC3-SHA !ECDHE-RSA-DES-CBC3-SHA !ECDHE-ECDSA-DES-CBC3-SHA</code></pre> </div> </li> <li class="listitem"> <p> The following categories of ciphers are permanently restricted: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa11359119"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">!aNULL !eNULL !EXPORT !LOW !MD5 !DES !RC2 !RC4 !PSK !SSLv3</code></pre> </div> </li> </ul> </div> <p> If the server is started with the <a class="link" href="server-system-variables.html#sysvar_ssl_cert"> <code class="literal"> ssl_cert </code> </a> system variable set to a certificate that uses any of the preceding restricted ciphers or cipher categories, the server starts with support for encrypted connections disabled. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-protocol-negotiation"> </a> Connection TLS Protocol Negotiation </h4> </div> </div> </div> <p> Connection attempts in MySQL negotiate use of the highest TLS protocol version available on both sides for which a protocol-compatible encryption cipher is available on both sides. The negotiation process depends on factors such as the SSL library used to compile the server and client, the TLS protocol and encryption cipher configuration, and which key size is used: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For a connection attempt to succeed, the server and client TLS protocol configuration must permit some protocol in common. </p> </li> <li class="listitem"> <p> Similarly, the server and client encryption cipher configuration must permit some cipher in common. A given cipher may work only with particular TLS protocols, so a protocol available to the negotiation process is not chosen unless there is also a compatible cipher. </p> </li> <li class="listitem"> <p> If TLSv1.3 is available, it is used if possible. (This means that server and client configuration both must permit TLSv1.3, and both must also permit some TLSv1.3-compatible encryption cipher.) Otherwise, MySQL continues through the list of available protocols, using TLSv1.2 if possible, and so forth. Negotiation proceeds from more secure protocols to less secure. Negotiation order is independent of the order in which protocols are configured. For example, negotiation order is the same regardless of whether <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> has a value of <code class="literal"> TLSv1.2,TLSv1.3 </code> or <code class="literal"> TLSv1.3,TLSv1.2 </code> . </p> </li> <li class="listitem"> <p> For better security, use a certificate with an RSA key size of at least 2048 bits. </p> </li> </ul> </div> <p> If the server and client do not have a permitted protocol in common, and a protocol-compatible cipher in common, the server terminates the connection request. </p> <p> MySQL permits specifying a list of protocols to support. This list is passed directly down to the underlying SSL library and is ultimately up to that library what protocols it actually enables from the supplied list. Please refer to the MySQL source code and the OpenSSL <a class="ulink" href="https://www.openssl.org/docs/man1.1.0/ssl/SSL_CTX_new.html" target="_blank"> <code class="literal"> SSL_CTX_new() </code> </a> documentation for information about how the SSL library handles this. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="encrypted-connection-protocol-monitoring"> </a> Monitoring Current Client Session TLS Protocol and Cipher </h4> </div> </div> </div> <p> To determine which encryption TLS protocol and cipher the current client session uses, check the session values of the <a class="link" href="server-status-variables.html#statvar_Ssl_version"> <code class="literal"> Ssl_version </code> </a> and <a class="link" href="server-status-variables.html#statvar_Ssl_cipher"> <code class="literal"> Ssl_cipher </code> </a> status variables: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa52834629"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>session_status <span class="token keyword">WHERE</span> VARIABLE_NAME <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token string">'Ssl_version'</span><span class="token punctuation">,</span><span class="token string">'Ssl_cipher'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> VARIABLE_NAME <span class="token punctuation">|</span> VARIABLE_VALUE <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Ssl_cipher <span class="token punctuation">|</span> DHE<span class="token punctuation">-</span>RSA<span class="token punctuation">-</span>AES128<span class="token punctuation">-</span>GCM<span class="token punctuation">-</span>SHA256 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> Ssl_version <span class="token punctuation">|</span> TLSv1.2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> If the connection is not encrypted, both variables have an empty value. </p> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/table.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="table"> </a> 15.2.16 TABLE Statement </h3> </div> </div> </div> <a class="indexterm" name="idm46045179562896"> </a> <a class="indexterm" name="idm46045179561824"> </a> <a class="indexterm" name="idm46045179560368"> </a> <p> <code class="literal"> TABLE </code> is a DML statement which returns rows and columns of the named table. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa74040423"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">TABLE</span> <span class="token keyword"><em class="replaceable">table_name</em></span> <span class="token punctuation">[</span><span class="token keyword">ORDER</span> <span class="token keyword">BY</span> <span class="token keyword"><em class="replaceable">column_name</em></span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">LIMIT</span> <span class="token keyword"><em class="replaceable">number</em></span> <span class="token punctuation">[</span><span class="token keyword">OFFSET</span> <span class="token keyword"><em class="replaceable">number</em></span><span class="token punctuation">]</span><span class="token punctuation">]</span></code></pre> </div> <p> The <code class="literal"> TABLE </code> statement in some ways acts like <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> . Given the existence of a table named <code class="literal"> t </code> , the following two statements produce identical output: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa28115064"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">TABLE</span> t<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t<span class="token punctuation">;</span></code></pre> </div> <p> You can order and limit the number of rows produced by <code class="literal"> TABLE </code> using <code class="literal"> ORDER BY </code> and <code class="literal"> LIMIT </code> clauses, respectively. These function identically to the same clauses when used with <code class="literal"> SELECT </code> (including an optional <code class="literal"> OFFSET </code> clause with <code class="literal"> LIMIT </code> ), as you can see here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa8192908"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> 7 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 9 <span class="token punctuation">|</span> 5 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 10 <span class="token punctuation">|</span> <span class="token punctuation">-</span>4 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span> <span class="token punctuation">-</span>1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 13 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 14 <span class="token punctuation">|</span> 6 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">7 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> b<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 10 <span class="token punctuation">|</span> <span class="token punctuation">-</span>4 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span> <span class="token punctuation">-</span>1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 13 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 9 <span class="token punctuation">|</span> 5 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 14 <span class="token punctuation">|</span> 6 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> 7 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">7 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t <span class="token keyword">LIMIT</span> <span class="token number">3</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> 7 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 9 <span class="token punctuation">|</span> 5 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> b <span class="token keyword">LIMIT</span> <span class="token number">3</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 10 <span class="token punctuation">|</span> <span class="token punctuation">-</span>4 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span> <span class="token punctuation">-</span>1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> b <span class="token keyword">LIMIT</span> <span class="token number">3</span> <span class="token keyword">OFFSET</span> <span class="token number">2</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 13 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 9 <span class="token punctuation">|</span> 5 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span></code></pre> </div> <p> <code class="literal"> TABLE </code> differs from <code class="literal"> SELECT </code> in two key respects: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> TABLE </code> always displays all columns of the table. </p> <p> <span class="emphasis"> <em> Exception </em> </span> : The output of <code class="literal"> TABLE </code> does <span class="emphasis"> <em> not </em> </span> include invisible columns. See <a class="xref" href="invisible-columns.html" title="15.1.20.10 Invisible Columns"> Section 15.1.20.10, “Invisible Columns” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE </code> does not allow for any arbitrary filtering of rows; that is, <code class="literal"> TABLE </code> does not support any <code class="literal"> WHERE </code> clause. </p> </li> </ul> </div> <p> For limiting which table columns are returned, filtering rows beyond what can be accomplished using <code class="literal"> ORDER BY </code> and <code class="literal"> LIMIT </code> , or both, use <code class="literal"> SELECT </code> . </p> <p> <code class="literal"> TABLE </code> can be used with temporary tables. </p> <p> <code class="literal"> TABLE </code> can also be used in place of <code class="literal"> SELECT </code> in a number of other constructs, including those listed here: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> With set operators such as <a class="link" href="union.html" title="15.2.18 UNION Clause"> <code class="literal"> UNION </code> </a> , as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa74014246"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t1<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 10 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 7 <span class="token punctuation">|</span> 8 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t2<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> 7 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">3 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">UNION</span> <span class="token keyword">TABLE</span> t2<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 10 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 7 <span class="token punctuation">|</span> 8 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> 7 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">6 rows in set (0.00 sec)</span></code></pre> </div> <p> The <a class="link" href="union.html" title="15.2.18 UNION Clause"> <code class="literal"> UNION </code> </a> just shown is equivalent to the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa90121703"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">UNION</span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t2<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> a <span class="token punctuation">|</span> b <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 2 <span class="token punctuation">|</span> 10 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span> 3 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 7 <span class="token punctuation">|</span> 8 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 3 <span class="token punctuation">|</span> 4 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 6 <span class="token punctuation">|</span> 7 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">6 rows in set (0.00 sec)</span></code></pre> </div> <p> <code class="literal"> TABLE </code> can also be used together in set operations with <code class="literal"> SELECT </code> statements, <a class="link" href="values.html" title="15.2.19 VALUES Statement"> <code class="literal"> VALUES </code> </a> statements, or both. See <a class="xref" href="union.html" title="15.2.18 UNION Clause"> Section 15.2.18, “UNION Clause” </a> , <a class="xref" href="except.html" title="15.2.4 EXCEPT Clause"> Section 15.2.4, “EXCEPT Clause” </a> , and <a class="xref" href="intersect.html" title="15.2.8 INTERSECT Clause"> Section 15.2.8, “INTERSECT Clause” </a> , for more information and examples. See also <a class="xref" href="set-operations.html" title="15.2.14 Set Operations with UNION, INTERSECT, and EXCEPT"> Section 15.2.14, “Set Operations with UNION, INTERSECT, and EXCEPT” </a> . </p> </li> <li class="listitem"> <p> With <code class="literal"> INTO </code> to populate user variables, and with <code class="literal"> INTO OUTFILE </code> or <code class="literal"> INTO DUMPFILE </code> to write table data to a file. See <a class="xref" href="select-into.html" title="15.2.13.1 SELECT ... INTO Statement"> Section 15.2.13.1, “SELECT ... INTO Statement” </a> , for more specific information and examples. </p> </li> <li class="listitem"> <p> In many cases where you can employ subqueries. Given any table <code class="literal"> t1 </code> with a column named <code class="literal"> a </code> , and a second table <code class="literal"> t2 </code> having a single column, statements such as the following are possible: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa54037426"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> a <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">TABLE</span> t2<span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> Assuming that the single column of table <code class="literal"> t1 </code> is named <code class="literal"> x </code> , the preceding is equivalent to each of the statements shown here (and produces exactly the same result in either case): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa75553223"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> a <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> x <span class="token keyword">FROM</span> t2<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t1 <span class="token keyword">WHERE</span> a <span class="token keyword">IN</span> <span class="token punctuation">(</span><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> t2<span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> See <a class="xref" href="subqueries.html" title="15.2.15 Subqueries"> Section 15.2.15, “Subqueries” </a> , for more information. </p> </li> <li class="listitem"> <p> With <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> and <a class="link" href="replace.html" title="15.2.12 REPLACE Statement"> <code class="literal"> REPLACE </code> </a> statements, where you would otherwise use <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT * </code> </a> . See <a class="xref" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement"> Section 15.2.7.1, “INSERT ... SELECT Statement” </a> , for more information and examples. </p> </li> <li class="listitem"> <p> <a class="link" href="table.html" title="15.2.16 TABLE Statement"> <code class="literal"> TABLE </code> </a> can also be used in many cases in place of the <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> in <a class="link" href="create-table-select.html" title="15.1.20.4 CREATE TABLE ... SELECT Statement"> <code class="literal"> CREATE TABLE ... SELECT </code> </a> or <a class="link" href="create-view.html" title="15.1.23 CREATE VIEW Statement"> <code class="literal"> CREATE VIEW ... SELECT </code> </a> . See the descriptions of these statements for more information and examples. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-configurator.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysql-configurator"> </a> 2.3.2 Configuration: Using MySQL Configurator </h3> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="mysql-configurator-workflow-server.html"> 2.3.2.1 MySQL Server Configuration with MySQL Configurator </a> </span> </dt> </dl> </div> <a class="indexterm" name="idm46045332375040"> </a> <p> MySQL Configurator is a standalone application designed to ease the complexity of configuring a MySQL server to run MySQL on Microsoft Windows. It is bundled with the MySQL server, in both the MSI and standalone Zip archive. </p> <h4> <a name="mysql-configurator-starting"> </a> Methods to Start MySQL Configurator </h4> <p> MySQL Configurator can both configure and reconfigure MySQL server; and the methods to start MySQL Configurator are: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The MySQL server MSI prompts to execute MySQL Configurator immediately after it installs the MySQL server. </p> </li> <li class="listitem"> <p> From the Start Menu: the MSI creates a MySQL Configurator start menu item. </p> </li> <li class="listitem"> <p> From the command line: the <code class="filename"> mysql-configurator.exe </code> executable is located in the same directory as <code class="filename"> mysqld.exe </code> and other MySQL binaries installed with the MySQL server. </p> <p> Typically this location is in <code class="filename"> C:\Program Files\MySQL\MySQL Server <em class="replaceable"> <code> X.Y </code> </em> \bin </code> if installed via the MSI, or a custom directory for the Zip archive. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-programs-ndbd.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysql-cluster-programs-ndbd"> </a> 25.5.1 ndbd — The NDB Cluster Data Node Daemon </h3> </div> </div> </div> <a class="indexterm" name="idm46045108436576"> </a> <a class="indexterm" name="idm46045108435632"> </a> <a class="indexterm" name="idm46045108434272"> </a> <a class="indexterm" name="idm46045108432912"> </a> <a class="indexterm" name="idm46045108432000"> </a> <p> The <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> binary provides the single-threaded version of the process that is used to handle all the data in tables employing the <code class="literal"> NDBCLUSTER </code> storage engine. This data node process enables a data node to accomplish distributed transaction handling, node recovery, checkpointing to disk, online backup, and related tasks. In NDB 8.4.1 and later, when started, <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> logs a warning similar to that shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa64625762"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">2024-05-28 13<span class="token punctuation">:</span>32<span class="token punctuation">:</span>16 <span class="token punctuation">[</span>ndbd<span class="token punctuation">]</span> WARNING <span class="token property">--</span> Running ndbd with a single thread of signal execution<span class="token punctuation">.</span> For multi-threaded signal execution run the ndbmtd binary<span class="token punctuation">.</span></code></pre> </div> <p> <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> is the multi-threaded version of this binary. </p> <p> In an NDB Cluster, a set of <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> processes cooperate in handling data. These processes can execute on the same computer (host) or on different computers. The correspondences between data nodes and Cluster hosts is completely configurable. </p> <a class="indexterm" name="idm46045108421648"> </a> <a class="indexterm" name="idm46045108420160"> </a> <a class="indexterm" name="idm46045108418672"> </a> <a class="indexterm" name="idm46045108417216"> </a> <p> Options that can be used with <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> are shown in the following table. Additional descriptions follow the table. </p> <p> </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> All of these options also apply to the multithreaded version of this program ( <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> ) and you may substitute <span class="quote"> “ <span class="quote"> <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> </span> ” </span> for <span class="quote"> “ <span class="quote"> <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> </span> ” </span> wherever the latter occurs in this section. </p> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_ndbd_bind-address"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_bind-address"> <code class="option"> --bind-address </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for bind-address"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --bind-address=name </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> </code> </td> </tr> </tbody> </table> </div> <p> Causes <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> to bind to a specific network interface (host name or IP address). This option has no default value. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_character-sets-dir"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_character-sets-dir"> <code class="option"> --character-sets-dir </code> </a> </p> <a class="indexterm" name="idm46045108392032"> </a> <a class="indexterm" name="idm46045108390576"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for character-sets-dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --character-sets-dir=path </code> </td> </tr> </tbody> </table> </div> <p> Directory containing character sets. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_connect-delay"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-delay"> <code class="option"> --connect-delay= <em class="replaceable"> <code> # </code> </em> </code> </a> </p> <a class="indexterm" name="idm46045108380464"> </a> <a class="indexterm" name="idm46045108378976"> </a> <a class="indexterm" name="idm46045108377488"> </a> <a class="indexterm" name="idm46045108376000"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-delay=# </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 3600 </code> </td> </tr> </tbody> </table> </div> <p> Determines the time to wait between attempts to contact a management server when starting (the number of attempts is controlled by the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retries"> <code class="option"> --connect-retries </code> </a> option). The default is 5 seconds. </p> <p> This option is deprecated, and is subject to removal in a future release of NDB Cluster. Use <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retry-delay"> <code class="option"> --connect-retry-delay </code> </a> instead. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_connect-retries"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retries"> <code class="option"> --connect-retries= <em class="replaceable"> <code> # </code> </em> </code> </a> </p> <a class="indexterm" name="idm46045108351696"> </a> <a class="indexterm" name="idm46045108350208"> </a> <a class="indexterm" name="idm46045108348720"> </a> <a class="indexterm" name="idm46045108347232"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-retries"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-retries=# </code> </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 12 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> -1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> Set the number of times to retry a connection before giving up; 0 means 1 attempt only (and no retries). The default is 12 attempts. The time to wait between attempts is controlled by the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retry-delay"> <code class="option"> --connect-retry-delay </code> </a> option. </p> <p> It is also possible to set this option to -1, in which case, the data node process continues indefinitely to try to connect. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_connect-retry-delay"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retry-delay"> <code class="option"> --connect-retry-delay= <em class="replaceable"> <code> # </code> </em> </code> </a> </p> <a class="indexterm" name="idm46045108326288"> </a> <a class="indexterm" name="idm46045108324832"> </a> <a class="indexterm" name="idm46045108323328"> </a> <a class="indexterm" name="idm46045108321824"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-retry-delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-retry-delay=# </code> </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Determines the time to wait between attempts to contact a management server when starting (the time between attempts is controlled by the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-retries"> <code class="option"> --connect-retries </code> </a> option). The default is 5 seconds. </p> <p> This option takes the place of the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-delay"> <code class="option"> --connect-delay </code> </a> option, which is now deprecated and subject to removal in a future release of NDB Cluster. </p> <p> The short form <code class="option"> -r </code> for this option is also deprecated, and thus subject to removal. Use the long form instead. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_connect-string"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_connect-string"> <code class="option"> --connect-string </code> </a> </p> <a class="indexterm" name="idm46045108298896"> </a> <a class="indexterm" name="idm46045108297408"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-string"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-string=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Same as <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_core-file"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_core-file"> <code class="option"> --core-file </code> </a> </p> <a class="indexterm" name="idm46045108282048"> </a> <a class="indexterm" name="idm46045108280560"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for core-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --core-file </code> </td> </tr> </tbody> </table> </div> <p> Write core file on error; used in debugging. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_daemon"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_daemon"> <code class="option"> --daemon </code> </a> , <code class="option"> -d </code> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for daemon"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --daemon </code> </td> </tr> </tbody> </table> </div> <p> Instructs <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> to execute as a daemon process. This is the default behavior. <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nodaemon"> <code class="option"> --nodaemon </code> </a> can be used to prevent the process from running as a daemon. </p> <p> This option has no effect when running <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> on Windows platforms. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_defaults-extra-file"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_defaults-extra-file"> <code class="option"> --defaults-extra-file </code> </a> </p> <a class="indexterm" name="idm46045108255440"> </a> <a class="indexterm" name="idm46045108253984"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-extra-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-extra-file=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read given file after global files are read. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_defaults-file"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_defaults-file"> <code class="option"> --defaults-file </code> </a> </p> <a class="indexterm" name="idm46045108239568"> </a> <a class="indexterm" name="idm46045108238080"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-file=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read default options from given file only. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_defaults-group-suffix"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_defaults-group-suffix"> <code class="option"> --defaults-group-suffix </code> </a> </p> <a class="indexterm" name="idm46045108223808"> </a> <a class="indexterm" name="idm46045108222352"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-group-suffix"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-group-suffix=string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Also read groups with concat(group, suffix). </p> </li> <li class="listitem"> <p> <a name="option_ndbd_filesystem-password"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_filesystem-password"> <code class="option"> --filesystem-password </code> </a> </p> <a class="indexterm" name="idm46045108208112"> </a> <a class="indexterm" name="idm46045108206656"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for filesystem-password"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --filesystem-password=password </code> </td> </tr> </tbody> </table> </div> <p> Pass the filesystem encryption and decryption password to the data node process using <code class="literal"> stdin </code> , <code class="literal"> tty </code> , or the <code class="filename"> my.cnf </code> file. </p> <p> Requires <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-encryptedfilesystem"> <code class="literal"> EncryptedFileSystem = 1 </code> </a> . </p> <p> For more information, see <a class="xref" href="mysql-cluster-tde.html" title="25.6.14 File System Encryption for NDB Cluster"> Section 25.6.14, “File System Encryption for NDB Cluster” </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_filesystem-password-from-stdin"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_filesystem-password-from-stdin"> <code class="option"> --filesystem-password-from-stdin </code> </a> </p> <a class="indexterm" name="idm46045108191824"> </a> <a class="indexterm" name="idm46045108190320"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for filesystem-password-from-stdin"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --filesystem-password-from-stdin={TRUE|FALSE} </code> </td> </tr> </tbody> </table> </div> <p> Pass the filesystem encryption and decryption password to the data node process from <code class="literal"> stdin </code> (only). </p> <p> Requires <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-encryptedfilesystem"> <code class="literal"> EncryptedFileSystem = 1 </code> </a> . </p> <p> For more information, see <a class="xref" href="mysql-cluster-tde.html" title="25.6.14 File System Encryption for NDB Cluster"> Section 25.6.14, “File System Encryption for NDB Cluster” </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_foreground"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_foreground"> <code class="option"> --foreground </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for foreground"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --foreground </code> </td> </tr> </tbody> </table> </div> <p> Causes <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> to execute as a foreground process, primarily for debugging purposes. This option implies the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nodaemon"> <code class="option"> --nodaemon </code> </a> option. </p> <p> This option has no effect when running <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> on Windows platforms. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_help"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_help"> <code class="option"> --help </code> </a> </p> <a class="indexterm" name="idm46045108162224"> </a> <a class="indexterm" name="idm46045108160736"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for help"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --help </code> </td> </tr> </tbody> </table> </div> <p> Display help text and exit. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_initial"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial"> <code class="option"> --initial </code> </a> </p> <a class="indexterm" name="idm46045108151168"> </a> <a class="indexterm" name="idm46045108149680"> </a> <a class="indexterm" name="idm46045108148192"> </a> <a class="indexterm" name="idm46045108146704"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for initial"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --initial </code> </td> </tr> </tbody> </table> </div> <p> Instructs <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> to perform an initial start. An initial start erases any files created for recovery purposes by earlier instances of <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> . It also re-creates recovery log files. On some operating systems, this process can take a substantial amount of time. </p> <p> The option also causes the removal of all data files associated with Disk Data tablespaces and undo log files associated with log file groups that existed previously on this data node (see <a class="xref" href="mysql-cluster-disk-data.html" title="25.6.11 NDB Cluster Disk Data Tables"> Section 25.6.11, “NDB Cluster Disk Data Tables” </a> ). </p> <p> An <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial"> <code class="option"> --initial </code> </a> start is to be used <span class="emphasis"> <em> only </em> </span> when starting the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process under very special circumstances; this is because this option causes all files to be removed from the NDB Cluster file system and all redo log files to be re-created. These circumstances are listed here: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> When performing a software upgrade which has changed the contents of any files. </p> </li> <li class="listitem"> <p> When restarting the node with a new version of <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> . </p> </li> <li class="listitem"> <p> As a measure of last resort when for some reason the node restart or system restart repeatedly fails. In this case, be aware that this node can no longer be used to restore data due to the destruction of the data files. </p> </li> </ul> </div> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> To avoid the possibility of eventual data loss, it is recommended that you <span class="emphasis"> <em> not </em> </span> use the <code class="option"> --initial </code> option together with <code class="literal"> StopOnError = 0 </code> . Instead, set <code class="literal"> StopOnError </code> to 0 in <code class="filename"> config.ini </code> only after the cluster has been started, then restart the data nodes normally—that is, without the <code class="option"> --initial </code> option. See the description of the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-stoponerror"> <code class="literal"> StopOnError </code> </a> parameter for a detailed explanation of this issue. (Bug #24945638) </p> </div> <p> Use of this option prevents the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-startpartialtimeout"> <code class="literal"> StartPartialTimeout </code> </a> and <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-startpartitionedtimeout"> <code class="literal"> StartPartitionedTimeout </code> </a> configuration parameters from having any effect. </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> This option does <span class="emphasis"> <em> not </em> </span> affect backup files that have already been created by the affected node. </p> <p> This option also has no effect on recovery of data by a data node that is just starting (or restarting) from data nodes that are already running (unless they also were started with <code class="option"> --initial </code> , as part of an initial restart). This recovery of data occurs automatically, and requires no user intervention in an NDB Cluster that is running normally. </p> </div> <p> It is permissible to use this option when starting the cluster for the very first time (that is, before any data node files have been created); however, it is <span class="emphasis"> <em> not </em> </span> necessary to do so. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_initial-start"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial-start"> <code class="option"> --initial-start </code> </a> </p> <a class="indexterm" name="idm46045108111280"> </a> <a class="indexterm" name="idm46045108109792"> </a> <a class="indexterm" name="idm46045108108304"> </a> <a class="indexterm" name="idm46045108106816"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for initial-start"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --initial-start </code> </td> </tr> </tbody> </table> </div> <p> This option is used when performing a partial initial start of the cluster. Each node should be started with this option, as well as <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nowait-nodes"> <code class="option"> --nowait-nodes </code> </a> . </p> <p> Suppose that you have a 4-node cluster whose data nodes have the IDs 2, 3, 4, and 5, and you wish to perform a partial initial start using only nodes 2, 4, and 5—that is, omitting node 3: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa53739334"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">ndbd</span> <span class="token constant">--ndb-nodeid</span><span class="token attr-value"><span class="token punctuation">=</span>2</span> <span class="token constant">--nowait-nodes</span><span class="token attr-value"><span class="token punctuation">=</span>3</span> <span class="token property">--initial-start</span> <span class="token prompt">$> </span><span class="token command">ndbd</span> <span class="token constant">--ndb-nodeid</span><span class="token attr-value"><span class="token punctuation">=</span>4</span> <span class="token constant">--nowait-nodes</span><span class="token attr-value"><span class="token punctuation">=</span>3</span> <span class="token property">--initial-start</span> <span class="token prompt">$> </span><span class="token command">ndbd</span> <span class="token constant">--ndb-nodeid</span><span class="token attr-value"><span class="token punctuation">=</span>5</span> <span class="token constant">--nowait-nodes</span><span class="token attr-value"><span class="token punctuation">=</span>3</span> <span class="token property">--initial-start</span></code></pre> </div> <p> When using this option, you must also specify the node ID for the data node being started with the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-nodeid"> <code class="option"> --ndb-nodeid </code> </a> option. </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> Do not confuse this option with the <a class="link" href="mysql-cluster-programs-ndb-mgmd.html#option_ndb_mgmd_nowait-nodes"> <code class="option"> --nowait-nodes </code> </a> option for <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> , which can be used to enable a cluster configured with multiple management servers to be started without all management servers being online. </p> </div> </li> <li class="listitem"> <p> <a name="option_ndbd_install"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_install"> <code class="option"> --install[= <em class="replaceable"> <code> name </code> </em> ] </code> </a> </p> <a class="indexterm" name="idm46045108086592"> </a> <a class="indexterm" name="idm46045108085104"> </a> <a class="indexterm" name="idm46045108083616"> </a> <a class="indexterm" name="idm46045108082128"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for install"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --install[=name] </code> </td> </tr> <tr> <th> Platform Specific </th> <td> Windows </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ndbd </code> </td> </tr> </tbody> </table> </div> <p> Causes <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> to be installed as a Windows service. Optionally, you can specify a name for the service; if not set, the service name defaults to <code class="literal"> ndbd </code> . Although it is preferable to specify other <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> program options in a <code class="filename"> my.ini </code> or <code class="filename"> my.cnf </code> configuration file, it is possible to use together with <code class="option"> --install </code> . However, in such cases, the <code class="option"> --install </code> option must be specified first, before any other options are given, for the Windows service installation to succeed. </p> <p> It is generally not advisable to use this option together with the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial"> <code class="option"> --initial </code> </a> option, since this causes the data node file system to be wiped and rebuilt every time the service is stopped and started. Extreme care should also be taken if you intend to use any of the other <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> options that affect the starting of data nodes—including <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_initial-start"> <code class="option"> --initial-start </code> </a> , <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nostart"> <code class="option"> --nostart </code> </a> , and <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nowait-nodes"> <code class="option"> --nowait-nodes </code> </a> —together with <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_install"> <code class="option"> --install </code> </a> , and you should make absolutely certain you fully understand and allow for any possible consequences of doing so. </p> <p> The <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_install"> <code class="option"> --install </code> </a> option has no effect on non-Windows platforms. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_logbuffer-size"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_logbuffer-size"> <code class="option"> --logbuffer-size= <em class="replaceable"> <code> # </code> </em> </code> </a> </p> <a class="indexterm" name="idm46045108050864"> </a> <a class="indexterm" name="idm46045108049376"> </a> <a class="indexterm" name="idm46045108047888"> </a> <a class="indexterm" name="idm46045108046400"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for logbuffer-size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --logbuffer-size=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 32768 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 2048 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Sets the size of the data node log buffer. When debugging with high amounts of extra logging, it is possible for the log buffer to run out of space if there are too many log messages, in which case some log messages can be lost. This should not occur during normal operations. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_login-path"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_login-path"> <code class="option"> --login-path </code> </a> </p> <a class="indexterm" name="idm46045108027056"> </a> <a class="indexterm" name="idm46045108025568"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for login-path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --login-path=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read given path from login file. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_no-login-paths"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_no-login-paths"> <code class="option"> --no-login-paths </code> </a> </p> <a class="indexterm" name="idm46045108011248"> </a> <a class="indexterm" name="idm46045108009760"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-login-paths"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-login-paths </code> </td> </tr> </tbody> </table> </div> <p> Skips reading options from the login path file. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-connectstring"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> </p> <a class="indexterm" name="idm46045108000160"> </a> <a class="indexterm" name="idm46045107998704"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-connectstring"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-connectstring=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Set connection string for connecting to <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> . Syntax: <code class="literal"> [nodeid= <em class="replaceable"> <code> id </code> </em> ;][host=] <em class="replaceable"> <code> hostname </code> </em> [: <em class="replaceable"> <code> port </code> </em> ] </code> . Overrides entries in <code class="literal"> NDB_CONNECTSTRING </code> and <code class="filename"> my.cnf </code> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-mgmd-host"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-mgmd-host"> <code class="option"> --ndb-mgmd-host </code> </a> </p> <a class="indexterm" name="idm46045107979664"> </a> <a class="indexterm" name="idm46045107978176"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-mgmd-host"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-mgmd-host=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Same as <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-mgm-tls"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-mgm-tls"> <code class="option"> --ndb-mgm-tls </code> </a> </p> <a class="indexterm" name="idm46045107963056"> </a> <a class="indexterm" name="idm46045107961568"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-mgm-tls"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-mgm-tls=level </code> </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> relaxed </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> relaxed </code> </p> <p class="valid-value"> <code class="literal"> strict </code> </p> </td> </tr> </tbody> </table> </div> <p> Sets the level of TLS support required to connect to the management server; one of <code class="literal"> relaxed </code> or <code class="literal"> strict </code> . <code class="literal"> relaxed </code> (the default) means that a TLS connection is attempted, but success is not required; <code class="literal"> strict </code> means that TLS is required to connect. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-nodeid"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-nodeid"> <code class="option"> --ndb-nodeid </code> </a> </p> <a class="indexterm" name="idm46045107940688"> </a> <a class="indexterm" name="idm46045107939200"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-nodeid"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-nodeid=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Set node ID for this node, overriding any ID set by --ndb-connectstring. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-optimized-node-selection"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-optimized-node-selection"> <code class="option"> --ndb-optimized-node-selection </code> </a> </p> <a class="indexterm" name="idm46045107924800"> </a> <a class="indexterm" name="idm46045107923296"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-optimized-node-selection"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-optimized-node-selection </code> </td> </tr> </tbody> </table> </div> <p> Enable optimizations for selection of nodes for transactions. Enabled by default; use <code class="option"> --skip-ndb-optimized-node-selection </code> to disable. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_ndb-tls-search-path"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-tls-search-path"> <code class="option"> --ndb-tls-search-path </code> </a> </p> <a class="indexterm" name="idm46045107913008"> </a> <a class="indexterm" name="idm46045107911552"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-tls-search-path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-tls-search-path=list </code> </td> </tr> <tr> <th> Type </th> <td> Path name </td> </tr> <tr> <th> Default Value (Unix) </th> <td> <code class="literal"> $HOME/ndb-tls </code> </td> </tr> <tr> <th> Default Value (Windows) </th> <td> <code class="literal"> $HOMEDIR/ndb-tls </code> </td> </tr> </tbody> </table> </div> <p> Specify a list of directories to search for a CA file. On Unix platforms, the directory names are separated by colons ( <code class="literal"> : </code> ); on Windows systems, the semicolon character ( <code class="literal"> ; </code> ) is used as the separator. A directory reference may be relative or absolute; it may contain one or more environment variables, each denoted by a prefixed dollar sign ( <code class="literal"> $ </code> ), and expanded prior to use. </p> <p> Searching begins with the leftmost named directory and proceeds from left to right until a file is found. An empty string denotes an empty search path, which causes all searches to fail. A string consisting of a single dot ( <code class="literal"> . </code> ) indicates that the search path limited to the current working directory. </p> <p> If no search path is supplied, the compiled-in default value is used. This value depends on the platform used: On Windows, this is <code class="literal"> \ndb-tls </code> ; on other platforms (including Linux), it is <code class="literal"> $HOME/ndb-tls </code> . This can be overridden by compiling NDB Cluster using <a class="link" href="source-configuration-options.html#option_cmake_with_ndb_tls_search_path"> <code class="option"> -DWITH_NDB_TLS_SEARCH_PATH </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndbd_nodaemon"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nodaemon"> <code class="option"> --nodaemon </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for nodaemon"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --nodaemon </code> </td> </tr> </tbody> </table> </div> <p> Prevents <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> from executing as a daemon process. This option overrides the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_daemon"> <code class="option"> --daemon </code> </a> option. This is useful for redirecting output to the screen when debugging the binary. </p> <p> The default behavior for <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> and <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> on Windows is to run in the foreground, making this option unnecessary on Windows platforms, where it has no effect. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_no-defaults"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_no-defaults"> <code class="option"> --no-defaults </code> </a> </p> <a class="indexterm" name="idm46045107872960"> </a> <a class="indexterm" name="idm46045107871472"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-defaults </code> </td> </tr> </tbody> </table> </div> <p> Do not read default options from any option file other than login file. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_nostart"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nostart"> <code class="option"> --nostart </code> </a> , <code class="option"> -n </code> </p> <a class="indexterm" name="idm46045107861504"> </a> <a class="indexterm" name="idm46045107860016"> </a> <a class="indexterm" name="idm46045107858528"> </a> <a class="indexterm" name="idm46045107857040"> </a> <a class="indexterm" name="idm46045107855552"> </a> <a class="indexterm" name="idm46045107854064"> </a> <a class="indexterm" name="idm46045107852576"> </a> <a class="indexterm" name="idm46045107851088"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for nostart"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --nostart </code> </td> </tr> </tbody> </table> </div> <p> Instructs <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> not to start automatically. When this option is used, <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> connects to the management server, obtains configuration data from it, and initializes communication objects. However, it does not actually start the execution engine until specifically requested to do so by the management server. This can be accomplished by issuing the proper <a class="link" href="mysql-cluster-mgm-client-commands.html#ndbclient-start"> <code class="literal"> START </code> </a> command in the management client (see <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> ). </p> </li> <li class="listitem"> <p> <a name="option_ndbd_nowait-nodes"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_nowait-nodes"> <code class="option"> --nowait-nodes= <em class="replaceable"> <code> node_id_1 </code> </em> [, <em class="replaceable"> <code> node_id_2 </code> </em> [, ...]] </code> </a> </p> <a class="indexterm" name="idm46045107835600"> </a> <a class="indexterm" name="idm46045107834112"> </a> <a class="indexterm" name="idm46045107832624"> </a> <a class="indexterm" name="idm46045107831136"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for nowait-nodes"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --nowait-nodes=list </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> </code> </td> </tr> </tbody> </table> </div> <p> This option takes a list of data nodes for which the cluster does not wait, prior to starting. </p> <p> This can be used to start the cluster in a partitioned state. For example, to start the cluster with only half of the data nodes (nodes 2, 3, 4, and 5) running in a 4-node cluster, you can start each <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process with <code class="option"> --nowait-nodes=3,5 </code> . In this case, the cluster starts as soon as nodes 2 and 4 connect, and does <span class="emphasis"> <em> not </em> </span> wait <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-startpartitionedtimeout"> <code class="literal"> StartPartitionedTimeout </code> </a> milliseconds for nodes 3 and 5 to connect as it would otherwise. </p> <p> If you wanted to start up the same cluster as in the previous example without one <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> (say, for example, that the host machine for node 3 has suffered a hardware failure) then start nodes 2, 4, and 5 with <code class="option"> --nowait-nodes=3 </code> . Then the cluster starts as soon as nodes 2, 4, and 5 connect, and does not wait for node 3 to start. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_print-defaults"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_print-defaults"> <code class="option"> --print-defaults </code> </a> </p> <a class="indexterm" name="idm46045107810304"> </a> <a class="indexterm" name="idm46045107808816"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for print-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --print-defaults </code> </td> </tr> </tbody> </table> </div> <p> Print program argument list and exit. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_remove"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_remove"> <code class="option"> --remove[= <em class="replaceable"> <code> name </code> </em> ] </code> </a> </p> <a class="indexterm" name="idm46045107798912"> </a> <a class="indexterm" name="idm46045107797424"> </a> <a class="indexterm" name="idm46045107795936"> </a> <a class="indexterm" name="idm46045107794448"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for remove"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --remove[=name] </code> </td> </tr> <tr> <th> Platform Specific </th> <td> Windows </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ndbd </code> </td> </tr> </tbody> </table> </div> <p> Causes an <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process that was previously installed as a Windows service to be removed. Optionally, you can specify a name for the service to be uninstalled; if not set, the service name defaults to <code class="literal"> ndbd </code> . </p> <p> The <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_remove"> <code class="option"> --remove </code> </a> option has no effect on non-Windows platforms. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_usage"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_usage"> <code class="option"> --usage </code> </a> </p> <a class="indexterm" name="idm46045107774624"> </a> <a class="indexterm" name="idm46045107773136"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for usage"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --usage </code> </td> </tr> </tbody> </table> </div> <p> Display help text and exit; same as --help. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_verbose"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_verbose"> <code class="option"> --verbose </code> </a> , <code class="option"> -v </code> </p> <a class="indexterm" name="idm46045107763120"> </a> <a class="indexterm" name="idm46045107761632"> </a> <a class="indexterm" name="idm46045107760144"> </a> <a class="indexterm" name="idm46045107758656"> </a> <p> Causes extra debug output to be written to the node log. </p> <p> You can also use <a class="link" href="mysql-cluster-mgm-client-commands.html#ndbclient-nodelog-debug"> <code class="literal"> NODELOG DEBUG ON </code> </a> and <a class="link" href="mysql-cluster-mgm-client-commands.html#ndbclient-nodelog-debug"> <code class="literal"> NODELOG DEBUG OFF </code> </a> to enable and disable this extra logging while the data node is running. </p> </li> <li class="listitem"> <p> <a name="option_ndbd_version"> </a> <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_version"> <code class="option"> --version </code> </a> </p> <a class="indexterm" name="idm46045107751328"> </a> <a class="indexterm" name="idm46045107749840"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --version </code> </td> </tr> </tbody> </table> </div> <p> Display version information and exit. </p> </li> </ul> </div> <a class="indexterm" name="idm46045107742128"> </a> <a class="indexterm" name="idm46045107740640"> </a> <p> <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> generates a set of log files which are placed in the directory specified by <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datadir"> <code class="literal"> DataDir </code> </a> in the <code class="filename"> config.ini </code> configuration file. </p> <p> These log files are listed below. <em class="replaceable"> <code> node_id </code> </em> is and represents the node's unique identifier. For example, <code class="filename"> ndb_2_error.log </code> is the error log generated by the data node whose node ID is <code class="literal"> 2 </code> . </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045107732688"> </a> <a class="indexterm" name="idm46045107731200"> </a> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _error.log </code> is a file containing records of all crashes which the referenced <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process has encountered. Each record in this file contains a brief error string and a reference to a trace file for this crash. A typical entry in this file might appear as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa79311823"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">Date<span class="token operator">/</span>Time<span class="token operator">:</span> Saturday 30 July 2004 <span class="token operator">-</span> 00<span class="token operator">:</span>20<span class="token operator">:</span>01 Type of error<span class="token operator">:</span> error Message<span class="token operator">:</span> Internal program error <span class="token punctuation">(</span>failed ndbrequire<span class="token punctuation">)</span> Fault ID<span class="token operator">:</span> 2341 Problem data<span class="token operator">:</span> DbtupFixAlloc<span class="token punctuation">.</span>cpp Object of reference<span class="token operator">:</span> DBTUP <span class="token punctuation">(</span>Line<span class="token operator">:</span> 173<span class="token punctuation">)</span> ProgramName<span class="token operator">:</span> NDB Kernel ProcessID<span class="token operator">:</span> 14909 TraceFile<span class="token operator">:</span> ndb_2_trace<span class="token punctuation">.</span>log<span class="token punctuation">.</span>2 <span class="token operator">**</span><span class="token operator">*</span>EOM<span class="token operator">**</span><span class="token operator">*</span></code></pre> </div> <p> Listings of possible <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> exit codes and messages generated when a data node process shuts down prematurely can be found in <a class="ulink" href="/doc/ndb-internals/en/ndb-node-error-messages.html" target="_top"> Data Node Error Messages </a> . </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> <span class="emphasis"> <em> The last entry in the error log file is not necessarily the newest one </em> </span> (nor is it likely to be). Entries in the error log are <span class="emphasis"> <em> not </em> </span> listed in chronological order; rather, they correspond to the order of the trace files as determined in the <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _trace.log.next </code> file (see below). Error log entries are thus overwritten in a cyclical and not sequential fashion. </p> </div> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045107719616"> </a> <a class="indexterm" name="idm46045107718128"> </a> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _trace.log. <em class="replaceable"> <code> trace_id </code> </em> </code> is a trace file describing exactly what happened just before the error occurred. This information is useful for analysis by the NDB Cluster development team. </p> <p> It is possible to configure the number of these trace files that are created before old files are overwritten. <em class="replaceable"> <code> trace_id </code> </em> is a number which is incremented for each successive trace file. </p> </li> <li class="listitem"> <p> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _trace.log.next </code> is the file that keeps track of the next trace file number to be assigned. </p> </li> <li class="listitem"> <p> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _out.log </code> is a file containing any data output by the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process. This file is created only if <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> is started as a daemon, which is the default behavior. </p> </li> <li class="listitem"> <p> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> .pid </code> is a file containing the process ID of the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process when started as a daemon. It also functions as a lock file to avoid the starting of nodes with the same identifier. </p> </li> <li class="listitem"> <p> <code class="filename"> ndb_ <em class="replaceable"> <code> node_id </code> </em> _signal.log </code> is a file used only in debug versions of <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> , where it is possible to trace all incoming, outgoing, and internal messages with their data in the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process. </p> </li> </ul> </div> <p> It is recommended not to use a directory mounted through NFS because in some environments this can cause problems whereby the lock on the <code class="filename"> .pid </code> file remains in effect even after the process has terminated. </p> <p> To start <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> , it may also be necessary to specify the host name of the management server and the port on which it is listening. Optionally, one may also specify the node ID that the process is to use. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa14028626"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">ndbd</span> <span class="token constant">--connect-string</span>=<span class="token atrule">"nodeid=2;host=ndb_mgmd.mysql.com:1186"</span></code></pre> </div> <p> See <a class="xref" href="mysql-cluster-connection-strings.html" title="25.4.3.3 NDB Cluster Connection Strings"> Section 25.4.3.3, “NDB Cluster Connection Strings” </a> , for additional information about this issue. For more information about data node configuration parameters, see <a class="xref" href="mysql-cluster-ndbd-definition.html" title="25.4.3.6 Defining NDB Cluster Data Nodes"> Section 25.4.3.6, “Defining NDB Cluster Data Nodes” </a> . </p> <p> When <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> starts, it actually initiates two processes. The first of these is called the <span class="quote"> “ <span class="quote"> angel process </span> ” </span> ; its only job is to discover when the execution process has been completed, and then to restart the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process if it is configured to do so. Thus, if you attempt to kill <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> using the Unix <a class="link" href="kill.html" title="15.7.8.4 KILL Statement"> <span class="command"> <strong> kill </strong> </span> </a> command, it is necessary to kill both processes, beginning with the angel process. The preferred method of terminating an <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process is to use the management client and stop the process from there. </p> <p> The execution process uses one thread for reading, writing, and scanning data, as well as all other activities. This thread is implemented asynchronously so that it can easily handle thousands of concurrent actions. In addition, a watch-dog thread supervises the execution thread to make sure that it does not hang in an endless loop. A pool of threads handles file I/O, with each thread able to handle one open file. Threads can also be used for transporter connections by the transporters in the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process. In a multi-processor system performing a large number of operations (including updates), the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process can consume up to 2 CPUs if permitted to do so. </p> <p> For a machine with many CPUs it is possible to use several <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> processes which belong to different node groups; however, such a configuration is still considered experimental and is not supported for MySQL 8.4 in a production setting. See <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-tablespaces-brief-table.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-innodb-tablespaces-brief-table"> </a> 28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045076375216"> </a> <p> The <a class="link" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> <code class="literal"> INNODB_TABLESPACES_BRIEF </code> </a> table provides space ID, name, path, flag, and space type metadata for file-per-table, general, undo, and system tablespaces. </p> <p> <a class="link" href="information-schema-innodb-tablespaces-table.html" title="28.4.24 The INFORMATION_SCHEMA INNODB_TABLESPACES Table"> <code class="literal"> INNODB_TABLESPACES </code> </a> provides the same metadata but loads more slowly because other metadata provided by the table, such as <code class="literal"> FS_BLOCK_SIZE </code> , <code class="literal"> FILE_SIZE </code> , and <code class="literal"> ALLOCATED_SIZE </code> , must be loaded dynamically. </p> <p> Space and path metadata is also provided by the <a class="link" href="information-schema-innodb-datafiles-table.html" title="28.4.10 The INFORMATION_SCHEMA INNODB_DATAFILES Table"> <code class="literal"> INNODB_DATAFILES </code> </a> table. </p> <p> The <a class="link" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> <code class="literal"> INNODB_TABLESPACES_BRIEF </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> SPACE </code> </p> <p> The tablespace ID. </p> </li> <li class="listitem"> <p> <code class="literal"> NAME </code> </p> <p> The tablespace name. For file-per-table tablespaces, the name is in the form of <em class="replaceable"> <code> schema/table_name </code> </em> . </p> </li> <li class="listitem"> <p> <code class="literal"> PATH </code> </p> <p> The tablespace data file path. If a <a class="link" href="glossary.html#glos_file_per_table" title="file-per-table"> file-per-table </a> tablespace is created in a location outside the MySQL data directory, the path value is a fully qualified directory path. Otherwise, the path is relative to the data directory. </p> </li> <li class="listitem"> <p> <code class="literal"> FLAG </code> </p> <p> A numeric value that represents bit-level information about tablespace format and storage characteristics. </p> </li> <li class="listitem"> <p> <code class="literal"> SPACE_TYPE </code> </p> <p> The type of tablespace. Possible values include <code class="literal"> General </code> for <code class="literal"> InnoDB </code> general tablespaces, <code class="literal"> Single </code> for <code class="literal"> InnoDB </code> file-per-table tablespaces, and <code class="literal"> System </code> for the <code class="literal"> InnoDB </code> system tablespace. </p> </li> </ul> </div> <h4> <a name="idm46045076348432"> </a> Example </h4> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa49506278"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_TABLESPACES_BRIEF <span class="token keyword">WHERE</span> SPACE <span class="token operator">=</span> <span class="token number">7</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> SPACE <span class="token punctuation">|</span> NAME <span class="token punctuation">|</span> PATH <span class="token punctuation">|</span> FLAG <span class="token punctuation">|</span> SPACE_TYPE <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 7 <span class="token punctuation">|</span> test/t1 <span class="token punctuation">|</span> ./test/t1.ibd <span class="token punctuation">|</span> 16417 <span class="token punctuation">|</span> Single <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <h4> <a name="idm46045076345760"> </a> Notes </h4> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> You must have the <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> privilege to query this table. </p> </li> <li class="listitem"> <p> Use the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> <code class="literal"> COLUMNS </code> </a> table or the <a class="link" href="show-columns.html" title="15.7.7.6 SHOW COLUMNS Statement"> <code class="literal"> SHOW COLUMNS </code> </a> statement to view additional information about the columns of this table, including data types and default values. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/sys-memory-by-thread-by-current-bytes.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-memory-by-thread-by-current-bytes"> </a> 30.4.3.17 The memory_by_thread_by_current_bytes and x$memory_by_thread_by_current_bytes Views </h4> </div> </div> </div> <a class="indexterm" name="idm46045062847808"> </a> <a class="indexterm" name="idm46045062846352"> </a> <a class="indexterm" name="idm46045062844848"> </a> <a class="indexterm" name="idm46045062843328"> </a> <p> These views summarize memory use, grouped by thread. By default, rows are sorted by descending amount of memory used. </p> <p> The <a class="link" href="sys-memory-by-thread-by-current-bytes.html" title="30.4.3.17 The memory_by_thread_by_current_bytes and x$memory_by_thread_by_current_bytes Views"> <code class="literal"> memory_by_thread_by_current_bytes </code> </a> and <a class="link" href="sys-memory-by-thread-by-current-bytes.html" title="30.4.3.17 The memory_by_thread_by_current_bytes and x$memory_by_thread_by_current_bytes Views"> <code class="literal"> x$memory_by_thread_by_current_bytes </code> </a> views have these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> thread_id </code> </p> <p> The thread ID. </p> </li> <li class="listitem"> <p> <code class="literal"> user </code> </p> <p> The thread user or thread name. </p> </li> <li class="listitem"> <p> <code class="literal"> current_count_used </code> </p> <p> The current number of allocated memory blocks that have not been freed yet for the thread. </p> </li> <li class="listitem"> <p> <code class="literal"> current_allocated </code> </p> <p> The current number of allocated bytes that have not been freed yet for the thread. </p> </li> <li class="listitem"> <p> <code class="literal"> current_avg_alloc </code> </p> <p> The current number of allocated bytes per memory block for the thread. </p> </li> <li class="listitem"> <p> <code class="literal"> current_max_alloc </code> </p> <p> The largest single current memory allocation in bytes for the thread. </p> </li> <li class="listitem"> <p> <code class="literal"> total_allocated </code> </p> <p> The total memory allocation in bytes for the thread. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/privilege-checking.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="privilege-checking"> </a> 10.15.6 Privilege Checking </h3> </div> </div> </div> <p> In complex scenarios where the query uses SQL SECURITY DEFINER views or stored routines, it may be that a user is denied from seeing the trace of its query because it lacks some extra privileges on those objects. In that case, the trace will be shown as empty and the INSUFFICIENT_PRIVILEGES column will show "1". </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/stored-routines-syntax.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="stored-routines-syntax"> </a> 27.2.1 Stored Routine Syntax </h3> </div> </div> </div> <p> A stored routine is either a procedure or a function. Stored routines are created with the <a class="link" href="create-procedure.html" title="15.1.17 CREATE PROCEDURE and CREATE FUNCTION Statements"> <code class="literal"> CREATE PROCEDURE </code> </a> and <a class="link" href="create-function.html" title="15.1.14 CREATE FUNCTION Statement"> <code class="literal"> CREATE FUNCTION </code> </a> statements (see <a class="xref" href="create-procedure.html" title="15.1.17 CREATE PROCEDURE and CREATE FUNCTION Statements"> Section 15.1.17, “CREATE PROCEDURE and CREATE FUNCTION Statements” </a> ). A procedure is invoked using a <a class="link" href="call.html" title="15.2.1 CALL Statement"> <code class="literal"> CALL </code> </a> statement (see <a class="xref" href="call.html" title="15.2.1 CALL Statement"> Section 15.2.1, “CALL Statement” </a> ), and can only pass back values using output variables. A function can be called from inside a statement just like any other function (that is, by invoking the function's name), and can return a scalar value. The body of a stored routine can use compound statements (see <a class="xref" href="sql-compound-statements.html" title="15.6 Compound Statement Syntax"> Section 15.6, “Compound Statement Syntax” </a> ). </p> <p> Stored routines can be dropped with the <a class="link" href="drop-procedure.html" title="15.1.29 DROP PROCEDURE and DROP FUNCTION Statements"> <code class="literal"> DROP PROCEDURE </code> </a> and <a class="link" href="drop-function.html" title="15.1.26 DROP FUNCTION Statement"> <code class="literal"> DROP FUNCTION </code> </a> statements (see <a class="xref" href="drop-procedure.html" title="15.1.29 DROP PROCEDURE and DROP FUNCTION Statements"> Section 15.1.29, “DROP PROCEDURE and DROP FUNCTION Statements” </a> ), and altered with the <a class="link" href="alter-procedure.html" title="15.1.7 ALTER PROCEDURE Statement"> <code class="literal"> ALTER PROCEDURE </code> </a> and <a class="link" href="alter-function.html" title="15.1.4 ALTER FUNCTION Statement"> <code class="literal"> ALTER FUNCTION </code> </a> statements (see <a class="xref" href="alter-procedure.html" title="15.1.7 ALTER PROCEDURE Statement"> Section 15.1.7, “ALTER PROCEDURE Statement” </a> ). </p> <p> A stored procedure or function is associated with a particular database. This has several implications: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> When the routine is invoked, an implicit <code class="literal"> USE <em class="replaceable"> <code> db_name </code> </em> </code> is performed (and undone when the routine terminates). <a class="link" href="use.html" title="15.8.4 USE Statement"> <code class="literal"> USE </code> </a> statements within stored routines are not permitted. </p> </li> <li class="listitem"> <p> You can qualify routine names with the database name. This can be used to refer to a routine that is not in the current database. For example, to invoke a stored procedure <code class="literal"> p </code> or function <code class="literal"> f </code> that is associated with the <code class="literal"> test </code> database, you can say <code class="literal"> CALL test.p() </code> or <code class="literal"> test.f() </code> . </p> </li> <li class="listitem"> <p> When a database is dropped, all stored routines associated with it are dropped as well. </p> </li> </ul> </div> <p> Stored functions cannot be recursive. </p> <p> Recursion in stored procedures is permitted but disabled by default. To enable recursion, set the <a class="link" href="server-system-variables.html#sysvar_max_sp_recursion_depth"> <code class="literal"> max_sp_recursion_depth </code> </a> server system variable to a value greater than zero. Stored procedure recursion increases the demand on thread stack space. If you increase the value of <a class="link" href="server-system-variables.html#sysvar_max_sp_recursion_depth"> <code class="literal"> max_sp_recursion_depth </code> </a> , it may be necessary to increase thread stack size by increasing the value of <a class="link" href="server-system-variables.html#sysvar_thread_stack"> <code class="literal"> thread_stack </code> </a> at server startup. See <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> , for more information. </p> <p> MySQL supports a very useful extension that enables the use of regular <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> statements (that is, without using cursors or local variables) inside a stored procedure. The result set of such a query is simply sent directly to the client. Multiple <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> statements generate multiple result sets, so the client must use a MySQL client library that supports multiple result sets. This means the client must use a client library from a version of MySQL at least as recent as 4.1. The client should also specify the <code class="literal"> CLIENT_MULTI_RESULTS </code> option when it connects. For C programs, this can be done with the <a class="ulink" href="/doc/c-api/8.4/en/mysql-real-connect.html" target="_top"> <code class="literal"> mysql_real_connect() </code> </a> C API function. See <a class="ulink" href="/doc/c-api/8.4/en/mysql-real-connect.html" target="_top"> mysql_real_connect() </a> , and <a class="ulink" href="/doc/c-api/8.4/en/c-api-multiple-queries.html" target="_top"> Multiple Statement Execution Support </a> . </p> <p> A user variable referenced by a statement in a stored procedure has its type determined the first time the procedure is invoked, and retains this type each time the procedure is invoked thereafter. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/example-maximum-column-group.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="example-maximum-column-group"> </a> 5.6.3 Maximum of Column per Group </h3> </div> </div> </div> <p> <span class="emphasis"> <em> Task: Find the highest price per article. </em> </span> </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa87041549"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> article<span class="token punctuation">,</span> <span class="token function">MAX</span><span class="token punctuation">(</span>price<span class="token punctuation">)</span> <span class="token keyword">AS</span> price <span class="token keyword">FROM</span> shop <span class="token keyword">GROUP</span> <span class="token keyword">BY</span> article <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> article<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> article <span class="token punctuation">|</span> price <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 0001 <span class="token punctuation">|</span> 3.99 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 0002 <span class="token punctuation">|</span> 10.99 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 0003 <span class="token punctuation">|</span> 1.69 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 0004 <span class="token punctuation">|</span> 19.95 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/replication-mode-change-online-disable-gtids.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-mode-change-online-disable-gtids"> </a> 19.1.4.3 Disabling GTID Transactions Online </h4> </div> </div> </div> <a class="indexterm" name="idm46045145395808"> </a> <p> This section describes how to disable GTID transactions on servers that are already online. This procedure does not require taking the server offline and is suited to use in production. However, if you have the possibility to take the servers offline when disabling GTIDs mode that process is easier. </p> <p> The process is similar to enabling GTID transactions while the server is online, but reversing the steps. The only thing that differs is the point at which you wait for logged transactions to replicate. </p> <p> Before starting, all servers must meet the following conditions: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> All servers have <a class="link" href="replication-options-gtids.html#sysvar_gtid_mode"> <code class="literal"> gtid_mode </code> </a> set to <code class="literal"> ON </code> . </p> </li> <li class="listitem"> <p> The <a class="link" href="replication-options-replica.html#option_mysqld_replicate-same-server-id"> <code class="option"> --replicate-same-server-id </code> </a> option is not set on any server. You cannot disable GTID transactions if this option is set together with the <a class="link" href="replication-options-binary-log.html#sysvar_log_replica_updates"> <code class="option"> --log-replica-updates </code> </a> option (default) and binary logging is enabled (also the default). Without GTIDs, this combination of options causes infinite loops in circular replication. </p> </li> </ul> </div> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Execute the following statements on each replica, and if you are using multi-source replication, do so for each channel, including the <code class="literal"> FOR CHANNEL </code> clause when using multi-source replication: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa63905681"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">STOP</span> <span class="token keyword">REPLICA</span> <span class="token punctuation">[</span><span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'<em class="replaceable">channel</em>'</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token keyword">CHANGE</span> <span class="token keyword">REPLICATION</span> <span class="token keyword">SOURCE</span> <span class="token keyword">TO</span> <span class="token keyword">SOURCE_AUTO_POSITION</span> <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token keyword">SOURCE_LOG_FILE</span> <span class="token operator">=</span> <span class="token string">'<em class="replaceable">file</em>'</span><span class="token punctuation">,</span> <span class="token keyword">SOURCE_LOG_POS</span> <span class="token operator">=</span> <em class="replaceable">position</em> <span class="token punctuation">[</span><span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'<em class="replaceable">channel</em>'</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token keyword">START</span> <span class="token keyword">REPLICA</span> <span class="token punctuation">[</span><span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'<em class="replaceable">channel</em>'</span><span class="token punctuation">]</span><span class="token punctuation">;</span></code></pre> </div> <p> You can obtain the values for <em class="replaceable"> <code> file </code> </em> and <em class="replaceable"> <code> position </code> </em> from the <code class="literal"> relay_source_log_file </code> and <code class="literal"> exec_source_log_position </code> columns in the output of <a class="link" href="show-replica-status.html" title="15.7.7.35 SHOW REPLICA STATUS Statement"> <code class="literal"> SHOW REPLICA STATUS </code> </a> . The <em class="replaceable"> <code> file </code> </em> and <em class="replaceable"> <code> channel </code> </em> names are strings; both of these must be quoted when used in the <a class="link" href="stop-replica.html" title="15.4.2.5 STOP REPLICA Statement"> <code class="literal"> STOP REPLICA </code> </a> , <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> , and <a class="link" href="start-replica.html" title="15.4.2.4 START REPLICA Statement"> <code class="literal"> START REPLICA </code> </a> statements. </p> </li> <li class="listitem"> <p> On each server, execute the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa54749112"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@@global.gtid_mode</span> <span class="token operator">=</span> ON_PERMISSIVE<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> On each server, execute the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa22579326"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@@global.gtid_mode</span> <span class="token operator">=</span> OFF_PERMISSIVE<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> On each server, wait until the global value of <a class="link" href="replication-options-gtids.html#sysvar_gtid_owned"> <code class="literal"> gtid_owned </code> </a> is equal to the empty string. This can be checked using the statement shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa30474902"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token variable">@@global.gtid_owned</span><span class="token punctuation">;</span></code></pre> </div> <p> On a replica, it is theoretically possible that this is empty and then becomes nonempty again. This is not a problem; it suffices that the value is empty at least once. </p> </li> <li class="listitem"> <p> Wait for all transactions that currently exist in any binary log to be committed on all replicas. See <a class="xref" href="replication-mode-change-online-verify-transactions.html" title="19.1.4.4 Verifying Replication of Anonymous Transactions"> Section 19.1.4.4, “Verifying Replication of Anonymous Transactions” </a> , for one method of checking that all anonymous transactions have replicated to all servers. </p> </li> <li class="listitem"> <p> If you use binary logs for anything other than replication—for example, to perform point-in-time backup or restore—wait until you no longer need any old binary logs containing GTID transactions. </p> <p> For instance, after the previous step has completed, you can execute <a class="link" href="flush.html#flush-logs"> <code class="literal"> FLUSH LOGS </code> </a> on the server where you are taking the backup. Then, either take a backup manually, or wait for the next iteration of any periodic backup routine you may have set up. </p> <p> Ideally, you should wait for the server to purge all binary logs that existed when step 5 was completed, and for any backup taken before then to expire. </p> <p> You should keep in mind that logs containing GTID transactions cannot be used after the next step. For this reason, before proceeding further, you must be sure that no uncommitted GTID transactions exist anywhere in the topology. </p> </li> <li class="listitem"> <p> On each server, execute the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa92523296"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@@global.gtid_mode</span> <span class="token operator">=</span> <span class="token keyword">OFF</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> On each server, set <a class="link" href="replication-options-gtids.html#sysvar_gtid_mode"> <code class="literal"> gtid_mode=OFF </code> </a> in <code class="filename"> my.cnf </code> . </p> <p> Optionally, you can also set <a class="link" href="replication-options-gtids.html#sysvar_enforce_gtid_consistency"> <code class="literal"> enforce_gtid_consistency=OFF </code> </a> . After doing so, you should add <a class="link" href="replication-options-gtids.html#sysvar_enforce_gtid_consistency"> <code class="literal"> enforce_gtid_consistency=OFF </code> </a> to your configuration file. </p> </li> </ol> </div> <p> If you want to downgrade to an earlier version of MySQL, you can do so now, using the normal downgrade procedure. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/replication-features-current-user.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-features-current-user"> </a> 19.5.1.8 Replication of CURRENT_USER() </h4> </div> </div> </div> <p> The following statements support use of the <a class="link" href="information-functions.html#function_current-user"> <code class="literal"> CURRENT_USER() </code> </a> function to take the place of the name of, and possibly the host for, an affected user or a definer: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="drop-user.html" title="15.7.1.5 DROP USER Statement"> <code class="literal"> DROP USER </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="rename-user.html" title="15.7.1.7 RENAME USER Statement"> <code class="literal"> RENAME USER </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="revoke.html" title="15.7.1.8 REVOKE Statement"> <code class="literal"> REVOKE </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-function.html" title="15.1.14 CREATE FUNCTION Statement"> <code class="literal"> CREATE FUNCTION </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-procedure.html" title="15.1.17 CREATE PROCEDURE and CREATE FUNCTION Statements"> <code class="literal"> CREATE PROCEDURE </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-trigger.html" title="15.1.22 CREATE TRIGGER Statement"> <code class="literal"> CREATE TRIGGER </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-event.html" title="15.1.13 CREATE EVENT Statement"> <code class="literal"> CREATE EVENT </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="create-view.html" title="15.1.23 CREATE VIEW Statement"> <code class="literal"> CREATE VIEW </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="alter-event.html" title="15.1.3 ALTER EVENT Statement"> <code class="literal"> ALTER EVENT </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="alter-view.html" title="15.1.11 ALTER VIEW Statement"> <code class="literal"> ALTER VIEW </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="set-password.html" title="15.7.1.10 SET PASSWORD Statement"> <code class="literal"> SET PASSWORD </code> </a> </p> </li> </ul> </div> <p> When binary logging is enabled and <a class="link" href="information-functions.html#function_current-user"> <code class="literal"> CURRENT_USER() </code> </a> or <a class="link" href="information-functions.html#function_current-user"> <code class="literal"> CURRENT_USER </code> </a> is used as the definer in any of these statements, MySQL Server ensures that the statement is applied to the same user on both the source and the replica when the statement is replicated. In some cases, such as statements that change passwords, the function reference is expanded before it is written to the binary log, so that the statement includes the user name. For all other cases, the name of the current user on the source is replicated to the replica as metadata, and the replica applies the statement to the current user named in the metadata, rather than to the current user on the replica. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/error-log-rule-based-filtering.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="error-log-rule-based-filtering"> </a> 7.4.2.6 Rule-Based Error Log Filtering (log_filter_dragnet) </h4> </div> </div> </div> <p> The <code class="literal"> log_filter_dragnet </code> log filter component enables log filtering based on user-defined rules. </p> <p> To enable the <code class="literal"> log_filter_dragnet </code> filter, first load the filter component, then modify the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value. The following example enables <code class="literal"> log_filter_dragnet </code> in combination with the built-in log sink: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa4617011"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSTALL</span> <span class="token keyword">COMPONENT</span> <span class="token string">'file://component_log_filter_dragnet'</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> log_error_services <span class="token operator">=</span> <span class="token string">'log_filter_dragnet; log_sink_internal'</span><span class="token punctuation">;</span></code></pre> </div> <p> To set <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> to take effect at server startup, use the instructions at <a class="xref" href="error-log-configuration.html" title="7.4.2.1 Error Log Configuration"> Section 7.4.2.1, “Error Log Configuration” </a> . Those instructions apply to other error-logging system variables as well. </p> <p> With <code class="literal"> log_filter_dragnet </code> enabled, define its filter rules by setting the <a class="link" href="server-system-variables.html#sysvar_dragnet.log_error_filter_rules"> <code class="literal"> dragnet.log_error_filter_rules </code> </a> system variable. A rule set consists of zero or more rules, where each rule is an <code class="literal"> IF </code> statement terminated by a period ( <code class="literal"> . </code> ) character. If the variable value is empty (zero rules), no filtering occurs. </p> <p> Example 1. This rule set drops information events, and, for other events, removes the <code class="literal"> source_line </code> field: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59750531"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> dragnet<span class="token punctuation">.</span>log_error_filter_rules <span class="token operator">=</span> <span class="token string">'IF prio>=INFORMATION THEN drop. IF EXISTS source_line THEN unset source_line.'</span><span class="token punctuation">;</span></code></pre> </div> <p> The effect is similar to the filtering performed by the <code class="literal"> log_sink_internal </code> filter with a setting of <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> <code class="literal"> log_error_verbosity=2 </code> </a> . </p> <p> For readability, you might find it preferable to list the rules on separate lines. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa65232995"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> dragnet<span class="token punctuation">.</span>log_error_filter_rules <span class="token operator">=</span> <span class="token string">' IF prio>=INFORMATION THEN drop. IF EXISTS source_line THEN unset source_line. '</span><span class="token punctuation">;</span></code></pre> </div> <p> Example 2: This rule limits information events to no more than one per 60 seconds: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa92804478"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> dragnet<span class="token punctuation">.</span>log_error_filter_rules <span class="token operator">=</span> <span class="token string">'IF prio>=INFORMATION THEN throttle 1/60.'</span><span class="token punctuation">;</span></code></pre> </div> <p> Once you have the filtering configuration set up as you desire, consider assigning <a class="link" href="server-system-variables.html#sysvar_dragnet.log_error_filter_rules"> <code class="literal"> dragnet.log_error_filter_rules </code> </a> using <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET PERSIST </code> </a> rather than <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET GLOBAL </code> </a> to make the setting persist across server restarts. Alternatively, add the setting to the server option file. </p> <p> When using <code class="literal"> log_filter_dragnet </code> , <a class="link" href="server-system-variables.html#sysvar_log_error_suppression_list"> <code class="literal"> log_error_suppression_list </code> </a> is ignored. </p> <p> To stop using the filtering language, first remove it from the set of error logging components. Usually this means using a different filter component rather than no filter component. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa17077236"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> log_error_services <span class="token operator">=</span> <span class="token string">'log_filter_internal; log_sink_internal'</span><span class="token punctuation">;</span></code></pre> </div> <p> Again, consider using <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET PERSIST </code> </a> rather than <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET GLOBAL </code> </a> to make the setting persist across server restarts. </p> <p> Then uninstall the filter <code class="literal"> log_filter_dragnet </code> component: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa38590988"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UNINSTALL</span> <span class="token keyword">COMPONENT</span> <span class="token string">'file://component_log_filter_dragnet'</span><span class="token punctuation">;</span></code></pre> </div> <p> The following sections describe aspects of <code class="literal"> log_filter_dragnet </code> operation in more detail: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-language" title="Grammar for log_filter_dragnet Rule Language"> Grammar for log_filter_dragnet Rule Language </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-actions" title="Actions for log_filter_dragnet Rules"> Actions for log_filter_dragnet Rules </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-fields" title="Field References in log_filter_dragnet Rules"> Field References in log_filter_dragnet Rules </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="error-log-dragnet-filtering-language"> </a> Grammar for log_filter_dragnet Rule Language </h5> </div> </div> </div> <p> The following grammar defines the language for <code class="literal"> log_filter_dragnet </code> filter rules. Each rule is an <code class="literal"> IF </code> statement terminated by a period ( <code class="literal"> . </code> ) character. The language is not case-sensitive. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa11116140"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple"><em class="replaceable">rule</em><span class="token operator">:</span> IF <em class="replaceable">condition</em> THEN <em class="replaceable">action</em> <span class="token punctuation">[</span>ELSEIF <em class="replaceable">condition</em> THEN <em class="replaceable">action</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token punctuation">[</span>ELSE <em class="replaceable">action</em><span class="token punctuation">]</span> <span class="token punctuation">.</span> <em class="replaceable">condition</em><span class="token operator">:</span> <span class="token punctuation">{</span> <em class="replaceable">field</em> <em class="replaceable">comparator</em> <em class="replaceable">value</em> <span class="token operator">|</span> <span class="token punctuation">[</span>NOT<span class="token punctuation">]</span> EXISTS <em class="replaceable">field</em> <span class="token operator">|</span> <em class="replaceable">condition</em> <span class="token punctuation">{</span>AND <span class="token operator">|</span> OR<span class="token punctuation">}</span> <em class="replaceable">condition</em> <span class="token punctuation">}</span> <em class="replaceable">action</em><span class="token operator">:</span> <span class="token punctuation">{</span> drop <span class="token operator">|</span> throttle <span class="token punctuation">{</span><em class="replaceable">count</em> <span class="token operator">|</span> <em class="replaceable">count</em> <span class="token operator">/</span> <em class="replaceable">window_size</em><span class="token punctuation">}</span> <span class="token operator">|</span> set <em class="replaceable">field</em> <span class="token punctuation">[</span><span class="token operator">:</span><span class="token operator">=</span> <span class="token operator">|</span> <span class="token operator">=</span><span class="token punctuation">]</span> <em class="replaceable">value</em> <span class="token operator">|</span> unset <span class="token punctuation">[</span><em class="replaceable">field</em><span class="token punctuation">]</span> <span class="token punctuation">}</span> <em class="replaceable">field</em><span class="token operator">:</span> <span class="token punctuation">{</span> <em class="replaceable">core_field</em> <span class="token operator">|</span> <em class="replaceable">optional_field</em> <span class="token operator">|</span> <em class="replaceable">user_defined_field</em> <span class="token punctuation">}</span> <em class="replaceable">core_field</em><span class="token operator">:</span> <span class="token punctuation">{</span> time <span class="token operator">|</span> msg <span class="token operator">|</span> prio <span class="token operator">|</span> err_code <span class="token operator">|</span> err_symbol <span class="token operator">|</span> SQL_state <span class="token operator">|</span> subsystem <span class="token punctuation">}</span> <em class="replaceable">optional_field</em><span class="token operator">:</span> <span class="token punctuation">{</span> OS_errno <span class="token operator">|</span> OS_errmsg <span class="token operator">|</span> label <span class="token operator">|</span> user <span class="token operator">|</span> host <span class="token operator">|</span> thread <span class="token operator">|</span> query_id <span class="token operator">|</span> source_file <span class="token operator">|</span> source_line <span class="token operator">|</span> function <span class="token operator">|</span> component <span class="token punctuation">}</span> <em class="replaceable">user_defined_field</em><span class="token operator">:</span> <em class="replaceable">sequence of characters in <span class="token punctuation">[</span>a<span class="token operator">-</span>zA<span class="token operator">-</span>Z0<span class="token operator">-</span>9_<span class="token punctuation">]</span> class</em> <em class="replaceable">comparator</em><span class="token operator">:</span> <span class="token punctuation">{</span><span class="token operator">==</span> <span class="token operator">|</span> <span class="token operator">!=</span> <span class="token operator">|</span> <span class="token operator"><</span><span class="token operator">></span> <span class="token operator">|</span> <span class="token operator">>=</span> <span class="token operator">|</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token operator">|</span> <span class="token operator"><=</span> <span class="token operator">|</span> <span class="token operator">=</span><span class="token operator"><</span> <span class="token operator">|</span> <span class="token operator"><</span> <span class="token operator">|</span> <span class="token operator">></span><span class="token punctuation">}</span> <em class="replaceable">value</em><span class="token operator">:</span> <span class="token punctuation">{</span> <em class="replaceable">string_literal</em> <span class="token operator">|</span> <em class="replaceable">integer_literal</em> <span class="token operator">|</span> <em class="replaceable">float_literal</em> <span class="token operator">|</span> <em class="replaceable">error_symbol</em> <span class="token operator">|</span> <em class="replaceable">priority</em> <span class="token punctuation">}</span> <em class="replaceable">count</em><span class="token operator">:</span> <em class="replaceable">integer_literal</em> <em class="replaceable">window_size</em><span class="token operator">:</span> <em class="replaceable">integer_literal</em> <em class="replaceable">string_literal</em><span class="token operator">:</span> <em class="replaceable">sequence of characters quoted as '<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>' or "<span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span>"</em> <em class="replaceable">integer_literal</em><span class="token operator">:</span> <em class="replaceable">sequence of characters in <span class="token punctuation">[</span>0<span class="token operator">-</span>9<span class="token punctuation">]</span> class</em> <em class="replaceable">float_literal</em><span class="token operator">:</span> <em class="replaceable">integer_literal</em><span class="token punctuation">[</span><span class="token punctuation">.</span><em class="replaceable">integer_literal</em><span class="token punctuation">]</span> <em class="replaceable">error_symbol</em><span class="token operator">:</span> <em class="replaceable">valid MySQL error symbol such as ER_ACCESS_DENIED_ERROR or ER_STARTUP</em> <em class="replaceable">priority</em><span class="token operator">:</span> <span class="token punctuation">{</span> ERROR <span class="token operator">|</span> WARNING <span class="token operator">|</span> INFORMATION <span class="token punctuation">}</span></code></pre> </div> <p> Simple conditions compare a field to a value or test field existence. To construct more complex conditions, use the <code class="literal"> AND </code> and <code class="literal"> OR </code> operators. Both operators have the same precedence and evaluate left to right. </p> <p> To escape a character within a string, precede it by a backslash ( <code class="literal"> \ </code> ). A backslash is required to include backslash itself or the string-quoting character, optional for other characters. </p> <p> For convenience, <code class="literal"> log_filter_dragnet </code> supports symbolic names for comparisons to certain fields. For readability and portability, symbolic values are preferable (where applicable) to numeric values. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Event priority values 1, 2, and 3 can be specified as <code class="literal"> ERROR </code> , <code class="literal"> WARNING </code> , and <code class="literal"> INFORMATION </code> . Priority symbols are recognized only in comparisons with the <code class="literal"> prio </code> field. These comparisons are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa21641723"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">=</span><span class="token operator">=</span> INFORMATION <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> prio <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">3</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> Error codes can be specified in numeric form or as the corresponding error symbol. For example, <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_startup" target="_top"> <code class="literal"> ER_STARTUP </code> </a> is the symbolic name for error <code class="literal"> 1408 </code> , so these comparisons are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa39210395"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_STARTUP <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">1408</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> Error symbols are recognized only in comparisons with the <code class="literal"> err_code </code> field and user-defined fields. </p> <p> To find the error symbol corresponding to a given error code number, use one of these methods: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Check the list of server errors at <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html" target="_top"> Server Error Message Reference </a> . </p> </li> <li class="listitem"> <p> Use the <a class="link" href="perror.html" title="6.8.1 perror — Display MySQL Error Message Information"> <span class="command"> <strong> perror </strong> </span> </a> command. Given an error number argument, <a class="link" href="perror.html" title="6.8.1 perror — Display MySQL Error Message Information"> <span class="command"> <strong> perror </strong> </span> </a> displays information about the error, including its symbol. </p> </li> </ul> </div> <p> Suppose that a rule set with error numbers looks like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa12698513"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">10927</span> <span class="token operator">OR</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">10914</span> <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">1131</span> <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> <p> Using <a class="link" href="perror.html" title="6.8.1 perror — Display MySQL Error Message Information"> <span class="command"> <strong> perror </strong> </span> </a> , determine the error symbols: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa96826383"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">perror</span> 10927 10914 1131 MySQL error code MY-010927 <span class="token punctuation">(</span>ER_ACCESS_DENIED_FOR_USER_ACCOUNT_LOCKED<span class="token punctuation">)</span><span class="token punctuation">:</span> Access denied for user <span class="token atrule">'%-.48s'</span>@<span class="token atrule">'%-.64s'</span><span class="token punctuation">.</span> Account is locked<span class="token punctuation">.</span> MySQL error code MY-010914 <span class="token punctuation">(</span>ER_ABORTING_USER_CONNECTION<span class="token punctuation">)</span><span class="token punctuation">:</span> Aborted connection %u to db<span class="token punctuation">:</span> <span class="token atrule">'%-.192s'</span> user<span class="token punctuation">:</span> <span class="token atrule">'%-.48s'</span> host<span class="token punctuation">:</span> <span class="token atrule">'%-.64s'</span> <span class="token punctuation">(</span>%-<span class="token punctuation">.</span>64s<span class="token punctuation">)</span><span class="token punctuation">.</span> MySQL error code MY-001131 <span class="token punctuation">(</span>ER_PASSWORD_ANONYMOUS_USER<span class="token punctuation">)</span><span class="token punctuation">:</span> You are using MySQL as an anonymous user and anonymous users are not allowed to change passwords</code></pre> </div> <p> Substituting error symbols for numbers, the rule set becomes: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa34039885"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_ACCESS_DENIED_FOR_USER_ACCOUNT_LOCKED <span class="token operator">OR</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_ABORTING_USER_CONNECTION <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_PASSWORD_ANONYMOUS_USER <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> </li> </ul> </div> <p> Symbolic names can be specified as quoted strings for comparison with string fields, but in such cases the names are strings that have no special meaning and <code class="literal"> log_filter_dragnet </code> does not resolve them to the corresponding numeric value. Also, typos may go undetected, whereas an error occurs immediately on <code class="literal"> SET </code> for attempts to use an unquoted symbol unknown to the server. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="error-log-dragnet-filtering-actions"> </a> Actions for log_filter_dragnet Rules </h5> </div> </div> </div> <p> <code class="literal"> log_filter_dragnet </code> supports these actions in filter rules: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> drop </code> : Drop the current log event (do not log it). </p> </li> <li class="listitem"> <p> <code class="literal"> throttle </code> : Apply rate limiting to reduce log verbosity for events matching particular conditions. The argument indicates a rate, in the form <em class="replaceable"> <code> count </code> </em> or <em class="replaceable"> <code> count </code> </em> / <em class="replaceable"> <code> window_size </code> </em> . The <em class="replaceable"> <code> count </code> </em> value indicates the permitted number of event occurrences to log per time window. The <em class="replaceable"> <code> window_size </code> </em> value is the time window in seconds; if omitted, the default window is 60 seconds. Both values must be integer literals. </p> <p> This rule throttles plugin-shutdown messages to 5 occurrences per 60 seconds: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa64309872"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_PLUGIN_SHUTTING_DOWN_PLUGIN <span class="token keyword">THEN</span> throttle <span class="token number">5</span><span class="token punctuation">.</span></code></pre> </div> <p> This rule throttles errors and warnings to 1000 occurrences per hour and information messages to 100 occurrences per hour: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa64509969"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator"><=</span> INFORMATION <span class="token keyword">THEN</span> throttle <span class="token number">1000</span><span class="token operator">/</span><span class="token number">3600</span> <span class="token keyword">ELSE</span> throttle <span class="token number">100</span><span class="token operator">/</span><span class="token number">3600</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> <code class="literal"> set </code> : Assign a value to a field (and cause the field to exist if it did not already). In subsequent rules, <code class="literal"> EXISTS </code> tests against the field name are true, and the new value can be tested by comparison conditions. </p> </li> <li class="listitem"> <p> <code class="literal"> unset </code> : Discard a field. In subsequent rules, <code class="literal"> EXISTS </code> tests against the field name are false, and comparisons of the field against any value are false. </p> <p> In the special case that the condition refers to exactly one field name, the field name following <code class="literal"> unset </code> is optional and <code class="literal"> unset </code> discards the named field. These rules are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa91475582"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> myfield <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">2</span> <span class="token keyword">THEN</span> unset myfield<span class="token punctuation">.</span> <span class="token keyword">IF</span> myfield <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">2</span> <span class="token keyword">THEN</span> unset<span class="token punctuation">.</span></code></pre> </div> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="error-log-dragnet-filtering-fields"> </a> Field References in log_filter_dragnet Rules </h5> </div> </div> </div> <p> <code class="literal"> log_filter_dragnet </code> rules support references to core, optional, and user-defined fields in error events. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-core-field-references" title="Core Field References"> Core Field References </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-optional-field-references" title="Optional Field References"> Optional Field References </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-user-defined-field-references" title="User-Defined Field References"> User-Defined Field References </a> </p> </li> </ul> </div> <h6> <a name="error-log-dragnet-core-field-references"> </a> Core Field References </h6> <p> The <code class="literal"> log_filter_dragnet </code> grammar at <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-language" title="Grammar for log_filter_dragnet Rule Language"> Grammar for log_filter_dragnet Rule Language </a> names the core fields that filter rules recognize. For general descriptions of these fields, see <a class="xref" href="error-log-event-fields.html" title="7.4.2.3 Error Event Fields"> Section 7.4.2.3, “Error Event Fields” </a> , with which you are assumed to be familiar. The following remarks provide additional information only as it pertains specifically to core field references as used within <code class="literal"> log_filter_dragnet </code> rules. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> prio </code> </p> <p> The event priority, to indicate an error, warning, or note/information event. In comparisons, each priority can be specified as a symbolic priority name or an integer literal. Priority symbols are recognized only in comparisons with the <code class="literal"> prio </code> field. These comparisons are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa65630554"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">=</span><span class="token operator">=</span> INFORMATION <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> prio <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">3</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> The following table shows the permitted priority levels. </p> <div class="informaltable"> <table summary="Error event priority levels."> <colgroup> <col style="width: 25%"/> <col style="width: 25%"/> <col style="width: 25%"/> </colgroup> <thead> <tr> <th scope="col"> Event Type </th> <th scope="col"> Priority Symbol </th> <th scope="col"> Numeric Priority </th> </tr> </thead> <tbody> <tr> <th align="left" scope="row"> Error event </th> <td> <code class="literal"> ERROR </code> </td> <td> 1 </td> </tr> <tr> <th align="left" scope="row"> Warning event </th> <td> <code class="literal"> WARNING </code> </td> <td> 2 </td> </tr> <tr> <th align="left" scope="row"> Note/information event </th> <td> <code class="literal"> INFORMATION </code> </td> <td> 3 </td> </tr> </tbody> </table> </div> <p> There is also a message priority of <code class="literal"> SYSTEM </code> , but system messages cannot be filtered and are always written to the error log. </p> <p> Priority values follow the principle that higher priorities have lower values, and vice versa. Priority values begin at 1 for the most severe events (errors) and increase for events with decreasing priority. For example, to discard events with priority lower than warnings, test for priority values higher than <code class="literal"> WARNING </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa13729542"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">></span> WARNING <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> <p> The following examples show the <code class="literal"> log_filter_dragnet </code> rules to achieve an effect similar to each <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> <code class="literal"> log_error_verbosity </code> </a> value permitted by the <code class="literal"> log_filter_internal </code> filter: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Errors only ( <code class="literal"> log_error_verbosity=1 </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa88074856"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">></span> <span class="token keyword">ERROR</span> <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> Errors and warnings ( <code class="literal"> log_error_verbosity=2 </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa32155938"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">></span> WARNING <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> Errors, warnings, and notes ( <code class="literal"> log_error_verbosity=3 </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa35059797"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> prio <span class="token operator">></span> INFORMATION <span class="token keyword">THEN</span> <span class="token keyword">drop</span><span class="token punctuation">.</span></code></pre> </div> <p> This rule can actually be omitted because there are no <code class="literal"> prio </code> values greater than <code class="literal"> INFORMATION </code> , so effectively it drops nothing. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> err_code </code> </p> <p> The numeric event error code. In comparisons, the value to test can be specified as a symbolic error name or an integer literal. Error symbols are recognized only in comparisons with the <code class="literal"> err_code </code> field and user-defined fields. These comparisons are equivalent: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa30834351"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> ER_ACCESS_DENIED_ERROR <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token keyword">IF</span> err_code <span class="token operator">=</span><span class="token operator">=</span> <span class="token number">1045</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> </li> <li class="listitem"> <p> <code class="literal"> err_symbol </code> </p> <p> The event error symbol, as a string (for example, <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_dup_key" target="_top"> <code class="literal"> 'ER_DUP_KEY' </code> </a> ). <code class="literal"> err_symbol </code> values are intended more for identifying particular lines in log output than for use in filter rule comparisons because <code class="literal"> log_filter_dragnet </code> does not resolve comparison values specified as strings to the equivalent numeric error code. (For that to occur, an error must be specified using its unquoted symbol.) </p> </li> </ul> </div> <h6> <a name="error-log-dragnet-optional-field-references"> </a> Optional Field References </h6> <p> The <code class="literal"> log_filter_dragnet </code> grammar at <a class="xref" href="error-log-rule-based-filtering.html#error-log-dragnet-filtering-language" title="Grammar for log_filter_dragnet Rule Language"> Grammar for log_filter_dragnet Rule Language </a> names the optional fields that filter rules recognize. For general descriptions of these fields, see <a class="xref" href="error-log-event-fields.html" title="7.4.2.3 Error Event Fields"> Section 7.4.2.3, “Error Event Fields” </a> , with which you are assumed to be familiar. The following remarks provide additional information only as it pertains specifically to optional field references as used within <code class="literal"> log_filter_dragnet </code> rules. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> label </code> </p> <p> The label corresponding to the <code class="literal"> prio </code> value, as a string. Filter rules can change the label for log sinks that support custom labels. <code class="literal"> label </code> values are intended more for identifying particular lines in log output than for use in filter rule comparisons because <code class="literal"> log_filter_dragnet </code> does not resolve comparison values specified as strings to the equivalent numeric priority. </p> </li> <li class="listitem"> <p> <code class="literal"> source_file </code> </p> <p> The source file in which the event occurred, without any leading path. For example, to test for the <code class="filename"> sql/gis/distance.cc </code> file, write the comparison like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa97396776"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">IF</span> source_file <span class="token operator">=</span><span class="token operator">=</span> <span class="token string">"distance.cc"</span> <span class="token keyword">THEN</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> </li> </ul> </div> <h6> <a name="error-log-dragnet-user-defined-field-references"> </a> User-Defined Field References </h6> <p> Any field name in a <code class="literal"> log_filter_dragnet </code> filter rule not recognized as a core or optional field name is taken to refer to a user-defined field. </p> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-disk-write-speed-base.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-ndbinfo-disk-write-speed-base"> </a> 25.6.17.28 The ndbinfo disk_write_speed_base Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045089525856"> </a> <p> The <code class="literal"> disk_write_speed_base </code> table provides base information about the speed of disk writes during LCP, backup, and restore operations. </p> <p> The <code class="literal"> disk_write_speed_base </code> table contains the following columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> node_id </code> </p> <p> Node ID of this node </p> </li> <li class="listitem"> <p> <code class="literal"> thr_no </code> </p> <p> Thread ID of this LDM thread </p> </li> <li class="listitem"> <p> <code class="literal"> millis_ago </code> </p> <p> Milliseconds since this reporting period ended </p> </li> <li class="listitem"> <p> <code class="literal"> millis_passed </code> </p> <p> Milliseconds elapsed in this reporting period </p> </li> <li class="listitem"> <p> <code class="literal"> backup_lcp_bytes_written </code> </p> <p> Number of bytes written to disk by local checkpoints and backup processes during this period </p> </li> <li class="listitem"> <p> <code class="literal"> redo_bytes_written </code> </p> <p> Number of bytes written to REDO log during this period </p> </li> <li class="listitem"> <p> <code class="literal"> target_disk_write_speed </code> </p> <p> Actual speed of disk writes per LDM thread (base data) </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/optimizing-innodb-many-tables.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="optimizing-innodb-many-tables"> </a> 10.5.10 Optimizing InnoDB for Systems with Many Tables </h3> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If you have configured <a class="link" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> non-persistent optimizer statistics </a> (a non-default configuration), <code class="literal"> InnoDB </code> computes index <a class="link" href="glossary.html#glos_cardinality" title="cardinality"> cardinality </a> values for a table the first time that table is accessed after startup, instead of storing such values in the table. This step can take significant time on systems that partition the data into many tables. Since this overhead only applies to the initial table open operation, to <span class="quote"> “ <span class="quote"> warm up </span> ” </span> a table for later use, access it immediately after startup by issuing a statement such as <code class="literal"> SELECT 1 FROM <em class="replaceable"> <code> tbl_name </code> </em> LIMIT 1 </code> . </p> <p> Optimizer statistics are persisted to disk by default, enabled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> configuration option. For information about persistent optimizer statistics, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/sys-sys-config.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-sys-config"> </a> 30.4.2.1 The sys_config Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045063503696"> </a> <a class="indexterm" name="idm46045063502208"> </a> <p> This table contains <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema configuration options, one row per option. Configuration changes made by updating this table persist across client sessions and server restarts. </p> <p> The <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> variable </code> </p> <p> The configuration option name. </p> </li> <li class="listitem"> <p> <code class="literal"> value </code> </p> <p> The configuration option value. </p> </li> <li class="listitem"> <p> <code class="literal"> set_time </code> </p> <p> The timestamp of the most recent modification to the row. </p> </li> <li class="listitem"> <p> <code class="literal"> set_by </code> </p> <p> The account that made the most recent modification to the row. The value is <code class="literal"> NULL </code> if the row has not been changed since the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema was installed. </p> </li> </ul> </div> <p> As an efficiency measure to minimize the number of direct reads from the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table, <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema functions that use a value from this table check for a user-defined variable with a corresponding name, which is the user-defined variable having the same name plus a <code class="literal"> @sys. </code> prefix. (For example, the variable corresponding to the <code class="literal"> diagnostics.include_raw </code> option is <code class="literal"> @sys.diagnostics.include_raw </code> .) If the user-defined variable exists in the current session and is non- <code class="literal"> NULL </code> , the function uses its value in preference to the value in the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table. Otherwise, the function reads and uses the value from the table. In the latter case, the calling function conventionally also sets the corresponding user-defined variable to the table value so that further references to the configuration option within the same session use the variable and need not read the table again. </p> <p> For example, the <code class="literal"> statement_truncate_len </code> option controls the maximum length of statements returned by the <a class="link" href="sys-format-statement.html" title="30.4.5.5 The format_statement() Function"> <code class="literal"> format_statement() </code> </a> function. The default is 64. To temporarily change the value to 32 for your current session, set the corresponding <code class="literal"> @sys.statement_truncate_len </code> user-defined variable: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59966965"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@stmt</span> <span class="token operator">=</span> <span class="token string">'SELECT variable, value, set_time, set_by FROM sys_config'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> sys<span class="token punctuation">.</span>format_statement<span class="token punctuation">(</span><span class="token variable">@stmt</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> sys.format_statement(@stmt) <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> SELECT variable, value, set_time, set_by FROM sys_config <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@sys.statement_truncate_len</span> <span class="token operator">=</span> <span class="token number">32</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> sys<span class="token punctuation">.</span>format_statement<span class="token punctuation">(</span><span class="token variable">@stmt</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> sys.format_statement(@stmt) <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> SELECT variabl ... ROM sys_config <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> Subsequent invocations of <a class="link" href="sys-format-statement.html" title="30.4.5.5 The format_statement() Function"> <code class="literal"> format_statement() </code> </a> within the session continue to use the user-defined variable value (32), rather than the value stored in the table (64). </p> <p> To stop using the user-defined variable and revert to using the value in the table, set the variable to <code class="literal"> NULL </code> within your session: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa4167757"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@sys.statement_truncate_len</span> <span class="token operator">=</span> <span class="token boolean">NULL</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> sys<span class="token punctuation">.</span>format_statement<span class="token punctuation">(</span><span class="token variable">@stmt</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> sys.format_statement(@stmt) <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> SELECT variable, value, set_time, set_by FROM sys_config <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> Alternatively, end your current session (causing the user-defined variable to no longer exist) and begin a new session. </p> <p> The conventional relationship just described between options in the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table and user-defined variables can be exploited to make temporary configuration changes that end when your session ends. However, if you set a user-defined variable and then subsequently change the corresponding table value within the same session, the changed table value is not used in that session as long as the user-defined variable exists with a non- <code class="literal"> NULL </code> value. (The changed table value <span class="emphasis"> <em> is </em> </span> used in other sessions in which the user-defined variable is not assigned.) </p> <p> The following list describes the options in the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table and the corresponding user-defined variables: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> diagnostics.allow_i_s_tables </code> , <code class="literal"> @sys.diagnostics.allow_i_s_tables </code> </p> <p> If this option is <code class="literal"> ON </code> , the <a class="link" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> <code class="literal"> diagnostics() </code> </a> procedure is permitted to perform table scans on the Information Schema <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> table. This can be expensive if there are many tables. The default is <code class="literal"> OFF </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> diagnostics.include_raw </code> , <code class="literal"> @sys.diagnostics.include_raw </code> </p> <p> If this option is <code class="literal"> ON </code> , the <a class="link" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> <code class="literal"> diagnostics() </code> </a> procedure includes the raw output from querying the <a class="link" href="sys-metrics.html" title="30.4.3.21 The metrics View"> <code class="literal"> metrics </code> </a> view. The default is <code class="literal"> OFF </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> ps_thread_trx_info.max_length </code> , <code class="literal"> @sys.ps_thread_trx_info.max_length </code> </p> <p> The maximum length for JSON output produced by the <a class="link" href="sys-ps-thread-trx-info.html" title="30.4.5.17 The ps_thread_trx_info() Function"> <code class="literal"> ps_thread_trx_info() </code> </a> function. The default is 65535. </p> </li> <li class="listitem"> <p> <code class="literal"> statement_performance_analyzer.limit </code> , <code class="literal"> @sys.statement_performance_analyzer.limit </code> </p> <p> The maximum number of rows to return for views that have no built-in limit. (For example, the <a class="link" href="sys-statements-with-runtimes-in-95th-percentile.html" title="30.4.3.38 The statements_with_runtimes_in_95th_percentile and x$statements_with_runtimes_in_95th_percentile Views"> <code class="literal"> statements_with_runtimes_in_95th_percentile </code> </a> view has a built-in limit in the sense that it returns only statements with average execution time in the 95th percentile.) The default is 100. </p> </li> <li class="listitem"> <p> <code class="literal"> statement_performance_analyzer.view </code> , <code class="literal"> @sys.statement_performance_analyzer.view </code> </p> <p> The custom query or view to be used by the <a class="link" href="sys-statement-performance-analyzer.html" title="30.4.4.25 The statement_performance_analyzer() Procedure"> <code class="literal"> statement_performance_analyzer() </code> </a> procedure (which is itself invoked by the <a class="link" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> <code class="literal"> diagnostics() </code> </a> procedure). If the option value contains a space, it is interpreted as a query. Otherwise, it must be the name of an existing view that queries the Performance Schema <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> table. There cannot be any <code class="literal"> LIMIT </code> clause in the query or view definition if the <code class="literal"> statement_performance_analyzer.limit </code> configuration option is greater than 0. The default is <code class="literal"> NULL </code> (no custom view defined). </p> </li> <li class="listitem"> <p> <code class="literal"> statement_truncate_len </code> , <code class="literal"> @sys.statement_truncate_len </code> </p> <p> The maximum length of statements returned by the <a class="link" href="sys-format-statement.html" title="30.4.5.5 The format_statement() Function"> <code class="literal"> format_statement() </code> </a> function. Longer statements are truncated to this length. The default is 64. </p> </li> </ul> </div> <p> Other options can be added to the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table. For example, the <a class="link" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> <code class="literal"> diagnostics() </code> </a> and <a class="link" href="sys-execute-prepared-stmt.html" title="30.4.4.3 The execute_prepared_stmt() Procedure"> <code class="literal"> execute_prepared_stmt() </code> </a> procedures use the <code class="literal"> debug </code> option if it exists, but this option is not part of the <a class="link" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> <code class="literal"> sys_config </code> </a> table by default because debug output normally is enabled only temporarily, by setting the corresponding <code class="literal"> @sys.debug </code> user-defined variable. To enable debug output without having to set that variable in individual sessions, add the option to the table: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa59684147"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> sys<span class="token punctuation">.</span>sys_config <span class="token punctuation">(</span>variable<span class="token punctuation">,</span> <span class="token keyword">value</span><span class="token punctuation">)</span> <span class="token keyword">VALUES</span><span class="token punctuation">(</span><span class="token string">'debug'</span><span class="token punctuation">,</span> <span class="token string">'ON'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> To change the debug setting in the table, do two things. First, modify the value in the table itself: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa73381260"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">UPDATE</span> sys<span class="token punctuation">.</span>sys_config <span class="token keyword">SET</span> <span class="token keyword">value</span> <span class="token operator">=</span> <span class="token string">'OFF'</span> <span class="token keyword">WHERE</span> variable <span class="token operator">=</span> <span class="token string">'debug'</span><span class="token punctuation">;</span></code></pre> </div> <p> Second, to also ensure that procedure invocations within the current session use the changed value from the table, set the corresponding user-defined variable to <code class="literal"> NULL </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa13522173"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@sys.debug</span> <span class="token operator">=</span> <span class="token boolean">NULL</span><span class="token punctuation">;</span></code></pre> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/performance-schema-instrument-naming.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="performance-schema-instrument-naming"> </a> 29.6 Performance Schema Instrument Naming Conventions </h2> </div> </div> </div> <p> An instrument name consists of a sequence of elements separated by <code class="literal"> '/' </code> characters. Example names: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa75729489"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">wait/io/file/myisam/log wait/io/file/mysys/charset wait/lock/table/sql/handler wait/synch/cond/mysys/COND_alarm wait/synch/cond/sql/BINLOG::update_cond wait/synch/mutex/mysys/BITMAP_mutex wait/synch/mutex/sql/LOCK_delete wait/synch/rwlock/sql/Query_cache_query::lock stage/sql/closing tables stage/sql/Sorting result statement/com/Execute statement/com/Query statement/sql/create_table statement/sql/lock_tables errors</code></pre> </div> <p> The instrument name space has a tree-like structure. The elements of an instrument name from left to right provide a progression from more general to more specific. The number of elements a name has depends on the type of instrument. </p> <p> The interpretation of a given element in a name depends on the elements to the left of it. For example, <code class="literal"> myisam </code> appears in both of the following names, but <code class="literal"> myisam </code> in the first name is related to file I/O, whereas in the second it is related to a synchronization instrument: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa43228060"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">wait/io/file/myisam/log wait/synch/cond/myisam/MI_SORT_INFO::cond</code></pre> </div> <p> Instrument names consist of a prefix with a structure defined by the Performance Schema implementation and a suffix defined by the developer implementing the instrument code. The top-level element of an instrument prefix indicates the type of instrument. This element also determines which event timer in the <a class="link" href="performance-schema-performance-timers-table.html" title="29.12.22.6 The performance_timers Table"> <code class="literal"> performance_timers </code> </a> table applies to the instrument. For the prefix part of instrument names, the top level indicates the type of instrument. </p> <p> The suffix part of instrument names comes from the code for the instruments themselves. Suffixes may include levels such as these: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A name for the major element (a server module such as <code class="literal"> myisam </code> , <code class="literal"> innodb </code> , <code class="literal"> mysys </code> , or <code class="literal"> sql </code> ) or a plugin name. </p> </li> <li class="listitem"> <p> The name of a variable in the code, in the form <em class="replaceable"> <code> XXX </code> </em> (a global variable) or <code class="literal"> <em class="replaceable"> <code> CCC </code> </em> :: <em class="replaceable"> <code> MMM </code> </em> </code> (a member <em class="replaceable"> <code> MMM </code> </em> in class <em class="replaceable"> <code> CCC </code> </em> ). Examples: <code class="literal"> COND_thread_cache </code> , <code class="literal"> THR_LOCK_myisam </code> , <code class="literal"> BINLOG::LOCK_index </code> . </p> </li> </ul> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-top-level-instrument-elements" title="Top-Level Instrument Elements"> Top-Level Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-idle-instrument-elements" title="Idle Instrument Elements"> Idle Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-error-instrument-elements" title="Error Instrument Elements"> Error Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-memory-instrument-elements" title="Memory Instrument Elements"> Memory Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-stage-instrument-elements" title="Stage Instrument Elements"> Stage Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-statement-instrument-elements" title="Statement Instrument Elements"> Statement Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-thread-instrument-elements" title="Thread Instrument Elements"> Thread Instrument Elements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="performance-schema-instrument-naming.html#performance-schema-wait-instrument-elements" title="Wait Instrument Elements"> Wait Instrument Elements </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-top-level-instrument-elements"> </a> Top-Level Instrument Elements </h3> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> idle </code> : An instrumented idle event. This instrument has no further elements. </p> </li> <li class="listitem"> <p> <code class="literal"> error </code> : An instrumented error event. This instrument has no further elements. </p> </li> <li class="listitem"> <p> <code class="literal"> memory </code> : An instrumented memory event. </p> </li> <li class="listitem"> <p> <code class="literal"> stage </code> : An instrumented stage event. </p> </li> <li class="listitem"> <p> <code class="literal"> statement </code> : An instrumented statement event. </p> </li> <li class="listitem"> <p> <code class="literal"> transaction </code> : An instrumented transaction event. This instrument has no further elements. </p> </li> <li class="listitem"> <p> <code class="literal"> wait </code> : An instrumented wait event. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-idle-instrument-elements"> </a> Idle Instrument Elements </h3> </div> </div> </div> <p> The <code class="literal"> idle </code> instrument is used for idle events, which The Performance Schema generates as discussed in the description of the <code class="literal"> socket_instances.STATE </code> column in <a class="xref" href="performance-schema-socket-instances-table.html" title="29.12.3.5 The socket_instances Table"> Section 29.12.3.5, “The socket_instances Table” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-error-instrument-elements"> </a> Error Instrument Elements </h3> </div> </div> </div> <p> The <code class="literal"> error </code> instrument indicates whether to collect information for server errors and warnings. This instrument is enabled by default. The <code class="literal"> TIMED </code> column for the <code class="literal"> error </code> row in the <a class="link" href="performance-schema-setup-instruments-table.html" title="29.12.2.3 The setup_instruments Table"> <code class="literal"> setup_instruments </code> </a> table is inapplicable because timing information is not collected. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-memory-instrument-elements"> </a> Memory Instrument Elements </h3> </div> </div> </div> <p> Memory instrumentation is enabled by default. Memory instrumentation can be enabled or disabled at startup, or dynamically at runtime by updating the <code class="literal"> ENABLED </code> column of the relevant instruments in the <a class="link" href="performance-schema-setup-instruments-table.html" title="29.12.2.3 The setup_instruments Table"> <code class="literal"> setup_instruments </code> </a> table. Memory instruments have names of the form <code class="literal"> memory/ <em class="replaceable"> <code> code_area </code> </em> / <em class="replaceable"> <code> instrument_name </code> </em> </code> where <em class="replaceable"> <code> code_area </code> </em> is a value such as <code class="literal"> sql </code> or <code class="literal"> myisam </code> , and <em class="replaceable"> <code> instrument_name </code> </em> is the instrument detail. </p> <p> Instruments named with the prefix <code class="literal"> memory/performance_schema/ </code> expose how much memory is allocated for internal buffers in the Performance Schema. The <code class="literal"> memory/performance_schema/ </code> instruments are built in, always enabled, and cannot be disabled at startup or runtime. Built-in memory instruments are displayed only in the <a class="link" href="performance-schema-memory-summary-tables.html" title="29.12.20.10 Memory Summary Tables"> <code class="literal"> memory_summary_global_by_event_name </code> </a> table. For more information, see <a class="xref" href="performance-schema-memory-model.html" title="29.17 The Performance Schema Memory-Allocation Model"> Section 29.17, “The Performance Schema Memory-Allocation Model” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-stage-instrument-elements"> </a> Stage Instrument Elements </h3> </div> </div> </div> <p> Stage instruments have names of the form <code class="literal"> stage/ <em class="replaceable"> <code> code_area </code> </em> / <em class="replaceable"> <code> stage_name </code> </em> </code> , where <em class="replaceable"> <code> code_area </code> </em> is a value such as <code class="literal"> sql </code> or <code class="literal"> myisam </code> , and <em class="replaceable"> <code> stage_name </code> </em> indicates the stage of statement processing, such as <code class="literal"> Sorting result </code> or <code class="literal"> Sending data </code> . Stages correspond to the thread states displayed by <a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement"> <code class="literal"> SHOW PROCESSLIST </code> </a> or that are visible in the Information Schema <a class="link" href="information-schema-processlist-table.html" title="28.3.23 The INFORMATION_SCHEMA PROCESSLIST Table"> <code class="literal"> PROCESSLIST </code> </a> table. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-statement-instrument-elements"> </a> Statement Instrument Elements </h3> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> statement/abstract/* </code> : An abstract instrument for statement operations. Abstract instruments are used during the early stages of statement classification before the exact statement type is known, then changed to a more specific statement instrument when the type is known. For a description of this process, see <a class="xref" href="performance-schema-statement-tables.html" title="29.12.6 Performance Schema Statement Event Tables"> Section 29.12.6, “Performance Schema Statement Event Tables” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> statement/com </code> : An instrumented command operation. These have names corresponding to <code class="literal"> COM_ <em class="replaceable"> <code> xxx </code> </em> </code> operations (see the <code class="filename"> mysql_com.h </code> header file and <code class="filename"> sql/sql_parse.cc </code> . For example, the <code class="literal"> statement/com/Connect </code> and <code class="literal"> statement/com/Init DB </code> instruments correspond to the <code class="literal"> COM_CONNECT </code> and <code class="literal"> COM_INIT_DB </code> commands. </p> </li> <li class="listitem"> <p> <code class="literal"> statement/scheduler/event </code> : A single instrument to track all events executed by the Event Scheduler. This instrument comes into play when a scheduled event begins executing. </p> </li> <li class="listitem"> <p> <code class="literal"> statement/sp </code> : An instrumented internal instruction executed by a stored program. For example, the <code class="literal"> statement/sp/cfetch </code> and <code class="literal"> statement/sp/freturn </code> instruments are used cursor fetch and function return instructions. </p> </li> <li class="listitem"> <p> <code class="literal"> statement/sql </code> : An instrumented SQL statement operation. For example, the <code class="literal"> statement/sql/create_db </code> and <code class="literal"> statement/sql/select </code> instruments are used for <a class="link" href="create-database.html" title="15.1.12 CREATE DATABASE Statement"> <code class="literal"> CREATE DATABASE </code> </a> and <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> statements. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-thread-instrument-elements"> </a> Thread Instrument Elements </h3> </div> </div> </div> <p> Instrumented threads are displayed in the <a class="link" href="performance-schema-setup-threads-table.html" title="29.12.2.5 The setup_threads Table"> <code class="literal"> setup_threads </code> </a> table, which exposes thread class names and attributes. </p> <p> Thread instruments begin with <code class="literal"> thread </code> (for example, <code class="literal"> thread/sql/parser_service </code> or <code class="literal"> thread/performance_schema/setup </code> ). </p> <p> The names of thread instruments for <code class="literal"> ndbcluster </code> plugin threads begin with <code class="literal"> thread/ndbcluster/ </code> ; for more information about these, see <a class="xref" href="mysql-cluster-ps-tables.html#mysql-cluster-plugin-threads" title="ndbcluster Plugin Threads"> ndbcluster Plugin Threads </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="performance-schema-wait-instrument-elements"> </a> Wait Instrument Elements </h3> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> wait/io </code> </p> <p> An instrumented I/O operation. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> wait/io/file </code> </p> <p> An instrumented file I/O operation. For files, the wait is the time waiting for the file operation to complete (for example, a call to <code class="literal"> fwrite() </code> ). Due to caching, the physical file I/O on the disk might not happen within this call. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/io/socket </code> </p> <p> An instrumented socket operation. Socket instruments have names of the form <code class="literal"> wait/io/socket/sql/ <em class="replaceable"> <code> socket_type </code> </em> </code> . The server has a listening socket for each network protocol that it supports. The instruments associated with listening sockets for TCP/IP or Unix socket file connections have a <em class="replaceable"> <code> socket_type </code> </em> value of <code class="literal"> server_tcpip_socket </code> or <code class="literal"> server_unix_socket </code> , respectively. When a listening socket detects a connection, the server transfers the connection to a new socket managed by a separate thread. The instrument for the new connection thread has a <em class="replaceable"> <code> socket_type </code> </em> value of <code class="literal"> client_connection </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> wait/io/table </code> </p> <p> An instrumented table I/O operation. These include row-level accesses to persistent base tables or temporary tables. Operations that affect rows are fetch, insert, update, and delete. For a view, waits are associated with base tables referenced by the view. </p> <p> Unlike most waits, a table I/O wait can include other waits. For example, table I/O might include file I/O or memory operations. Thus, <a class="link" href="performance-schema-events-waits-current-table.html" title="29.12.4.1 The events_waits_current Table"> <code class="literal"> events_waits_current </code> </a> for a table I/O wait usually has two rows. For more information, see <a class="xref" href="performance-schema-atom-molecule-events.html" title="29.8 Performance Schema Atom and Molecule Events"> Section 29.8, “Performance Schema Atom and Molecule Events” </a> . </p> <p> Some row operations might cause multiple table I/O waits. For example, an insert might activate a trigger that causes an update. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> wait/lock </code> </p> <p> An instrumented lock operation. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> wait/lock/table </code> </p> <p> An instrumented table lock operation. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/lock/metadata/sql/mdl </code> </p> <p> An instrumented metadata lock operation. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> wait/synch </code> </p> <p> An instrumented synchronization object. For synchronization objects, the <code class="literal"> TIMER_WAIT </code> time includes the amount of time blocked while attempting to acquire a lock on the object, if any. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> wait/synch/cond </code> </p> <p> A condition is used by one thread to signal to other threads that something they were waiting for has happened. If a single thread was waiting for a condition, it can wake up and proceed with its execution. If several threads were waiting, they can all wake up and compete for the resource for which they were waiting. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/synch/mutex </code> </p> <p> A mutual exclusion object used to permit access to a resource (such as a section of executable code) while preventing other threads from accessing the resource. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/synch/prlock </code> </p> <p> A priority <a class="link" href="glossary.html#glos_rw_lock" title="rw-lock"> rwlock </a> lock object. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/synch/rwlock </code> </p> <p> A plain <a class="link" href="glossary.html#glos_rw_lock" title="rw-lock"> read/write lock </a> object used to lock a specific variable for access while preventing its use by other threads. A shared read lock can be acquired simultaneously by multiple threads. An exclusive write lock can be acquired by only one thread at a time. </p> </li> <li class="listitem"> <p> <code class="literal"> wait/synch/sxlock </code> </p> <p> A shared-exclusive (SX) lock is a type of <a class="link" href="glossary.html#glos_rw_lock" title="rw-lock"> rwlock </a> lock object that provides write access to a common resource while permitting inconsistent reads by other threads. <code class="literal"> sxlocks </code> optimize concurrency and improve scalability for read-write workloads. </p> </li> </ul> </div> </li> </ul> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/source-ssl-library-configuration.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="source-ssl-library-configuration"> </a> 2.8.6 Configuring SSL Library Support </h3> </div> </div> </div> <a class="indexterm" name="idm46045329404896"> </a> <a class="indexterm" name="idm46045329403408"> </a> <p> An SSL library is required for support of encrypted connections, entropy for random number generation, and other encryption-related operations. </p> <p> If you compile MySQL from a source distribution, <span class="command"> <strong> CMake </strong> </span> configures the distribution to use the installed OpenSSL library by default. </p> <p> To compile using OpenSSL, use this procedure: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Ensure that OpenSSL 1.0.1 or newer is installed on your system. If the installed OpenSSL version is older than 1.0.1, <span class="command"> <strong> CMake </strong> </span> produces an error at MySQL configuration time. If it is necessary to obtain OpenSSL, visit <a class="ulink" href="http://www.openssl.org" target="_blank"> http://www.openssl.org </a> . </p> </li> <li class="listitem"> <p> The <a class="link" href="source-configuration-options.html#option_cmake_with_ssl"> <code class="option"> WITH_SSL </code> </a> <span class="command"> <strong> CMake </strong> </span> option determines which SSL library to use for compiling MySQL (see <a class="xref" href="source-configuration-options.html" title="2.8.7 MySQL Source-Configuration Options"> Section 2.8.7, “MySQL Source-Configuration Options” </a> ). The default is <a class="link" href="source-configuration-options.html#option_cmake_with_ssl"> <code class="option"> -DWITH_SSL=system </code> </a> , which uses OpenSSL. To make this explicit, specify that option. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa1980377"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cmake <span class="token punctuation">.</span> <span class="token constant">-DWITH_SSL</span><span class="token attr-value"><span class="token punctuation">=</span>system</span></code></pre> </div> <p> That command configures the distribution to use the installed OpenSSL library. Alternatively, to explicitly specify the path name to the OpenSSL installation, use the following syntax. This can be useful if you have multiple versions of OpenSSL installed, to prevent <span class="command"> <strong> CMake </strong> </span> from choosing the wrong one: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa66585106"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cmake <span class="token punctuation">.</span> <span class="token constant">-DWITH_SSL</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">path_name</em></span></code></pre> </div> <p> Alternative OpenSSL system packages are supported by using <code class="option"> WITH_SSL=openssl11 </code> on EL7 or <code class="option"> WITH_SSL=openssl3 </code> on EL8. Authentication plugins, such as LDAP and Kerberos, are disabled since they do not support these alternative versions of OpenSSL. </p> </li> <li class="listitem"> <p> Compile and install the distribution. </p> </li> </ol> </div> <p> To check whether a <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> server supports encrypted connections, examine the value of the <a class="link" href="server-system-variables.html#sysvar_tls_version"> <code class="literal"> tls_version </code> </a> system variable: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa39730916"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'tls_version'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Variable_name <span class="token punctuation">|</span> Value <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> tls_version <span class="token punctuation">|</span> TLSv1.2,TLSv1.3 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> If the value contains TLS versions then the server supports encrypted connections, otherwise it does not. </p> <p> For additional information, see <a class="xref" href="using-encrypted-connections.html" title="8.3.1 Configuring MySQL to Use Encrypted Connections"> Section 8.3.1, “Configuring MySQL to Use Encrypted Connections” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/telemetry-metrics-meter-metrics.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="telemetry-metrics-meter-metrics"> </a> 35.4.3 Server Metrics </h3> </div> </div> </div> <p> The following server metrics are registered by default: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats" title="mysql.stats Metrics"> mysql.stats Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-com" title="mysql.stats.com Metrics"> mysql.stats.com Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-connection" title="mysql.stats.connection Metrics"> mysql.stats.connection Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-perf-schema" title="mysql.perf_schema Metrics"> mysql.perf_schema Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-handler" title="mysql.stats.handler Metrics"> mysql.stats.handler Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-myisam" title="mysql.stats.myisam Metrics"> mysql.stats.myisam Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-stats-ssl" title="mysql.stats.ssl Metrics"> mysql.stats.ssl Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-inno" title="mysql.inno Metrics"> mysql.inno Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-inno-bufferpool" title="mysql.inno.buffer_pool Metrics"> mysql.inno.buffer_pool Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-inno-data" title="mysql.inno.data Metrics"> mysql.inno.data Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-x" title="mysql.x Metrics"> mysql.x Metrics </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="telemetry-metrics-meter-metrics.html#telemetry-metrics-meter-metrics-mysql-x-stmt" title="mysql.x.stmt Metrics"> mysql.x.stmt Metrics </a> </p> </li> </ul> </div> <p> The maximum number of metric instruments which can be created is set by <a class="link" href="performance-schema-system-variables.html#sysvar_performance_schema_max_metric_classes"> <code class="literal"> performance_schema_max_metric_classes </code> </a> . </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats"> </a> mysql.stats Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045058440592"> </a> <p class="title"> <b> Table 35.3 mysql.stats Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> aborted_clients </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Aborted_clients"> <code class="literal"> Aborted_clients </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections that were aborted because the client died without closing the connection properly </p> </td> </tr> <tr> <td> <p> <code class="literal"> aborted_connects </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Aborted_connects"> <code class="literal"> Aborted_connects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of failed attempts to connect to the MySQL server </p> </td> </tr> <tr> <td> <p> <code class="literal"> acl_cache_items_count </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Acl_cache_items_count"> <code class="literal"> Acl_cache_items_count </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of cached privilege objects </p> </td> </tr> <tr> <td> <p> <code class="literal"> binlog_cache.disk_use </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Binlog_cache_disk_use"> <code class="literal"> Binlog_cache_disk_use </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of transactions that used the temporary binary log cache but that exceeded the value of binlog_cache_size and used a temporary file to store statements from the transaction </p> </td> </tr> <tr> <td> <p> <code class="literal"> binlog_cache.use </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Binlog_cache_use"> <code class="literal"> Binlog_cache_use </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of transactions that used the binary log cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> binlog_stmt_cache_disk_use </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Binlog_stmt_cache_disk_use"> <code class="literal"> Binlog_stmt_cache_disk_use </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of nontransaction statements that used the binary log statement cache but that exceeded the value of binlog_stmt_cache_size and used a temporary file to store those statements. </p> </td> </tr> <tr> <td> <p> <code class="literal"> binlog_stmt_cache_use </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Binlog_stmt_cache_use"> <code class="literal"> Binlog_stmt_cache_use </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of nontransactional statements that used the binary log statement cache </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_received </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Bytes_received"> <code class="literal"> Bytes_received </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes received from all clients </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_sent </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Bytes_sent"> <code class="literal"> Bytes_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes sent to all clients </p> </td> </tr> <tr> <td> <p> <code class="literal"> created.tmp_disk_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Created_tmp_disk_tables"> <code class="literal"> Created_tmp_disk_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of internal on-disk temporary tables created by the server while executing statements </p> </td> </tr> <tr> <td> <p> <code class="literal"> created.tmp_files </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Created_tmp_files"> <code class="literal"> Created_tmp_files </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many temporary files mysqld has created </p> </td> </tr> <tr> <td> <p> <code class="literal"> created.tmp_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Created_tmp_tables"> <code class="literal"> Created_tmp_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of internal temporary tables created by the server while executing statements </p> </td> </tr> <tr> <td> <p> <code class="literal"> error_log.buffered_bytes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Error_log_buffered_bytes"> <code class="literal"> Error_log_buffered_bytes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of bytes currently used in the Performance Schema error_log table </p> </td> </tr> <tr> <td> <p> <code class="literal"> error_log.buffered_events </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Error_log_buffered_events"> <code class="literal"> Error_log_buffered_events </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of events currently present in the Performance Schema error_log table </p> </td> </tr> <tr> <td> <p> <code class="literal"> error_log.expired_events </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Error_log_expired_events"> <code class="literal"> Error_log_expired_events </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of events discarded from the Performance Schema error_log table to make room for new events </p> </td> </tr> <tr> <td> <p> <code class="literal"> flush_commands </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Flush_commands"> <code class="literal"> Flush_commands </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times the server flushes tables </p> </td> </tr> <tr> <td> <p> <code class="literal"> global_connection_memory </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Global_connection_memory"> <code class="literal"> Global_connection_memory </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The memory used by all user connections to the server </p> </td> </tr> <tr> <td> <p> <code class="literal"> locked_connects </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Locked_connects"> <code class="literal"> Locked_connects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of attempts to connect to locked user accounts </p> </td> </tr> <tr> <td> <p> <code class="literal"> max_execution_time_exceeded </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_exceeded"> <code class="literal"> Max_execution_time_exceeded </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SELECT statements for which the execution timeout was exceeded </p> </td> </tr> <tr> <td> <p> <code class="literal"> max_execution_time_set </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_set"> <code class="literal"> Max_execution_time_set </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SELECT statements for which a nonzero execution timeout was set </p> </td> </tr> <tr> <td> <p> <code class="literal"> max_execution_time_set_failed </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_set_failed"> <code class="literal"> Max_execution_time_set_failed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of <code class="literal"> SELECT </code> statements for which the attempt to set an execution timeout failed </p> </td> </tr> <tr> <td> <p> <code class="literal"> max_used_connections </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Max_used_connections"> <code class="literal"> Max_used_connections </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The maximum number of connections that have been in use simultaneously since the server started </p> </td> </tr> <tr> <td> <p> <code class="literal"> ongoing_anonymous_transaction_count </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ongoing_anonymous_transaction_count"> <code class="literal"> Ongoing_anonymous_transaction_count </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Shows the number of ongoing transactions which have been marked as anonymous </p> </td> </tr> <tr> <td> <p> <code class="literal"> open_files </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Open_files"> <code class="literal"> Open_files </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of files that are open. This count includes regular files opened by the server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> open_streams </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Open_streams"> <code class="literal"> Open_streams </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of streams that are open, used mainly for logging </p> </td> </tr> <tr> <td> <p> <code class="literal"> open_table_definitions </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Open_table_definitions"> <code class="literal"> Open_table_definitions </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of cached table definitions </p> </td> </tr> <tr> <td> <p> <code class="literal"> open_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Open_tables"> <code class="literal"> Open_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of tables that are open. </p> </td> </tr> <tr> <td> <p> <code class="literal"> opened_files </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Opened_files"> <code class="literal"> Opened_files </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of files that have been opened with <code class="literal"> my_open() </code> . </p> </td> </tr> <tr> <td> <p> <code class="literal"> opened_table_definitions </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Opened_table_definitions"> <code class="literal"> Opened_table_definitions </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of table definitions that have been cached. </p> </td> </tr> <tr> <td> <p> <code class="literal"> opened_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Opened_tables"> <code class="literal"> Opened_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of tables that have been opened </p> </td> </tr> <tr> <td> <p> <code class="literal"> prepared_stmt_count </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Prepared_stmt_count"> <code class="literal"> Prepared_stmt_count </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The current number of prepared statements </p> </td> </tr> <tr> <td> <p> <code class="literal"> queries </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Queries"> <code class="literal"> Queries </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of statements executed by the server, including ones executed within stored programs. It does not count <code class="literal"> COM_PING </code> or <code class="literal"> COM_STATISTICS </code> commands. </p> </td> </tr> <tr> <td> <p> <code class="literal"> questions </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Questions"> <code class="literal"> Questions </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of statements executed by the server. This includes only statements sent to the server by clients and not statements executed within stored programs. </p> </td> </tr> <tr> <td> <p> <code class="literal"> replica_open_temp_tables </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Replica_open_temp_tables"> <code class="literal"> Replica_open_temp_tables </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of temporary tables that the replication SQL thread currently has open. </p> </td> </tr> <tr> <td> <p> <code class="literal"> secondary_engine_execution_count </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Secondary_engine_execution_count"> <code class="literal"> Secondary_engine_execution_count </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of queries offloaded to a secondary engine </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_full_join </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_full_join"> <code class="literal"> Select_full_join </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins that perform table scans because they do not use indexes </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_full_range_join </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_full_range_join"> <code class="literal"> Select_full_range_join </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins that used a range search on a reference table </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_range </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_range"> <code class="literal"> Select_range </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins that used ranges on the first table </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_range_check </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_range_check"> <code class="literal"> Select_range_check </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins without keys that check for key usage after each row </p> </td> </tr> <tr> <td> <p> <code class="literal"> select_scan </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Select_scan"> <code class="literal"> Select_scan </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of joins that did a full scan of the first table </p> </td> </tr> <tr> <td> <p> <code class="literal"> slow_launch_threads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Slow_launch_threads"> <code class="literal"> Slow_launch_threads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of threads that have taken more than slow_launch_time seconds to create. </p> </td> </tr> <tr> <td> <p> <code class="literal"> slow_queries </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Slow_queries"> <code class="literal"> Slow_queries </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of queries that have taken more than long_query_time seconds </p> </td> </tr> <tr> <td> <p> <code class="literal"> sort_merge_passes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Sort_merge_passes"> <code class="literal"> Sort_merge_passes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of merge passes that the sort algorithm has had to do </p> </td> </tr> <tr> <td> <p> <code class="literal"> sort_range </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Sort_range"> <code class="literal"> Sort_range </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sorts that were done using ranges </p> </td> </tr> <tr> <td> <p> <code class="literal"> sort_rows </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Sort_rows"> <code class="literal"> Sort_rows </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sorted rows. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sort_scan </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Sort_scan"> <code class="literal"> Sort_scan </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sorts that were done by scanning the table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_locks_immediate </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_locks_immediate"> <code class="literal"> Table_locks_immediate </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times that a request for a table lock could be granted immediately </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_locks_waited </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_locks_waited"> <code class="literal"> Table_locks_waited </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times that a request for a table lock could not be granted immediately and a wait was needed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_open_cache_hits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_hits"> <code class="literal"> Table_open_cache_hits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of hits for open tables cache lookups. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_open_cache_misses </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_misses"> <code class="literal"> Table_open_cache_misses </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of misses for open tables cache lookups. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_open_cache_overflows </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_overflows"> <code class="literal"> Table_open_cache_overflows </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of overflows for the open tables cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> tc_log_page_waits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Tc_log_page_waits"> <code class="literal"> Tc_log_page_waits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> For the memory-mapped implementation of the recovery log, this variable increments each time the server was not able to commit a transaction and had to wait for a free page in the log. </p> </td> </tr> <tr> <td> <p> <code class="literal"> threads_cached </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Threads_cached"> <code class="literal"> Threads_cached </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of threads in the thread cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> threads_connected </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Threads_connected"> <code class="literal"> Threads_connected </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of currently open connections </p> </td> </tr> <tr> <td> <p> <code class="literal"> threads_created </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Threads_created"> <code class="literal"> Threads_created </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of threads created to handle connections. </p> </td> </tr> <tr> <td> <p> <code class="literal"> threads_running </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Threads_running"> <code class="literal"> Threads_running </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of threads that are not sleeping. </p> </td> </tr> <tr> <td> <p> <code class="literal"> uptime </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Uptime"> <code class="literal"> Uptime </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of seconds that the server has been up. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 801px;"> <thead> <tr> <th style="width: 291.391px;"> Name </th> <th style="width: 291.391px;"> Source Variable </th> <th style="width: 63.875px;"> OTEL Type </th> <th style="width: 153.016px;"> Description </th> </tr> </thead> </table> </div> </div> <p> <br class="table-break"/> </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-com"> </a> mysql.stats.com Metrics </h4> </div> </div> </div> <p> The <code class="literal"> mysql.stats.com </code> metrics correspond to the <code class="literal"> Com_ <em class="replaceable"> <code> xxx </code> </em> </code> statement counter variables. See <a class="xref" href="server-status-variables.html" title="7.1.10 Server Status Variables"> Section 7.1.10, “Server Status Variables” </a> and <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xxx </a> for more information. </p> <p> The <code class="literal"> mysql.stats.com </code> metrics are named for those variables, without the <code class="literal"> Com_ </code> prefix. For example, the <code class="literal"> select </code> metric corresponds to the <code class="literal"> Com_select </code> statement counter variable. </p> <p> These metrics are of OTEL Type <code class="literal"> ASYNC COUNTER </code> and record the number of times (INTEGER) the corresponding command statement has been executed. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-connection"> </a> mysql.stats.connection Metrics </h4> </div> </div> </div> <p> The <code class="literal"> mysql.stats.connection </code> metrics correspond to the <code class="literal"> Connections </code> and <code class="literal"> Connection_ <em class="replaceable"> <code> XXX </code> </em> </code> status variables. </p> <div class="table"> <a name="idm46045058010112"> </a> <p class="title"> <b> Table 35.4 mysql.stats.connection Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> total </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connections"> <code class="literal"> Connections </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Cumulative count of total connections created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_accept </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_accept"> <code class="literal"> Connection_errors_accept </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors that occurred during calls to <code class="literal"> accept() </code> on the listening port. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_internal </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_internal"> <code class="literal"> Connection_errors_internal </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections refused due to internal errors in the server, such as failure to start a new thread or an out-of-memory condition. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_max_connections </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_max_connections"> <code class="literal"> Connection_errors_max_connections </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections refused because the server max_connections limit was reached. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_peer_address </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_peer_address"> <code class="literal"> Connection_errors_peer_address </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors that occurred while searching for connecting client IP addresses. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_select </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_select"> <code class="literal"> Connection_errors_select </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors that occurred during calls to select() or poll() on the listening port. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_tcpwrap </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Connection_errors_tcpwrap"> <code class="literal"> Connection_errors_tcpwrap </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections refused by the <code class="literal"> libwrap </code> library. </p> </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-perf-schema"> </a> mysql.perf_schema Metrics </h4> </div> </div> </div> <p> The <code class="literal"> mysql.perf_schema </code> correspond to the <code class="literal"> Performance_schema_ <em class="replaceable"> <code> XXX </code> </em> </code> status variables. See <a class="xref" href="performance-schema-status-monitoring.html" title="29.7 Performance Schema Status Monitoring"> Section 29.7, “Performance Schema Status Monitoring” </a> . </p> <div class="table"> <a name="idm46045057945936"> </a> <p class="title"> <b> Table 35.5 mysql.perf_schema Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> accounts_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_accounts_lost"> <code class="literal"> Performance_schema_accounts_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times a row could not be added to the accounts table because it was full. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cond_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_cond_classes_lost"> <code class="literal"> Performance_schema_cond_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many condition instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cond_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_cond_instances_lost"> <code class="literal"> Performance_schema_cond_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many condition instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> digest_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_digest_lost"> <code class="literal"> Performance_schema_digest_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of digest instances that could not be instrumented in the <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> file_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_classes_lost"> <code class="literal"> Performance_schema_file_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many file instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> file_handles_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_handles_lost"> <code class="literal"> Performance_schema_file_handles_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many file instrument instances could not be opened. </p> </td> </tr> <tr> <td> <p> <code class="literal"> file_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_instances_lost"> <code class="literal"> Performance_schema_file_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many file instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> hosts_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_hosts_lost"> <code class="literal"> Performance_schema_hosts_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times a row could not be added to the hosts table because it was full. </p> </td> </tr> <tr> <td> <p> <code class="literal"> index_stat_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_index_stat_lost"> <code class="literal"> Performance_schema_index_stat_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of indexes for which statistics were lost. </p> </td> </tr> <tr> <td> <p> <code class="literal"> locker_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_locker_lost"> <code class="literal"> Performance_schema_locker_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many events are lost or not recorded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> memory_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_memory_classes_lost"> <code class="literal"> Performance_schema_memory_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times a memory instrument could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> metadata_lock_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_metadata_lock_lost"> <code class="literal"> Performance_schema_metadata_lock_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of metadata locks that could not be instrumented in the <a class="link" href="performance-schema-metadata-locks-table.html" title="29.12.13.3 The metadata_locks Table"> <code class="literal"> metadata_locks </code> </a> table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> meter_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_meter_lost"> <code class="literal"> Performance_schema_meter_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many meter instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> metric_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_metric_lost"> <code class="literal"> Performance_schema_metric_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many metric instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> mutex_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_mutex_classes_lost"> <code class="literal"> Performance_schema_mutex_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many mutex instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> mutex_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_mutex_instances_lost"> <code class="literal"> Performance_schema_mutex_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many mutex instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> nested_statement_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_nested_statement_lost"> <code class="literal"> Performance_schema_nested_statement_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of stored program statements for which statistics were lost. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prepared_statements_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_prepared_statements_lost"> <code class="literal"> Performance_schema_prepared_statements_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of prepared statements that could not be instrumented in the <a class="link" href="performance-schema-prepared-statements-instances-table.html" title="29.12.6.4 The prepared_statements_instances Table"> <code class="literal"> prepared_statements_instances </code> </a> table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> program_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_program_lost"> <code class="literal"> Performance_schema_program_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of stored programs for which statistics were lost. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rwlock_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_rwlock_classes_lost"> <code class="literal"> Performance_schema_rwlock_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many rwlock instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rwlock_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_rwlock_instances_lost"> <code class="literal"> Performance_schema_rwlock_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many rwlock instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_connect_attrs_longest_seen </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_session_connect_attrs_longest_seen"> <code class="literal"> Performance_schema_session_connect_attrs_longest_seen </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Longest seen connection attribute received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_connect_attrs_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_session_connect_attrs_lost"> <code class="literal"> Performance_schema_session_connect_attrs_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections for which connection attribute truncation has occurred </p> </td> </tr> <tr> <td> <p> <code class="literal"> socket_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_socket_classes_lost"> <code class="literal"> Performance_schema_socket_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many socket instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> socket_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_socket_instances_lost"> <code class="literal"> Performance_schema_socket_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many socket instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> stage_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_stage_classes_lost"> <code class="literal"> Performance_schema_stage_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many stage instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> statement_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_statement_classes_lost"> <code class="literal"> Performance_schema_statement_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many statement instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_handles_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_handles_lost"> <code class="literal"> Performance_schema_table_handles_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many table instrument instances could not be opened. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_instances_lost"> <code class="literal"> Performance_schema_table_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many table instrument instances could not be created. </p> </td> </tr> <tr> <td> <p> <code class="literal"> table_lock_stat_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_lock_stat_lost"> <code class="literal"> Performance_schema_table_lock_stat_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of tables for which lock statistics were lost. </p> </td> </tr> <tr> <td> <p> <code class="literal"> thread_classes_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_thread_classes_lost"> <code class="literal"> Performance_schema_thread_classes_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many thread instruments could not be loaded. </p> </td> </tr> <tr> <td> <p> <code class="literal"> thread_instances_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_thread_instances_lost"> <code class="literal"> Performance_schema_thread_instances_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of thread instances that could not be instrumented in the <a class="link" href="performance-schema-threads-table.html" title="29.12.22.8 The threads Table"> <code class="literal"> threads </code> </a> table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> users_lost </code> </p> </td> <td> <p> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_users_lost"> <code class="literal"> Performance_schema_users_lost </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times a row could not be added to the <a class="link" href="performance-schema-users-table.html" title="29.12.8.3 The users Table"> <code class="literal"> users </code> </a> table because it was full. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 1077px;"> <thead> <tr> <th style="width: 283.266px;"> Name </th> <th style="width: 437.656px;"> Source Variable </th> <th style="width: 63.875px;"> OTEL Type </th> <th style="width: 291.391px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-handler"> </a> mysql.stats.handler Metrics </h4> </div> </div> </div> <p> The <code class="literal"> mysql.stats.handler </code> metrics correspond to the <code class="literal"> Handler_ <em class="replaceable"> <code> XXX </code> </em> </code> status variables. </p> <div class="table"> <a name="idm46045057692032"> </a> <p class="title"> <b> Table 35.6 mysql.perf_schema Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> commit </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_commit"> <code class="literal"> Handler_commit </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of internal COMMIT statements. </p> </td> </tr> <tr> <td> <p> <code class="literal"> delete </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_delete"> <code class="literal"> Handler_delete </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times that rows have been deleted from tables </p> </td> </tr> <tr> <td> <p> <code class="literal"> discover </code> </p> </td> <td> <p> <a class="link" href="mysql-cluster-options-variables.html#statvar_Handler_discover"> <code class="literal"> Handler_discover </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times that tables have been discovered. </p> </td> </tr> <tr> <td> <p> <code class="literal"> external_lock </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_external_lock"> <code class="literal"> Handler_external_lock </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The server increments this variable for each call to its external_lock() function, which generally occurs at the beginning and end of access to a table instance. </p> </td> </tr> <tr> <td> <p> <code class="literal"> mrr_init </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_mrr_init"> <code class="literal"> Handler_mrr_init </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times the server uses a storage engine's own Multi-Range Read implementation for table access. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prepare </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_prepare"> <code class="literal"> Handler_prepare </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> A counter for the prepare phase of two-phase commit operations. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_first </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_first"> <code class="literal"> Handler_read_first </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of times the first entry in an index was read. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_key </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_key"> <code class="literal"> Handler_read_key </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read a row based on a key. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_last </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_last"> <code class="literal"> Handler_read_last </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read the last key in an index. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_next </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_next"> <code class="literal"> Handler_read_next </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read the next row in key order. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_prev </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_prev"> <code class="literal"> Handler_read_prev </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read the previous row in key order. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_rnd </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_rnd"> <code class="literal"> Handler_read_rnd </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read a row based on a fixed position. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_rnd_next </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_read_rnd_next"> <code class="literal"> Handler_read_rnd_next </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read the next row in the data file. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rollback </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_rollback"> <code class="literal"> Handler_rollback </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests for a storage engine to perform a rollback operation. </p> </td> </tr> <tr> <td> <p> <code class="literal"> savepoint </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_savepoint"> <code class="literal"> Handler_savepoint </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests for a storage engine to place a savepoint. </p> </td> </tr> <tr> <td> <p> <code class="literal"> savepoint_rollback </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_savepoint_rollback"> <code class="literal"> Handler_savepoint_rollback </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests for a storage engine to roll back to a savepoint. </p> </td> </tr> <tr> <td> <p> <code class="literal"> update </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_update"> <code class="literal"> Handler_update </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to update a row in a table. </p> </td> </tr> <tr> <td> <p> <code class="literal"> write </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Handler_write"> <code class="literal"> Handler_write </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to insert a row in a table. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 153.266px;"> Name </th> <th style="width: 218.266px;"> Source Variable </th> <th style="width: 124.016px;"> OTEL Type </th> <th style="width: 242.453px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-myisam"> </a> mysql.stats.myisam Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057554096"> </a> <p class="title"> <b> Table 35.7 mysql.perf_schema Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> key_blocks_not_flushed </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_blocks_not_flushed"> <code class="literal"> Key_blocks_not_flushed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of key blocks in the MyISAM key cache that have changed but have not yet been flushed to disk. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_blocks_unused </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_blocks_unused"> <code class="literal"> Key_blocks_unused </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of unused blocks in the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_blocks_used </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_blocks_used"> <code class="literal"> Key_blocks_used </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of used blocks in the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_read_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_read_requests"> <code class="literal"> Key_read_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to read a key block from the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_reads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_reads"> <code class="literal"> Key_reads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of physical reads of a key block from disk into the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_write_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_write_requests"> <code class="literal"> Key_write_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to write a key block to the MyISAM key cache. </p> </td> </tr> <tr> <td> <p> <code class="literal"> key_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Key_writes"> <code class="literal"> Key_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of physical writes of a key block from the MyISAM key cache to disk. </p> </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-stats-ssl"> </a> mysql.stats.ssl Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057494256"> </a> <p class="title"> <b> Table 35.8 mysql.stats.ssl Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> client_connects </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_client_connects"> <code class="literal"> Ssl_client_connects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL connection attempts to an SSL-enabled replication source server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connect_renegotiates </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_connect_renegotiates"> <code class="literal"> Ssl_connect_renegotiates </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of negotiates needed to establish the connection to an SSL-enabled replication source server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> finished_accepts </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_finished_accepts"> <code class="literal"> Ssl_finished_accepts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of successful SSL connections to the server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> finished_connects </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_finished_connects"> <code class="literal"> Ssl_finished_connects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of successful replica connections to an SSL-enabled replication source server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_hits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_hits"> <code class="literal"> Ssl_session_cache_hits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL session cache hits. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_misses </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_misses"> <code class="literal"> Ssl_session_cache_misses </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL session cache misses. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_overflows </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_overflows"> <code class="literal"> Ssl_session_cache_overflows </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL session cache overflows. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_size </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_size"> <code class="literal"> Ssl_session_cache_size </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The SSL session cache size. </p> </td> </tr> <tr> <td> <p> <code class="literal"> session_cache_timeouts </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_timeouts"> <code class="literal"> Ssl_session_cache_timeouts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of SSL session cache timeouts. </p> </td> </tr> <tr> <td> <p> <code class="literal"> used_session_cache_entries </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_used_session_cache_entries"> <code class="literal"> Ssl_used_session_cache_entries </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> How many SSL session cache entries were used. </p> </td> </tr> <tr> <td> <p> <code class="literal"> accept_renegotiates </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_accept_renegotiates"> <code class="literal"> Ssl_accept_renegotiates </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of negotiates needed to establish the connection. </p> </td> </tr> <tr> <td> <p> <code class="literal"> accepts </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_accepts"> <code class="literal"> Ssl_accepts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of accepted SSL connections. </p> </td> </tr> <tr> <td> <p> <code class="literal"> callback_cache_hits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Ssl_callback_cache_hits"> <code class="literal"> Ssl_callback_cache_hits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of callback cache hits. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 218.266px;"> Name </th> <th style="width: 250.766px;"> Source Variable </th> <th style="width: 97.4062px;"> OTEL Type </th> <th style="width: 171.562px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-inno"> </a> mysql.inno Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057391856"> </a> <p class="title"> <b> Table 35.9 mysql.inno Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> dblwr_pages_written </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_pages_written"> <code class="literal"> Innodb_dblwr_pages_written </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages that have been written for doublewrite operations </p> </td> </tr> <tr> <td> <p> <code class="literal"> dblwr_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_writes"> <code class="literal"> Innodb_dblwr_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of doublewrite operations that have been performed </p> </td> </tr> <tr> <td> <p> <code class="literal"> redo_log_logical_size </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_logical_size"> <code class="literal"> Innodb_redo_log_logical_size </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> LSN range size in bytes containing in-use redo log data. </p> </td> </tr> <tr> <td> <p> <code class="literal"> redo_log_physical_size </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_physical_size"> <code class="literal"> Innodb_redo_log_physical_size </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Disk space in bytes currently consumed by all redo log files on disk, excluding spare redo log files </p> </td> </tr> <tr> <td> <p> <code class="literal"> redo_log_capacity_resized </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_capacity_resized"> <code class="literal"> Innodb_redo_log_capacity_resized </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Redo log capacity in bytes for all redo log files, after the last completed capacity resize operation </p> </td> </tr> <tr> <td> <p> <code class="literal"> log_waits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_log_waits"> <code class="literal"> Innodb_log_waits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of log waits due to small log buffer </p> </td> </tr> <tr> <td> <p> <code class="literal"> log_write_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_log_write_requests"> <code class="literal"> Innodb_log_write_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of log write requests </p> </td> </tr> <tr> <td> <p> <code class="literal"> log_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_log_writes"> <code class="literal"> Innodb_log_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of physical writes to the InnoDB redo log file </p> </td> </tr> <tr> <td> <p> <code class="literal"> os_log_fsyncs </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_fsyncs"> <code class="literal"> Innodb_os_log_fsyncs </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of fsync log writes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> os_log_pending_fsyncs </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_fsyncs"> <code class="literal"> Innodb_os_log_pending_fsyncs </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of pending fsync writes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> os_log_pending_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_writes"> <code class="literal"> Innodb_os_log_pending_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of pending log file writes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> os_log_written </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_written"> <code class="literal"> Innodb_os_log_written </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Bytes of log written. </p> </td> </tr> <tr> <td> <p> <code class="literal"> page_size </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_page_size"> <code class="literal"> Innodb_page_size </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> InnoDB page size in bytes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_created </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_created"> <code class="literal"> Innodb_pages_created </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages created </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_read </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_read"> <code class="literal"> Innodb_pages_read </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages read. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_written </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_written"> <code class="literal"> Innodb_pages_written </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages written. </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_current_waits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_current_waits"> <code class="literal"> Innodb_row_lock_current_waits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of row locks currently being waited for. </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_time </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time"> <code class="literal"> Innodb_row_lock_time </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Time spent in acquiring row locks, in milliseconds </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_time_avg </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_avg"> <code class="literal"> Innodb_row_lock_time_avg </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The average time to acquire a row lock, in milliseconds </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_time_max </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_max"> <code class="literal"> Innodb_row_lock_time_max </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The maximum time to acquire a row lock, in milliseconds. </p> </td> </tr> <tr> <td> <p> <code class="literal"> row_lock_waits </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_waits"> <code class="literal"> Innodb_row_lock_waits </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of times a row lock had to be waited for. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rows_deleted </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_deleted"> <code class="literal"> Innodb_rows_deleted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of rows inserted into InnoDB tables. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rows_read </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_read"> <code class="literal"> Innodb_rows_read </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of rows read from InnoDB tables </p> </td> </tr> <tr> <td> <p> <code class="literal"> rows_updated </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_updated"> <code class="literal"> Innodb_rows_updated </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of rows updated in InnoDB tables. </p> </td> </tr> <tr> <td> <p> <code class="literal"> system_rows_deleted </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_deleted"> <code class="literal"> Innodb_system_rows_deleted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of rows deleted from InnoDB tables belonging to system-created schemas. </p> </td> </tr> <tr> <td> <p> <code class="literal"> system_rows_inserted </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_inserted"> <code class="literal"> Innodb_system_rows_inserted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of rows inserted into InnoDB tables belonging to system-created schemas </p> </td> </tr> <tr> <td> <p> <code class="literal"> system_rows_read </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_read"> <code class="literal"> Innodb_system_rows_read </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of rows read from InnoDB tables belonging to system-created schemas. </p> </td> </tr> <tr> <td> <p> <code class="literal"> system_rows_updated </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_updated"> <code class="literal"> Innodb_system_rows_updated </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of rows updated in InnoDB tables belonging to system-created schemas. </p> </td> </tr> <tr> <td> <p> <code class="literal"> num_open_files </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_num_open_files"> <code class="literal"> Innodb_num_open_files </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of files currently open. </p> </td> </tr> <tr> <td> <p> <code class="literal"> truncated_status_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_truncated_status_writes"> <code class="literal"> Innodb_truncated_status_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of times output from the <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> statement has been truncated. </p> </td> </tr> <tr> <td> <p> <code class="literal"> undo_tablespaces_total </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_total"> <code class="literal"> Innodb_undo_tablespaces_total </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Total number of undo tablespaces. </p> </td> </tr> <tr> <td> <p> <code class="literal"> undo_tablespaces_explicit </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_explicit"> <code class="literal"> Innodb_undo_tablespaces_explicit </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of user-created undo tablespaces. </p> </td> </tr> <tr> <td> <p> <code class="literal"> undo_tablespaces_active </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_active"> <code class="literal"> Innodb_undo_tablespaces_active </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of active undo tablespaces, including implicit and explicit tablespaces </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 210.141px;"> Name </th> <th style="width: 267.016px;"> Source Variable </th> <th style="width: 95.0625px;"> OTEL Type </th> <th style="width: 165.781px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-inno-bufferpool"> </a> mysql.inno.buffer_pool Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057146720"> </a> <p class="title"> <b> Table 35.10 mysql.inno.buffer_pool Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> pages_data </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_data"> <code class="literal"> Innodb_buffer_pool_pages_data </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer pages containing data. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_data </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_data"> <code class="literal"> Innodb_buffer_pool_bytes_data </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer bytes containing data. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_dirty </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_dirty"> <code class="literal"> Innodb_buffer_pool_pages_dirty </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer pages currently dirty. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_dirty </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_dirty"> <code class="literal"> Innodb_buffer_pool_bytes_dirty </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer bytes currently dirty </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_flushed </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_flushed"> <code class="literal"> Innodb_buffer_pool_pages_flushed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of requests to flush pages from the InnoDB buffer pool. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_free </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_free"> <code class="literal"> Innodb_buffer_pool_pages_free </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer pages currently free. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_misc </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_misc"> <code class="literal"> Innodb_buffer_pool_pages_misc </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Buffer pages for misc use such as row locks or the adaptive hash index. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pages_total </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_total"> <code class="literal"> Innodb_buffer_pool_pages_total </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Total buffer pool size in pages. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_ahead_rnd </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_rnd"> <code class="literal"> Innodb_buffer_pool_read_ahead_rnd </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of 'random' read-aheads initiated by InnoDB. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_ahead </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead"> <code class="literal"> Innodb_buffer_pool_read_ahead </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of pages read as read ahead. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_ahead_evicted </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_evicted"> <code class="literal"> Innodb_buffer_pool_read_ahead_evicted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Read-ahead pages evicted without being accessed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_requests"> <code class="literal"> Innodb_buffer_pool_read_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of logical read requests. </p> </td> </tr> <tr> <td> <p> <code class="literal"> reads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_reads"> <code class="literal"> Innodb_buffer_pool_reads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of reads directly from disk. </p> </td> </tr> <tr> <td> <p> <code class="literal"> wait_free </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_wait_free"> <code class="literal"> Innodb_buffer_pool_wait_free </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of times waited for free buffer. </p> </td> </tr> <tr> <td> <p> <code class="literal"> write_requests </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_write_requests"> <code class="literal"> Innodb_buffer_pool_write_requests </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of write requests. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 153.266px;"> Name </th> <th style="width: 307.641px;"> Source Variable </th> <th style="width: 99.75px;"> OTEL Type </th> <th style="width: 177.344px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-inno-data"> </a> mysql.inno.data Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045057030256"> </a> <p class="title"> <b> Table 35.11 mysql.inno.data Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> fsyncs </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_fsyncs"> <code class="literal"> Innodb_data_fsyncs </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of <code class="literal"> fsync() </code> calls. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pending_fsyncs </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_fsyncs"> <code class="literal"> Innodb_data_pending_fsyncs </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> Number of pending fsync operations. </p> </td> </tr> <tr> <td> <p> <code class="literal"> pending_reads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_reads"> <code class="literal"> Innodb_data_pending_reads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The current number of pending reads </p> </td> </tr> <tr> <td> <p> <code class="literal"> pending_writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_writes"> <code class="literal"> Innodb_data_pending_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The current number of pending writes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> read </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_read"> <code class="literal"> Innodb_data_read </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Amount of data read in bytes. </p> </td> </tr> <tr> <td> <p> <code class="literal"> reads </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_reads"> <code class="literal"> Innodb_data_reads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of reads initiated. </p> </td> </tr> <tr> <td> <p> <code class="literal"> writes </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_writes"> <code class="literal"> Innodb_data_writes </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of writes initiated. </p> </td> </tr> <tr> <td> <p> <code class="literal"> written </code> </p> </td> <td> <p> <a class="link" href="server-status-variables.html#statvar_Innodb_data_written"> <code class="literal"> Innodb_data_written </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Amount of data written in bytes. </p> </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-x"> </a> mysql.x Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045056962976"> </a> <p class="title"> <b> Table 35.12 mysql.x Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> aborted_clients </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_aborted_clients"> <code class="literal"> Mysqlx_aborted_clients </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of clients that were disconnected because of an input or output error. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_received </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received"> <code class="literal"> Mysqlx_bytes_received </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The total number of bytes received through the network, measured before decompression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_received_compressed_payload </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_compressed_payload"> <code class="literal"> Mysqlx_bytes_received_compressed_payload </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes received as compressed message payloads, measured before decompression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_received_uncompressed_frame </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_uncompressed_frame"> <code class="literal"> Mysqlx_bytes_received_uncompressed_frame </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes received as compressed message payloads, measured after decompression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent"> <code class="literal"> Mysqlx_bytes_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The total number of bytes sent through the network. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_sent_compressed_payload </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_compressed_payload"> <code class="literal"> Mysqlx_bytes_sent_compressed_payload </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes sent as compressed message payloads, measured after compression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> bytes_sent_uncompressed_frame </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_uncompressed_frame"> <code class="literal"> Mysqlx_bytes_sent_uncompressed_frame </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of bytes sent as compressed message payloads, measured before compression. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connection_accept_errors </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_accept_errors"> <code class="literal"> Mysqlx_connection_accept_errors </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have caused accept errors. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connection_errors </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_errors"> <code class="literal"> Mysqlx_connection_errors </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have caused errors. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connections_accepted </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_accepted"> <code class="literal"> Mysqlx_connections_accepted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have been accepted. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connections_closed </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_closed"> <code class="literal"> Mysqlx_connections_closed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have been closed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> connections_rejected </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_rejected"> <code class="literal"> Mysqlx_connections_rejected </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of connections which have been rejected. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_create_view </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_create_view"> <code class="literal"> Mysqlx_crud_create_view </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of create view requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_delete </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_delete"> <code class="literal"> Mysqlx_crud_delete </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of delete requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_drop_view </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_drop_view"> <code class="literal"> Mysqlx_crud_drop_view </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of drop view requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_find </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_find"> <code class="literal"> Mysqlx_crud_find </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of find requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_insert </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_insert"> <code class="literal"> Mysqlx_crud_insert </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of insert requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_modify_view </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_modify_view"> <code class="literal"> Mysqlx_crud_modify_view </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of modify view requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> crud_update </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_update"> <code class="literal"> Mysqlx_crud_update </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of update requests received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cursor_close </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_close"> <code class="literal"> Mysqlx_cursor_close </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of cursor-close messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cursor_fetch </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_fetch"> <code class="literal"> Mysqlx_cursor_fetch </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of cursor-fetch messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> cursor_open </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_open"> <code class="literal"> Mysqlx_cursor_open </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of cursor-open messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_sent"> <code class="literal"> Mysqlx_errors_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors sent to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> errors_unknown_message_type </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_unknown_message_type"> <code class="literal"> Mysqlx_errors_unknown_message_type </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of unknown message types that have been received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> expect_close </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_close"> <code class="literal"> Mysqlx_expect_close </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of expectation blocks closed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> expect_open </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_open"> <code class="literal"> Mysqlx_expect_open </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of expectation blocks opened. </p> </td> </tr> <tr> <td> <p> <code class="literal"> init_error </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_init_error"> <code class="literal"> Mysqlx_init_error </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of errors during initialisation. </p> </td> </tr> <tr> <td> <p> <code class="literal"> messages_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_messages_sent"> <code class="literal"> Mysqlx_messages_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The total number of messages of all types sent to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> notice_global_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_global_sent"> <code class="literal"> Mysqlx_notice_global_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of global notifications sent to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> notice_other_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_other_sent"> <code class="literal"> Mysqlx_notice_other_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of other types of notices sent back to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> notice_warning_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_warning_sent"> <code class="literal"> Mysqlx_notice_warning_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of warning notices sent back to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> notified_by_group_replication </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notified_by_group_replication"> <code class="literal"> Mysqlx_notified_by_group_replication </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> Number of Group Replication notifications sent to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prep_deallocate </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_deallocate"> <code class="literal"> Mysqlx_prep_deallocate </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of prepared-statement-deallocate messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prep_execute </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_execute"> <code class="literal"> Mysqlx_prep_execute </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of prepared-statement-execute messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> prep_prepare </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_prepare"> <code class="literal"> Mysqlx_prep_prepare </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of prepared-statement messages received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> rows_sent </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_rows_sent"> <code class="literal"> Mysqlx_rows_sent </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of rows sent back to clients. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions"> <code class="literal"> Mysqlx_sessions </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sessions that have been opened. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_accepted </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_accepted"> <code class="literal"> Mysqlx_sessions_accepted </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of session attempts which have been accepted. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_closed </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_closed"> <code class="literal"> Mysqlx_sessions_closed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sessions that have been closed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_fatal_error </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_fatal_error"> <code class="literal"> Mysqlx_sessions_fatal_error </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sessions that have closed with a fatal error. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_killed </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_killed"> <code class="literal"> Mysqlx_sessions_killed </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of sessions which have been killed. </p> </td> </tr> <tr> <td> <p> <code class="literal"> sessions_rejected </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_rejected"> <code class="literal"> Mysqlx_sessions_rejected </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of session attempts which have been rejected. </p> </td> </tr> <tr> <td> <p> <code class="literal"> ssl_accepts </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_accepts"> <code class="literal"> Mysqlx_ssl_accepts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of accepted SSL connections. </p> </td> </tr> <tr> <td> <p> <code class="literal"> ssl_finished_accepts </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_finished_accepts"> <code class="literal"> Mysqlx_ssl_finished_accepts </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of successful SSL connections to the server. </p> </td> </tr> <tr> <td> <p> <code class="literal"> worker_threads </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads"> <code class="literal"> Mysqlx_worker_threads </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC GAUGE COUNTER </code> </p> </td> <td> <p> The number of worker threads available. </p> </td> </tr> <tr> <td> <p> <code class="literal"> worker_threads_active </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads_active"> <code class="literal"> Mysqlx_worker_threads_active </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of worker threads currently used. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 780px;"> <thead> <tr> <th style="width: 275.141px;"> Name </th> <th style="width: 332.016px;"> Source Variable </th> <th style="width: 63.875px;"> OTEL Type </th> <th style="width: 107.703px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="telemetry-metrics-meter-metrics-mysql-x-stmt"> </a> mysql.x.stmt Metrics </h4> </div> </div> </div> <p> </p> <div class="table"> <a name="idm46045056626752"> </a> <p class="title"> <b> Table 35.13 mysql.x.stmt Metrics </b> </p> <div class="table-contents"> <table frame="void"> <colgroup> <col width="20%"/> <col width="20%"/> <col width="20%"/> <col width="40%"/> </colgroup> <thead> <tr> <th> Name </th> <th> Source Variable </th> <th> OTEL Type </th> <th> Description </th> </tr> </thead> <tbody> <tr> <td> <p> <code class="literal"> create_collection </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection"> <code class="literal"> Mysqlx_stmt_create_collection </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of create collection statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> create_collection_index </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection_index"> <code class="literal"> Mysqlx_stmt_create_collection_index </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of create collection index statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> disable_notices </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_disable_notices"> <code class="literal"> Mysqlx_stmt_disable_notices </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of disable notice statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> drop_collection </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection"> <code class="literal"> Mysqlx_stmt_drop_collection </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of drop collection statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> drop_collection_index </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection_index"> <code class="literal"> Mysqlx_stmt_drop_collection_index </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of drop collection index statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> enable_notices </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_enable_notices"> <code class="literal"> Mysqlx_stmt_enable_notices </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of enable notice statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> ensure_collection </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ensure_collection"> <code class="literal"> Mysqlx_stmt_ensure_collection </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of ensure collection statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> execute_mysqlx </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_mysqlx"> <code class="literal"> Mysqlx_stmt_execute_mysqlx </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of StmtExecute messages received with namespace set to mysqlx. </p> </td> </tr> <tr> <td> <p> <code class="literal"> execute_sql </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_sql"> <code class="literal"> Mysqlx_stmt_execute_sql </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of StmtExecute requests received for the SQL namespace. </p> </td> </tr> <tr> <td> <p> <code class="literal"> get_collection_options </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_get_collection_options"> <code class="literal"> Mysqlx_stmt_get_collection_options </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of get collection object statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> kill_client </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_kill_client"> <code class="literal"> Mysqlx_stmt_kill_client </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of kill client statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> list_clients </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_clients"> <code class="literal"> Mysqlx_stmt_list_clients </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of list client statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> list_notices </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_notices"> <code class="literal"> Mysqlx_stmt_list_notices </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of list notice statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> list_objects </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_objects"> <code class="literal"> Mysqlx_stmt_list_objects </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of list object statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> modify_collection_options </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_modify_collection_options"> <code class="literal"> Mysqlx_stmt_modify_collection_options </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of modify collection options statements received. </p> </td> </tr> <tr> <td> <p> <code class="literal"> ping </code> </p> </td> <td> <p> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ping"> <code class="literal"> Mysqlx_stmt_ping </code> </a> </p> </td> <td> <p> <code class="literal"> ASYNC COUNTER </code> </p> </td> <td> <p> The number of ping statements received. </p> </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th style="width: 210.141px;"> Name </th> <th style="width: 307.641px;"> Source Variable </th> <th style="width: 83.3281px;"> OTEL Type </th> <th style="width: 136.891px;"> Description </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/group-replication-message-compression.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="group-replication-message-compression"> </a> 20.7.4 Message Compression </h3> </div> </div> </div> <a class="indexterm" name="idm46045132157984"> </a> <p> For messages sent between online group members, Group Replication enables message compression by default. Whether a specific message is compressed depends on the threshold that you configure using the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> system variable. Messages that have a payload larger than the specified number of bytes are compressed. </p> <p> The default compression threshold is 1000000 bytes. You could use the following statements to increase the compression threshold to 2MB, for example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa7024708"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">STOP</span> <span class="token keyword">GROUP_REPLICATION</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> group_replication_compression_threshold <span class="token operator">=</span> <span class="token number">2097152</span><span class="token punctuation">;</span> <span class="token keyword">START</span> <span class="token keyword">GROUP_REPLICATION</span><span class="token punctuation">;</span></code></pre> </div> <p> If you set <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> to zero, message compression is disabled. </p> <p> Group Replication uses the LZ4 compression algorithm to compress messages sent in the group. Note that the maximum supported input size for the LZ4 compression algorithm is 2113929216 bytes. This limit is lower than the maximum possible value for the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> system variable, which is matched to the maximum message size accepted by XCom. The LZ4 maximum input size is therefore a practical limit for message compression, and transactions above this size cannot be committed when message compression is enabled. With the LZ4 compression algorithm, do not set a value greater than 2113929216 bytes for <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> . </p> <p> The value of <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> is not required by Group Replication to be the same on all group members. However, it is advisable to set the same value on all group members in order to avoid unnecessary rollback of transactions, failure of message delivery, or failure of message recovery. </p> <p> You can also configure compression for messages sent for distributed recovery by the method of state transfer from a donor's binary log. Compression for these messages, which are sent from a donor already in the group to a joining member, is controlled separately using the <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_compression_algorithms"> <code class="literal"> group_replication_recovery_compression_algorithms </code> </a> and <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_zstd_compression_level"> <code class="literal"> group_replication_recovery_zstd_compression_level </code> </a> system variables. For more information, see <a class="xref" href="connection-compression-control.html" title="6.2.8 Connection Compression Control"> Section 6.2.8, “Connection Compression Control” </a> . </p> <p> Binary log transaction compression, enabled by the <a class="link" href="replication-options-binary-log.html#sysvar_binlog_transaction_compression"> <code class="literal"> binlog_transaction_compression </code> </a> system variable, can also be used to save bandwidth. The transaction payloads remain compressed when they are transferred between group members. If you use binary log transaction compression in combination with Group Replication's message compression, message compression has less opportunity to act on the data, but can still compress headers and those events and transaction payloads that are uncompressed. For more information on binary log transaction compression, see <a class="xref" href="binary-log-transaction-compression.html" title="7.4.4.5 Binary Log Transaction Compression"> Section 7.4.4.5, “Binary Log Transaction Compression” </a> . </p> <p> Compression for messages sent in the group happens at the group communication engine level, before the data is handed over to the group communication thread, so it takes place within the context of the <code class="literal"> mysql </code> user session thread. If the message payload size exceeds the threshold set by <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> <code class="literal"> group_replication_compression_threshold </code> </a> , the transaction payload is compressed before being sent out to the group, and decompressed when it is received. Upon receiving a message, the member checks the message envelope to verify whether it is compressed or not. If needed, then the member decompresses the transaction, before delivering it to the upper layer. This process is shown in the following figure. </p> <div class="figure"> <a name="idm46045132135168"> </a> <p class="title"> <b> Figure 20.13 Compression Support </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="The MySQL Group Replication plugin architecture is shown as described in an earlier topic, with the five layers of the plugin positioned between the MySQL server and the replication group. Compression and decompression are handled by the Group Communication System API, which is the fourth layer of the Group Replication plugin. The group communication engine (the fifth layer of the plugin) and the group members use the compressed transactions with the smaller data size. The MySQL Server core and the three higher layers of the Group Replication plugin (the APIs, the capture, applier, and recovery components, and the replication protocol module) use the original transactions with the larger data size." src="images/gr-compress-decompress.png" style="width: 100%; max-width: 588px;"/> </div> </div> </div> <br class="figure-break"/> <p> When network bandwidth is a bottleneck, message compression can provide up to 30-40% throughput improvement at the group communication level. This is especially important within the context of large groups of servers under load. The TCP peer-to-peer nature of the interconnections between <span class="emphasis"> <em> N </em> </span> participants in the group makes the sender send the same amount of data <span class="emphasis"> <em> N </em> </span> times. Furthermore, binary logs are likely to exhibit a high compression ratio. This makes compression a compelling feature for Group Replication workloads that contain large transactions. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/group-replication-view-changes.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="group-replication-view-changes"> </a> 20.5.4.5 How Distributed Recovery Works </h4> </div> </div> </div> <a class="indexterm" name="idm46045132932672"> </a> <a class="indexterm" name="idm46045132931184"> </a> <p> When Group Replication's distributed recovery process is carrying out state transfer from the binary log, to synchronize the joining member with the donor up to a specific point in time, the joining member and donor make use of GTIDs (see <a class="xref" href="replication-gtids.html" title="19.1.3 Replication with Global Transaction Identifiers"> Section 19.1.3, “Replication with Global Transaction Identifiers” </a> ). However, GTIDs only provide a means to realize which transactions the joining member is missing. They do not help marking a specific point in time to which the server joining the group must catch up, nor do they convey certification information. This is the job of binary log view markers, which mark view changes in the binary log stream, and also contain additional metadata information, supplying the joining member with missing certification-related data. </p> <p> This topic explains the role of view changes and the view change identifier, and the steps to carry out state transfer from the binary log. </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-view-and-view-changes"> </a> View and View Changes </h5> </div> </div> </div> <p> A <span class="emphasis"> <em> view </em> </span> corresponds to a group of members participating actively in the current configuration, in other words at a specific point in time. They are functioning correctly and online in the group. </p> <p> A <span class="emphasis"> <em> view change </em> </span> occurs when a modification to the group configuration happens, such as a member joining or leaving. Any group membership change results in an independent view change communicated to all members at the same logical point in time. </p> <p> A <span class="emphasis"> <em> view identifier </em> </span> uniquely identifies a view. It is generated whenever a view change happens. </p> <p> At the group communication layer, view changes with their associated view identifiers mark boundaries between the data exchanged before and after a member joins. This concept is implemented through a binary log event: the "view change log event" (VCLE). The view identifier is recorded to demarcate transactions transmitted before and after changes happen in the group membership. </p> <p> The view identifier itself is built from two parts: a randomly generated part, and a monotonically increasing integer. The randomly generated part is generated when the group is created, and remains unchanged while there is at least one member in the group. The integer is incremented every time a view change happens. Using these two different parts enables the view identifier to identify incremental group changes caused by members joining or leaving, and also to identify the situation where all members leave the group in a full group shutdown, so no information remains of what view the group was in. Randomly generating part of the identifier when the group is started from the beginning ensures that the data markers in the binary log remain unique, and an identical identifier is not reused after a full group shutdown, as this would cause issues with distributed recovery in the future. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-begin-stable-group"> </a> Begin: Stable Group </h5> </div> </div> </div> <p> All servers are online and processing incoming transactions from the group. Some servers may be a little behind in terms of transactions replicated, but eventually they converge. The group acts as one distributed and replicated database. </p> <div class="figure"> <a name="idm46045132918672"> </a> <p class="title"> <b> Figure 20.8 Stable Group </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Servers S1, S2, and S3 are members of the group. The most recent item in all of their binary logs is transaction T20." src="images/gr-recovery-1.png" style="width: 100%; max-width: 653px;"/> </div> </div> </div> <br class="figure-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-view-change-member-joins"> </a> View Change: a Member Joins </h5> </div> </div> </div> <p> Whenever a new member joins the group and therefore a view change is performed, every online server queues a view change log event for execution. This is queued because before the view change, several transactions can be queued on the server to be applied and as such, these belong to the old view. Queuing the view change event after them guarantees a correct marking of when this happened. </p> <p> Meanwhile, the joining member selects a suitable donor from the list of online servers as stated by the membership service through the view abstraction. A member joins on view 4 and the online members write a view change event to the binary log. </p> <div class="figure"> <a name="idm46045132909072"> </a> <p class="title"> <b> Figure 20.9 A Member Joins </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Server S4 joins the group and looks for a donor. Servers S1, S2, and S3 each queue the view change entry VC4 for their binary logs. Meanwhile, server S1 is receiving new transaction T21." src="images/gr-recovery-2.png" style="width: 100%; max-width: 606px;"/> </div> </div> </div> <br class="figure-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-state-transfer-catching-up"> </a> State Transfer: Catching Up </h5> </div> </div> </div> <p> If group members and the joining member are set up with the clone plugin (see <a class="xref" href="group-replication-cloning.html" title="20.5.4.2 Cloning for Distributed Recovery"> Section 20.5.4.2, “Cloning for Distributed Recovery” </a> ), and the difference in transactions between the joining member and the group exceeds the threshold set for a remote cloning operation ( <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_clone_threshold"> <code class="literal"> group_replication_clone_threshold </code> </a> ), Group Replication begins distributed recovery with a remote cloning operation. A remote cloning operation is also carried out if required transactions are no longer present in any group member's binary log files. During a remote cloning operation, the existing data on the joining member is removed, and replaced with a copy of the donor's data. When the remote cloning operation is complete and the joining member has restarted, state transfer from a donor's binary log is carried out to get the transactions that the group applied while the remote cloning operation was in progress. If there is not a large transaction gap, or if the clone plugin is not installed, Group Replication proceeds directly to state transfer from a donor's binary log. </p> <p> For state transfer from a donor's binary log, a connection is established between the joining member and the donor and state transfer begins. This interaction with the donor continues until the server joining the group's applier thread processes the view change log event that corresponds to the view change triggered when the server joining the group came into the group. In other words, the server joining the group replicates from the donor, until it gets to the marker with the view identifier which matches the view marker it is already in. </p> <div class="figure"> <a name="idm46045132896352"> </a> <p class="title"> <b> Figure 20.10 State Transfer: Catching Up </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Server S4 has chosen server S2 as the donor. State transfer is executed from server S2 to server S4 until the view change entry VC4 is reached (view_id = VC4). Server S4 uses a temporary applier buffer for state transfer, and its binary log is currently empty." src="images/gr-recovery-3.png" style="width: 100%; max-width: 620px;"/> </div> </div> </div> <br class="figure-break"/> <p> As view identifiers are transmitted to all members in the group at the same logical time, the server joining the group knows at which view identifier it should stop replicating. This avoids complex GTID set calculations because the view identifier clearly marks which data belongs to each group view. </p> <p> While the server joining the group is replicating from the donor, it is also caching incoming transactions from the group. Eventually, it stops replicating from the donor and switches to applying those that are cached. </p> <div class="figure"> <a name="idm46045132887984"> </a> <p class="title"> <b> Figure 20.11 Queued Transactions </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="State transfer is complete. Server S4 has applied the transactions up to T20 and written them to its binary log. Server S4 has cached transaction T21, which arrived after the view change, in a temporary applier buffer while recovering." src="images/gr-recovery-4.png" style="width: 100%; max-width: 555px;"/> </div> </div> </div> <br class="figure-break"/> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="group-replication-finish-caught-up"> </a> Finish: Caught Up </h5> </div> </div> </div> <p> When the server joining the group recognizes a view change log event with the expected view identifier, the connection to the donor is terminated and it starts applying the cached transactions. Although it acts as a marker in the binary log, delimiting view changes, the view change log event also plays another role. It conveys the certification information as perceived by all servers when the server joining the group entered the group, in other words the last view change. Without it, the server joining the group would not have the necessary information to be able to certify (detect conflicts) subsequent transactions. </p> <p> The duration of the catch up is not deterministic, because it depends on the workload and the rate of incoming transactions to the group. This process is completely online and the server joining the group does not block any other server in the group while it is catching up. Therefore the number of transactions the server joining the group is behind when it moves to this stage can, for this reason, vary and thus increase or decrease according to the workload. </p> <p> When the server joining the group reaches zero queued transactions and its stored data is equal to the other members, its public state changes to online. </p> <div class="figure"> <a name="idm46045132877104"> </a> <p class="title"> <b> Figure 20.12 Instance Online </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Server S4 is now an online member of the group. It has applied cached transaction T21, so its binary log shows the same items as the binary logs of the other group members, and it no longer needs the temporary applier buffer. New incoming transaction T22 is now received and applied by all group members." src="images/gr-recovery-5.png" style="width: 100%; max-width: 652px;"/> </div> </div> </div> <br class="figure-break"/> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/gis-class-multicurve.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="gis-class-multicurve"> </a> 13.4.2.10 MultiCurve Class </h4> </div> </div> </div> <p> A <code class="literal"> MultiCurve </code> is a geometry collection composed of <code class="literal"> Curve </code> elements. <code class="literal"> MultiCurve </code> is a noninstantiable class. </p> <p> <span class="bold"> <strong> <code class="literal"> MultiCurve </code> Properties </strong> </span> </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A <code class="literal"> MultiCurve </code> is a one-dimensional geometry. </p> </li> <li class="listitem"> <p> A <code class="literal"> MultiCurve </code> is simple if and only if all of its elements are simple; the only intersections between any two elements occur at points that are on the boundaries of both elements. </p> </li> <li class="listitem"> <p> A <code class="literal"> MultiCurve </code> boundary is obtained by applying the <span class="quote"> “ <span class="quote"> mod 2 union rule </span> ” </span> (also known as the <span class="quote"> “ <span class="quote"> odd-even rule </span> ” </span> ): A point is in the boundary of a <code class="literal"> MultiCurve </code> if it is in the boundaries of an odd number of <code class="literal"> Curve </code> elements. </p> </li> <li class="listitem"> <p> A <code class="literal"> MultiCurve </code> is closed if all of its elements are closed. </p> </li> <li class="listitem"> <p> The boundary of a closed <code class="literal"> MultiCurve </code> is always empty. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/database-count-limit.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="database-count-limit"> </a> 10.4.5 Limits on Number of Databases and Tables </h3> </div> </div> </div> <a class="indexterm" name="idm46045226469792"> </a> <a class="indexterm" name="idm46045226468320"> </a> <a class="indexterm" name="idm46045226466816"> </a> <a class="indexterm" name="idm46045226465312"> </a> <p> MySQL has no limit on the number of databases. The underlying file system may have a limit on the number of directories. </p> <p> MySQL has no limit on the number of tables. The underlying file system may have a limit on the number of files that represent tables. Individual storage engines may impose engine-specific constraints. <code class="literal"> InnoDB </code> permits up to 4 billion tables. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-programs-ndb-drop-table.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysql-cluster-programs-ndb-drop-table"> </a> 25.5.11 ndb_drop_table — Drop an NDB Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045103509312"> </a> <p> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html" title="25.5.11 ndb_drop_table — Drop an NDB Table"> <span class="command"> <strong> ndb_drop_table </strong> </span> </a> drops the specified <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> table. (If you try to use this on a table created with a storage engine other than <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> , the attempt fails with the error <span class="errortext"> 723: No such table exists </span> .) This operation is extremely fast; in some cases, it can be an order of magnitude faster than using a MySQL <a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement"> <code class="literal"> DROP TABLE </code> </a> statement on an <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> table. </p> <h4> <a name="idm46045103501104"> </a> Usage </h4> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa5470933"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ndb_drop_table <span class="token property">-c</span> <em class="replaceable">connection_string</em> <em class="replaceable">tbl_name</em> <span class="token property">-d</span> <em class="replaceable">db_name</em></code></pre> </div> <p> Options that can be used with <a class="link" href="mysql-cluster-programs-ndb-drop-table.html" title="25.5.11 ndb_drop_table — Drop an NDB Table"> <span class="command"> <strong> ndb_drop_table </strong> </span> </a> are shown in the following table. Additional descriptions follow the table. </p> <p> </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_ndb_drop_table_character-sets-dir"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_character-sets-dir"> <code class="option"> --character-sets-dir </code> </a> </p> <a class="indexterm" name="idm46045103493280"> </a> <a class="indexterm" name="idm46045103491776"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for character-sets-dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --character-sets-dir=path </code> </td> </tr> </tbody> </table> </div> <p> Directory containing character sets. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_connect-retries"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_connect-retries"> <code class="option"> --connect-retries </code> </a> </p> <a class="indexterm" name="idm46045103481984"> </a> <a class="indexterm" name="idm46045103480496"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-retries"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-retries=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 12 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 12 </code> </td> </tr> </tbody> </table> </div> <p> Number of times to retry connection before giving up. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_connect-retry-delay"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_connect-retry-delay"> <code class="option"> --connect-retry-delay </code> </a> </p> <a class="indexterm" name="idm46045103461440"> </a> <a class="indexterm" name="idm46045103459936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-retry-delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-retry-delay=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 5 </code> </td> </tr> </tbody> </table> </div> <p> Number of seconds to wait between attempts to contact management server. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_connect-string"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_connect-string"> <code class="option"> --connect-string </code> </a> </p> <a class="indexterm" name="idm46045103440880"> </a> <a class="indexterm" name="idm46045103439392"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for connect-string"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --connect-string=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Same as <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_core-file"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_core-file"> <code class="option"> --core-file </code> </a> </p> <a class="indexterm" name="idm46045103423968"> </a> <a class="indexterm" name="idm46045103422480"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for core-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --core-file </code> </td> </tr> </tbody> </table> </div> <p> Write core file on error; used in debugging. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_database"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_database"> <code class="option"> --database </code> </a> , <code class="option"> -d </code> </p> <a class="indexterm" name="idm46045103412352"> </a> <a class="indexterm" name="idm46045103410864"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for database"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --database=name </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> TEST_DB </code> </td> </tr> </tbody> </table> </div> <p> Name of the database in which the table resides. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_defaults-extra-file"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_defaults-extra-file"> <code class="option"> --defaults-extra-file </code> </a> </p> <a class="indexterm" name="idm46045103396512"> </a> <a class="indexterm" name="idm46045103395008"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-extra-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-extra-file=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read given file after global files are read. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_defaults-file"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_defaults-file"> <code class="option"> --defaults-file </code> </a> </p> <a class="indexterm" name="idm46045103380720"> </a> <a class="indexterm" name="idm46045103379232"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-file=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read default options from given file only. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_defaults-group-suffix"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_defaults-group-suffix"> <code class="option"> --defaults-group-suffix </code> </a> </p> <a class="indexterm" name="idm46045103364880"> </a> <a class="indexterm" name="idm46045103363376"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-group-suffix"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-group-suffix=string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Also read groups with concat(group, suffix). </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_help"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_help"> <code class="option"> --help </code> </a> </p> <a class="indexterm" name="idm46045103349088"> </a> <a class="indexterm" name="idm46045103347600"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for help"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --help </code> </td> </tr> </tbody> </table> </div> <p> Display help text and exit. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_login-path"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_login-path"> <code class="option"> --login-path </code> </a> </p> <a class="indexterm" name="idm46045103337792"> </a> <a class="indexterm" name="idm46045103336304"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for login-path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --login-path=path </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Read given path from login file. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_no-login-paths"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_no-login-paths"> <code class="option"> --no-login-paths </code> </a> </p> <a class="indexterm" name="idm46045103322096"> </a> <a class="indexterm" name="idm46045103320608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-login-paths"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-login-paths </code> </td> </tr> </tbody> </table> </div> <p> Skips reading options from the login path file. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-connectstring"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> </p> <a class="indexterm" name="idm46045103311008"> </a> <a class="indexterm" name="idm46045103309552"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-connectstring"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-connectstring=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Set connection string for connecting to <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> . Syntax: <code class="literal"> [nodeid= <em class="replaceable"> <code> id </code> </em> ;][host=] <em class="replaceable"> <code> hostname </code> </em> [: <em class="replaceable"> <code> port </code> </em> ] </code> . Overrides entries in <code class="literal"> NDB_CONNECTSTRING </code> and <code class="filename"> my.cnf </code> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-mgm-tls"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-mgm-tls"> <code class="option"> --ndb-mgm-tls </code> </a> </p> <a class="indexterm" name="idm46045103290576"> </a> <a class="indexterm" name="idm46045103289088"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-mgm-tls"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-mgm-tls=level </code> </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> relaxed </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> relaxed </code> </p> <p class="valid-value"> <code class="literal"> strict </code> </p> </td> </tr> </tbody> </table> </div> <p> Sets the level of TLS support required to connect to the management server; one of <code class="literal"> relaxed </code> or <code class="literal"> strict </code> . <code class="literal"> relaxed </code> (the default) means that a TLS connection is attempted, but success is not required; <code class="literal"> strict </code> means that TLS is required to connect. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-mgmd-host"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-mgmd-host"> <code class="option"> --ndb-mgmd-host </code> </a> </p> <a class="indexterm" name="idm46045103268080"> </a> <a class="indexterm" name="idm46045103266592"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-mgmd-host"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-mgmd-host=connection_string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Same as <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-nodeid"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-nodeid"> <code class="option"> --ndb-nodeid </code> </a> </p> <a class="indexterm" name="idm46045103251280"> </a> <a class="indexterm" name="idm46045103249792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-nodeid"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-nodeid=# </code> </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <p> Set node ID for this node, overriding any ID set by <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-optimized-node-selection"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-optimized-node-selection"> <code class="option"> --ndb-optimized-node-selection </code> </a> </p> <a class="indexterm" name="idm46045103234480"> </a> <a class="indexterm" name="idm46045103232976"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-optimized-node-selection"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-optimized-node-selection </code> </td> </tr> </tbody> </table> </div> <p> Enable optimizations for selection of nodes for transactions. Enabled by default; use <code class="option"> --skip-ndb-optimized-node-selection </code> to disable. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_ndb-tls-search-path"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_ndb-tls-search-path"> <code class="option"> --ndb-tls-search-path </code> </a> </p> <a class="indexterm" name="idm46045103222544"> </a> <a class="indexterm" name="idm46045103221040"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for ndb-tls-search-path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --ndb-tls-search-path=list </code> </td> </tr> <tr> <th> Type </th> <td> Path name </td> </tr> <tr> <th> Default Value (Unix) </th> <td> <code class="literal"> $HOME/ndb-tls </code> </td> </tr> <tr> <th> Default Value (Windows) </th> <td> <code class="literal"> $HOMEDIR/ndb-tls </code> </td> </tr> </tbody> </table> </div> <p> Specify a list of directories to search for a CA file. On Unix platforms, the directory names are separated by colons ( <code class="literal"> : </code> ); on Windows systems, the semicolon character ( <code class="literal"> ; </code> ) is used as the separator. A directory reference may be relative or absolute; it may contain one or more environment variables, each denoted by a prefixed dollar sign ( <code class="literal"> $ </code> ), and expanded prior to use. </p> <p> Searching begins with the leftmost named directory and proceeds from left to right until a file is found. An empty string denotes an empty search path, which causes all searches to fail. A string consisting of a single dot ( <code class="literal"> . </code> ) indicates that the search path limited to the current working directory. </p> <p> If no search path is supplied, the compiled-in default value is used. This value depends on the platform used: On Windows, this is <code class="literal"> \ndb-tls </code> ; on other platforms (including Linux), it is <code class="literal"> $HOME/ndb-tls </code> . This can be overridden by compiling NDB Cluster using <a class="link" href="source-configuration-options.html#option_cmake_with_ndb_tls_search_path"> <code class="option"> -DWITH_NDB_TLS_SEARCH_PATH </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_no-defaults"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_no-defaults"> <code class="option"> --no-defaults </code> </a> </p> <a class="indexterm" name="idm46045103197280"> </a> <a class="indexterm" name="idm46045103195792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-defaults </code> </td> </tr> </tbody> </table> </div> <p> Do not read default options from any option file other than login file. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_print-defaults"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_print-defaults"> <code class="option"> --print-defaults </code> </a> </p> <a class="indexterm" name="idm46045103186032"> </a> <a class="indexterm" name="idm46045103184544"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for print-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --print-defaults </code> </td> </tr> </tbody> </table> </div> <p> Print program argument list and exit. </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_usage"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_usage"> <code class="option"> --usage </code> </a> </p> <a class="indexterm" name="idm46045103174832"> </a> <a class="indexterm" name="idm46045103173344"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for usage"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --usage </code> </td> </tr> </tbody> </table> </div> <p> Display help text and exit; same as <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_help"> <code class="option"> --help </code> </a> . </p> </li> <li class="listitem"> <p> <a name="option_ndb_drop_table_version"> </a> <a class="link" href="mysql-cluster-programs-ndb-drop-table.html#option_ndb_drop_table_version"> <code class="option"> --version </code> </a> </p> <a class="indexterm" name="idm46045103162592"> </a> <a class="indexterm" name="idm46045103161104"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --version </code> </td> </tr> </tbody> </table> </div> <p> Display version information and exit. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/system-schema.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="system-schema"> </a> 7.3 The mysql System Schema </h2> </div> </div> </div> <p> The <code class="literal"> mysql </code> schema is the system schema. It contains tables that store information required by the MySQL server as it runs. A broad categorization is that the <code class="literal"> mysql </code> schema contains data dictionary tables that store database object metadata, and system tables used for other operational purposes. The following discussion further subdivides the set of system tables into smaller categories. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-data-dictionary-tables" title="Data Dictionary Tables"> Data Dictionary Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-grant-tables" title="Grant System Tables"> Grant System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-object-tables" title="Object Information System Tables"> Object Information System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-log-tables" title="Log System Tables"> Log System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-help-tables" title="Server-Side Help System Tables"> Server-Side Help System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-time-zone-tables" title="Time Zone System Tables"> Time Zone System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-replication-tables" title="Replication System Tables"> Replication System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-optimizer-tables" title="Optimizer System Tables"> Optimizer System Tables </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="system-schema.html#system-schema-miscellaneous-tables" title="Miscellaneous System Tables"> Miscellaneous System Tables </a> </p> </li> </ul> </div> <p> The remainder of this section enumerates the tables in each category, with cross references for additional information. Data dictionary tables and system tables use the <code class="literal"> InnoDB </code> storage engine unless otherwise indicated. </p> <p> <code class="literal"> mysql </code> system tables and data dictionary tables reside in a single <code class="literal"> InnoDB </code> tablespace file named <code class="filename"> mysql.ibd </code> in the MySQL data directory. Previously, these tables were created in individual tablespace files in the <code class="literal"> mysql </code> database directory. </p> <p> Data-at-rest encryption can be enabled for the <code class="literal"> mysql </code> system schema tablespace. For more information, see <a class="xref" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> Section 17.13, “InnoDB Data-at-Rest Encryption” </a> . </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-data-dictionary-tables"> </a> Data Dictionary Tables </h3> </div> </div> </div> <p> These tables comprise the data dictionary, which contains metadata about database objects. For additional information, see <a class="xref" href="data-dictionary.html" title="Chapter 16 MySQL Data Dictionary"> Chapter 16, <i> MySQL Data Dictionary </i> </a> . </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> catalogs </code> : Catalog information. </p> <a class="indexterm" name="idm46045259885920"> </a> <a class="indexterm" name="idm46045259884432"> </a> </li> <li class="listitem"> <p> <code class="literal"> character_sets </code> : Information about available character sets. </p> <a class="indexterm" name="idm46045259881408"> </a> <a class="indexterm" name="idm46045259879920"> </a> </li> <li class="listitem"> <p> <code class="literal"> check_constraints </code> : Information about <code class="literal"> CHECK </code> constraints defined on tables. See <a class="xref" href="create-table-check-constraints.html" title="15.1.20.6 CHECK Constraints"> Section 15.1.20.6, “CHECK Constraints” </a> . </p> <a class="indexterm" name="idm46045259875312"> </a> <a class="indexterm" name="idm46045259873824"> </a> </li> <li class="listitem"> <p> <code class="literal"> collations </code> : Information about collations for each character set. </p> <a class="indexterm" name="idm46045259870784"> </a> <a class="indexterm" name="idm46045259869296"> </a> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259867168"> </a> <a class="indexterm" name="idm46045259865680"> </a> <code class="literal"> column_statistics </code> : Histogram statistics for column values. See <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> column_type_elements </code> : Information about types used by columns. </p> <a class="indexterm" name="idm46045259861136"> </a> <a class="indexterm" name="idm46045259859632"> </a> </li> <li class="listitem"> <p> <code class="literal"> columns </code> : Information about columns in tables. </p> <a class="indexterm" name="idm46045259856592"> </a> <a class="indexterm" name="idm46045259855104"> </a> </li> <li class="listitem"> <p> <code class="literal"> dd_properties </code> : A table that identifies data dictionary properties, such as its version. The server uses this to determine whether the data dictionary must be upgraded to a newer version. </p> <a class="indexterm" name="idm46045259851920"> </a> <a class="indexterm" name="idm46045259850432"> </a> </li> <li class="listitem"> <p> <code class="literal"> events </code> : Information about Event Scheduler events. See <a class="xref" href="event-scheduler.html" title="27.4 Using the Event Scheduler"> Section 27.4, “Using the Event Scheduler” </a> . If the server is started with the <a class="link" href="server-options.html#option_mysqld_skip-grant-tables"> <code class="option"> --skip-grant-tables </code> </a> option, the event scheduler is disabled and events registered in the table do not run. See <a class="xref" href="events-configuration.html" title="27.4.2 Event Scheduler Configuration"> Section 27.4.2, “Event Scheduler Configuration” </a> . </p> <a class="indexterm" name="idm46045259844736"> </a> <a class="indexterm" name="idm46045259843248"> </a> </li> <li class="listitem"> <p> <code class="literal"> foreign_keys </code> , <code class="literal"> foreign_key_column_usage </code> : Information about foreign keys. </p> <a class="indexterm" name="idm46045259839488"> </a> <a class="indexterm" name="idm46045259838000"> </a> <a class="indexterm" name="idm46045259836512"> </a> <a class="indexterm" name="idm46045259835008"> </a> </li> <li class="listitem"> <p> <code class="literal"> index_column_usage </code> : Information about columns used by indexes. </p> <a class="indexterm" name="idm46045259831968"> </a> <a class="indexterm" name="idm46045259830464"> </a> </li> <li class="listitem"> <p> <code class="literal"> index_partitions </code> : Information about partitions used by indexes. </p> <a class="indexterm" name="idm46045259827424"> </a> <a class="indexterm" name="idm46045259825936"> </a> </li> <li class="listitem"> <p> <code class="literal"> index_stats </code> : Used to store dynamic index statistics generated when <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> is executed. </p> <a class="indexterm" name="idm46045259821648"> </a> <a class="indexterm" name="idm46045259820160"> </a> </li> <li class="listitem"> <p> <code class="literal"> indexes </code> : Information about table indexes. </p> <a class="indexterm" name="idm46045259817152"> </a> <a class="indexterm" name="idm46045259815664"> </a> </li> <li class="listitem"> <p> <code class="literal"> innodb_ddl_log </code> : Stores DDL logs for crash-safe DDL operations. </p> <a class="indexterm" name="idm46045259812640"> </a> <a class="indexterm" name="idm46045259811152"> </a> </li> <li class="listitem"> <p> <code class="literal"> parameter_type_elements </code> : Information about stored procedure and function parameters, and about return values for stored functions. </p> <a class="indexterm" name="idm46045259808048"> </a> <a class="indexterm" name="idm46045259806544"> </a> </li> <li class="listitem"> <p> <code class="literal"> parameters </code> : Information about stored procedures and functions. See <a class="xref" href="stored-routines.html" title="27.2 Using Stored Routines"> Section 27.2, “Using Stored Routines” </a> . </p> <a class="indexterm" name="idm46045259802640"> </a> <a class="indexterm" name="idm46045259801152"> </a> </li> <li class="listitem"> <p> <code class="literal"> resource_groups </code> : Information about resource groups. See <a class="xref" href="resource-groups.html" title="7.1.16 Resource Groups"> Section 7.1.16, “Resource Groups” </a> . </p> <a class="indexterm" name="idm46045259797472"> </a> <a class="indexterm" name="idm46045259795984"> </a> </li> <li class="listitem"> <p> <code class="literal"> routines </code> : Information about stored procedures and functions. See <a class="xref" href="stored-routines.html" title="27.2 Using Stored Routines"> Section 27.2, “Using Stored Routines” </a> . </p> <a class="indexterm" name="idm46045259792272"> </a> <a class="indexterm" name="idm46045259790784"> </a> </li> <li class="listitem"> <p> <code class="literal"> schemata </code> : Information about schemata. In MySQL, a schema is a database, so this table provides information about databases. </p> <a class="indexterm" name="idm46045259787680"> </a> <a class="indexterm" name="idm46045259786192"> </a> </li> <li class="listitem"> <p> <code class="literal"> st_spatial_reference_systems </code> : Information about available spatial reference systems for spatial data. </p> <a class="indexterm" name="idm46045259783120"> </a> <a class="indexterm" name="idm46045259781616"> </a> </li> <li class="listitem"> <p> <code class="literal"> table_partition_values </code> : Information about values used by table partitions. </p> <a class="indexterm" name="idm46045259778560"> </a> <a class="indexterm" name="idm46045259777056"> </a> </li> <li class="listitem"> <p> <code class="literal"> table_partitions </code> : Information about partitions used by tables. </p> <a class="indexterm" name="idm46045259774016"> </a> <a class="indexterm" name="idm46045259772528"> </a> </li> <li class="listitem"> <p> <code class="literal"> table_stats </code> : Information about dynamic table statistics generated when <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> is executed. </p> <a class="indexterm" name="idm46045259768224"> </a> <a class="indexterm" name="idm46045259766736"> </a> </li> <li class="listitem"> <p> <code class="literal"> tables </code> : Information about tables in databases. </p> <a class="indexterm" name="idm46045259763712"> </a> <a class="indexterm" name="idm46045259762224"> </a> </li> <li class="listitem"> <p> <code class="literal"> tablespace_files </code> : Information about files used by tablespaces. </p> <a class="indexterm" name="idm46045259759200"> </a> <a class="indexterm" name="idm46045259757712"> </a> </li> <li class="listitem"> <p> <code class="literal"> tablespaces </code> : Information about active tablespaces. </p> <a class="indexterm" name="idm46045259754688"> </a> <a class="indexterm" name="idm46045259753200"> </a> </li> <li class="listitem"> <p> <code class="literal"> triggers </code> : Information about triggers. </p> <a class="indexterm" name="idm46045259750192"> </a> <a class="indexterm" name="idm46045259748704"> </a> </li> <li class="listitem"> <p> <code class="literal"> view_routine_usage </code> : Information about dependencies between views and stored functions used by them. </p> <a class="indexterm" name="idm46045259745632"> </a> <a class="indexterm" name="idm46045259744128"> </a> </li> <li class="listitem"> <p> <code class="literal"> view_table_usage </code> : Used to track dependencies between views and their underlying tables. </p> <a class="indexterm" name="idm46045259741056"> </a> <a class="indexterm" name="idm46045259739568"> </a> </li> </ul> </div> <p> Data dictionary tables are invisible. They cannot be read with <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> , do not appear in the output of <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> , are not listed in the <code class="literal"> INFORMATION_SCHEMA.TABLES </code> table, and so forth. However, in most cases there are corresponding <code class="literal"> INFORMATION_SCHEMA </code> tables that can be queried. Conceptually, the <code class="literal"> INFORMATION_SCHEMA </code> provides a view through which MySQL exposes data dictionary metadata. For example, you cannot select from the <code class="literal"> mysql.schemata </code> table directly: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa17852283"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> mysql<span class="token punctuation">.</span>schemata<span class="token punctuation">;</span> <span class="token output">ERROR 3554 (HY000)<span class="token punctuation">:</span> Access to data dictionary table 'mysql.schemata' is rejected.</span></code></pre> </div> <p> Instead, select that information from the corresponding <code class="literal"> INFORMATION_SCHEMA </code> table: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa53997455"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>SCHEMATA\G <span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> CATALOG_NAME<span class="token punctuation">:</span> def SCHEMA_NAME<span class="token punctuation">:</span> mysql DEFAULT_CHARACTER_SET_NAME<span class="token punctuation">:</span> utf8mb4 DEFAULT_COLLATION_NAME<span class="token punctuation">:</span> utf8mb4_0900_ai_ci SQL_PATH<span class="token punctuation">:</span> NULL DEFAULT_ENCRYPTION<span class="token punctuation">:</span> NO <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 2. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> CATALOG_NAME<span class="token punctuation">:</span> def SCHEMA_NAME<span class="token punctuation">:</span> information_schema DEFAULT_CHARACTER_SET_NAME<span class="token punctuation">:</span> utf8mb3 DEFAULT_COLLATION_NAME<span class="token punctuation">:</span> utf8mb3_general_ci SQL_PATH<span class="token punctuation">:</span> NULL DEFAULT_ENCRYPTION<span class="token punctuation">:</span> NO <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 3. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> CATALOG_NAME<span class="token punctuation">:</span> def SCHEMA_NAME<span class="token punctuation">:</span> performance_schema DEFAULT_CHARACTER_SET_NAME<span class="token punctuation">:</span> utf8mb4 DEFAULT_COLLATION_NAME<span class="token punctuation">:</span> utf8mb4_0900_ai_ci SQL_PATH<span class="token punctuation">:</span> NULL DEFAULT_ENCRYPTION<span class="token punctuation">:</span> NO ...</span></code></pre> </div> <p> There is no Information Schema table that corresponds exactly to <code class="literal"> mysql.indexes </code> , but <a class="link" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table"> <code class="literal"> INFORMATION_SCHEMA.STATISTICS </code> </a> contains much of the same information. </p> <p> As of yet, there are no <code class="literal"> INFORMATION_SCHEMA </code> tables that correspond exactly to <code class="literal"> mysql.foreign_keys </code> , <code class="literal"> mysql.foreign_key_column_usage </code> . The standard SQL way to obtain foreign key information is by using the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-referential-constraints-table.html" title="28.3.25 The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table"> <code class="literal"> REFERENTIAL_CONSTRAINTS </code> </a> and <a class="link" href="information-schema-key-column-usage-table.html" title="28.3.16 The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table"> <code class="literal"> KEY_COLUMN_USAGE </code> </a> tables; these tables are now implemented as views on the <code class="literal"> foreign_keys </code> , <code class="literal"> foreign_key_column_usage </code> , and other data dictionary tables. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-grant-tables"> </a> Grant System Tables </h3> </div> </div> </div> <p> These system tables contain grant information about user accounts and the privileges held by them. For additional information about the structure, contents, and purpose of the these tables, see <a class="xref" href="grant-tables.html" title="8.2.3 Grant Tables"> Section 8.2.3, “Grant Tables” </a> . </p> <p> The MySQL 8.4 grant tables are <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> (transactional) tables. Account-management statements are transactional and either succeed for all named users or roll back and have no effect if any error occurs. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> user </code> : User accounts, global privileges, and other nonprivilege columns. </p> <a class="indexterm" name="idm46045259710416"> </a> <a class="indexterm" name="idm46045259708928"> </a> <a class="indexterm" name="idm46045259707440"> </a> </li> <li class="listitem"> <p> <code class="literal"> global_grants </code> : Assignments of dynamic global privileges to users; see <a class="xref" href="privileges-provided.html#static-dynamic-privileges" title="Static Versus Dynamic Privileges"> Static Versus Dynamic Privileges </a> . </p> <a class="indexterm" name="idm46045259703472"> </a> <a class="indexterm" name="idm46045259701984"> </a> <a class="indexterm" name="idm46045259700496"> </a> </li> <li class="listitem"> <p> <code class="literal"> db </code> : Database-level privileges. </p> <a class="indexterm" name="idm46045259697536"> </a> <a class="indexterm" name="idm46045259696048"> </a> <a class="indexterm" name="idm46045259694560"> </a> </li> <li class="listitem"> <p> <code class="literal"> tables_priv </code> : Table-level privileges. </p> <a class="indexterm" name="idm46045259691568"> </a> <a class="indexterm" name="idm46045259690080"> </a> <a class="indexterm" name="idm46045259688592"> </a> </li> <li class="listitem"> <p> <code class="literal"> columns_priv </code> : Column-level privileges. </p> <a class="indexterm" name="idm46045259685600"> </a> <a class="indexterm" name="idm46045259684112"> </a> <a class="indexterm" name="idm46045259682624"> </a> </li> <li class="listitem"> <p> <code class="literal"> procs_priv </code> : Stored procedure and function privileges. </p> <a class="indexterm" name="idm46045259679600"> </a> <a class="indexterm" name="idm46045259678112"> </a> <a class="indexterm" name="idm46045259676624"> </a> </li> <li class="listitem"> <p> <code class="literal"> proxies_priv </code> : Proxy-user privileges. </p> <a class="indexterm" name="idm46045259673632"> </a> <a class="indexterm" name="idm46045259672144"> </a> <a class="indexterm" name="idm46045259670656"> </a> </li> <li class="listitem"> <p> <code class="literal"> default_roles </code> : This table lists default roles to be activated after a user connects and authenticates, or executes <a class="link" href="set-role.html" title="15.7.1.11 SET ROLE Statement"> <code class="literal"> SET ROLE DEFAULT </code> </a> . </p> <a class="indexterm" name="idm46045259666304"> </a> <a class="indexterm" name="idm46045259664816"> </a> <a class="indexterm" name="idm46045259663328"> </a> </li> <li class="listitem"> <p> <code class="literal"> role_edges </code> : This table lists edges for role subgraphs. </p> <p> A given <code class="literal"> user </code> table row might refer to a user account or a role. The server can distinguish whether a row represents a user account, a role, or both by consulting the <code class="literal"> role_edges </code> table for information about relations between authentication IDs. </p> <a class="indexterm" name="idm46045259658192"> </a> <a class="indexterm" name="idm46045259656704"> </a> <a class="indexterm" name="idm46045259655216"> </a> </li> <li class="listitem"> <p> <code class="literal"> password_history </code> : Information about password changes. </p> <a class="indexterm" name="idm46045259652192"> </a> <a class="indexterm" name="idm46045259650704"> </a> <a class="indexterm" name="idm46045259649216"> </a> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-object-tables"> </a> Object Information System Tables </h3> </div> </div> </div> <p> These system tables contain information about components, loadable functions, and server-side plugins: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> component </code> : The registry for server components installed using <a class="link" href="install-component.html" title="15.7.4.3 INSTALL COMPONENT Statement"> <code class="literal"> INSTALL COMPONENT </code> </a> . Any components listed in this table are installed by a loader service during the server startup sequence. See <a class="xref" href="component-loading.html" title="7.5.1 Installing and Uninstalling Components"> Section 7.5.1, “Installing and Uninstalling Components” </a> . </p> <a class="indexterm" name="idm46045259641664"> </a> <a class="indexterm" name="idm46045259640176"> </a> </li> <li class="listitem"> <p> <code class="literal"> func </code> : The registry for loadable functions installed using <a class="link" href="create-function-loadable.html" title="15.7.4.1 CREATE FUNCTION Statement for Loadable Functions"> <code class="literal"> CREATE FUNCTION </code> </a> . During the normal startup sequence, the server loads functions registered in this table. If the server is started with the <a class="link" href="server-options.html#option_mysqld_skip-grant-tables"> <code class="option"> --skip-grant-tables </code> </a> option, functions registered in the table are not loaded and are unavailable. See <a class="xref" href="function-loading.html" title="7.7.1 Installing and Uninstalling Loadable Functions"> Section 7.7.1, “Installing and Uninstalling Loadable Functions” </a> . </p> <a class="indexterm" name="idm46045259633776"> </a> <a class="indexterm" name="idm46045259632288"> </a> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Like the <code class="literal"> mysql.func </code> system table, the Performance Schema <a class="link" href="performance-schema-user-defined-functions-table.html" title="29.12.22.10 The user_defined_functions Table"> <code class="literal"> user_defined_functions </code> </a> table lists loadable functions installed using <a class="link" href="create-function-loadable.html" title="15.7.4.1 CREATE FUNCTION Statement for Loadable Functions"> <code class="literal"> CREATE FUNCTION </code> </a> . Unlike the <code class="literal"> mysql.func </code> table, the <a class="link" href="performance-schema-user-defined-functions-table.html" title="29.12.22.10 The user_defined_functions Table"> <code class="literal"> user_defined_functions </code> </a> table also lists functions installed automatically by server components or plugins. This difference makes <a class="link" href="performance-schema-user-defined-functions-table.html" title="29.12.22.10 The user_defined_functions Table"> <code class="literal"> user_defined_functions </code> </a> preferable to <code class="literal"> mysql.func </code> for checking which functions are installed. See <a class="xref" href="performance-schema-user-defined-functions-table.html" title="29.12.22.10 The user_defined_functions Table"> Section 29.12.22.10, “The user_defined_functions Table” </a> . </p> </div> </li> <li class="listitem"> <p> <code class="literal"> plugin </code> : The registry for server-side plugins installed using <a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> <code class="literal"> INSTALL PLUGIN </code> </a> . During the normal startup sequence, the server loads plugins registered in this table. If the server is started with the <a class="link" href="server-options.html#option_mysqld_skip-grant-tables"> <code class="option"> --skip-grant-tables </code> </a> option, plugins registered in the table are not loaded and are unavailable. See <a class="xref" href="plugin-loading.html" title="7.6.1 Installing and Uninstalling Plugins"> Section 7.6.1, “Installing and Uninstalling Plugins” </a> . </p> <a class="indexterm" name="idm46045259616640"> </a> <a class="indexterm" name="idm46045259615152"> </a> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-log-tables"> </a> Log System Tables </h3> </div> </div> </div> <p> The server uses these system tables for logging: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259610928"> </a> <a class="indexterm" name="idm46045259609440"> </a> <code class="literal"> general_log </code> : The general query log table. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259606432"> </a> <a class="indexterm" name="idm46045259604944"> </a> <code class="literal"> slow_log </code> : The slow query log table. </p> </li> </ul> </div> <p> Log tables use the <code class="literal"> CSV </code> storage engine. </p> <p> For more information, see <a class="xref" href="server-logs.html" title="7.4 MySQL Server Logs"> Section 7.4, “MySQL Server Logs” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-help-tables"> </a> Server-Side Help System Tables </h3> </div> </div> </div> <a class="indexterm" name="idm46045259598944"> </a> <a class="indexterm" name="idm46045259597456"> </a> <p> These system tables contain server-side help information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259594720"> </a> <a class="indexterm" name="idm46045259593232"> </a> <code class="literal"> help_category </code> : Information about help categories. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259590208"> </a> <a class="indexterm" name="idm46045259588720"> </a> <code class="literal"> help_keyword </code> : Keywords associated with help topics. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259585696"> </a> <a class="indexterm" name="idm46045259584208"> </a> <code class="literal"> help_relation </code> : Mappings between help keywords and topics. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259581184"> </a> <a class="indexterm" name="idm46045259579696"> </a> <code class="literal"> help_topic </code> : Help topic contents. </p> </li> </ul> </div> <p> For more information, see <a class="xref" href="server-side-help-support.html" title="7.1.17 Server-Side Help Support"> Section 7.1.17, “Server-Side Help Support” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-time-zone-tables"> </a> Time Zone System Tables </h3> </div> </div> </div> <a class="indexterm" name="idm46045259574624"> </a> <a class="indexterm" name="idm46045259573136"> </a> <p> These system tables contain time zone information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259570416"> </a> <a class="indexterm" name="idm46045259568928"> </a> <code class="literal"> time_zone </code> : Time zone IDs and whether they use leap seconds. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259565888"> </a> <a class="indexterm" name="idm46045259564432"> </a> <code class="literal"> time_zone_leap_second </code> : When leap seconds occur. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259561408"> </a> <a class="indexterm" name="idm46045259559920"> </a> <code class="literal"> time_zone_name </code> : Mappings between time zone IDs and names. </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259556896"> </a> <a class="indexterm" name="idm46045259555392"> </a> <a class="indexterm" name="idm46045259553888"> </a> <a class="indexterm" name="idm46045259552384"> </a> <code class="literal"> time_zone_transition </code> , <code class="literal"> time_zone_transition_type </code> : Time zone descriptions. </p> </li> </ul> </div> <p> For more information, see <a class="xref" href="time-zone-support.html" title="7.1.15 MySQL Server Time Zone Support"> Section 7.1.15, “MySQL Server Time Zone Support” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-replication-tables"> </a> Replication System Tables </h3> </div> </div> </div> <p> The server uses these system tables to support replication: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259545376"> </a> <a class="indexterm" name="idm46045259543888"> </a> <code class="literal"> gtid_executed </code> : Table for storing GTID values. See <a class="xref" href="replication-gtids-concepts.html#replication-gtids-gtid-executed-table" title="mysql.gtid_executed Table"> mysql.gtid_executed Table </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259539936"> </a> <a class="indexterm" name="idm46045259538448"> </a> <code class="literal"> ndb_binlog_index </code> : Binary log information for NDB Cluster replication. This table is created only if the server is built with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> support. See <a class="xref" href="mysql-cluster-replication-schema.html" title="25.7.4 NDB Cluster Replication Schema and Tables"> Section 25.7.4, “NDB Cluster Replication Schema and Tables” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259532432"> </a> <a class="indexterm" name="idm46045259530944"> </a> <a class="indexterm" name="idm46045259529456"> </a> <a class="indexterm" name="idm46045259528000"> </a> <a class="indexterm" name="idm46045259526496"> </a> <a class="indexterm" name="idm46045259525008"> </a> <code class="literal"> slave_master_info </code> , <code class="literal"> slave_relay_log_info </code> , <code class="literal"> slave_worker_info </code> : Used to store replication information on replica servers. See <a class="xref" href="replica-logs.html" title="19.2.4 Relay Log and Replication Metadata Repositories"> Section 19.2.4, “Relay Log and Replication Metadata Repositories” </a> . </p> </li> </ul> </div> <p> All of the tables just listed use the <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> storage engine. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-optimizer-tables"> </a> Optimizer System Tables </h3> </div> </div> </div> <p> These system tables are for use by the optimizer: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259516000"> </a> <a class="indexterm" name="idm46045259514544"> </a> <a class="indexterm" name="idm46045259513040"> </a> <a class="indexterm" name="idm46045259511536"> </a> <code class="literal"> innodb_index_stats </code> , <code class="literal"> innodb_table_stats </code> : Used for <code class="literal"> InnoDB </code> persistent optimizer statistics. See <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259506400"> </a> <a class="indexterm" name="idm46045259504912"> </a> <a class="indexterm" name="idm46045259503424"> </a> <a class="indexterm" name="idm46045259501936"> </a> <code class="literal"> server_cost </code> , <code class="literal"> engine_cost </code> : The optimizer cost model uses tables that contain cost estimate information about operations that occur during query execution. <code class="literal"> server_cost </code> contains optimizer cost estimates for general server operations. <code class="literal"> engine_cost </code> contains estimates for operations specific to particular storage engines. See <a class="xref" href="cost-model.html" title="10.9.5 The Optimizer Cost Model"> Section 10.9.5, “The Optimizer Cost Model” </a> . </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="system-schema-miscellaneous-tables"> </a> Miscellaneous System Tables </h3> </div> </div> </div> <p> Other system tables do not fit the preceding categories: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="indexterm" name="idm46045259493504"> </a> <a class="indexterm" name="idm46045259492016"> </a> <a class="indexterm" name="idm46045259490528"> </a> <a class="indexterm" name="idm46045259489040"> </a> <code class="literal"> audit_log_filter </code> , <code class="literal"> audit_log_user </code> : If MySQL Enterprise Audit is installed, these tables provide persistent storage of audit log filter definitions and user accounts. See <a class="xref" href="audit-log-reference.html#audit-log-tables" title="Audit Log Tables"> Audit Log Tables </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259484400"> </a> <a class="indexterm" name="idm46045259482896"> </a> <a class="indexterm" name="idm46045259481392"> </a> <a class="indexterm" name="idm46045259479904"> </a> <a class="indexterm" name="idm46045259478416"> </a> <a class="indexterm" name="idm46045259476912"> </a> <a class="indexterm" name="idm46045259475408"> </a> <a class="indexterm" name="idm46045259473920"> </a> <a class="indexterm" name="idm46045259472432"> </a> <a class="indexterm" name="idm46045259470928"> </a> <code class="literal"> firewall_group_allowlist </code> , <code class="literal"> firewall_groups </code> , <code class="literal"> firewall_memebership </code> , <code class="literal"> firewall_users </code> , <code class="literal"> firewall_whitelist </code> : If MySQL Enterprise Firewall is installed, these tables provide persistent storage for information used by the firewall. See <a class="xref" href="firewall.html" title="8.4.7 MySQL Enterprise Firewall"> Section 8.4.7, “MySQL Enterprise Firewall” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259464224"> </a> <a class="indexterm" name="idm46045259462736"> </a> <code class="literal"> servers </code> : Used by the <code class="literal"> FEDERATED </code> storage engine. See <a class="xref" href="federated-create-server.html" title="18.8.2.2 Creating a FEDERATED Table Using CREATE SERVER"> Section 18.8.2.2, “Creating a FEDERATED Table Using CREATE SERVER” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045259458160"> </a> <a class="indexterm" name="idm46045259456656"> </a> <code class="literal"> innodb_dynamic_metadata </code> : Used by the <code class="literal"> InnoDB </code> storage engine to store fast-changing table metadata such as auto-increment counter values and index tree corruption flags. Replaces the data dictionary buffer table that resided in the <code class="literal"> InnoDB </code> system tablespace. </p> </li> </ul> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/populating-spatial-columns.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="populating-spatial-columns"> </a> 13.4.7 Populating Spatial Columns </h3> </div> </div> </div> <p> After you have created spatial columns, you can populate them with spatial data. </p> <p> Values should be stored in internal geometry format, but you can convert them to that format from either Well-Known Text (WKT) or Well-Known Binary (WKB) format. The following examples demonstrate how to insert geometry values into a table by converting WKT values to internal geometry format: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Perform the conversion directly in the <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa40367248"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token string">'POINT(1 1)'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'POINT(1 1)'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> Perform the conversion prior to the <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa60588488"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token string">'POINT(1 1)'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> </ul> </div> <p> The following examples insert more complex geometries into the table: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa3958881"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'LINESTRING(0 0,1 1,2 2)'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'GEOMETRYCOLLECTION(POINT(1 1),LINESTRING(0 0,1 1,2 2,3 3,4 4))'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> The preceding examples use <a class="link" href="gis-wkt-functions.html#function_st-geomfromtext"> <code class="literal"> ST_GeomFromText() </code> </a> to create geometry values. You can also use type-specific functions: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa86706678"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'POINT(1 1)'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_PointFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'LINESTRING(0 0,1 1,2 2)'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_LineStringFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'POLYGON((0 0,10 0,10 10,0 10,0 0),(5 5,7 5,7 7,5 7, 5 5))'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_PolygonFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">SET</span> <span class="token variable">@g</span> <span class="token operator">=</span> <span class="token string">'GEOMETRYCOLLECTION(POINT(1 1),LINESTRING(0 0,1 1,2 2,3 3,4 4))'</span><span class="token punctuation">;</span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomCollFromText</span><span class="token punctuation">(</span><span class="token variable">@g</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> A client application program that wants to use WKB representations of geometry values is responsible for sending correctly formed WKB in queries to the server. There are several ways to satisfy this requirement. For example: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Inserting a <code class="literal"> POINT(1 1) </code> value with hex literal syntax: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa15629375"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromWKB</span><span class="token punctuation">(</span>X<span class="token string">'0101000000000000000000F03F000000000000F03F'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> An ODBC application can send a WKB representation, binding it to a placeholder using an argument of <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> type: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa24970565"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> geom <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token function">ST_GeomFromWKB</span><span class="token punctuation">(</span>?<span class="token punctuation">)</span><span class="token punctuation">)</span></code></pre> </div> <p> Other programming interfaces may support a similar placeholder mechanism. </p> </li> <li class="listitem"> <p> In a C program, you can escape a binary value using <a class="ulink" href="/doc/c-api/8.4/en/mysql-real-escape-string-quote.html" target="_top"> <code class="literal"> mysql_real_escape_string_quote() </code> </a> and include the result in a query string that is sent to the server. See <a class="ulink" href="/doc/c-api/8.4/en/mysql-real-escape-string-quote.html" target="_top"> mysql_real_escape_string_quote() </a> . </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/sys-statement-performance-analyzer.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-statement-performance-analyzer"> </a> 30.4.4.25 The statement_performance_analyzer() Procedure </h4> </div> </div> </div> <a class="indexterm" name="idm46045061216480"> </a> <a class="indexterm" name="idm46045061214960"> </a> <p> Creates a report of the statements running on the server. The views are calculated based on the overall and/or delta activity. </p> <p> This procedure disables binary logging during its execution by manipulating the session value of the <a class="link" href="replication-options-binary-log.html#sysvar_sql_log_bin"> <code class="literal"> sql_log_bin </code> </a> system variable. That is a restricted operation, so the procedure requires privileges sufficient to set restricted session variables. See <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> . </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-statement-performance-analyzer-parameters"> </a> Parameters </h5> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> in_action ENUM('snapshot', 'overall', 'delta', 'create_tmp', 'create_table', 'save', 'cleanup') </code> : The action to take. These values are permitted: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> snapshot </code> : Store a snapshot. The default is to make a snapshot of the current content of the Performance Schema <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> table. By setting <code class="literal"> in_table </code> , this can be overwritten to copy the content of the specified table. The snapshot is stored in the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema <code class="literal"> tmp_digests </code> temporary table. </p> </li> <li class="listitem"> <p> <code class="literal"> overall </code> : Generate an analysis based on the content of the table specified by <code class="literal"> in_table </code> . For the overall analysis, <code class="literal"> in_table </code> can be <a class="link" href="date-and-time-functions.html#function_now"> <code class="literal"> NOW() </code> </a> to use a fresh snapshot. This overwrites an existing snapshot. Use <code class="literal"> NULL </code> for <code class="literal"> in_table </code> to use the existing snapshot. If <code class="literal"> in_table </code> is <code class="literal"> NULL </code> and no snapshot exists, a new snapshot is created. The <code class="literal"> in_views </code> parameter and the <code class="literal"> statement_performance_analyzer.limit </code> configuration option affect the operation of this procedure. </p> </li> <li class="listitem"> <p> <code class="literal"> delta </code> : Generate a delta analysis. The delta is calculated between the reference table specified by <code class="literal"> in_table </code> and the snapshot, which must exist. This action uses the <a class="link" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> <code class="literal"> sys </code> </a> schema <code class="literal"> tmp_digests_delta </code> temporary table. The <code class="literal"> in_views </code> parameter and the <code class="literal"> statement_performance_analyzer.limit </code> configuration option affect the operation of this procedure. </p> </li> <li class="listitem"> <p> <code class="literal"> create_table </code> : Create a regular table suitable for storing the snapshot for later use (for example, for calculating deltas). </p> </li> <li class="listitem"> <p> <code class="literal"> create_tmp </code> : Create a temporary table suitable for storing the snapshot for later use (for example, for calculating deltas). </p> </li> <li class="listitem"> <p> <code class="literal"> save </code> : Save the snapshot in the table specified by <code class="literal"> in_table </code> . The table must exist and have the correct structure. If no snapshot exists, a new snapshot is created. </p> </li> <li class="listitem"> <p> <code class="literal"> cleanup </code> : Remove the temporary tables used for the snapshot and delta. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> in_table VARCHAR(129) </code> : The table parameter used for some of the actions specified by the <code class="literal"> in_action </code> parameter. Use the format <em class="replaceable"> <code> db_name.tbl_name </code> </em> or <em class="replaceable"> <code> tbl_name </code> </em> without using any backtick ( <code class="literal"> ` </code> ) identifier-quoting characters. Periods ( <code class="literal"> . </code> ) are not supported in database and table names. </p> <p> The meaning of the <code class="literal"> in_table </code> value for each <code class="literal"> in_action </code> value is detailed in the individual <code class="literal"> in_action </code> value descriptions. </p> </li> <li class="listitem"> <p> <code class="literal"> in_views SET ('with_runtimes_in_95th_percentile', 'analysis', 'with_errors_or_warnings', 'with_full_table_scans', 'with_sorting', 'with_temp_tables', 'custom') </code> : Which views to include. This parameter is a <code class="literal"> SET </code> value, so it can contain multiple view names, separated by commas. The default is to include all views except <code class="literal"> custom </code> . The following values are permitted: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> with_runtimes_in_95th_percentile </code> : Use the <a class="link" href="sys-statements-with-runtimes-in-95th-percentile.html" title="30.4.3.38 The statements_with_runtimes_in_95th_percentile and x$statements_with_runtimes_in_95th_percentile Views"> <code class="literal"> statements_with_runtimes_in_95th_percentile </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> analysis </code> : Use the <a class="link" href="sys-statement-analysis.html" title="30.4.3.35 The statement_analysis and x$statement_analysis Views"> <code class="literal"> statement_analysis </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> with_errors_or_warnings </code> : Use the <a class="link" href="sys-statements-with-errors-or-warnings.html" title="30.4.3.36 The statements_with_errors_or_warnings and x$statements_with_errors_or_warnings Views"> <code class="literal"> statements_with_errors_or_warnings </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> with_full_table_scans </code> : Use the <a class="link" href="sys-statements-with-full-table-scans.html" title="30.4.3.37 The statements_with_full_table_scans and x$statements_with_full_table_scans Views"> <code class="literal"> statements_with_full_table_scans </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> with_sorting </code> : Use the <a class="link" href="sys-statements-with-sorting.html" title="30.4.3.39 The statements_with_sorting and x$statements_with_sorting Views"> <code class="literal"> statements_with_sorting </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> with_temp_tables </code> : Use the <a class="link" href="sys-statements-with-temp-tables.html" title="30.4.3.40 The statements_with_temp_tables and x$statements_with_temp_tables Views"> <code class="literal"> statements_with_temp_tables </code> </a> view. </p> </li> <li class="listitem"> <p> <code class="literal"> custom </code> : Use a custom view. This view must be specified using the <code class="literal"> statement_performance_analyzer.view </code> configuration option to name a query or an existing view. </p> </li> </ul> </div> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-statement-performance-analyzer-configuration-options"> </a> Configuration Options </h5> </div> </div> </div> <p> <a class="link" href="sys-statement-performance-analyzer.html" title="30.4.4.25 The statement_performance_analyzer() Procedure"> <code class="literal"> statement_performance_analyzer() </code> </a> operation can be modified using the following configuration options or their corresponding user-defined variables (see <a class="xref" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> Section 30.4.2.1, “The sys_config Table” </a> ): </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> debug </code> , <code class="literal"> @sys.debug </code> </p> <p> If this option is <code class="literal"> ON </code> , produce debugging output. The default is <code class="literal"> OFF </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> statement_performance_analyzer.limit </code> , <code class="literal"> @sys.statement_performance_analyzer.limit </code> </p> <p> The maximum number of rows to return for views that have no built-in limit. The default is 100. </p> </li> <li class="listitem"> <p> <code class="literal"> statement_performance_analyzer.view </code> , <code class="literal"> @sys.statement_performance_analyzer.view </code> </p> <p> The custom query or view to be used. If the option value contains a space, it is interpreted as a query. Otherwise, it must be the name of an existing view that queries the Performance Schema <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> table. There cannot be any <code class="literal"> LIMIT </code> clause in the query or view definition if the <code class="literal"> statement_performance_analyzer.limit </code> configuration option is greater than 0. If specifying a view, use the same format as for the <code class="literal"> in_table </code> parameter. The default is <code class="literal"> NULL </code> (no custom view defined). </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-statement-performance-analyzer-example"> </a> Example </h5> </div> </div> </div> <p> To create a report with the queries in the 95th percentile since the last truncation of <a class="link" href="performance-schema-statement-summary-tables.html" title="29.12.20.3 Statement Summary Tables"> <code class="literal"> events_statements_summary_by_digest </code> </a> and with a one-minute delta period: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Create a temporary table to store the initial snapshot. </p> </li> <li class="listitem"> <p> Create the initial snapshot. </p> </li> <li class="listitem"> <p> Save the initial snapshot in the temporary table. </p> </li> <li class="listitem"> <p> Wait one minute. </p> </li> <li class="listitem"> <p> Create a new snapshot. </p> </li> <li class="listitem"> <p> Perform analysis based on the new snapshot. </p> </li> <li class="listitem"> <p> Perform analysis based on the delta between the initial and new snapshots. </p> </li> </ol> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa93939511"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'create_tmp'</span><span class="token punctuation">,</span> <span class="token string">'mydb.tmp_digests_ini'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.08 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'snapshot'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.02 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'save'</span><span class="token punctuation">,</span> <span class="token string">'mydb.tmp_digests_ini'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">DO</span> <span class="token function">SLEEP</span><span class="token punctuation">(</span><span class="token number">60</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (1 min 0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'snapshot'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.02 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'overall'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token string">'with_runtimes_in_95th_percentile'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Next Output <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Queries with Runtime in 95th Percentile <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">1 row in set (0.05 sec)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'delta'</span><span class="token punctuation">,</span> <span class="token string">'mydb.tmp_digests_ini'</span><span class="token punctuation">,</span> <span class="token string">'with_runtimes_in_95th_percentile'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Next Output <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Queries with Runtime in 95th Percentile <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">1 row in set (0.03 sec)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> Create an overall report of the 95th percentile queries and the top 10 queries with full table scans: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa54901623"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'snapshot'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.01 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@sys.statement_performance_analyzer.limit</span> <span class="token operator">=</span> <span class="token number">10</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'overall'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">,</span> <span class="token string">'with_runtimes_in_95th_percentile,with_full_table_scans'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Next Output <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Queries with Runtime in 95th Percentile <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">1 row in set (0.01 sec)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Next Output <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Top 10 Queries with Full Table Scan <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">1 row in set (0.09 sec)</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> Use a custom view showing the top 10 queries sorted by total execution time, refreshing the view every minute using the <span class="command"> <strong> watch </strong> </span> command in Linux: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78470561"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token operator">OR</span> <span class="token keyword">REPLACE</span> <span class="token keyword">VIEW</span> mydb<span class="token punctuation">.</span>my_statements <span class="token keyword">AS</span> <span class="token keyword">SELECT</span> sys<span class="token punctuation">.</span>format_statement<span class="token punctuation">(</span>DIGEST_TEXT<span class="token punctuation">)</span> <span class="token keyword">AS</span> <span class="token keyword">query</span><span class="token punctuation">,</span> <span class="token keyword">SCHEMA_NAME</span> <span class="token keyword">AS</span> db<span class="token punctuation">,</span> COUNT_STAR <span class="token keyword">AS</span> exec_count<span class="token punctuation">,</span> sys<span class="token punctuation">.</span>format_time<span class="token punctuation">(</span>SUM_TIMER_WAIT<span class="token punctuation">)</span> <span class="token keyword">AS</span> total_latency<span class="token punctuation">,</span> sys<span class="token punctuation">.</span>format_time<span class="token punctuation">(</span>AVG_TIMER_WAIT<span class="token punctuation">)</span> <span class="token keyword">AS</span> avg_latency<span class="token punctuation">,</span> <span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token function">IFNULL</span><span class="token punctuation">(</span>SUM_ROWS_SENT <span class="token operator">/</span> <span class="token function">NULLIF</span><span class="token punctuation">(</span>COUNT_STAR<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> rows_sent_avg<span class="token punctuation">,</span> <span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token function">IFNULL</span><span class="token punctuation">(</span>SUM_ROWS_EXAMINED <span class="token operator">/</span> <span class="token function">NULLIF</span><span class="token punctuation">(</span>COUNT_STAR<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> rows_examined_avg<span class="token punctuation">,</span> <span class="token function">ROUND</span><span class="token punctuation">(</span><span class="token function">IFNULL</span><span class="token punctuation">(</span>SUM_ROWS_AFFECTED <span class="token operator">/</span> <span class="token function">NULLIF</span><span class="token punctuation">(</span>COUNT_STAR<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">AS</span> rows_affected_avg<span class="token punctuation">,</span> DIGEST <span class="token keyword">AS</span> digest <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>events_statements_summary_by_digest <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> SUM_TIMER_WAIT <span class="token keyword">DESC</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.10 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>statement_performance_analyzer<span class="token punctuation">(</span><span class="token string">'create_table'</span><span class="token punctuation">,</span> <span class="token string">'mydb.digests_prev'</span><span class="token punctuation">,</span> <span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.10 sec)</span> $<span class="token operator">></span> watch <span class="token operator">-</span>n <span class="token number">60</span> <span class="token string">"mysql sys --table -e \" > SET @sys.statement_performance_analyzer.view = 'mydb.my_statements'; > SET @sys.statement_performance_analyzer.limit = 10; > CALL statement_performance_analyzer('snapshot', NULL, NULL); > CALL statement_performance_analyzer('delta', 'mydb.digests_prev', 'custom'); > CALL statement_performance_analyzer('save', 'mydb.digests_prev', NULL); > \""</span> <span class="token keyword">Every</span> <span class="token number">60</span><span class="token punctuation">.</span>0s: mysql sys <span class="token comment" spellcheck="true">--table -e " ... Mon Dec 22 10:58:51 2014</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Next Output <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Top 10 Queries Using Custom View <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> query <span class="token punctuation">|</span> db <span class="token punctuation">|</span> exec_count <span class="token punctuation">|</span> total_latency <span class="token punctuation">|</span> avg_latency <span class="token punctuation">|</span> rows_sent_avg <span class="token punctuation">|</span> rows_examined_avg <span class="token punctuation">|</span> rows_affected_avg <span class="token punctuation">|</span> digest <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/information-schema-view-routine-usage-table.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-view-routine-usage-table"> </a> 28.3.48 The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045077951552"> </a> <p> The <a class="link" href="information-schema-view-routine-usage-table.html" title="28.3.48 The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table"> <code class="literal"> VIEW_ROUTINE_USAGE </code> </a> table provides access to information about stored functions used in view definitions. The table does not list information about built-in (native) functions or loadable functions used in the definitions. </p> <p> You can see information only for views for which you have some privilege, and only for functions for which you have some privilege. </p> <p> The <a class="link" href="information-schema-view-routine-usage-table.html" title="28.3.48 The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table"> <code class="literal"> VIEW_ROUTINE_USAGE </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> TABLE_CATALOG </code> </p> <p> The name of the catalog to which the view belongs. This value is always <code class="literal"> def </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_SCHEMA </code> </p> <p> The name of the schema (database) to which the view belongs. </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_NAME </code> </p> <p> The name of the view. </p> </li> <li class="listitem"> <p> <code class="literal"> SPECIFIC_CATALOG </code> </p> <p> The name of the catalog to which the function used in the view definition belongs. This value is always <code class="literal"> def </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> SPECIFIC_SCHEMA </code> </p> <p> The name of the schema (database) to which the function used in the view definition belongs. </p> </li> <li class="listitem"> <p> <code class="literal"> SPECIFIC_NAME </code> </p> <p> The name of the function used in the view definition. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/network-namespace-support.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="network-namespace-support"> </a> 7.1.14 Network Namespace Support </h3> </div> </div> </div> <a class="indexterm" name="idm46045260630096"> </a> <a class="indexterm" name="idm46045260629024"> </a> <p> A network namespace is a logical copy of the network stack from the host system. Network namespaces are useful for setting up containers or virtual environments. Each namespace has its own IP addresses, network interfaces, routing tables, and so forth. The default or global namespace is the one in which the host system physical interfaces exist. </p> <p> Namespace-specific address spaces can lead to problems when MySQL connections cross namespaces. For example, the network address space for a MySQL instance running in a container or virtual network may differ from the address space of the host machine. This can produce phenomena such as a client connection from an address in one namespace appearing to the MySQL server to be coming from a different address, even for client and server running on the same machine. Suppose that both processes run on a host with IP address <code class="literal"> 203.0.113.10 </code> but use different namespaces. A connection may produce a result like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa99221306"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">$<span class="token operator">></span> mysql <span class="token operator">--</span>user<span class="token operator">=</span>admin <span class="token operator">--</span>host<span class="token operator">=</span>203<span class="token punctuation">.</span>0<span class="token punctuation">.</span>113<span class="token punctuation">.</span>10 <span class="token operator">--</span>protocol<span class="token operator">=</span>tcp mysql<span class="token operator">></span> SELECT USER<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token operator">+</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">+</span> <span class="token operator">|</span> USER<span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">|</span> <span class="token operator">+</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">+</span> <span class="token operator">|</span> admin@198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>2 <span class="token operator">|</span> <span class="token operator">+</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">+</span></code></pre> </div> <p> In this case, the expected <a class="link" href="information-functions.html#function_user"> <code class="literal"> USER() </code> </a> value is <code class="literal"> [email protected] </code> . Such behavior can make it difficult to assign account permissions properly if the address from which an connection originates is not what it appears. </p> <p> To address this issue, MySQL enables specifying the network namespace to use for TCP/IP connections, so that both endpoints of connections use an agreed-upon common address space. </p> <p> MySQL supports network namespaces on platforms that implement them. Support within MySQL applies to: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The MySQL server, <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . </p> </li> <li class="listitem"> <p> X Plugin. </p> </li> <li class="listitem"> <p> The <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client and the <span class="command"> <strong> mysqlxtest </strong> </span> test suite client. (Other clients are not supported. They must be invoked from within the network namespace of the server to which they are to connect.) </p> </li> <li class="listitem"> <p> Regular replication. </p> </li> <li class="listitem"> <p> Group Replication, only when using the MySQL communication stack to establish group communication connections. </p> </li> </ul> </div> <p> The following sections describe how to use network namespaces in MySQL: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="network-namespace-support.html#network-namespaces-host-prerequisites" title="Host System Prerequisites"> Host System Prerequisites </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="network-namespace-support.html#network-namespaces-mysql-configuration" title="MySQL Configuration"> MySQL Configuration </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="network-namespace-support.html#network-namespaces-monitoring" title="Network Namespace Monitoring"> Network Namespace Monitoring </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="network-namespaces-host-prerequisites"> </a> Host System Prerequisites </h4> </div> </div> </div> <p> Prior to using network namespace support in MySQL, these host system prerequisites must be satisfied: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The host operating system must support network namespaces. (For example, Linux.) </p> </li> <li class="listitem"> <p> Any network namespace to be used by MySQL must first be created on the host system. </p> </li> <li class="listitem"> <p> Host name resolution must be configured by the system administrator to support network namespaces. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> A known limitation is that, within MySQL, host name resolution does not work for names specified in network namespace-specific host files. For example, if the address for a host name in the <code class="literal"> red </code> namespace is specified in the <code class="filename"> /etc/netns/red/hosts </code> file, binding to the name fails on both the server and client sides. The workaround is to use the IP address rather than the host name. </p> </div> </li> <li class="listitem"> <p> The system administrator must enable the <code class="literal"> CAP_SYS_ADMIN </code> operating system privilege for the MySQL binaries that support network namespaces ( <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> , <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> , <span class="command"> <strong> mysqlxtest </strong> </span> ). </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> Enabling <code class="literal"> CAP_SYS_ADMIN </code> is a security sensitive operation because it enables a process to perform other privileged actions in addition to setting namespaces. For a description of its effects, see <a class="ulink" href="https://man7.org/linux/man-pages/man7/capabilities.7.html" target="_blank"> https://man7.org/linux/man-pages/man7/capabilities.7.html </a> . </p> <p> Because <code class="literal"> CAP_SYS_ADMIN </code> must be enabled explicitly by the system administrator, MySQL binaries by default do not have network namespace support enabled. The system administrator should evaluate the security implications of running MySQL processes with <code class="literal"> CAP_SYS_ADMIN </code> before enabling it. </p> </div> </li> </ul> </div> <p> The instructions in the following example set up network namespaces named <code class="literal"> red </code> and <code class="literal"> blue </code> . The names you choose may differ, as may the network addresses and interfaces on your host system. </p> <p> Invoke the commands shown here either as the <code class="literal"> root </code> operating system user or by prefixing each command with <span class="command"> <strong> sudo </strong> </span> . For example, to invoke the <span class="command"> <strong> ip </strong> </span> or <span class="command"> <strong> setcap </strong> </span> command if you are not <code class="literal"> root </code> , use <span class="command"> <strong> sudo ip </strong> </span> or <span class="command"> <strong> sudo setcap </strong> </span> . </p> <p> To configure network namespaces, use the <span class="command"> <strong> ip </strong> </span> command. For some operations, the <span class="command"> <strong> ip </strong> </span> command must execute within a particular namespace (which must already exist). In such cases, begin the command like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa69926930"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip netns exec <em class="replaceable">namespace_name</em></code></pre> </div> <p> For example, this command executes within the <code class="literal"> red </code> namespace to bring up the loopback interface: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa92041966"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip netns exec red ip link set lo up</code></pre> </div> <p> To add namespaces named <code class="literal"> red </code> and <code class="literal"> blue </code> , each with its own virtual Ethernet device used as a link between namespaces and its own loopback interface: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa75626178"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip netns add red ip link add veth-red type veth peer name vpeer-red ip link set vpeer-red netns red ip addr add 192<span class="token punctuation">.</span>0<span class="token punctuation">.</span>2<span class="token punctuation">.</span>1/24 dev veth-red ip link set veth-red up ip netns exec red ip addr add 192<span class="token punctuation">.</span>0<span class="token punctuation">.</span>2<span class="token punctuation">.</span>2/24 dev vpeer-red ip netns exec red ip link set vpeer-red up ip netns exec red ip link set lo up ip netns add blue ip link add veth-blue type veth peer name vpeer-blue ip link set vpeer-blue netns blue ip addr add 198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>1/24 dev veth-blue ip link set veth-blue up ip netns exec blue ip addr add 198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>2/24 dev vpeer-blue ip netns exec blue ip link set vpeer-blue up ip netns exec blue ip link set lo up <span class="token comment" spellcheck="true"># if you want to enable inter-subnet routing...</span> sysctl net<span class="token punctuation">.</span>ipv4<span class="token punctuation">.</span>ip_forward<span class="token attr-value"><span class="token punctuation">=</span>1</span> ip netns exec red ip route add default via 192<span class="token punctuation">.</span>0<span class="token punctuation">.</span>2<span class="token punctuation">.</span>1 ip netns exec blue ip route add default via 198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>1</code></pre> </div> <p> A diagram of the links between namespaces looks like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa67975921"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">red global blue 192.0.2.2 <=> 192.0.2.1 (vpeer-red) (veth-red) 198.51.100.1 <=> 198.51.100.2 (veth-blue) (vpeer-blue)</code></pre> </div> <p> To check which namespaces and links exist: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa29643824"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip netns list ip link list</code></pre> </div> <p> To see the routing tables for the global and named namespaces: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa88437224"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip route show ip netns exec red ip route show ip netns exec blue ip route show</code></pre> </div> <p> To remove the <code class="literal"> red </code> and <code class="literal"> blue </code> links and namespaces: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa84054608"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">ip link del veth-red ip link del veth-blue ip netns del red ip netns del blue sysctl net<span class="token punctuation">.</span>ipv4<span class="token punctuation">.</span>ip_forward<span class="token attr-value"><span class="token punctuation">=</span>0</span></code></pre> </div> <p> So that the MySQL binaries that include network namespace support can actually use namespaces, you must grant them the <code class="literal"> CAP_SYS_ADMIN </code> capability. The following <span class="command"> <strong> setcap </strong> </span> commands assume that you have changed location to the directory containing your MySQL binaries (adjust the pathname for your system as necessary): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa92882441"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cd /usr/local/mysql/bin</code></pre> </div> <p> To grant <code class="literal"> CAP_SYS_ADMIN </code> capability to the appropriate binaries: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa47369150"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">setcap cap_sys_admin+ep <span class="token punctuation">.</span>/mysqld setcap cap_sys_admin+ep <span class="token punctuation">.</span>/mysql setcap cap_sys_admin+ep <span class="token punctuation">.</span>/mysqlxtest</code></pre> </div> <p> To check <code class="literal"> CAP_SYS_ADMIN </code> capability: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa30592321"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">getcap</span> <span class="token punctuation">.</span>/mysqld <span class="token punctuation">.</span>/mysql <span class="token punctuation">.</span>/mysqlxtest <span class="token punctuation">.</span>/mysqld = cap_sys_admin+ep <span class="token punctuation">.</span>/mysql = cap_sys_admin+ep <span class="token punctuation">.</span>/mysqlxtest = cap_sys_admin+ep</code></pre> </div> <p> To remove <code class="literal"> CAP_SYS_ADMIN </code> capability: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa91835259"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">setcap <span class="token property">-r</span> <span class="token punctuation">.</span>/mysqld setcap <span class="token property">-r</span> <span class="token punctuation">.</span>/mysql setcap <span class="token property">-r</span> <span class="token punctuation">.</span>/mysqlxtest</code></pre> </div> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> If you reinstall binaries to which you have previously applied <span class="command"> <strong> setcap </strong> </span> , you must use <span class="command"> <strong> setcap </strong> </span> again. For example, if you perform an in-place MySQL upgrade, failure to grant the <code class="literal"> CAP_SYS_ADMIN </code> capability again results in namespace-related failures. The server fails with this error for attempts to bind to an address with a named namespace: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa2792879"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[ERROR] [MY-013408] [Server] setns() failed with error 'Operation not permitted'</code></pre> </div> <p> A client invoked with the <a class="link" href="mysql-command-options.html#option_mysql_network-namespace"> <code class="option"> --network-namespace </code> </a> option fails like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa85496059"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">ERROR: Network namespace error: Operation not permitted</code></pre> </div> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="network-namespaces-mysql-configuration"> </a> MySQL Configuration </h4> </div> </div> </div> <p> Assuming that the preceding host system prerequisites have been satisfied, MySQL enables configuring the server-side namespace for the listening (inbound) side of connections and the client-side namespace for the outbound side of connections. </p> <p> On the server side, the <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> , <a class="link" href="server-system-variables.html#sysvar_admin_address"> <code class="literal"> admin_address </code> </a> , and <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_bind_address"> <code class="literal"> mysqlx_bind_address </code> </a> system variables have extended syntax for specifying the network namespace to use for a given IP address or host name on which to listen for incoming connections. To specify a namespace for an address, add a slash and the namespace name. For example, a server <code class="filename"> my.cnf </code> file might contain these lines: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa85576297"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 127.0.1.1,192.0.2.2/red,198.51.100.2/blue</span> <span class="token constant">admin_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 102.0.2.2/red</span> <span class="token constant">mysqlx_bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 102.0.2.2/red</span></code></pre> </div> <p> These rules apply: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A network namespace can be specified for an IP address or a host name. </p> </li> <li class="listitem"> <p> A network namespace cannot be specified for a wildcard IP address. </p> </li> <li class="listitem"> <p> For a given address, the network namespace is optional. If given, it must be specified as a <code class="literal"> / <em class="replaceable"> <code> ns </code> </em> </code> suffix immediately following the address. </p> </li> <li class="listitem"> <p> An address with no <code class="literal"> / <em class="replaceable"> <code> ns </code> </em> </code> suffix uses the host system global namespace. The global namespace is therefore the default. </p> </li> <li class="listitem"> <p> An address with a <code class="literal"> / <em class="replaceable"> <code> ns </code> </em> </code> suffix uses the namespace named <em class="replaceable"> <code> ns </code> </em> . </p> </li> <li class="listitem"> <p> The host system must support network namespaces and each named namespace must previously have been set up. Naming a nonexistent namespace produces an error. </p> </li> <li class="listitem"> <p> <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> and <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_bind_address"> <code class="literal"> mysqlx_bind_address </code> </a> accept a list of multiple comma-separated addresses, the variable value can specify addresses in the global namespace, in named namespaces, or a mix. </p> </li> </ul> </div> <p> If an error occurs during server startup for attempts to use a namespace, the server does not start. If errors occur for X Plugin during plugin initialization such that it is unable to bind to any address, the plugin fails its initialization sequence and the server does not load it. </p> <p> On the client side, a network namespace can be specified in these contexts: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client and the <span class="command"> <strong> mysqlxtest </strong> </span> test suite client, use the <a class="link" href="mysql-command-options.html#option_mysql_network-namespace"> <code class="option"> --network-namespace </code> </a> option. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa42222649"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token constant">--host</span><span class="token attr-value"><span class="token punctuation">=</span>192.0.2.2</span> <span class="token constant">--network-namespace</span><span class="token attr-value"><span class="token punctuation">=</span>red</span></code></pre> </div> <p> If the <a class="link" href="mysql-command-options.html#option_mysql_network-namespace"> <code class="option"> --network-namespace </code> </a> option is omitted, the connection uses the default (global) namespace. </p> </li> <li class="listitem"> <p> For replication connections from replica servers to source servers, use the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement and specify the <code class="literal"> NETWORK_NAMESPACE </code> option. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa69766761"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CHANGE</span> <span class="token keyword">REPLICATION</span> <span class="token keyword">SOURCE</span> <span class="token keyword">TO</span> <span class="token keyword">SOURCE_HOST</span> <span class="token operator">=</span> <span class="token string">'192.0.2.2'</span><span class="token punctuation">,</span> <span class="token keyword">NETWORK_NAMESPACE</span> <span class="token operator">=</span> <span class="token string">'red'</span><span class="token punctuation">;</span></code></pre> </div> <p> If the <code class="literal"> NETWORK_NAMESPACE </code> option is omitted, replication connections use the default (global) namespace. </p> </li> </ul> </div> <p> The following example sets up a MySQL server that listens for connections in the global, <code class="literal"> red </code> , and <code class="literal"> blue </code> namespaces, and shows how to configure accounts that connect from the <code class="literal"> red </code> and <code class="literal"> blue </code> namespaces. It is assumed that the <code class="literal"> red </code> and <code class="literal"> blue </code> namespaces have already been created as shown in <a class="xref" href="network-namespace-support.html#network-namespaces-host-prerequisites" title="Host System Prerequisites"> Host System Prerequisites </a> . </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Configure the server to listen on addresses in multiple namespaces. Put these lines in the server <code class="filename"> my.cnf </code> file and start the server: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa25984069"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">bind_address</span> <span class="token attr-value"><span class="token punctuation">=</span> 127.0.1.1,192.0.2.2/red,198.51.100.2/blue</span></code></pre> </div> <p> The value tells the server to listen on the loopback address <code class="literal"> 127.0.0.1 </code> in the global namespace, the address <code class="literal"> 192.0.2.2 </code> in the <code class="literal"> red </code> namespace, and the address <code class="literal"> 198.51.100.2 </code> in the <code class="literal"> blue </code> namespace. </p> </li> <li class="listitem"> <p> Connect to the server in the global namespace and create accounts that have permission to connect from an address in the address space of each named namespace: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa67139881"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> root <span class="token property">-h</span> 127<span class="token punctuation">.</span>0<span class="token punctuation">.</span>0<span class="token punctuation">.</span>1 <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> <em class="replaceable">root_password</em> <span class="token prompt">mysql></span><span class="token command"> CREATE</span> USER <span class="token atrule">'red_user'</span>@<span class="token atrule">'192.0.2.2'</span> IDENTIFIED BY <span class="token atrule">'<em class="replaceable">red_user_password</em>'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span><span class="token command"> CREATE</span> USER <span class="token atrule">'blue_user'</span>@<span class="token atrule">'198.51.100.2'</span> IDENTIFIED BY <span class="token atrule">'<em class="replaceable">blue_user_password</em>'</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> Verify that you can connect to the server in each named namespace: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa63667850"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> red_user <span class="token property">-h</span> 192<span class="token punctuation">.</span>0<span class="token punctuation">.</span>2<span class="token punctuation">.</span>2 <span class="token constant">--network-namespace</span><span class="token attr-value"><span class="token punctuation">=</span>red</span> <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> <em class="replaceable">red_user_password</em> <span class="token prompt">mysql></span><span class="token command"> SELECT</span> USER<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> USER() <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> [email protected] <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa92628822"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> blue_user <span class="token property">-h</span> 198<span class="token punctuation">.</span>51<span class="token punctuation">.</span>100<span class="token punctuation">.</span>2 <span class="token constant">--network-namespace</span><span class="token attr-value"><span class="token punctuation">=</span>blue</span> <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> <em class="replaceable">blue_user_password</em> <span class="token prompt">mysql></span><span class="token command"> SELECT</span> USER<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> USER() <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> [email protected] <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> You might see different results from <a class="link" href="information-functions.html#function_user"> <code class="literal"> USER() </code> </a> , which can return a value that includes a host name rather than an IP address if your DNS is configured to be able to resolve the address to the corresponding host name and the server is not run with the <a class="link" href="server-system-variables.html#sysvar_skip_name_resolve"> <code class="literal"> skip_name_resolve </code> </a> system variable enabled. </p> </div> <p> You might also try invoking <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> without the <a class="link" href="mysql-command-options.html#option_mysql_network-namespace"> <code class="option"> --network-namespace </code> </a> option to see whether the connection attempt succeeds, and, if so, how the <a class="link" href="information-functions.html#function_user"> <code class="literal"> USER() </code> </a> value is affected. </p> </li> </ol> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="network-namespaces-monitoring"> </a> Network Namespace Monitoring </h4> </div> </div> </div> <p> For replication monitoring purposes, these information sources have a column that displays the applicable network namespace for connections: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The Performance Schema <code class="literal"> replication_connection_configuration </code> table. See <a class="xref" href="performance-schema-replication-connection-configuration-table.html" title="29.12.11.11 The replication_connection_configuration Table"> Section 29.12.11.11, “The replication_connection_configuration Table” </a> . </p> </li> <li class="listitem"> <p> The replica server connection metadata repository. See <a class="xref" href="replica-logs-status.html" title="19.2.4.2 Replication Metadata Repositories"> Section 19.2.4.2, “Replication Metadata Repositories” </a> . </p> </li> <li class="listitem"> <p> The <a class="link" href="show-replica-status.html" title="15.7.7.35 SHOW REPLICA STATUS Statement"> <code class="literal"> SHOW REPLICA STATUS </code> </a> statement. </p> </li> </ul> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/replication-privilege-checks.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="replication-privilege-checks"> </a> 19.3.3 Replication Privilege Checks </h3> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="replication-privilege-checks-account.html"> 19.3.3.1 Privileges For The Replication PRIVILEGE_CHECKS_USER Account </a> </span> </dt> <dt> <span class="section"> <a href="replication-privilege-checks-gr.html"> 19.3.3.2 Privilege Checks For Group Replication Channels </a> </span> </dt> <dt> <span class="section"> <a href="replication-privilege-checks-recover.html"> 19.3.3.3 Recovering From Failed Replication Privilege Checks </a> </span> </dt> </dl> </div> <p> By default, MySQL replication (including Group Replication) does not carry out privilege checks when transactions that were already accepted by another server are applied on a replica or group member. You can create a user account with the appropriate privileges to apply the transactions that are normally replicated on a channel, and specify this as the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account for the replication applier, using a <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement. MySQL then checks each transaction against the user account's privileges to verify that you have authorized the operation for that channel. The account can also be safely used by an administrator to apply or reapply transactions from <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> output, for example to recover from a replication error on the channel. </p> <p> The use of a <code class="literal"> PRIVILEGE_CHECKS_USER </code> account helps secure a replication channel against the unauthorized or accidental use of privileged or unwanted operations. The <code class="literal"> PRIVILEGE_CHECKS_USER </code> account provides an additional layer of security in situations such as these: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> You are replicating between a server instance on your organization's network, and a server instance on another network, such as an instance supplied by a cloud service provider. </p> </li> <li class="listitem"> <p> You want to have multiple on-premise or off-site deployments administered as separate units, without giving one administrator account privileges on all the deployments. </p> </li> <li class="listitem"> <p> You want to have an administrator account that enables an administrator to perform only operations that are directly relevant to the replication channel and the databases it replicates, rather than having wide privileges on the server instance. </p> </li> </ul> </div> <p> You can increase the security of a replication channel where privilege checks are applied by adding one or both of these options to the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement when you specify the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account for the channel: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The <code class="literal"> REQUIRE_ROW_FORMAT </code> option makes the replication channel accept only row-based replication events. When <code class="literal"> REQUIRE_ROW_FORMAT </code> is set, you must use row-based binary logging ( <a class="link" href="replication-options-binary-log.html#sysvar_binlog_format"> <code class="literal"> binlog_format=ROW </code> </a> ) on the source server. With statement-based binary logging, some administrator-level privileges might be required for the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account to execute transactions successfully. </p> </li> <li class="listitem"> <p> The <code class="literal"> REQUIRE_TABLE_PRIMARY_KEY_CHECK </code> option makes the replication channel use its own policy for primary key checks. Setting <code class="literal"> ON </code> means that primary keys are always required, and setting <code class="literal"> OFF </code> means that primary keys are never required. The default setting, <code class="literal"> STREAM </code> , sets the session value of the <a class="link" href="server-system-variables.html#sysvar_sql_require_primary_key"> <code class="literal"> sql_require_primary_key </code> </a> system variable using the value that is replicated from the source for each transaction. When <code class="literal"> PRIVILEGE_CHECKS_USER </code> is set, setting <code class="literal"> REQUIRE_TABLE_PRIMARY_KEY_CHECK </code> to either <code class="literal"> ON </code> or <code class="literal"> OFF </code> means that the user account does not need session administration level privileges to set restricted session variables, which are required to change the value of <a class="link" href="server-system-variables.html#sysvar_sql_require_primary_key"> <code class="literal"> sql_require_primary_key </code> </a> . It also normalizes the behavior across replication channels for different sources. </p> </li> </ul> </div> <p> You grant the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege to enable a user account to appear as the <code class="literal"> PRIVILEGE_CHECKS_USER </code> for a replication applier thread, and to execute the internal-use <a class="link" href="binlog.html" title="15.7.8.1 BINLOG Statement"> <code class="literal"> BINLOG </code> </a> statements used by mysqlbinlog. The user name and host name for the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account must follow the syntax described in <a class="xref" href="account-names.html" title="8.2.4 Specifying Account Names"> Section 8.2.4, “Specifying Account Names” </a> , and the user must not be an anonymous user (with a blank user name) or the <code class="literal"> CURRENT_USER </code> . To create a new account, use <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> . To grant this account the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege, use the <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> statement. For example, to create a user account <code class="literal"> priv_repl </code> , which can be used manually by an administrator from any host in the <code class="literal"> example.com </code> domain, and requires an encrypted connection, issue the following statements: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa21760136"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> sql_log_bin <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'priv_repl'</span>@<span class="token string">'%.example.com'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">password</em>'</span> <span class="token keyword">REQUIRE</span> <span class="token keyword">SSL</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> REPLICATION_APPLIER <span class="token keyword">ON</span> <span class="token operator">*</span><span class="token punctuation">.</span><span class="token operator">*</span> <span class="token keyword">TO</span> <span class="token string">'priv_repl'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> sql_log_bin <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span></code></pre> </div> <p> The <code class="literal"> SET sql_log_bin </code> statements are used so that the account management statements are not added to the binary log and sent to the replication channels (see <a class="xref" href="set-sql-log-bin.html" title="15.4.1.3 SET sql_log_bin Statement"> Section 15.4.1.3, “SET sql_log_bin Statement” </a> ). </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> The <code class="literal"> caching_sha2_password </code> authentication plugin is the default for new users (for details, see <a class="xref" href="caching-sha2-pluggable-authentication.html" title="8.4.1.2 Caching SHA-2 Pluggable Authentication"> Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication” </a> ). To connect to a server using a user account that authenticates with this plugin, you must either set up an encrypted connection as described in <a class="xref" href="replication-encrypted-connections.html" title="19.3.1 Setting Up Replication to Use Encrypted Connections"> Section 19.3.1, “Setting Up Replication to Use Encrypted Connections” </a> , or enable the unencrypted connection to support password exchange using an RSA key pair. </p> </div> <p> After setting up the user account, use the <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> statement to grant additional privileges to enable the user account to make the database changes that you expect the applier thread to carry out, such as updating specific tables held on the server. These same privileges enable an administrator to use the account if they need to execute any of those transactions manually on the replication channel. If an unexpected operation is attempted for which you did not grant the appropriate privileges, the operation is disallowed and the replication applier thread stops with an error. <a class="xref" href="replication-privilege-checks-account.html" title="19.3.3.1 Privileges For The Replication PRIVILEGE_CHECKS_USER Account"> Section 19.3.3.1, “Privileges For The Replication PRIVILEGE_CHECKS_USER Account” </a> explains what additional privileges the account needs. For example, to grant the <code class="literal"> priv_repl </code> user account the <a class="link" href="privileges-provided.html#priv_insert"> <code class="literal"> INSERT </code> </a> privilege to add rows to the <code class="literal"> cust </code> table in <code class="literal"> db1 </code> , issue the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa20609017"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> <span class="token keyword">INSERT</span> <span class="token keyword">ON</span> db1<span class="token punctuation">.</span>cust <span class="token keyword">TO</span> <span class="token string">'priv_repl'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">;</span></code></pre> </div> <p> You assign the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account for a replication channel using a <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement. If replication is running, issue <a class="link" href="stop-replica.html" title="15.4.2.5 STOP REPLICA Statement"> <code class="literal"> STOP REPLICA </code> </a> before the <a class="link" href="change-replication-source-to.html" title="15.4.2.2 CHANGE REPLICATION SOURCE TO Statement"> <code class="literal"> CHANGE REPLICATION SOURCE TO </code> </a> statement, and <a class="link" href="start-replica.html" title="15.4.2.4 START REPLICA Statement"> <code class="literal"> START REPLICA </code> </a> after it. The use of row-based binary logging is strongly recommended when <code class="literal"> PRIVILEGE_CHECKS_USER </code> is set; you can use the statement to set <code class="literal"> REQUIRE_ROW_FORMAT </code> to enforce this. </p> <p> When you restart the replication channel, checks on dynamic privileges are applied from that point on. However, static global privileges are not active in the applier's context until you reload the grant tables, because these privileges are not changed for a connected client. To activate static privileges, perform a flush-privileges operation. This can be done by issuing a <a class="link" href="flush.html#flush-privileges"> <code class="literal"> FLUSH PRIVILEGES </code> </a> statement or by executing a <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin flush-privileges </strong> </span> </a> or <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin reload </strong> </span> </a> command. </p> <p> For example, to start privilege checks on the channel <code class="literal"> channel_1 </code> on a running replica, issue the following statements: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa47531897"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">STOP</span> <span class="token keyword">REPLICA</span> <span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'channel_1'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CHANGE</span> <span class="token keyword">REPLICATION</span> <span class="token keyword">SOURCE</span> <span class="token keyword">TO</span> <span class="token operator">></span> <span class="token keyword">PRIVILEGE_CHECKS_USER</span> <span class="token operator">=</span> <span class="token string">'priv_repl'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">,</span> <span class="token operator">></span> <span class="token keyword">REQUIRE_ROW_FORMAT</span> <span class="token operator">=</span> <span class="token number">1</span> <span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'channel_1'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">FLUSH</span> <span class="token keyword">PRIVILEGES</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">START</span> <span class="token keyword">REPLICA</span> <span class="token keyword">FOR</span> <span class="token keyword">CHANNEL</span> <span class="token string">'channel_1'</span><span class="token punctuation">;</span></code></pre> </div> <p> If you do not specify a channel and no other channels exist, the statement is applied to the default channel. The user name and host name for the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account for a channel are shown in the Performance Schema <a class="link" href="performance-schema-replication-applier-configuration-table.html" title="29.12.11.2 The replication_applier_configuration Table"> <code class="literal"> replication_applier_configuration </code> </a> table, where they are properly escaped so they can be copied directly into SQL statements to execute individual transactions. </p> <p> If you are using the <code class="literal"> Rewriter </code> plugin, you should grant the <code class="literal"> PRIVILEGE_CHECKS_USER </code> user account the <a class="link" href="privileges-provided.html#priv_skip-query-rewrite"> <code class="literal"> SKIP_QUERY_REWRITE </code> </a> privilege. This prevents statements issued by this user from being rewritten. See <a class="xref" href="rewriter-query-rewrite-plugin.html" title="7.6.4 The Rewriter Query Rewrite Plugin"> Section 7.6.4, “The Rewriter Query Rewrite Plugin” </a> , for more information. </p> <p> When <code class="literal"> REQUIRE_ROW_FORMAT </code> is set for a replication channel, the replication applier does not create or drop temporary tables, and so does not set the <a class="link" href="server-system-variables.html#sysvar_pseudo_thread_id"> <code class="literal"> pseudo_thread_id </code> </a> session system variable. It does not execute <code class="literal"> LOAD DATA INFILE </code> instructions, and so does not attempt file operations to access or delete the temporary files associated with data loads (logged as a <code class="literal"> Format_description_log_event </code> ). It does not execute <code class="literal"> INTVAR </code> , <code class="literal"> RAND </code> , and <code class="literal"> USER_VAR </code> events, which are used to reproduce the client's connection state for statement-based replication. (An exception is <code class="literal"> USER_VAR </code> events that are associated with DDL queries, which are executed.) It does not execute any statements that are logged within DML transactions. If the replication applier detects any of these types of event while attempting to queue or apply a transaction, the event is not applied, and replication stops with an error. </p> <p> You can set <code class="literal"> REQUIRE_ROW_FORMAT </code> for a replication channel whether or not you set a <code class="literal"> PRIVILEGE_CHECKS_USER </code> account. The restrictions implemented when you set this option increase the security of the replication channel even without privilege checks. You can also specify the <code class="option"> --require-row-format </code> option when you use <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> , to enforce row-based replication events in <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> output. </p> <p> <b> Security Context. </b> By default, when a replication applier thread is started with a user account specified as the <code class="literal"> PRIVILEGE_CHECKS_USER </code> , the security context is created using default roles, or with all roles if <a class="link" href="server-system-variables.html#sysvar_activate_all_roles_on_login"> <code class="literal"> activate_all_roles_on_login </code> </a> is set to <code class="literal"> ON </code> . </p> <p> You can use roles to supply a general privilege set to accounts that are used as <code class="literal"> PRIVILEGE_CHECKS_USER </code> accounts, as in the following example. Here, instead of granting the <a class="link" href="privileges-provided.html#priv_insert"> <code class="literal"> INSERT </code> </a> privilege for the <code class="literal"> db1.cust </code> table directly to a user account as in the earlier example, this privilege is granted to the role <code class="literal"> priv_repl_role </code> along with the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege. The role is then used to grant the privilege set to two user accounts, both of which can now be used as <code class="literal"> PRIVILEGE_CHECKS_USER </code> accounts: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa94585178"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> sql_log_bin <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'priv_repa'</span>@<span class="token string">'%.example.com'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">password</em>'</span> <span class="token keyword">REQUIRE</span> <span class="token keyword">SSL</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'priv_repb'</span>@<span class="token string">'%.example.com'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">password</em>'</span> <span class="token keyword">REQUIRE</span> <span class="token keyword">SSL</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">ROLE</span> <span class="token string">'priv_repl_role'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> REPLICATION_APPLIER <span class="token keyword">TO</span> <span class="token string">'priv_repl_role'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> <span class="token keyword">INSERT</span> <span class="token keyword">ON</span> db1<span class="token punctuation">.</span>cust <span class="token keyword">TO</span> <span class="token string">'priv_repl_role'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">GRANT</span> <span class="token string">'priv_repl_role'</span> <span class="token keyword">TO</span> <span class="token string">'priv_repa'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">,</span> <span class="token string">'priv_repb'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token keyword">DEFAULT</span> <span class="token keyword">ROLE</span> <span class="token string">'priv_repl_role'</span> <span class="token keyword">TO</span> <span class="token string">'priv_repa'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">,</span> <span class="token string">'priv_repb'</span>@<span class="token string">'%.example.com'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> sql_log_bin <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span></code></pre> </div> <p> Be aware that when the replication applier thread creates the security context, it checks the privileges for the <code class="literal"> PRIVILEGE_CHECKS_USER </code> account, but does not carry out password validation, and does not carry out checks relating to account management, such as checking whether the account is locked. The security context that is created remains unchanged for the lifetime of the replication applier thread. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replication.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="mysql-cluster-replication"> </a> 25.7 NDB Cluster Replication </h2> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="mysql-cluster-replication-abbreviations.html"> 25.7.1 NDB Cluster Replication: Abbreviations and Symbols </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-general.html"> 25.7.2 General Requirements for NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-issues.html"> 25.7.3 Known Issues in NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-schema.html"> 25.7.4 NDB Cluster Replication Schema and Tables </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-preparation.html"> 25.7.5 Preparing the NDB Cluster for Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-starting.html"> 25.7.6 Starting NDB Cluster Replication (Single Replication Channel) </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-two-channels.html"> 25.7.7 Using Two Replication Channels for NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-failover.html"> 25.7.8 Implementing Failover with NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-backups.html"> 25.7.9 NDB Cluster Backups With NDB Cluster Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-multi-source.html"> 25.7.10 NDB Cluster Replication: Bidirectional and Circular Replication </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-mta.html"> 25.7.11 NDB Cluster Replication Using the Multithreaded Applier </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-replication-conflict-resolution.html"> 25.7.12 NDB Cluster Replication Conflict Resolution </a> </span> </dt> </dl> </div> <a class="indexterm" name="idm46045086859680"> </a> <a class="indexterm" name="idm46045086857776"> </a> <a class="indexterm" name="idm46045086855872"> </a> <a class="indexterm" name="idm46045086854800"> </a> <a class="indexterm" name="idm46045086853344"> </a> <p> NDB Cluster supports <span class="firstterm"> asynchronous replication </span> , more usually referred to simply as <span class="quote"> “ <span class="quote"> replication </span> ” </span> . This section explains how to set up and manage a configuration in which one group of computers operating as an NDB Cluster replicates to a second computer or group of computers. We assume some familiarity on the part of the reader with standard MySQL replication as discussed elsewhere in this Manual. (See <a class="xref" href="replication.html" title="Chapter 19 Replication"> Chapter 19, <i> Replication </i> </a> ). </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> NDB Cluster does not support replication using GTIDs; semisynchronous replication and group replication are also not supported by the <code class="literal"> NDB </code> storage engine. </p> </div> <p> Normal (non-clustered) replication involves a source server and a replica server, the source being so named because operations and data to be replicated originate with it, and the replica being the recipient of these. In NDB Cluster, replication is conceptually very similar but can be more complex in practice, as it may be extended to cover a number of different configurations including replicating between two complete clusters. Although an NDB Cluster itself depends on the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine for clustering functionality, it is not necessary to use <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> as the storage engine for the replica's copies of the replicated tables (see <a class="xref" href="mysql-cluster-replication-issues.html#mysql-cluster-replication-ndb-to-non-ndb" title="Replication from NDB to other storage engines"> Replication from NDB to other storage engines </a> ). However, for maximum availability, it is possible (and preferable) to replicate from one NDB Cluster to another, and it is this scenario that we discuss, as shown in the following figure: </p> <div class="figure"> <a name="fig-mysql-cluster-cluster-replication"> </a> <p class="title"> <b> Figure 25.10 NDB Cluster-to-Cluster Replication Layout </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Much of the content is described in the surrounding text. It visualizes how a MySQL source is replicated. The replica differs in that it shows an I/O (receiver) thread pointing to a relay binary log which points to an SQL (applier) thread. In addition, while the binary log points to and from the NDBCLUSTER engine on the source server, on the replica it points directly to an SQL node (MySQL server)." src="images/cluster-replication-overview.png" style="width: 100%; max-width: 716px;"/> </div> </div> </div> <br class="figure-break"/> <p> In this scenario, the replication process is one in which successive states of a source cluster are logged and saved to a replica cluster. This process is accomplished by a special thread known as the NDB binary log injector thread, which runs on each MySQL server and produces a binary log ( <code class="literal"> binlog </code> ). This thread ensures that all changes in the cluster producing the binary log—and not just those changes that are effected through the MySQL Server—are inserted into the binary log with the correct serialization order. We refer to the MySQL source and replica servers as replication servers or replication nodes, and the data flow or line of communication between them as a <span class="firstterm"> replication channel </span> . </p> <p> For information about performing point-in-time recovery with NDB Cluster and NDB Cluster Replication, see <a class="xref" href="mysql-cluster-replication-pitr.html" title="25.7.9.2 Point-In-Time Recovery Using NDB Cluster Replication"> Section 25.7.9.2, “Point-In-Time Recovery Using NDB Cluster Replication” </a> . </p> <a class="indexterm" name="idm46045086831712"> </a> <a class="indexterm" name="idm46045086830256"> </a> <p> <b> NDB API replica status variables. </b> NDB API counters can provide enhanced monitoring capabilities on replica clusters. These counters are implemented as NDB statistics <code class="literal"> _replica </code> status variables, as seen in the output of <a class="link" href="show-status.html" title="15.7.7.37 SHOW STATUS Statement"> <code class="literal"> SHOW STATUS </code> </a> , or in the results of queries against the Performance Schema <a class="link" href="performance-schema-status-variable-tables.html" title="29.12.15 Performance Schema Status Variable Tables"> <code class="literal"> session_status </code> </a> or <a class="link" href="performance-schema-status-variable-tables.html" title="29.12.15 Performance Schema Status Variable Tables"> <code class="literal"> global_status </code> </a> table in a <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client session connected to a MySQL Server that is acting as a replica in NDB Cluster Replication. By comparing the values of these status variables before and after the execution of statements affecting replicated <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables, you can observe the corresponding actions taken on the NDB API level by the replica, which can be useful when monitoring or troubleshooting NDB Cluster Replication. <a class="xref" href="mysql-cluster-ndb-api-statistics.html" title="25.6.16 NDB API Statistics Counters and Variables"> Section 25.6.16, “NDB API Statistics Counters and Variables” </a> , provides additional information. </p> <p> <b> Replication from NDB to non-NDB tables. </b> It is possible to replicate <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables from an NDB Cluster acting as the replication source to tables using other MySQL storage engines such as <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> or <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> on a replica <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . This is subject to a number of conditions; see <a class="xref" href="mysql-cluster-replication-issues.html#mysql-cluster-replication-ndb-to-non-ndb" title="Replication from NDB to other storage engines"> Replication from NDB to other storage engines </a> , and <a class="xref" href="mysql-cluster-replication-issues.html#mysql-cluster-replication-ndb-to-nontransactional" title="Replication from NDB to a nontransactional storage engine"> Replication from NDB to a nontransactional storage engine </a> , for more information. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/group-replication-performance-xcom-cache-reduce.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="group-replication-performance-xcom-cache-reduce"> </a> 20.7.6.2 Reducing the cache size </h4> </div> </div> </div> <p> The minimum setting for the XCom message cache size in MySQL 8.4 is 128 MB, which enables deployment on a host that has a restricted amount of available memory. Having a very low <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_message_cache_size"> <code class="literal"> group_replication_message_cache_size </code> </a> setting is not recommended if the host is on an unstable network, because a smaller message cache makes it harder for group members to reconnect after a transient loss of connectivity. </p> <p> If a reconnecting member cannot retrieve all the messages it needs from the XCom message cache, the member must leave the group and rejoin it, in order to retrieve the missing transactions from another member's binary log using distributed recovery. A member that has left a group makes three auto-rejoin attempts by default, so the process of rejoining the group can still take place without operator intervention. However, rejoining using distributed recovery is a significantly longer and more complex process than retrieving messages from an XCom message cache, so the member takes longer to become available and the performance of the group can be impacted. On a stable network, which minimizes the frequency and duration of transient losses of connectivity for members, the frequency of this occurrence should also be minimized, so the group might be able to tolerate a smaller XCom message cache size without a significant impact on its performance. </p> <p> If you are considering reducing the cache size limit, you can query the Performance Schema table <a class="link" href="performance-schema-memory-summary-tables.html" title="29.12.20.10 Memory Summary Tables"> <code class="literal"> memory_summary_global_by_event_name </code> </a> using the following statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa6704907"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>memory_summary_global_by_event_name <span class="token keyword">WHERE</span> EVENT_NAME <span class="token operator">LIKE</span> <span class="token string">'memory/group_rpl/GCS_XCom::xcom_cache'</span><span class="token punctuation">;</span></code></pre> </div> <p> This returns memory usage statistics for the message cache, including the current number of cached entries and current size of the cache. If you reduce the cache size limit, XCom removes the oldest entries that have been decided and delivered until the current size is below the limit. XCom might temporarily exceed the cache size limit while this removal process is ongoing. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/information-schema-tables-extensions-table.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-tables-extensions-table"> </a> 28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045078297552"> </a> <p> The <a class="link" href="information-schema-tables-extensions-table.html" title="28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table"> <code class="literal"> TABLES_EXTENSIONS </code> </a> table provides information about table attributes defined for primary and secondary storage engines. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The <a class="link" href="information-schema-tables-extensions-table.html" title="28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table"> <code class="literal"> TABLES_EXTENSIONS </code> </a> table is reserved for future use. </p> </div> <p> The <a class="link" href="information-schema-tables-extensions-table.html" title="28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table"> <code class="literal"> TABLES_EXTENSIONS </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> TABLE_CATALOG </code> </p> <p> The name of the catalog to which the table belongs. This value is always <code class="literal"> def </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_SCHEMA </code> </p> <p> The name of the schema (database) to which the table belongs. </p> </li> <li class="listitem"> <p> <code class="literal"> TABLE_NAME </code> </p> <p> The name of the table. </p> </li> <li class="listitem"> <p> <code class="literal"> ENGINE_ATTRIBUTE </code> </p> <p> Table attributes defined for the primary storage engine. Reserved for future use. </p> </li> <li class="listitem"> <p> <code class="literal"> SECONDARY_ENGINE_ATTRIBUTE </code> </p> <p> Table attributes defined for the secondary storage engine. Reserved for future use. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/information-schema-introduction.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="information-schema-introduction"> </a> 28.1 Introduction </h2> </div> </div> </div> <p> <code class="literal"> INFORMATION_SCHEMA </code> provides access to database <span class="firstterm"> metadata </span> , information about the MySQL server such as the name of a database or table, the data type of a column, or access privileges. Other terms that are sometimes used for this information are <span class="firstterm"> data dictionary </span> and <span class="firstterm"> system catalog </span> . </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-usage-notes" title="INFORMATION_SCHEMA Usage Notes"> INFORMATION_SCHEMA Usage Notes </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-character-set-considerations" title="Character Set Considerations"> Character Set Considerations </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-as-show-alternative" title="INFORMATION_SCHEMA as Alternative to SHOW Statements"> INFORMATION_SCHEMA as Alternative to SHOW Statements </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-privileges" title="INFORMATION_SCHEMA and Privileges"> INFORMATION_SCHEMA and Privileges </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-performance-considerations" title="Performance Considerations"> Performance Considerations </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-standards-considerations" title="Standards Considerations"> Standards Considerations </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-conventions" title="Conventions in the INFORMATION_SCHEMA Reference Sections"> Conventions in the INFORMATION_SCHEMA Reference Sections </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="information-schema-introduction.html#information-schema-related-information" title="Related Information"> Related Information </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-usage-notes"> </a> INFORMATION_SCHEMA Usage Notes </h3> </div> </div> </div> <p> <code class="literal"> INFORMATION_SCHEMA </code> is a database within each MySQL instance, the place that stores information about all the other databases that the MySQL server maintains. The <code class="literal"> INFORMATION_SCHEMA </code> database contains several read-only tables. They are actually views, not base tables, so there are no files associated with them, and you cannot set triggers on them. Also, there is no database directory with that name. </p> <p> Although you can select <code class="literal"> INFORMATION_SCHEMA </code> as the default database with a <a class="link" href="use.html" title="15.8.4 USE Statement"> <code class="literal"> USE </code> </a> statement, you can only read the contents of tables, not perform <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , or <a class="link" href="delete.html" title="15.2.2 DELETE Statement"> <code class="literal"> DELETE </code> </a> operations on them. </p> <p> Here is an example of a statement that retrieves information from <code class="literal"> INFORMATION_SCHEMA </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa89260799"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token keyword">table_name</span><span class="token punctuation">,</span> table_type<span class="token punctuation">,</span> <span class="token keyword">engine</span> <span class="token keyword">FROM</span> information_schema<span class="token punctuation">.</span><span class="token keyword">tables</span> <span class="token keyword">WHERE</span> table_schema <span class="token operator">=</span> <span class="token string">'db5'</span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> <span class="token keyword">table_name</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> table_name <span class="token punctuation">|</span> table_type <span class="token punctuation">|</span> engine <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> fk <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> InnoDB <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> fk2 <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> InnoDB <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> goto <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> into <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> k <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> kurs <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> loop <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> pk <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> InnoDB <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> t <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> t2 <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> t3 <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> t7 <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> tables <span class="token punctuation">|</span> BASE TABLE <span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> v <span class="token punctuation">|</span> VIEW <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> v2 <span class="token punctuation">|</span> VIEW <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> v3 <span class="token punctuation">|</span> VIEW <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> v56 <span class="token punctuation">|</span> VIEW <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">17 rows in set (0.01 sec)</span></code></pre> </div> <p> Explanation: The statement requests a list of all the tables in database <code class="literal"> db5 </code> , showing just three pieces of information: the name of the table, its type, and its storage engine. </p> <p> Information about generated invisible primary keys is visible by default in all <code class="literal"> INFORMATION_SCHEMA </code> tables describing table columns, keys, or both, such as the <a class="link" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> <code class="literal"> COLUMNS </code> </a> and <a class="link" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table"> <code class="literal"> STATISTICS </code> </a> tables. If you wish to make such information hidden from queries that select from these tables, you can do so by setting the value of the <a class="link" href="server-system-variables.html#sysvar_show_gipk_in_create_table_and_information_schema"> <code class="literal"> show_gipk_in_create_table_and_information_schema </code> </a> server system variable to <code class="literal"> OFF </code> . For more information, see <a class="xref" href="create-table-gipks.html" title="15.1.20.11 Generated Invisible Primary Keys"> Section 15.1.20.11, “Generated Invisible Primary Keys” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-character-set-considerations"> </a> Character Set Considerations </h3> </div> </div> </div> <p> The definition for character columns (for example, <code class="literal"> TABLES.TABLE_NAME </code> ) is generally <code class="literal"> VARCHAR( <em class="replaceable"> <code> N </code> </em> ) CHARACTER SET utf8mb3 </code> where <em class="replaceable"> <code> N </code> </em> is at least 64. MySQL uses the default collation for this character set ( <code class="literal"> utf8mb3_general_ci </code> ) for all searches, sorts, comparisons, and other string operations on such columns. </p> <p> Because some MySQL objects are represented as files, searches in <code class="literal"> INFORMATION_SCHEMA </code> string columns can be affected by file system case sensitivity. For more information, see <a class="xref" href="charset-collation-information-schema.html" title="12.8.7 Using Collation in INFORMATION_SCHEMA Searches"> Section 12.8.7, “Using Collation in INFORMATION_SCHEMA Searches” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-as-show-alternative"> </a> INFORMATION_SCHEMA as Alternative to SHOW Statements </h3> </div> </div> </div> <p> The <code class="literal"> SELECT ... FROM INFORMATION_SCHEMA </code> statement is intended as a more consistent way to provide access to the information provided by the various <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statements that MySQL supports ( <a class="link" href="show-databases.html" title="15.7.7.15 SHOW DATABASES Statement"> <code class="literal"> SHOW DATABASES </code> </a> , <a class="link" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> <code class="literal"> SHOW TABLES </code> </a> , and so forth). Using <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> has these advantages, compared to <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> : </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> It conforms to Codd's rules, because all access is done on tables. </p> </li> <li class="listitem"> <p> You can use the familiar syntax of the <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> statement, and only need to learn some table and column names. </p> </li> <li class="listitem"> <p> The implementor need not worry about adding keywords. </p> </li> <li class="listitem"> <p> You can filter, sort, concatenate, and transform the results from <code class="literal"> INFORMATION_SCHEMA </code> queries into whatever format your application needs, such as a data structure or a text representation to parse. </p> </li> <li class="listitem"> <p> This technique is more interoperable with other database systems. For example, Oracle Database users are familiar with querying tables in the Oracle data dictionary. </p> </li> </ul> </div> <p> Because <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> is familiar and widely used, the <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statements remain as an alternative. In fact, along with the implementation of <code class="literal"> INFORMATION_SCHEMA </code> , there are enhancements to <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> as described in <a class="xref" href="extended-show.html" title="28.8 Extensions to SHOW Statements"> Section 28.8, “Extensions to SHOW Statements” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-privileges"> </a> INFORMATION_SCHEMA and Privileges </h3> </div> </div> </div> <p> For most <code class="literal"> INFORMATION_SCHEMA </code> tables, each MySQL user has the right to access them, but can see only the rows in the tables that correspond to objects for which the user has the proper access privileges. In some cases (for example, the <code class="literal"> ROUTINE_DEFINITION </code> column in the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-routines-table.html" title="28.3.30 The INFORMATION_SCHEMA ROUTINES Table"> <code class="literal"> ROUTINES </code> </a> table), users who have insufficient privileges see <code class="literal"> NULL </code> . Some tables have different privilege requirements; for these, the requirements are mentioned in the applicable table descriptions. For example, <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> tables (tables with names that begin with <code class="literal"> INNODB_ </code> ) require the <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> privilege. </p> <p> The same privileges apply to selecting information from <code class="literal"> INFORMATION_SCHEMA </code> and viewing the same information through <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statements. In either case, you must have some privilege on an object to see information about it. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-performance-considerations"> </a> Performance Considerations </h3> </div> </div> </div> <p> <code class="literal"> INFORMATION_SCHEMA </code> queries that search for information from more than one database might take a long time and impact performance. To check the efficiency of a query, you can use <a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement"> <code class="literal"> EXPLAIN </code> </a> . For information about using <a class="link" href="explain.html" title="15.8.2 EXPLAIN Statement"> <code class="literal"> EXPLAIN </code> </a> output to tune <code class="literal"> INFORMATION_SCHEMA </code> queries, see <a class="xref" href="information-schema-optimization.html" title="10.2.3 Optimizing INFORMATION_SCHEMA Queries"> Section 10.2.3, “Optimizing INFORMATION_SCHEMA Queries” </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-standards-considerations"> </a> Standards Considerations </h3> </div> </div> </div> <p> The implementation for the <code class="literal"> INFORMATION_SCHEMA </code> table structures in MySQL follows the ANSI/ISO SQL:2003 standard Part 11 <em class="citetitle"> Schemata </em> . Our intent is approximate compliance with SQL:2003 core feature F021 <em class="citetitle"> Basic information schema </em> . </p> <p> Users of SQL Server 2000 (which also follows the standard) may notice a strong similarity. However, MySQL has omitted many columns that are not relevant for our implementation, and added columns that are MySQL-specific. One such added column is the <code class="literal"> ENGINE </code> column in the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> table. </p> <p> Although other DBMSs use a variety of names, like <code class="literal"> syscat </code> or <code class="literal"> system </code> , the standard name is <code class="literal"> INFORMATION_SCHEMA </code> . </p> <p> To avoid using any name that is reserved in the standard or in DB2, SQL Server, or Oracle, we changed the names of some columns marked <span class="quote"> “ <span class="quote"> MySQL extension </span> ” </span> . (For example, we changed <code class="literal"> COLLATION </code> to <code class="literal"> TABLE_COLLATION </code> in the <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> table.) See the list of reserved words near the end of this article: <a class="ulink" href="https://web.archive.org/web/20070428032454/http://www.dbazine.com/db2/db2-disarticles/gulutzan5" target="_blank"> https://web.archive.org/web/20070428032454/http://www.dbazine.com/db2/db2-disarticles/gulutzan5 </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-conventions"> </a> Conventions in the INFORMATION_SCHEMA Reference Sections </h3> </div> </div> </div> <p> The following sections describe each of the tables and columns in <code class="literal"> INFORMATION_SCHEMA </code> . For each column, there are three pieces of information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <span class="quote"> “ <span class="quote"> <code class="literal"> INFORMATION_SCHEMA </code> Name </span> ” </span> indicates the name for the column in the <code class="literal"> INFORMATION_SCHEMA </code> table. This corresponds to the standard SQL name unless the <span class="quote"> “ <span class="quote"> Remarks </span> ” </span> field says <span class="quote"> “ <span class="quote"> MySQL extension. </span> ” </span> </p> </li> <li class="listitem"> <p> <span class="quote"> “ <span class="quote"> <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> Name </span> ” </span> indicates the equivalent field name in the closest <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statement, if there is one. </p> </li> <li class="listitem"> <p> <span class="quote"> “ <span class="quote"> Remarks </span> ” </span> provides additional information where applicable. If this field is <code class="literal"> NULL </code> , it means that the value of the column is always <code class="literal"> NULL </code> . If this field says <span class="quote"> “ <span class="quote"> MySQL extension, </span> ” </span> the column is a MySQL extension to standard SQL. </p> </li> </ul> </div> <p> Many sections indicate what <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statement is equivalent to a <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> that retrieves information from <code class="literal"> INFORMATION_SCHEMA </code> . For <a class="link" href="show.html" title="15.7.7 SHOW Statements"> <code class="literal"> SHOW </code> </a> statements that display information for the default database if you omit a <code class="literal"> FROM <em class="replaceable"> <code> db_name </code> </em> </code> clause, you can often select information for the default database by adding an <code class="literal"> AND TABLE_SCHEMA = SCHEMA() </code> condition to the <code class="literal"> WHERE </code> clause of a query that retrieves information from an <code class="literal"> INFORMATION_SCHEMA </code> table. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h3 class="title"> <a name="information-schema-related-information"> </a> Related Information </h3> </div> </div> </div> <p> These sections discuss additional <code class="literal"> INFORMATION_SCHEMA </code> -related topics: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> information about <code class="literal"> INFORMATION_SCHEMA </code> tables specific to the <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> storage engine: <a class="xref" href="innodb-information-schema-tables.html" title="28.4 INFORMATION_SCHEMA InnoDB Tables"> Section 28.4, “INFORMATION_SCHEMA InnoDB Tables” </a> </p> </li> <li class="listitem"> <p> information about <code class="literal"> INFORMATION_SCHEMA </code> tables specific to the thread pool plugin: <a class="xref" href="thread-pool-information-schema-tables.html" title="28.5 INFORMATION_SCHEMA Thread Pool Tables"> Section 28.5, “INFORMATION_SCHEMA Thread Pool Tables” </a> </p> </li> <li class="listitem"> <p> information about <code class="literal"> INFORMATION_SCHEMA </code> tables specific to the <code class="literal"> CONNECTION_CONTROL </code> plugin: <a class="xref" href="connection-control-information-schema-tables.html" title="28.6 INFORMATION_SCHEMA Connection-Control Tables"> Section 28.6, “INFORMATION_SCHEMA Connection-Control Tables” </a> </p> </li> <li class="listitem"> <p> Answers to questions that are often asked concerning the <code class="literal"> INFORMATION_SCHEMA </code> database: <a class="xref" href="faqs-information-schema.html" title="A.7 MySQL 8.4 FAQ: INFORMATION_SCHEMA"> Section A.7, “MySQL 8.4 FAQ: INFORMATION_SCHEMA” </a> </p> </li> <li class="listitem"> <p> <code class="literal"> INFORMATION_SCHEMA </code> queries and the optimizer: <a class="xref" href="information-schema-optimization.html" title="10.2.3 Optimizing INFORMATION_SCHEMA Queries"> Section 10.2.3, “Optimizing INFORMATION_SCHEMA Queries” </a> </p> </li> <li class="listitem"> <p> The effect of collation on <code class="literal"> INFORMATION_SCHEMA </code> comparisons: <a class="xref" href="charset-collation-information-schema.html" title="12.8.7 Using Collation in INFORMATION_SCHEMA Searches"> Section 12.8.7, “Using Collation in INFORMATION_SCHEMA Searches” </a> </p> </li> </ul> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-data-node-memory-management.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-data-node-memory-management"> </a> 25.4.3.13 Data Node Memory Management </h4> </div> </div> </div> <p> All memory allocation for a data node is performed when the node is started. This ensures that the data node can run in a stable manner without using swap memory, so that <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> can be used for latency-sensitive (realtime) applications. The following types of memory are allocated on data node startup: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Data memory </p> </li> <li class="listitem"> <p> Shared global memory </p> </li> <li class="listitem"> <p> Redo log buffers </p> </li> <li class="listitem"> <p> Job buffers </p> </li> <li class="listitem"> <p> Send buffers </p> </li> <li class="listitem"> <p> Page cache for disk data records </p> </li> <li class="listitem"> <p> Schema transaction memory </p> </li> <li class="listitem"> <p> Transaction memory </p> </li> <li class="listitem"> <p> Undo log buffer </p> </li> <li class="listitem"> <p> Query memory </p> </li> <li class="listitem"> <p> Block objects </p> </li> <li class="listitem"> <p> Schema memory </p> </li> <li class="listitem"> <p> Block data structures </p> </li> <li class="listitem"> <p> Long signal memory </p> </li> <li class="listitem"> <p> Shared memory communication buffers </p> </li> </ul> </div> <p> The <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> memory manager, which regulates most data node memory, handles the following memory resources: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Data Memory ( <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> ) </p> </li> <li class="listitem"> <p> Redo log buffers ( <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redobuffer"> <code class="literal"> RedoBuffer </code> </a> ) </p> </li> <li class="listitem"> <p> Job buffers </p> </li> <li class="listitem"> <p> Send buffers ( <a class="link" href="mysql-cluster-tcp-definition.html#ndbparam-tcp-sendbuffermemory"> <code class="literal"> SendBufferMemory </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-totalsendbuffermemory"> <code class="literal"> TotalSendBufferMemory </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-extrasendbuffermemory"> <code class="literal"> ExtraSendBufferMemory </code> </a> ) </p> </li> <li class="listitem"> <p> Disk Data record page cache ( <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-diskpagebuffermemory"> <code class="literal"> DiskPageBufferMemory </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-diskpagebufferentries"> <code class="literal"> DiskPageBufferEntries </code> </a> ) </p> </li> <li class="listitem"> <p> Transaction memory ( <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> ) </p> </li> <li class="listitem"> <p> Query memory </p> </li> <li class="listitem"> <p> Disk access records </p> </li> <li class="listitem"> <p> File buffers </p> </li> </ul> </div> <p> Each of these resources is set up with a reserved memory area and a maximum memory area. The reserved memory area can be used only by the resource for which it is reserved and cannot be shared with other resources; a given resource can never allocate more than the maximum memory allowed for the resource. A resource that has no maximum memory can expand to use all the shared memory in the memory manager. </p> <p> The size of the global shared memory for these resources is controlled by the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-sharedglobalmemory"> <code class="literal"> SharedGlobalMemory </code> </a> configuration parameter (default: 128 MB). </p> <p> Data memory is always reserved and never acquires any memory from shared memory. It is controlled using the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> configuration parameter, whose maximum is 16384 GB. <code class="literal"> DataMemory </code> is where records are stored, including hash indexes (approximately 15 bytes per row), ordered indexes (10-12 bytes per row per index), and row headers (16-32 bytes per row). </p> <p> Redo log buffers also use reserved memory only; this is controlled by the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-redobuffer"> <code class="literal"> RedoBuffer </code> </a> configuration parameter, which sets the size of the redo log buffer per LDM thread. This means that the actual amount of memory used is the value of this parameter multiplied by the number of LDM threads in the data node. </p> <p> Job buffers use reserved memory only; the size of this memory is calculated by <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> , based on the numbers of threads of various types. </p> <p> Send buffers have a reserved part but can also allocate an additional 25% of shared global memory. The send buffer reserved size is calculated in two steps: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Use the value of the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-totalsendbuffermemory"> <code class="literal"> TotalSendBufferMemory </code> </a> configuration parameter (no default value) or the sum of the individual send buffers used by all individual connections to the data node. A data node is connected to all other data nodes, to all API nodes, and to all management nodes. This means that, in a cluster with 2 data nodes, 2 management nodes, and 10 API nodes each data node has 13 node connections. Since the default value for <a class="link" href="mysql-cluster-tcp-definition.html#ndbparam-tcp-sendbuffermemory"> <code class="literal"> SendBufferMemory </code> </a> for a data node connection is 2 MByte, this works out to 26 MB total. </p> </li> <li class="listitem"> <p> To obtain the total reserved size for the send buffer, the value of the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-extrasendbuffermemory"> <code class="literal"> ExtraSendBufferMemory </code> </a> configuration parameter, if any (default value 0). is added to the value obtained in the previous step. </p> </li> </ol> </div> <p> In other words, if <code class="literal"> TotalSendBufferMemory </code> has been set, the send buffer size is <code class="literal"> TotalSendBufferMemory + ExtraSendBufferMemory </code> ; otherwise, the size of the send buffer is equal to <code class="literal"> ([ <em class="replaceable"> <code> number of node connections </code> </em> ] * SendBufferMemory) + ExtraSendBufferMemory </code> . </p> <p> The page cache for disk data records uses a reserved resource only; the size of this resource is controlled by the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-diskpagebuffermemory"> <code class="literal"> DiskPageBufferMemory </code> </a> configuration parameter (default 64 MB). Memory for 32 KB disk page entries is also allocated; the number of these is determined by the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-diskpagebufferentries"> <code class="literal"> DiskPageBufferEntries </code> </a> configuration parameter (default 10). </p> <p> Transaction memory has a reserved part that either is calculated by <code class="literal"> NDB </code> , or is set explicitly using the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> configuration parameter; transaction memory can also use an unlimited amount of shared global memory. Transaction memory is used for all operational resources handling transactions, scans, locks, scan buffers, and trigger operations. It also holds table rows as they are updated, before the next commit writes them to data memory. </p> <p> Resources are allocated from a common transaction memory resource and can also use resources from global shared memory. the size of this resource can be controlled using a single <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> configuration parameter. </p> <p> Reserved memory for undo log buffers can be set using the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-initiallogfilegroup"> <code class="literal"> InitialLogFileGroup </code> </a> configuration parameter. If an undo log buffer is created as part of a <a class="link" href="create-logfile-group.html" title="15.1.16 CREATE LOGFILE GROUP Statement"> <code class="literal"> CREATE LOGFILE GROUP </code> </a> SQL statement, the memory is taken from the transaction memory. </p> <p> A number of resources relating to metadata for Disk Data resources also have no reserved part, and use shared global memory only. Shared global shared memory is thus shared between send buffers, transaction memory, and Disk Data metadata. </p> <p> If <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> is not set, it is calculated based on the following parameters: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentoperations"> <code class="literal"> MaxNoOfConcurrentOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrenttransactions"> <code class="literal"> MaxNoOfConcurrentTransactions </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooffiredtriggers"> <code class="literal"> MaxNoOfFiredTriggers </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocaloperations"> <code class="literal"> MaxNoOfLocalOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentindexoperations"> <code class="literal"> MaxNoOfConcurrentIndexOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentscans"> <code class="literal"> MaxNoOfConcurrentScans </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocalscans"> <code class="literal"> MaxNoOfLocalScans </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-batchsizeperlocalscan"> <code class="literal"> BatchSizePerLocalScan </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionbuffermemory"> <code class="literal"> TransactionBufferMemory </code> </a> </p> </li> </ul> </div> <p> When <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionmemory"> <code class="literal"> TransactionMemory </code> </a> is set explicitly, none of the configuration parameters just listed are used to calculate memory size. In addition, the parameters <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentindexoperations"> <code class="literal"> MaxNoOfConcurrentIndexOperations </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooffiredtriggers"> <code class="literal"> MaxNoOfFiredTriggers </code> </a> , <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocaloperations"> <code class="literal"> MaxNoOfLocalOperations </code> </a> , and <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocalscans"> <code class="literal"> MaxNoOfLocalScans </code> </a> are incompatible with <code class="literal"> TransactionMemory </code> and cannot be set concurrently with it; if <code class="literal"> TransactionMemory </code> is set and any of these four parameters are also set in the <code class="filename"> config.ini </code> configuration file, the management server cannot start. </p> <p> The <code class="literal"> MaxNoOfConcurrentIndexOperations </code> , <code class="literal"> MaxNoOfFiredTriggers </code> , <code class="literal"> MaxNoOfLocalOperations </code> , and <code class="literal"> MaxNoOfLocalScans </code> parameters are all deprecated; you should expect them to be removed from a future release of MySQL NDB Cluster. </p> <p> The transaction memory resource contains a large number of memory pools. Each memory pool represents an object type and contains a set of objects; each pool includes a reserved part allocated to the pool at startup; this reserved memory is never returned to shared global memory. Reserved records are found using a data structure having only a single level for fast retrieval, which means that a number of records in each pool should be reserved. The number of reserved records in each pool has some impact on performance and reserved memory allocation, but is generally necessary only in certain very advanced use cases to set the reserved sizes explicitly. </p> <p> The size of the reserved part of the pool can be controlled by setting the following configuration parameters: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedconcurrentindexoperations"> <code class="literal"> ReservedConcurrentIndexOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedfiredtriggers"> <code class="literal"> ReservedFiredTriggers </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedconcurrentoperations"> <code class="literal"> ReservedConcurrentOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedlocalscans"> <code class="literal"> ReservedLocalScans </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedconcurrenttransactions"> <code class="literal"> ReservedConcurrentTransactions </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedconcurrentscans"> <code class="literal"> ReservedConcurrentScans </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-reservedtransactionbuffermemory"> <code class="literal"> ReservedTransactionBufferMemory </code> </a> </p> </li> </ul> </div> <p> For any of the parameters just listed that is not set explicitly in <code class="filename"> config.ini </code> , the reserved setting is calculated as 25% of the corresponding maximum setting. For example, if unset, <code class="literal"> ReservedConcurrentIndexOperations </code> is calculated as 25% of <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentindexoperations"> <code class="literal"> MaxNoOfConcurrentIndexOperations </code> </a> , and <code class="literal"> ReservedLocalScans </code> is calculated as 25% of <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooflocalscans"> <code class="literal"> MaxNoOfLocalScans </code> </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> If <code class="literal"> ReservedTransactionBufferMemory </code> is not set, it is calculated as 25% of <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-transactionbuffermemory"> <code class="literal"> TransactionBufferMemory </code> </a> . </p> </div> <p> The number of reserved records is per data node; these records are split among the threads handling them (LDM and TC threads) on each node. In most cases, it is sufficient to set <code class="literal"> TransactionMemory </code> alone, and to allow the number of records in pools to be governed by its value. </p> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentscans"> <code class="literal"> MaxNoOfConcurrentScans </code> </a> limits the number of concurrent scans that can be active in each TC thread. This is important in guarding against cluster overload. </p> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentoperations"> <code class="literal"> MaxNoOfConcurrentOperations </code> </a> limits the number of operations that can be active at any one time in updating transactions. (Simple reads are not affected by this parameter.) This number needs to be limited because it is necessary to preallocate memory for node failure handling, and a resource must be available for handling the maximum number of active operations in one TC thread when contending with node failures. It is imperative that <code class="literal"> MaxNoOfConcurrentOperations </code> be set to the same number on all nodes (this can be done most easily by setting a value for it once, in the <code class="literal"> [ndbd default] </code> section of the <code class="filename"> config.ini </code> global configuration file). While its value can be increased using a rolling restart (see <a class="xref" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster"> Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster” </a> ), decreasing it in this way is not considered safe due to the possibility of a node failure occurring during the rolling restart. </p> <p> It is possible to limit the size of a single transaction in NDB Cluster through the <code class="filename"> MaxDMLOperationsPerTransaction </code> parameter. If this is not set, the size of one transaction is limited by <code class="literal"> MaxNoOfConcurrentOperations </code> since this parameter limits the total number of concurrent operations per TC thread. </p> <p> Schema memory size is controlled by the following set of configuration parameters: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofsubscriptions"> <code class="literal"> MaxNoOfSubscriptions </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofsubscribers"> <code class="literal"> MaxNoOfSubscribers </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofconcurrentsuboperations"> <code class="literal"> MaxNoOfConcurrentSubOperations </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofattributes"> <code class="literal"> MaxNoOfAttributes </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooftables"> <code class="literal"> MaxNoOfTables </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooforderedindexes"> <code class="literal"> MaxNoOfOrderedIndexes </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnoofuniquehashindexes"> <code class="literal"> MaxNoOfUniqueHashIndexes </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-maxnooftriggers"> <code class="literal"> MaxNoOfTriggers </code> </a> </p> </li> </ul> </div> <p> The number of nodes and the number of LDM threads also have a major impact on the size of schema memory since the number of partitions in each table and each partition (and its fragment replicas) have to be represented in schema memory. </p> <p> In addition, a number of other records are allocated during startup. These are relatively small. Each block in each thread contains block objects that use memory. This memory size is also normally quite small compared to the other data node memory structures. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/information-schema-ndb-transid-mysql-connection-map-table.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="information-schema-ndb-transid-mysql-connection-map-table"> </a> 28.3.18 The INFORMATION_SCHEMA ndb_transid_mysql_connection_map Table </h3> </div> </div> </div> <a class="indexterm" name="idm46045079514080"> </a> <p> The <code class="literal"> ndb_transid_mysql_connection_map </code> table provides a mapping between <code class="literal"> NDB </code> transactions, <code class="literal"> NDB </code> transaction coordinators, and MySQL Servers attached to an NDB Cluster as API nodes. This information is used when populating the <a class="link" href="mysql-cluster-ndbinfo-server-operations.html" title="25.6.17.55 The ndbinfo server_operations Table"> <code class="literal"> server_operations </code> </a> and <a class="link" href="mysql-cluster-ndbinfo-server-transactions.html" title="25.6.17.56 The ndbinfo server_transactions Table"> <code class="literal"> server_transactions </code> </a> tables of the <a class="link" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> <code class="literal"> ndbinfo </code> </a> NDB Cluster information database. </p> <div class="informaltable"> <table summary="Columns in the INFORMATION_SCHEMA ndb_transid_mysql_connection_map table. The table lists INFORMATION_SCHEMA names along with corresponding SHOW names (if applicable), and remarks."> <colgroup> <col style="width: 40%"/> <col style="width: 30%"/> <col style="width: 30%"/> </colgroup> <thead> <tr> <th scope="col"> <code class="literal"> INFORMATION_SCHEMA </code> Name </th> <th scope="col"> <code class="literal"> SHOW </code> Name </th> <th scope="col"> Remarks </th> </tr> </thead> <tbody> <tr> <th scope="row"> <code class="literal"> mysql_connection_id </code> </th> <td> </td> <td> MySQL Server connection ID </td> </tr> <tr> <th scope="row"> <code class="literal"> node_id </code> </th> <td> </td> <td> Transaction coordinator node ID </td> </tr> <tr> <th scope="row"> <code class="literal"> ndb_transid </code> </th> <td> </td> <td> <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> transaction ID </td> </tr> </tbody> </table> </div> <p> The <code class="literal"> mysql_connection_id </code> is the same as the connection or session ID shown in the output of <a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement"> <code class="literal"> SHOW PROCESSLIST </code> </a> . </p> <p> There are no <code class="literal"> SHOW </code> statements associated with this table. </p> <p> This is a nonstandard table, specific to NDB Cluster. It is implemented as an <code class="literal"> INFORMATION_SCHEMA </code> plugin; you can verify that it is supported by checking the output of <a class="link" href="show-plugins.html" title="15.7.7.27 SHOW PLUGINS Statement"> <code class="literal"> SHOW PLUGINS </code> </a> . If <code class="literal"> ndb_transid_mysql_connection_map </code> support is enabled, the output from this statement includes a plugin having this name, of type <code class="literal"> INFORMATION SCHEMA </code> , and having status <code class="literal"> ACTIVE </code> , as shown here (using emphasized text): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78673417"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">PLUGINS</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Name <span class="token punctuation">|</span> Status <span class="token punctuation">|</span> Type <span class="token punctuation">|</span> Library <span class="token punctuation">|</span> License <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> binlog <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> mysql_native_password <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> AUTHENTICATION <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> sha256_password <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> AUTHENTICATION <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> caching_sha2_password <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> AUTHENTICATION <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> sha2_cache_cleaner <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> AUDIT <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> daemon_keyring_proxy_plugin <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> DAEMON <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> CSV <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> MEMORY <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> InnoDB <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> INNODB_TRX <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> INFORMATION SCHEMA <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> INNODB_CMP <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> INFORMATION SCHEMA <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span> <span class="token output"><span class="token punctuation">|</span> INNODB_SESSION_TEMP_TABLESPACES <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> INFORMATION SCHEMA <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> MyISAM <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> MRG_MYISAM <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> PERFORMANCE_SCHEMA <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> TempTable <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> ARCHIVE <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> BLACKHOLE <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> ndbcluster <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> ndbinfo <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> STORAGE ENGINE <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation"></span><em><span class="token punctuation">|</span> ndb_transid_mysql_connection_map <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> INFORMATION SCHEMA <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></em><span class="token punctuation"></span></span> <span class="token output"><span class="token punctuation">|</span> ngram <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> FTPARSER <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> mysqlx_cache_cleaner <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> AUDIT <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> mysqlx <span class="token punctuation">|</span> ACTIVE <span class="token punctuation">|</span> DAEMON <span class="token punctuation">|</span> NULL <span class="token punctuation">|</span> GPL <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">47 rows in set (0.01 sec)</span></code></pre> </div> <p> The plugin is enabled by default. You can disable it (or force the server not to run unless the plugin starts) by starting the server with the <a class="link" href="mysql-cluster-options-variables.html#option_mysqld_ndb-transid-mysql-connection-map"> <code class="option"> --ndb-transid-mysql-connection-map </code> </a> option. If the plugin is disabled, the status is shown by <a class="link" href="show-plugins.html" title="15.7.7.27 SHOW PLUGINS Statement"> <code class="literal"> SHOW PLUGINS </code> </a> as <code class="literal"> DISABLED </code> . The plugin cannot be enabled or disabled at runtime. </p> <p> Although the names of this table and its columns are displayed using lowercase, you can use uppercase or lowercase when referring to them in SQL statements. </p> <p> For this table to be created, the MySQL Server must be a binary supplied with the NDB Cluster distribution, or one built from the NDB Cluster sources with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine support enabled. It is not available in the standard MySQL 8.4 Server. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/partitioning-maintenance.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="partitioning-maintenance"> </a> 26.3.4 Maintenance of Partitions </h3> </div> </div> </div> <a class="indexterm" name="idm46045083488768"> </a> <a class="indexterm" name="idm46045083487280"> </a> <a class="indexterm" name="idm46045083485792"> </a> <a class="indexterm" name="idm46045083484304"> </a> <a class="indexterm" name="idm46045083482816"> </a> <a class="indexterm" name="idm46045083481328"> </a> <a class="indexterm" name="idm46045083479840"> </a> <a class="indexterm" name="idm46045083478352"> </a> <p> A number of table and partition maintenance tasks can be carried out on partitioned tables using SQL statements intended for such purposes. </p> <p> Table maintenance of partitioned tables can be accomplished using the statements <a class="link" href="check-table.html" title="15.7.3.2 CHECK TABLE Statement"> <code class="literal"> CHECK TABLE </code> </a> , <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> , <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> , and <a class="link" href="repair-table.html" title="15.7.3.5 REPAIR TABLE Statement"> <code class="literal"> REPAIR TABLE </code> </a> , which are supported for partitioned tables. </p> <p> You can use a number of extensions to <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE </code> </a> for performing operations of this type on one or more partitions directly, as described in the following list: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <b> Rebuilding partitions. </b> Rebuilds the partition; this has the same effect as dropping all records stored in the partition, then reinserting them. This can be useful for purposes of defragmentation. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa20479541"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">REBUILD</span> <span class="token keyword">PARTITION</span> p0<span class="token punctuation">,</span> p1<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> <b> Optimizing partitions. </b> If you have deleted a large number of rows from a partition or if you have made many changes to a partitioned table with variable-length rows (that is, having <a class="link" href="char.html" title="13.3.2 The CHAR and VARCHAR Types"> <code class="literal"> VARCHAR </code> </a> , <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> , or <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> TEXT </code> </a> columns), you can use <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE ... OPTIMIZE PARTITION </code> </a> to reclaim any unused space and to defragment the partition data file. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa66451909"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">OPTIMIZE</span> <span class="token keyword">PARTITION</span> p0<span class="token punctuation">,</span> p1<span class="token punctuation">;</span></code></pre> </div> <p> Using <code class="literal"> OPTIMIZE PARTITION </code> on a given partition is equivalent to running <code class="literal"> CHECK PARTITION </code> , <code class="literal"> ANALYZE PARTITION </code> , and <code class="literal"> REPAIR PARTITION </code> on that partition. </p> <p> Some MySQL storage engines, including <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> , do not support per-partition optimization; in these cases, <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE ... OPTIMIZE PARTITION </code> </a> analyzes and rebuilds the entire table, and causes an appropriate warning to be issued. (Bug #11751825, Bug #42822) Use <code class="literal"> ALTER TABLE ... REBUILD PARTITION </code> and <code class="literal"> ALTER TABLE ... ANALYZE PARTITION </code> instead, to avoid this issue. </p> </li> <li class="listitem"> <p> <b> Analyzing partitions. </b> This reads and stores the key distributions for partitions. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa78820281"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ANALYZE</span> <span class="token keyword">PARTITION</span> p3<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> <b> Repairing partitions. </b> This repairs corrupted partitions. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa13725463"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">REPAIR</span> <span class="token keyword">PARTITION</span> p0<span class="token punctuation">,</span>p1<span class="token punctuation">;</span></code></pre> </div> <p> Normally, <code class="literal"> REPAIR PARTITION </code> fails when the partition contains duplicate key errors. You can use <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER IGNORE TABLE </code> </a> with this option, in which case all rows that cannot be moved due to the presence of duplicate keys are removed from the partition (Bug #16900947). </p> </li> <li class="listitem"> <p> <b> Checking partitions. </b> You can check partitions for errors in much the same way that you can use <code class="literal"> CHECK TABLE </code> with nonpartitioned tables. </p> <p> Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa37180981"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> trb3 <span class="token keyword">CHECK</span> <span class="token keyword">PARTITION</span> p1<span class="token punctuation">;</span></code></pre> </div> <p> This statement tells you whether the data or indexes in partition <code class="literal"> p1 </code> of table <code class="literal"> t1 </code> are corrupted. If this is the case, use <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER TABLE ... REPAIR PARTITION </code> </a> to repair the partition. </p> <p> Normally, <code class="literal"> CHECK PARTITION </code> fails when the partition contains duplicate key errors. You can use <a class="link" href="alter-table-partition-operations.html" title="15.1.9.1 ALTER TABLE Partition Operations"> <code class="literal"> ALTER IGNORE TABLE </code> </a> with this option, in which case the statement returns the contents of each row in the partition where a duplicate key violation is found. Only the values for the columns in the partitioning expression for the table are reported. (Bug #16900947) </p> </li> </ul> </div> <p> Each of the statements in the list just shown also supports the keyword <code class="literal"> ALL </code> in place of the list of partition names. Using <code class="literal"> ALL </code> causes the statement to act on all partitions in the table. </p> <p> You can also truncate partitions using <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE ... TRUNCATE PARTITION </code> </a> . This statement can be used to delete all rows from one or more partitions in much the same way that <a class="link" href="truncate-table.html" title="15.1.37 TRUNCATE TABLE Statement"> <code class="literal"> TRUNCATE TABLE </code> </a> deletes all rows from a table. </p> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE ... TRUNCATE PARTITION ALL </code> </a> truncates all partitions in the table. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/password-security-user.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="password-security-user"> </a> 8.1.2.1 End-User Guidelines for Password Security </h4> </div> </div> </div> <a class="indexterm" name="idm46045252899392"> </a> <p> MySQL users should use the following guidelines to keep passwords secure. </p> <p> When you run a client program to connect to the MySQL server, it is inadvisable to specify your password in a way that exposes it to discovery by other users. The methods you can use to specify your password when you run client programs are listed here, along with an assessment of the risks of each method. In short, the safest methods are to have the client program prompt for the password or to specify the password in a properly protected option file. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Use the <a class="link" href="mysql-config-editor.html" title="6.6.7 mysql_config_editor — MySQL Configuration Utility"> <span class="command"> <strong> mysql_config_editor </strong> </span> </a> utility, which enables you to store authentication credentials in an encrypted login path file named <code class="filename"> .mylogin.cnf </code> . The file can be read later by MySQL client programs to obtain authentication credentials for connecting to MySQL Server. See <a class="xref" href="mysql-config-editor.html" title="6.6.7 mysql_config_editor — MySQL Configuration Utility"> Section 6.6.7, “mysql_config_editor — MySQL Configuration Utility” </a> . </p> </li> <li class="listitem"> <p> <a class="indexterm" name="idm46045252892048"> </a> <a class="indexterm" name="idm46045252890976"> </a> Use a <code class="option"> --password= <em class="replaceable"> <code> password </code> </em> </code> or <code class="option"> -p <em class="replaceable"> <code> password </code> </em> </code> option on the command line. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa36429482"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> francis <span class="token property">-pfrank</span> <em class="replaceable">db_name</em></code></pre> </div> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> This is convenient <span class="emphasis"> <em> but insecure </em> </span> . On some systems, your password becomes visible to system status programs such as <span class="command"> <strong> ps </strong> </span> that may be invoked by other users to display command lines. MySQL clients typically overwrite the command-line password argument with zeros during their initialization sequence. However, there is still a brief interval during which the value is visible. Also, on some systems this overwriting strategy is ineffective and the password remains visible to <span class="command"> <strong> ps </strong> </span> . (SystemV Unix systems and perhaps others are subject to this problem.) </p> </div> <p> If your operating environment is set up to display your current command in the title bar of your terminal window, the password remains visible as long as the command is running, even if the command has scrolled out of view in the window content area. </p> </li> <li class="listitem"> <p> Use the <a class="link" href="connection-options.html#option_general_password"> <code class="option"> --password </code> </a> or <code class="option"> -p </code> option on the command line with no password value specified. In this case, the client program solicits the password interactively: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa65622640"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> francis <span class="token property">-p</span> <em class="replaceable">db_name</em> Enter password<span class="token punctuation">:</span> ********</code></pre> </div> <p> The <code class="literal"> * </code> characters indicate where you enter your password. The password is not displayed as you enter it. </p> <p> It is more secure to enter your password this way than to specify it on the command line because it is not visible to other users. However, this method of entering a password is suitable only for programs that you run interactively. If you want to invoke a client from a script that runs noninteractively, there is no opportunity to enter the password from the keyboard. On some systems, you may even find that the first line of your script is read and interpreted (incorrectly) as your password. </p> </li> <li class="listitem"> <p> Store your password in an option file. For example, on Unix, you can list your password in the <code class="literal"> [client] </code> section of the <code class="filename"> .my.cnf </code> file in your home directory: </p> <a class="indexterm" name="idm46045252873376"> </a> <a class="indexterm" name="idm46045252872304"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa11164331"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[client]</span> <span class="token constant">password</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">password</em></span></code></pre> </div> <p> To keep the password safe, the file should not be accessible to anyone but yourself. To ensure this, set the file access mode to <code class="literal"> 400 </code> or <code class="literal"> 600 </code> . For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa6131574"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">chmod</span> 600 <span class="token punctuation">.</span>my<span class="token punctuation">.</span>cnf</code></pre> </div> <p> To name from the command line a specific option file containing the password, use the <a class="link" href="option-file-options.html#option_general_defaults-file"> <code class="option"> --defaults-file= <em class="replaceable"> <code> file_name </code> </em> </code> </a> option, where <code class="filename"> file_name </code> is the full path name to the file. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa68688795"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token constant">--defaults-file</span><span class="token attr-value"><span class="token punctuation">=</span>/home/francis/mysql-opts</span></code></pre> </div> <p> <a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files"> Section 6.2.2.2, “Using Option Files” </a> , discusses option files in more detail. </p> </li> </ul> </div> <a class="indexterm" name="idm46045252860208"> </a> <p> On Unix, the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client writes a record of executed statements to a history file (see <a class="xref" href="mysql-logging.html" title="6.5.1.3 mysql Client Logging"> Section 6.5.1.3, “mysql Client Logging” </a> ). By default, this file is named <code class="filename"> .mysql_history </code> and is created in your home directory. Passwords can be written as plain text in SQL statements such as <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> and <a class="link" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> <code class="literal"> ALTER USER </code> </a> , so if you use these statements, they are logged in the history file. To keep this file safe, use a restrictive access mode, the same way as described earlier for the <code class="filename"> .my.cnf </code> file. </p> <p> If your command interpreter maintains a history, any file in which the commands are saved contains MySQL passwords entered on the command line. For example, <span class="command"> <strong> bash </strong> </span> uses <code class="filename"> ~/.bash_history </code> . Any such file should have a restrictive access mode. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-replication-auto-sync.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-replication-auto-sync"> </a> 25.7.9.1 NDB Cluster Replication: Automating Synchronization of the Replica to the Source Binary Log </h4> </div> </div> </div> <a class="indexterm" name="idm46045085828912"> </a> <a class="indexterm" name="idm46045085827456"> </a> <p> It is possible to automate much of the process described in the previous section (see <a class="xref" href="mysql-cluster-replication-backups.html" title="25.7.9 NDB Cluster Backups With NDB Cluster Replication"> Section 25.7.9, “NDB Cluster Backups With NDB Cluster Replication” </a> ). The following Perl script <code class="filename"> reset-replica.pl </code> serves as an example of how you can do this. </p> <a class="indexterm" name="idm46045085823936"> </a> <a class="indexterm" name="idm46045085822416"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-perl"><div class="docs-select-all right" id="sa18724443"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-perl"><span class="token comment" spellcheck="true">#!/user/bin/perl -w</span> <span class="token comment" spellcheck="true"># file: reset-replica.pl</span> <span class="token comment" spellcheck="true"># Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.</span> <span class="token comment" spellcheck="true"># This program is free software; you can redistribute it and/or modify</span> <span class="token comment" spellcheck="true"># it under the terms of the GNU General Public License as published by</span> <span class="token comment" spellcheck="true"># the Free Software Foundation; either version 2 of the License, or</span> <span class="token comment" spellcheck="true"># (at your option) any later version.</span> <span class="token comment" spellcheck="true"># This program is distributed in the hope that it will be useful,</span> <span class="token comment" spellcheck="true"># but WITHOUT ANY WARRANTY; without even the implied warranty of</span> <span class="token comment" spellcheck="true"># MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</span> <span class="token comment" spellcheck="true"># GNU General Public License for more details.</span> <span class="token comment" spellcheck="true"># You should have received a copy of the GNU General Public License</span> <span class="token comment" spellcheck="true"># along with this program; if not, write to:</span> <span class="token comment" spellcheck="true"># Free Software Foundation, Inc.</span> <span class="token comment" spellcheck="true"># 59 Temple Place, Suite 330</span> <span class="token comment" spellcheck="true"># Boston, MA 02111-1307 USA</span> <span class="token comment" spellcheck="true">#</span> <span class="token comment" spellcheck="true"># Version 1.1</span> <span class="token comment" spellcheck="true">######################## Includes ###############################</span> <span class="token keyword">use</span> DBI<span class="token punctuation">;</span> <span class="token comment" spellcheck="true">######################## Globals ################################</span> <span class="token keyword">my</span> <span class="token variable">$m_host</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$m_port</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$m_user</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$m_pass</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$s_host</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$s_port</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$s_user</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$s_pass</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$dbhM</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token keyword">my</span> <span class="token variable">$dbhS</span><span class="token operator">=</span><span class="token string">''</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">####################### Sub Prototypes ##########################</span> <span class="token function"><span class="token keyword">sub</span> CollectCommandPromptInfo</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> ConnectToDatabases</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> DisconnectFromDatabases</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> GetReplicaEpoch</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> GetSourceInfo</span><span class="token punctuation">;</span> <span class="token function"><span class="token keyword">sub</span> UpdateReplica</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">######################## Program Main ###########################</span> CollectCommandPromptInfo<span class="token punctuation">;</span> ConnectToDatabases<span class="token punctuation">;</span> GetReplicaEpoch<span class="token punctuation">;</span> GetSourceInfo<span class="token punctuation">;</span> UpdateReplica<span class="token punctuation">;</span> DisconnectFromDatabases<span class="token punctuation">;</span> <span class="token comment" spellcheck="true">################## Collect Command Prompt Info ##################</span> <span class="token function"><span class="token keyword">sub</span> CollectCommandPromptInfo</span> <span class="token punctuation">{</span> <span class="token comment" spellcheck="true">### Check that user has supplied correct number of command line args</span> <span class="token keyword">die</span> <span class="token string">"Usage:\n reset-replica >source MySQL host< >source MySQL port< \n >source user< >source pass< >replica MySQL host< \n >replica MySQL port< >replica user< >replica pass< \n All 8 arguments must be passed. Use BLANK for NULL passwords\n"</span> <span class="token keyword">unless</span> <span class="token variable">@ARGV</span> <span class="token operator">==</span> <span class="token number">8</span><span class="token punctuation">;</span> <span class="token variable">$m_host</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$m_port</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$m_user</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$m_pass</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">3</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$s_host</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">4</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$s_port</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">5</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$s_user</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">6</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token variable">$s_pass</span> <span class="token operator">=</span> <span class="token variable">$ARGV</span><span class="token punctuation">[</span><span class="token number">7</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token variable">$m_pass</span> <span class="token operator">eq</span> <span class="token string">"BLANK"</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token variable">$m_pass</span> <span class="token operator">=</span> <span class="token string">''</span><span class="token punctuation">;</span><span class="token punctuation">}</span> <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token variable">$s_pass</span> <span class="token operator">eq</span> <span class="token string">"BLANK"</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token variable">$s_pass</span> <span class="token operator">=</span> <span class="token string">''</span><span class="token punctuation">;</span><span class="token punctuation">}</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">############### Make connections to both databases #############</span> <span class="token function"><span class="token keyword">sub</span> ConnectToDatabases</span> <span class="token punctuation">{</span> <span class="token comment" spellcheck="true">### Connect to both source and replica cluster databases</span> <span class="token comment" spellcheck="true">### Connect to source</span> <span class="token variable">$dbhM</span> <span class="token operator">=</span> DBI<span class="token operator">-></span>connect<span class="token punctuation">(</span> <span class="token string">"dbi:mysql:database=mysql;host=$m_host;port=$m_port"</span><span class="token punctuation">,</span> <span class="token string">"$m_user"</span><span class="token punctuation">,</span> <span class="token string">"$m_pass"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Can't connect to source cluster MySQL process! Error: $DBI::errstr\n"</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">### Connect to replica</span> <span class="token variable">$dbhS</span> <span class="token operator">=</span> DBI<span class="token operator">-></span>connect<span class="token punctuation">(</span> <span class="token string">"dbi:mysql:database=mysql;host=$s_host"</span><span class="token punctuation">,</span> <span class="token string">"$s_user"</span><span class="token punctuation">,</span> <span class="token string">"$s_pass"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Can't connect to replica cluster MySQL process! Error: $DBI::errstr\n"</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">################ Disconnect from both databases ################</span> <span class="token function"><span class="token keyword">sub</span> DisconnectFromDatabases</span> <span class="token punctuation">{</span> <span class="token comment" spellcheck="true">### Disconnect from source</span> <span class="token variable">$dbhM</span><span class="token operator">-></span>disconnect <span class="token operator">or</span> warn <span class="token string">" Disconnection failed: $DBI::errstr\n"</span><span class="token punctuation">;</span> <span class="token comment" spellcheck="true">### Disconnect from replica</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>disconnect <span class="token operator">or</span> warn <span class="token string">" Disconnection failed: $DBI::errstr\n"</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">###################### Find the last good GCI ##################</span> <span class="token function"><span class="token keyword">sub</span> GetReplicaEpoch</span> <span class="token punctuation">{</span> <span class="token variable">$sth</span> <span class="token operator">=</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>prepare<span class="token punctuation">(</span><span class="token string">"SELECT MAX(epoch) FROM mysql.ndb_apply_status;"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Error while preparing to select epoch from replica: "</span><span class="token punctuation">,</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>execute <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Selecting epoch from replica error: "</span><span class="token punctuation">,</span> <span class="token variable">$sth</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>bind_col <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token operator">\</span><span class="token variable">$epoch</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>fetch<span class="token punctuation">;</span> <span class="token keyword">print</span> <span class="token string">"\tReplica epoch = $epoch\n"</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>finish<span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">####### Find the position of the last GCI in the binary log ########</span> <span class="token function"><span class="token keyword">sub</span> GetSourceInfo</span> <span class="token punctuation">{</span> <span class="token variable">$sth</span> <span class="token operator">=</span> <span class="token variable">$dbhM</span><span class="token operator">-></span>prepare<span class="token punctuation">(</span><span class="token string">"SELECT SUBSTRING_INDEX(File, '/', -1), Position FROM mysql.ndb_binlog_index WHERE epoch > $epoch ORDER BY epoch ASC LIMIT 1;"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Prepare to select from source error: "</span><span class="token punctuation">,</span> <span class="token variable">$dbhM</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>execute <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Selecting from source error: "</span><span class="token punctuation">,</span> <span class="token variable">$sth</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>bind_col <span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token operator">\</span><span class="token variable">$binlog</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>bind_col <span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">,</span> <span class="token operator">\</span><span class="token variable">$binpos</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>fetch<span class="token punctuation">;</span> <span class="token keyword">print</span> <span class="token string">"\tSource binary log file = $binlog\n"</span><span class="token punctuation">;</span> <span class="token keyword">print</span> <span class="token string">"\tSource binary log position = $binpos\n"</span><span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>finish<span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true">########## Set the replica to process from that location #########</span> <span class="token function"><span class="token keyword">sub</span> UpdateReplica</span> <span class="token punctuation">{</span> <span class="token variable">$sth</span> <span class="token operator">=</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>prepare<span class="token punctuation">(</span><span class="token string">"CHANGE REPLICATION SOURCE TO SOURCE_LOG_FILE='$binlog', SOURCE_LOG_POS=$binpos;"</span><span class="token punctuation">)</span> <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"Prepare to CHANGE REPLICATION SOURCE error: "</span><span class="token punctuation">,</span> <span class="token variable">$dbhS</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>execute <span class="token operator">or</span> <span class="token keyword">die</span> <span class="token string">"CHANGE REPLICATION SOURCE on replica error: "</span><span class="token punctuation">,</span> <span class="token variable">$sth</span><span class="token operator">-></span>errstr<span class="token punctuation">;</span> <span class="token variable">$sth</span><span class="token operator">-></span>finish<span class="token punctuation">;</span> <span class="token keyword">print</span> <span class="token string">"\tReplica has been updated. You may now start the replica.\n"</span><span class="token punctuation">;</span> <span class="token punctuation">}</span> <span class="token comment" spellcheck="true"># end reset-replica.pl</span></code></pre> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-general-info.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="mysql-cluster-general-info"> </a> 25.1 General Information </h2> </div> </div> </div> <p> MySQL NDB Cluster uses the MySQL server with the <code class="literal"> NDB </code> storage engine. Support for the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine is not included in standard MySQL Server 8.4 binaries built by Oracle. Instead, users of NDB Cluster binaries from Oracle should upgrade to the most recent binary release of NDB Cluster for supported platforms—these include RPMs that should work with most Linux distributions. NDB Cluster 8.4 users who build from source should use the sources provided for MySQL 8.4 and build with the options required to provide NDB support. (Locations where the sources can be obtained are listed later in this section.) </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> MySQL NDB Cluster does not support InnoDB Cluster, which must be deployed using MySQL Server <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> storage engine as well as additional applications that are not included in the NDB Cluster distribution. MySQL Server 8.4 binaries cannot be used with MySQL NDB Cluster. For more information about deploying and using InnoDB Cluster, see <a class="ulink" href="/doc/mysql-shell/8.4/en/admin-api-userguide.html" target="_top"> MySQL AdminAPI </a> . <a class="xref" href="mysql-cluster-compared.html" title="25.2.6 MySQL Server Using InnoDB Compared with NDB Cluster"> Section 25.2.6, “MySQL Server Using InnoDB Compared with NDB Cluster” </a> , discusses differences between the <code class="literal"> NDB </code> and <code class="literal"> InnoDB </code> storage engines. </p> </div> <a class="indexterm" name="idm46045124441728"> </a> <p> <b> Supported Platforms. </b> NDB Cluster is currently available and supported on a number of platforms. For exact levels of support available for on specific combinations of operating system versions, operating system distributions, and hardware platforms, please refer to <a class="ulink" href="https://www.mysql.com/support/supportedplatforms/cluster.html" target="_blank"> https://www.mysql.com/support/supportedplatforms/cluster.html </a> . </p> <p> <b> Availability. </b> NDB Cluster binary and source packages are available for supported platforms from <a class="ulink" href="https://dev.mysql.com/downloads/cluster/" target="_top"> https://dev.mysql.com/downloads/cluster/ </a> . </p> <p> <a name="mysql-cluster-version-strings"> </a> <b> Version strings used in NDB Cluster software. </b> The version string displayed by the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client supplied with the MySQL NDB Cluster distribution uses this format: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa81826473"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">mysql<span class="token operator">-</span><em class="replaceable">mysql_server_version</em><span class="token operator">-</span>cluster</code></pre> </div> <p> <em class="replaceable"> <code> mysql_server_version </code> </em> represents the version of the MySQL Server on which the NDB Cluster release is based. Building from source using <a class="link" href="source-configuration-options.html#option_cmake_with_ndb"> <code class="option"> -DWITH_NDB </code> </a> or the equivalent adds the <code class="literal"> -cluster </code> suffix to the version string. (See <a class="xref" href="mysql-cluster-install-linux-source.html" title="25.3.1.4 Building NDB Cluster from Source on Linux"> Section 25.3.1.4, “Building NDB Cluster from Source on Linux” </a> , and <a class="xref" href="mysql-cluster-install-windows-source.html" title="25.3.2.2 Compiling and Installing NDB Cluster from Source on Windows"> Section 25.3.2.2, “Compiling and Installing NDB Cluster from Source on Windows” </a> .) You can see this format used in the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client, as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa30579575"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> Welcome to the MySQL monitor<span class="token punctuation">.</span> Commands end with <span class="token punctuation">;</span> or \g<span class="token punctuation">.</span> Your MySQL connection id is 2 Server version<span class="token punctuation">:</span> 8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0-cluster Source distribution Type <span class="token atrule">'help;'</span> or <span class="token atrule">'\h'</span> for help<span class="token punctuation">.</span> Type <span class="token atrule">'\c'</span> to clear the buffer<span class="token punctuation">.</span> <span class="token prompt">mysql></span><span class="token command"> SELECT</span> VERSION<span class="token punctuation">(</span><span class="token punctuation">)</span>\G <span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> VERSION()<span class="token punctuation">:</span> 8.4.0-cluster </span><span class="token output">1 row in set (0.00 sec)</span></code></pre> </div> <p> The version string displayed by other NDB Cluster programs not normally included with the MySQL 8.4 distribution uses this format: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa31892298"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">mysql<span class="token operator">-</span><em class="replaceable">mysql_server_version</em> ndb<span class="token operator">-</span><em class="replaceable">ndb_engine_version</em></code></pre> </div> <p> <em class="replaceable"> <code> mysql_server_version </code> </em> represents the version of the MySQL Server on which the NDB Cluster release is based. For NDB Cluster 8.4, this is <code class="literal"> 8.4. <em class="replaceable"> <code> n </code> </em> </code> , where <em class="replaceable"> <code> n </code> </em> is the release number. <em class="replaceable"> <code> ndb_engine_version </code> </em> is the version of the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine used by this release of the NDB Cluster software. For NDB 8.4, this number is the same as the MySQL Server version. You can see this format used in the output of the <code class="literal"> SHOW </code> command in the <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> client, like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ndbmgm"><div class="docs-select-all right" id="sa30381207"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ndbmgm"><span class="token prompt">ndb_mgm></span> <span class="token keyword">SHOW</span> Connected to Management Server at<span class="token operator">:</span> localhost<span class="token operator">:</span>1186 <span class="token punctuation">(</span>using cleartext<span class="token punctuation">)</span> Cluster Configuration <span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">--</span><span class="token operator">-</span> <span class="token selector">[ndbd(NDB)]</span> 2 node<span class="token punctuation">(</span>s<span class="token punctuation">)</span> id<span class="token operator">=</span>1 @10<span class="token punctuation">.</span>0<span class="token punctuation">.</span>10<span class="token punctuation">.</span>6 <span class="token punctuation">(</span>mysql<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0 ndb<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0<span class="token punctuation">,</span> Nodegroup<span class="token operator">:</span> 0<span class="token punctuation">,</span> <span class="token operator">*</span><span class="token punctuation">)</span> id<span class="token operator">=</span>2 @10<span class="token punctuation">.</span>0<span class="token punctuation">.</span>10<span class="token punctuation">.</span>8 <span class="token punctuation">(</span>mysql<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0 ndb<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0<span class="token punctuation">,</span> Nodegroup<span class="token operator">:</span> 0<span class="token punctuation">)</span> <span class="token selector">[ndb_mgmd(MGM)]</span> 1 node<span class="token punctuation">(</span>s<span class="token punctuation">)</span> id<span class="token operator">=</span>3 @10<span class="token punctuation">.</span>0<span class="token punctuation">.</span>10<span class="token punctuation">.</span>2 <span class="token punctuation">(</span>mysql<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0 ndb<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0<span class="token punctuation">)</span> <span class="token selector">[mysqld(API)]</span> 2 node<span class="token punctuation">(</span>s<span class="token punctuation">)</span> id<span class="token operator">=</span>4 @10<span class="token punctuation">.</span>0<span class="token punctuation">.</span>10<span class="token punctuation">.</span>10 <span class="token punctuation">(</span>mysql<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0 ndb<span class="token operator">-</span>8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>0<span class="token punctuation">)</span> id<span class="token operator">=</span>5 <span class="token punctuation">(</span>not connected<span class="token punctuation">,</span> accepting connect from any host<span class="token punctuation">)</span></code></pre> </div> <p> <b> Compatibility with standard MySQL 8.4 releases. </b> While many standard MySQL schemas and applications can work using NDB Cluster, it is also true that unmodified applications and database schemas may be slightly incompatible or have suboptimal performance when run using NDB Cluster (see <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> ). Most of these issues can be overcome, but this also means that you are very unlikely to be able to switch an existing application datastore—that currently uses, for example, <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> or <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> —to use the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine without allowing for the possibility of changes in schemas, queries, and applications. A <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> compiled without <code class="literal"> NDB </code> support (that is, built without <a class="link" href="source-configuration-options.html#option_cmake_with_ndb"> <code class="option"> -DWITH_NDB </code> </a> or <a class="link" href="source-configuration-options.html#option_cmake_with_ndbcluster_storage_engine"> <code class="option"> -DWITH_NDBCLUSTER_STORAGE_ENGINE </code> </a> ) cannot function as a drop-in replacement for a <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> that is built with it. </p> <p> <b> NDB Cluster development source trees. </b> NDB Cluster development trees can also be accessed from <a class="ulink" href="https://github.com/mysql/mysql-server" target="_blank"> https://github.com/mysql/mysql-server </a> . </p> <p> The NDB Cluster development sources maintained at <a class="ulink" href="https://github.com/mysql/mysql-server" target="_blank"> https://github.com/mysql/mysql-server </a> are licensed under the GPL. For information about obtaining MySQL sources using Git and building them yourself, see <a class="xref" href="installing-development-tree.html" title="2.8.5 Installing MySQL Using a Development Source Tree"> Section 2.8.5, “Installing MySQL Using a Development Source Tree” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> As with MySQL Server 8.4, NDB Cluster 8.4 releases are built using <span class="command"> <strong> CMake </strong> </span> . </p> </div> <p class="ndb-rel-level"> NDB Cluster 8.4 is available as an LTS release, and is recommended for new deployments. NDB Cluster 8.0 is the previous GA release series (see <a class="ulink" href="/doc/refman/8.0/en/mysql-cluster.html" target="_top"> MySQL NDB Cluster 8.0 </a> ), still supported in production. NDB Cluster 7.6 and 7.5 are earlier GA releases still supported in production, although we recommend NDB Cluster 8.4 for new deployments intended for use in production. </p> <p> NDB Cluster 7.4 and 7.3 were previous GA releases which have been discontinued; they are no longer maintained or supported. </p> <p> Additional information regarding NDB Cluster can be found on the MySQL website at <a class="ulink" href="https://www.mysql.com/products/cluster/" target="_blank"> https://www.mysql.com/products/cluster/ </a> . </p> <a class="indexterm" name="idm46045124391344"> </a> <p> <b> Additional Resources. </b> More information about NDB Cluster can be found in the following places: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For answers to some commonly asked questions about NDB Cluster, see <a class="xref" href="faqs-mysql-cluster.html" title="A.10 MySQL 8.4 FAQ: NDB Cluster"> Section A.10, “MySQL 8.4 FAQ: NDB Cluster” </a> . </p> </li> <li class="listitem"> <p> The NDB Cluster Forum: <a class="ulink" href="https://forums.mysql.com/list.php?25" target="_blank"> https://forums.mysql.com/list.php?25 </a> . </p> </li> <li class="listitem"> <p> Many NDB Cluster users and developers blog about their experiences with NDB Cluster, and make feeds of these available through <a class="ulink" href="http://www.planetmysql.org/" target="_blank"> PlanetMySQL </a> . </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/data-directory.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="data-directory"> </a> 7.2 The MySQL Data Directory </h2> </div> </div> </div> <p> Information managed by the MySQL server is stored under a directory known as the data directory. The following list briefly describes the items typically found in the data directory, with cross references for additional information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Data directory subdirectories. Each subdirectory of the data directory is a database directory and corresponds to a database managed by the server. All MySQL installations have certain standard databases: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> The <code class="literal"> mysql </code> directory corresponds to the <code class="literal"> mysql </code> system schema, which contains information required by the MySQL server as it runs. This database contains data dictionary tables and system tables. See <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> . </p> </li> <li class="listitem"> <p> The <code class="literal"> performance_schema </code> directory corresponds to the Performance Schema, which provides information used to inspect the internal execution of the server at runtime. See <a class="xref" href="performance-schema.html" title="Chapter 29 MySQL Performance Schema"> Chapter 29, <i> MySQL Performance Schema </i> </a> . </p> </li> <li class="listitem"> <p> The <code class="literal"> sys </code> directory corresponds to the <code class="literal"> sys </code> schema, which provides a set of objects to help interpret Performance Schema information more easily. See <a class="xref" href="sys-schema.html" title="Chapter 30 MySQL sys Schema"> Chapter 30, <i> MySQL sys Schema </i> </a> . </p> </li> <li class="listitem"> <p> The <code class="literal"> ndbinfo </code> directory corresponds to the <code class="literal"> ndbinfo </code> database that stores information specific to NDB Cluster (present only for installations built to include NDB Cluster). See <a class="xref" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> Section 25.6.17, “ndbinfo: The NDB Cluster Information Database” </a> . </p> </li> </ul> </div> <p> Other subdirectories correspond to databases created by users or applications. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <a class="link" href="information-schema.html" title="Chapter 28 INFORMATION_SCHEMA Tables"> <code class="literal"> INFORMATION_SCHEMA </code> </a> is a standard database, but its implementation uses no corresponding database directory. </p> </div> </li> <li class="listitem"> <p> Log files written by the server. See <a class="xref" href="server-logs.html" title="7.4 MySQL Server Logs"> Section 7.4, “MySQL Server Logs” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> InnoDB </code> tablespace and log files. See <a class="xref" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> Chapter 17, <i> The InnoDB Storage Engine </i> </a> . </p> </li> <li class="listitem"> <p> Default/autogenerated SSL and RSA certificate and key files. See <a class="xref" href="creating-ssl-rsa-files.html" title="8.3.3 Creating SSL and RSA Certificates and Keys"> Section 8.3.3, “Creating SSL and RSA Certificates and Keys” </a> . </p> </li> <li class="listitem"> <p> The server process ID file (while the server is running). </p> </li> <li class="listitem"> <p> The <code class="filename"> mysqld-auto.cnf </code> file that stores persisted global system variable settings. See <a class="xref" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> Section 15.7.6.1, “SET Syntax for Variable Assignment” </a> . </p> </li> </ul> </div> <p> Some items in the preceding list can be relocated elsewhere by reconfiguring the server. In addition, the <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="option"> --datadir </code> </a> option enables the location of the data directory itself to be changed. For a given MySQL installation, check the server configuration to determine whether items have been moved. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/optimize-numeric.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="optimize-numeric"> </a> 10.4.2.1 Optimizing for Numeric Data </h4> </div> </div> </div> <a class="indexterm" name="idm46045226771088"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For unique IDs or other values that can be represented as either strings or numbers, prefer numeric columns to string columns. Since large numeric values can be stored in fewer bytes than the corresponding strings, it is faster and takes less memory to transfer and compare them. </p> </li> <li class="listitem"> <p> If you are using numeric data, it is faster in many cases to access information from a database (using a live connection) than to access a text file. Information in the database is likely to be stored in a more compact format than in the text file, so accessing it involves fewer disk accesses. You also save code in your application because you can avoid parsing the text file to find line and column boundaries. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/server-status-variable-reference.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="server-status-variable-reference"> </a> 7.1.6 Server Status Variable Reference </h3> </div> </div> </div> <p> The following table lists all status variables applicable within <code class="literal"> mysqld </code> . </p> <p> The table lists each variable's data type and scope. The last column indicates whether the scope for each variable is Global, Session, or both. Please see the corresponding item descriptions for details on setting and using the variables. Where appropriate, direct links to further information about the items are provided. </p> <div class="table"> <a name="idm46045283116784"> </a> <p class="title"> <b> Table 7.3 Status Variable Summary </b> </p> <div class="table-contents"> <table frame="box" rules="all" summary="Reference for status variables."> <colgroup> <col style="width: 40%"/> <col style="width: 20%"/> <col align="center" style="width: 20%"/> </colgroup> <thead> <tr> <th scope="col"> Variable Name </th> <th scope="col"> Variable Type </th> <th scope="col"> Variable Scope </th> </tr> </thead> <tbody> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Aborted_clients"> Aborted_clients </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Aborted_connects"> Aborted_connects </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Acl_cache_items_count"> Acl_cache_items_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_current_size"> Audit_log_current_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_direct_writes"> Audit_log_direct_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_event_max_drop_size"> Audit_log_event_max_drop_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_events"> Audit_log_events </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_events_filtered"> Audit_log_events_filtered </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_events_lost"> Audit_log_events_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_events_written"> Audit_log_events_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_total_size"> Audit_log_total_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#statvar_Audit_log_write_waits"> Audit_log_write_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Authentication_ldap_sasl_supported_methods"> Authentication_ldap_sasl_supported_methods </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Binlog_cache_disk_use"> Binlog_cache_disk_use </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Binlog_cache_use"> Binlog_cache_use </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Binlog_stmt_cache_disk_use"> Binlog_stmt_cache_disk_use </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Binlog_stmt_cache_use"> Binlog_stmt_cache_use </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Bytes_received"> Bytes_received </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Bytes_sent"> Bytes_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Caching_sha2_password_rsa_public_key"> Caching_sha2_password_rsa_public_key </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_admin_commands </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_event </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_function </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_procedure </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_resource_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_server </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_tablespace </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_alter_user_default_role </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_analyze </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_assign_to_keycache </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_begin </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_binlog </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_call_procedure </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_change_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_change_repl_filter </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_change_replication_source </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_check </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_checksum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_clone </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_commit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_event </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_function </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_index </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_procedure </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_resource_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_role </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_server </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_trigger </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_udf </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_create_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_dealloc_sql </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_delete </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_delete_multi </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_do </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_event </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_function </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_index </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_procedure </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_resource_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_role </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_server </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_trigger </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_drop_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_empty_query </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_execute_sql </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_explain_other </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_flush </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_get_diagnostics </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_grant </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_grant_roles </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_group_replication_start </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_group_replication_stop </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_ha_close </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_ha_open </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_ha_read </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_help </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_insert </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_insert_select </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_install_component </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_install_plugin </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_kill </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_load </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_lock_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_optimize </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_preload_keys </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_prepare_sql </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_purge </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_purge_before_date </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_release_savepoint </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_rename_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_rename_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_repair </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_replace </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_replace_select </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_replica_start </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_replica_stop </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_reset </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_resignal </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_restart </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_revoke </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_revoke_all </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_revoke_roles </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_rollback </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_rollback_to_savepoint </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_savepoint </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_select </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_set_option </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_set_resource_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_set_role </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_authors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_binary_log_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_binlog_events </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_binlogs </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_charsets </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_collations </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_contributors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_db </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_event </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_func </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_proc </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_table </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_trigger </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_create_user </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_databases </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_engine_logs </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_engine_mutex </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_engine_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_errors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_events </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_fields </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_function_code </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_function_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_grants </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_keys </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_ndb_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_open_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_plugins </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_privileges </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_procedure_code </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_procedure_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_processlist </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_profile </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_profiles </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_relaylog_events </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_replica_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_replicas </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_storage_engines </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_table_status </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_triggers </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_variables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_show_warnings </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_shutdown </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_signal </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_close </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_execute </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_fetch </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_prepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_reprepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_reset </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_stmt_send_long_data </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_truncate </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_uninstall_component </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_uninstall_plugin </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_unlock_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_update </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_update_multi </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_commit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_end </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_prepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_recover </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_rollback </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Com_xxx"> Com_xa_start </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Compression"> Compression </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Compression_algorithm"> Compression_algorithm </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Compression_level"> Compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="connection-control-variables.html#statvar_Connection_control_delay_generated"> Connection_control_delay_generated </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_accept"> Connection_errors_accept </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_internal"> Connection_errors_internal </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_max_connections"> Connection_errors_max_connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_peer_address"> Connection_errors_peer_address </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_select"> Connection_errors_select </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connection_errors_tcpwrap"> Connection_errors_tcpwrap </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Connections"> Connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Created_tmp_disk_tables"> Created_tmp_disk_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Created_tmp_files"> Created_tmp_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Created_tmp_tables"> Created_tmp_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_ca"> Current_tls_ca </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_capath"> Current_tls_capath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_cert"> Current_tls_cert </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_cipher"> Current_tls_cipher </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_ciphersuites"> Current_tls_ciphersuites </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_crl"> Current_tls_crl </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_crlpath"> Current_tls_crlpath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_key"> Current_tls_key </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Current_tls_version"> Current_tls_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Delayed_errors"> Delayed_errors </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Delayed_insert_threads"> Delayed_insert_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Delayed_writes"> Delayed_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Deprecated_use_i_s_processlist_count"> Deprecated_use_i_s_processlist_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Deprecated_use_i_s_processlist_last_timestamp"> Deprecated_use_i_s_processlist_last_timestamp </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_dragnet.Status"> dragnet.Status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Error_log_buffered_bytes"> Error_log_buffered_bytes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Error_log_buffered_events"> Error_log_buffered_events </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Error_log_expired_events"> Error_log_expired_events </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Error_log_latest_write"> Error_log_latest_write </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#statvar_Firewall_access_denied"> Firewall_access_denied </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#statvar_Firewall_access_granted"> Firewall_access_granted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#statvar_Firewall_cached_entries"> Firewall_cached_entries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Flush_commands"> Flush_commands </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Global_connection_memory"> Global_connection_memory </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_all_consensus_proposals_count"> Gr_all_consensus_proposals_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_all_consensus_time_sum"> Gr_all_consensus_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_certification_garbage_collector_count"> Gr_certification_garbage_collector_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_certification_garbage_collector_time_sum"> Gr_certification_garbage_collector_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_consensus_bytes_received_sum"> Gr_consensus_bytes_received_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_consensus_bytes_sent_sum"> Gr_consensus_bytes_sent_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_control_messages_sent_bytes_sum"> Gr_control_messages_sent_bytes_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_control_messages_sent_count"> Gr_control_messages_sent_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_control_messages_sent_roundtrip_time_sum"> Gr_control_messages_sent_roundtrip_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_data_messages_sent_bytes_sum"> Gr_data_messages_sent_bytes_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_data_messages_sent_count"> Gr_data_messages_sent_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_data_messages_sent_roundtrip_time_sum"> Gr_data_messages_sent_roundtrip_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_empty_consensus_proposals_count"> Gr_empty_consensus_proposals_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_extended_consensus_count"> Gr_extended_consensus_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> Gr_flow_control_throttle_active_count </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> Gr_flow_control_throttle_count </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> Gr_flow_control_throttle_last_throttle_timestamp </th> <td> Datetime </td> <td> Global </td> </tr> <tr> <th scope="row"> Gr_flow_control_throttle_time_sum </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_last_consensus_end_timestamp"> Gr_last_consensus_end_timestamp </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_total_messages_sent_count"> Gr_total_messages_sent_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_after_sync_count"> Gr_transactions_consistency_after_sync_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_after_sync_time_sum"> Gr_transactions_consistency_after_sync_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_after_termination_count"> Gr_transactions_consistency_after_termination_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_after_termination_time_sum"> Gr_transactions_consistency_after_termination_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_before_begin_count"> Gr_transactions_consistency_before_begin_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-status-variables.html#statvar_Gr_transactions_consistency_before_begin_time_sum"> Gr_transactions_consistency_before_begin_time_sum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_commit"> Handler_commit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_delete"> Handler_delete </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Handler_discover"> Handler_discover </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_external_lock"> Handler_external_lock </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_mrr_init"> Handler_mrr_init </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_prepare"> Handler_prepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_first"> Handler_read_first </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_key"> Handler_read_key </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_last"> Handler_read_last </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_next"> Handler_read_next </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_prev"> Handler_read_prev </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_rnd"> Handler_read_rnd </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_read_rnd_next"> Handler_read_rnd_next </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_rollback"> Handler_rollback </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_savepoint"> Handler_savepoint </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_savepoint_rollback"> Handler_savepoint_rollback </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_update"> Handler_update </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Handler_write"> Handler_write </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_data"> Innodb_buffer_pool_bytes_data </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_dirty"> Innodb_buffer_pool_bytes_dirty </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_dump_status"> Innodb_buffer_pool_dump_status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_load_status"> Innodb_buffer_pool_load_status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_data"> Innodb_buffer_pool_pages_data </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_dirty"> Innodb_buffer_pool_pages_dirty </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_flushed"> Innodb_buffer_pool_pages_flushed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_free"> Innodb_buffer_pool_pages_free </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_latched"> Innodb_buffer_pool_pages_latched </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_misc"> Innodb_buffer_pool_pages_misc </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_total"> Innodb_buffer_pool_pages_total </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead"> Innodb_buffer_pool_read_ahead </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_evicted"> Innodb_buffer_pool_read_ahead_evicted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_rnd"> Innodb_buffer_pool_read_ahead_rnd </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_requests"> Innodb_buffer_pool_read_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_reads"> Innodb_buffer_pool_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status"> Innodb_buffer_pool_resize_status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status_code"> Innodb_buffer_pool_resize_status_code </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status_progress"> Innodb_buffer_pool_resize_status_progress </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_wait_free"> Innodb_buffer_pool_wait_free </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_write_requests"> Innodb_buffer_pool_write_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_fsyncs"> Innodb_data_fsyncs </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_fsyncs"> Innodb_data_pending_fsyncs </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_reads"> Innodb_data_pending_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_writes"> Innodb_data_pending_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_read"> Innodb_data_read </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_reads"> Innodb_data_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_writes"> Innodb_data_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_written"> Innodb_data_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_pages_written"> Innodb_dblwr_pages_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_writes"> Innodb_dblwr_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_have_atomic_builtins"> Innodb_have_atomic_builtins </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_waits"> Innodb_log_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_write_requests"> Innodb_log_write_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_writes"> Innodb_log_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_num_open_files"> Innodb_num_open_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_fsyncs"> Innodb_os_log_fsyncs </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_fsyncs"> Innodb_os_log_pending_fsyncs </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_writes"> Innodb_os_log_pending_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_written"> Innodb_os_log_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_page_size"> Innodb_page_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_created"> Innodb_pages_created </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_read"> Innodb_pages_read </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_written"> Innodb_pages_written </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_capacity_resized"> Innodb_redo_log_capacity_resized </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_checkpoint_lsn"> Innodb_redo_log_checkpoint_lsn </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_current_lsn"> Innodb_redo_log_current_lsn </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_enabled"> Innodb_redo_log_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_flushed_to_disk_lsn"> Innodb_redo_log_flushed_to_disk_lsn </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_logical_size"> Innodb_redo_log_logical_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_physical_size"> Innodb_redo_log_physical_size </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_read_only"> Innodb_redo_log_read_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_resize_status"> Innodb_redo_log_resize_status </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_uuid"> Innodb_redo_log_uuid </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_current_waits"> Innodb_row_lock_current_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time"> Innodb_row_lock_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_avg"> Innodb_row_lock_time_avg </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_max"> Innodb_row_lock_time_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_waits"> Innodb_row_lock_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_deleted"> Innodb_rows_deleted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_inserted"> Innodb_rows_inserted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_read"> Innodb_rows_read </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_updated"> Innodb_rows_updated </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_deleted"> Innodb_system_rows_deleted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_inserted"> Innodb_system_rows_inserted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_read"> Innodb_system_rows_read </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_updated"> Innodb_system_rows_updated </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_truncated_status_writes"> Innodb_truncated_status_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_active"> Innodb_undo_tablespaces_active </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_explicit"> Innodb_undo_tablespaces_explicit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_implicit"> Innodb_undo_tablespaces_implicit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_total"> Innodb_undo_tablespaces_total </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_blocks_not_flushed"> Key_blocks_not_flushed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_blocks_unused"> Key_blocks_unused </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_blocks_used"> Key_blocks_used </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_read_requests"> Key_read_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_reads"> Key_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_write_requests"> Key_write_requests </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Key_writes"> Key_writes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Last_query_cost"> Last_query_cost </a> </th> <td> Numeric </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Last_query_partial_plans"> Last_query_partial_plans </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Locked_connects"> Locked_connects </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_exceeded"> Max_execution_time_exceeded </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_set"> Max_execution_time_set </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_execution_time_set_failed"> Max_execution_time_set_failed </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_used_connections"> Max_used_connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Max_used_connections_time"> Max_used_connections_time </a> </th> <td> Datetime </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_mecab_charset"> mecab_charset </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_aborted_clients"> Mysqlx_aborted_clients </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_address"> Mysqlx_address </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received"> Mysqlx_bytes_received </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_compressed_payload"> Mysqlx_bytes_received_compressed_payload </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_received_uncompressed_frame"> Mysqlx_bytes_received_uncompressed_frame </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent"> Mysqlx_bytes_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_compressed_payload"> Mysqlx_bytes_sent_compressed_payload </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_bytes_sent_uncompressed_frame"> Mysqlx_bytes_sent_uncompressed_frame </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_compression_algorithm"> Mysqlx_compression_algorithm </a> </th> <td> String </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_compression_level"> Mysqlx_compression_level </a> </th> <td> String </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_accept_errors"> Mysqlx_connection_accept_errors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connection_errors"> Mysqlx_connection_errors </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_accepted"> Mysqlx_connections_accepted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_closed"> Mysqlx_connections_closed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_connections_rejected"> Mysqlx_connections_rejected </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_create_view"> Mysqlx_crud_create_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_delete"> Mysqlx_crud_delete </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_drop_view"> Mysqlx_crud_drop_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_find"> Mysqlx_crud_find </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_insert"> Mysqlx_crud_insert </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_modify_view"> Mysqlx_crud_modify_view </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_crud_update"> Mysqlx_crud_update </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_close"> Mysqlx_cursor_close </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_fetch"> Mysqlx_cursor_fetch </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_cursor_open"> Mysqlx_cursor_open </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_sent"> Mysqlx_errors_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_errors_unknown_message_type"> Mysqlx_errors_unknown_message_type </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_close"> Mysqlx_expect_close </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_expect_open"> Mysqlx_expect_open </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_init_error"> Mysqlx_init_error </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_messages_sent"> Mysqlx_messages_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_global_sent"> Mysqlx_notice_global_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_other_sent"> Mysqlx_notice_other_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notice_warning_sent"> Mysqlx_notice_warning_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_notified_by_group_replication"> Mysqlx_notified_by_group_replication </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_port"> Mysqlx_port </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_deallocate"> Mysqlx_prep_deallocate </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_execute"> Mysqlx_prep_execute </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_prep_prepare"> Mysqlx_prep_prepare </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_rows_sent"> Mysqlx_rows_sent </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions"> Mysqlx_sessions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_accepted"> Mysqlx_sessions_accepted </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_closed"> Mysqlx_sessions_closed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_fatal_error"> Mysqlx_sessions_fatal_error </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_killed"> Mysqlx_sessions_killed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_sessions_rejected"> Mysqlx_sessions_rejected </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_socket"> Mysqlx_socket </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_accept_renegotiates"> Mysqlx_ssl_accept_renegotiates </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_accepts"> Mysqlx_ssl_accepts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_active"> Mysqlx_ssl_active </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_cipher"> Mysqlx_ssl_cipher </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_cipher_list"> Mysqlx_ssl_cipher_list </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_ctx_verify_depth"> Mysqlx_ssl_ctx_verify_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_ctx_verify_mode"> Mysqlx_ssl_ctx_verify_mode </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_finished_accepts"> Mysqlx_ssl_finished_accepts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_server_not_after"> Mysqlx_ssl_server_not_after </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_server_not_before"> Mysqlx_ssl_server_not_before </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_verify_depth"> Mysqlx_ssl_verify_depth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_verify_mode"> Mysqlx_ssl_verify_mode </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_ssl_version"> Mysqlx_ssl_version </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection"> Mysqlx_stmt_create_collection </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_create_collection_index"> Mysqlx_stmt_create_collection_index </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_disable_notices"> Mysqlx_stmt_disable_notices </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection"> Mysqlx_stmt_drop_collection </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_drop_collection_index"> Mysqlx_stmt_drop_collection_index </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_enable_notices"> Mysqlx_stmt_enable_notices </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ensure_collection"> Mysqlx_stmt_ensure_collection </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_mysqlx"> Mysqlx_stmt_execute_mysqlx </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_sql"> Mysqlx_stmt_execute_sql </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_execute_xplugin"> Mysqlx_stmt_execute_xplugin </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_get_collection_options"> Mysqlx_stmt_get_collection_options </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_kill_client"> Mysqlx_stmt_kill_client </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_clients"> Mysqlx_stmt_list_clients </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_notices"> Mysqlx_stmt_list_notices </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_list_objects"> Mysqlx_stmt_list_objects </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_modify_collection_options"> Mysqlx_stmt_modify_collection_options </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_stmt_ping"> Mysqlx_stmt_ping </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads"> Mysqlx_worker_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-status-variables.html#statvar_Mysqlx_worker_threads_active"> Mysqlx_worker_threads_active </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_deferred_count"> Ndb_api_adaptive_send_deferred_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_deferred_count_replica"> Ndb_api_adaptive_send_deferred_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_deferred_count_session"> Ndb_api_adaptive_send_deferred_count_session </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_deferred_count_slave"> Ndb_api_adaptive_send_deferred_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_forced_count"> Ndb_api_adaptive_send_forced_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_forced_count_replica"> Ndb_api_adaptive_send_forced_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_forced_count_session"> Ndb_api_adaptive_send_forced_count_session </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_forced_count_slave"> Ndb_api_adaptive_send_forced_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_unforced_count"> Ndb_api_adaptive_send_unforced_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_unforced_count_replica"> Ndb_api_adaptive_send_unforced_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_unforced_count_session"> Ndb_api_adaptive_send_unforced_count_session </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_adaptive_send_unforced_count_slave"> Ndb_api_adaptive_send_unforced_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_received_count"> Ndb_api_bytes_received_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_received_count_replica"> Ndb_api_bytes_received_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_received_count_session"> Ndb_api_bytes_received_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_received_count_slave"> Ndb_api_bytes_received_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_sent_count"> Ndb_api_bytes_sent_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_sent_count_replica"> Ndb_api_bytes_sent_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_sent_count_session"> Ndb_api_bytes_sent_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_bytes_sent_count_slave"> Ndb_api_bytes_sent_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_bytes_count"> Ndb_api_event_bytes_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_bytes_count_injector"> Ndb_api_event_bytes_count_injector </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_data_count"> Ndb_api_event_data_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_data_count_injector"> Ndb_api_event_data_count_injector </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_nondata_count"> Ndb_api_event_nondata_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_event_nondata_count_injector"> Ndb_api_event_nondata_count_injector </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pk_op_count"> Ndb_api_pk_op_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pk_op_count_replica"> Ndb_api_pk_op_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pk_op_count_session"> Ndb_api_pk_op_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pk_op_count_slave"> Ndb_api_pk_op_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pruned_scan_count"> Ndb_api_pruned_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pruned_scan_count_replica"> Ndb_api_pruned_scan_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pruned_scan_count_session"> Ndb_api_pruned_scan_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_pruned_scan_count_slave"> Ndb_api_pruned_scan_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_range_scan_count"> Ndb_api_range_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_range_scan_count_replica"> Ndb_api_range_scan_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_range_scan_count_session"> Ndb_api_range_scan_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_range_scan_count_slave"> Ndb_api_range_scan_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_read_row_count"> Ndb_api_read_row_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_read_row_count_replica"> Ndb_api_read_row_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_read_row_count_session"> Ndb_api_read_row_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_read_row_count_slave"> Ndb_api_read_row_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_scan_batch_count"> Ndb_api_scan_batch_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_scan_batch_count_replica"> Ndb_api_scan_batch_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_scan_batch_count_session"> Ndb_api_scan_batch_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_scan_batch_count_slave"> Ndb_api_scan_batch_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_table_scan_count"> Ndb_api_table_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_table_scan_count_replica"> Ndb_api_table_scan_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_table_scan_count_session"> Ndb_api_table_scan_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_table_scan_count_slave"> Ndb_api_table_scan_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_abort_count"> Ndb_api_trans_abort_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_abort_count_replica"> Ndb_api_trans_abort_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_abort_count_session"> Ndb_api_trans_abort_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_abort_count_slave"> Ndb_api_trans_abort_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_close_count"> Ndb_api_trans_close_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_close_count_replica"> Ndb_api_trans_close_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_close_count_session"> Ndb_api_trans_close_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_close_count_slave"> Ndb_api_trans_close_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_commit_count"> Ndb_api_trans_commit_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_commit_count_replica"> Ndb_api_trans_commit_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_commit_count_session"> Ndb_api_trans_commit_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_commit_count_slave"> Ndb_api_trans_commit_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_local_read_row_count"> Ndb_api_trans_local_read_row_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_local_read_row_count_replica"> Ndb_api_trans_local_read_row_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_local_read_row_count_session"> Ndb_api_trans_local_read_row_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_local_read_row_count_slave"> Ndb_api_trans_local_read_row_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_start_count"> Ndb_api_trans_start_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_start_count_replica"> Ndb_api_trans_start_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_start_count_session"> Ndb_api_trans_start_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_trans_start_count_slave"> Ndb_api_trans_start_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_uk_op_count"> Ndb_api_uk_op_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_uk_op_count_replica"> Ndb_api_uk_op_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_uk_op_count_session"> Ndb_api_uk_op_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_uk_op_count_slave"> Ndb_api_uk_op_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_exec_complete_count"> Ndb_api_wait_exec_complete_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_exec_complete_count_replica"> Ndb_api_wait_exec_complete_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_exec_complete_count_session"> Ndb_api_wait_exec_complete_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_exec_complete_count_slave"> Ndb_api_wait_exec_complete_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_meta_request_count"> Ndb_api_wait_meta_request_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_meta_request_count_replica"> Ndb_api_wait_meta_request_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_meta_request_count_session"> Ndb_api_wait_meta_request_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_meta_request_count_slave"> Ndb_api_wait_meta_request_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_nanos_count"> Ndb_api_wait_nanos_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_nanos_count_replica"> Ndb_api_wait_nanos_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_nanos_count_session"> Ndb_api_wait_nanos_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_nanos_count_slave"> Ndb_api_wait_nanos_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_scan_result_count"> Ndb_api_wait_scan_result_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_scan_result_count_replica"> Ndb_api_wait_scan_result_count_replica </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_scan_result_count_session"> Ndb_api_wait_scan_result_count_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_api_wait_scan_result_count_slave"> Ndb_api_wait_scan_result_count_slave </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_cluster_node_id"> Ndb_cluster_node_id </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_config_from_host"> Ndb_config_from_host </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_config_from_port"> Ndb_config_from_port </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_config_generation"> Ndb_config_generation </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_epoch"> Ndb_conflict_fn_epoch </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_epoch_trans"> Ndb_conflict_fn_epoch_trans </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_epoch2"> Ndb_conflict_fn_epoch2 </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_epoch2_trans"> Ndb_conflict_fn_epoch2_trans </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_max"> Ndb_conflict_fn_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_max_del_win"> Ndb_conflict_fn_max_del_win </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_max_del_win_ins"> Ndb_conflict_fn_max_del_win_ins </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_max_ins"> Ndb_conflict_fn_max_ins </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_fn_old"> Ndb_conflict_fn_old </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_last_conflict_epoch"> Ndb_conflict_last_conflict_epoch </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_last_stable_epoch"> Ndb_conflict_last_stable_epoch </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_reflected_op_discard_count"> Ndb_conflict_reflected_op_discard_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_reflected_op_prepare_count"> Ndb_conflict_reflected_op_prepare_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_refresh_op_count"> Ndb_conflict_refresh_op_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_conflict_commit_count"> Ndb_conflict_trans_conflict_commit_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_detect_iter_count"> Ndb_conflict_trans_detect_iter_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_reject_count"> Ndb_conflict_trans_reject_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_row_conflict_count"> Ndb_conflict_trans_row_conflict_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_conflict_trans_row_reject_count"> Ndb_conflict_trans_row_reject_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_epoch_delete_delete_count"> Ndb_epoch_delete_delete_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_execute_count"> Ndb_execute_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_last_commit_epoch_server"> Ndb_last_commit_epoch_server </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_last_commit_epoch_session"> Ndb_last_commit_epoch_session </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_metadata_detected_count"> Ndb_metadata_detected_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_metadata_excluded_count"> Ndb_metadata_excluded_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_metadata_synced_count"> Ndb_metadata_synced_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_cluster_node_id"> Ndb_cluster_node_id </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_number_of_data_nodes"> Ndb_number_of_data_nodes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pruned_scan_count"> Ndb_pruned_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pushed_queries_defined"> Ndb_pushed_queries_defined </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pushed_queries_dropped"> Ndb_pushed_queries_dropped </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pushed_queries_executed"> Ndb_pushed_queries_executed </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_pushed_reads"> Ndb_pushed_reads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_scan_count"> Ndb_scan_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_slave_max_replicated_epoch"> Ndb_slave_max_replicated_epoch </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#statvar_Ndb_trans_hint_count_session"> Ndb_trans_hint_count_session </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Not_flushed_delayed_rows"> Not_flushed_delayed_rows </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ongoing_anonymous_gtid_violating_transaction_count"> Ongoing_anonymous_gtid_violating_transaction_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ongoing_anonymous_transaction_count"> Ongoing_anonymous_transaction_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ongoing_automatic_gtid_violating_transaction_count"> Ongoing_automatic_gtid_violating_transaction_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Open_files"> Open_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Open_streams"> Open_streams </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Open_table_definitions"> Open_table_definitions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Open_tables"> Open_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Opened_files"> Opened_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Opened_table_definitions"> Opened_table_definitions </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Opened_tables"> Opened_tables </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_accounts_lost"> Performance_schema_accounts_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_cond_classes_lost"> Performance_schema_cond_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_cond_instances_lost"> Performance_schema_cond_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_digest_lost"> Performance_schema_digest_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_classes_lost"> Performance_schema_file_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_handles_lost"> Performance_schema_file_handles_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_file_instances_lost"> Performance_schema_file_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_hosts_lost"> Performance_schema_hosts_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_index_stat_lost"> Performance_schema_index_stat_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_locker_lost"> Performance_schema_locker_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_memory_classes_lost"> Performance_schema_memory_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_metadata_lock_lost"> Performance_schema_metadata_lock_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_meter_lost"> Performance_schema_meter_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_metric_lost"> Performance_schema_metric_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_mutex_classes_lost"> Performance_schema_mutex_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_mutex_instances_lost"> Performance_schema_mutex_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_nested_statement_lost"> Performance_schema_nested_statement_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_prepared_statements_lost"> Performance_schema_prepared_statements_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_program_lost"> Performance_schema_program_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_rwlock_classes_lost"> Performance_schema_rwlock_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_rwlock_instances_lost"> Performance_schema_rwlock_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_session_connect_attrs_longest_seen"> Performance_schema_session_connect_attrs_longest_seen </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_session_connect_attrs_lost"> Performance_schema_session_connect_attrs_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_socket_classes_lost"> Performance_schema_socket_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_socket_instances_lost"> Performance_schema_socket_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_stage_classes_lost"> Performance_schema_stage_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_statement_classes_lost"> Performance_schema_statement_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_handles_lost"> Performance_schema_table_handles_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_instances_lost"> Performance_schema_table_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_table_lock_stat_lost"> Performance_schema_table_lock_stat_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_thread_classes_lost"> Performance_schema_thread_classes_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_thread_instances_lost"> Performance_schema_thread_instances_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-status-variables.html#statvar_Performance_schema_users_lost"> Performance_schema_users_lost </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Prepared_stmt_count"> Prepared_stmt_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Queries"> Queries </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Questions"> Questions </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Replica_open_temp_tables"> Replica_open_temp_tables </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Resource_group_supported"> Resource_group_supported </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#statvar_Rewriter_number_loaded_rules"> Rewriter_number_loaded_rules </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#statvar_Rewriter_number_reloads"> Rewriter_number_reloads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#statvar_Rewriter_number_rewritten_queries"> Rewriter_number_rewritten_queries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#statvar_Rewriter_reload_error"> Rewriter_reload_error </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_clients"> Rpl_semi_sync_master_clients </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_net_avg_wait_time"> Rpl_semi_sync_master_net_avg_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_net_wait_time"> Rpl_semi_sync_master_net_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_net_waits"> Rpl_semi_sync_master_net_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_no_times"> Rpl_semi_sync_master_no_times </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_no_tx"> Rpl_semi_sync_master_no_tx </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_status"> Rpl_semi_sync_master_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_timefunc_failures"> Rpl_semi_sync_master_timefunc_failures </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_tx_avg_wait_time"> Rpl_semi_sync_master_tx_avg_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_tx_wait_time"> Rpl_semi_sync_master_tx_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_tx_waits"> Rpl_semi_sync_master_tx_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_wait_pos_backtraverse"> Rpl_semi_sync_master_wait_pos_backtraverse </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_wait_sessions"> Rpl_semi_sync_master_wait_sessions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_master_yes_tx"> Rpl_semi_sync_master_yes_tx </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_replica_status"> Rpl_semi_sync_replica_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_slave_status"> Rpl_semi_sync_slave_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_clients"> Rpl_semi_sync_source_clients </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_net_avg_wait_time"> Rpl_semi_sync_source_net_avg_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_net_wait_time"> Rpl_semi_sync_source_net_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_net_waits"> Rpl_semi_sync_source_net_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_no_times"> Rpl_semi_sync_source_no_times </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_no_tx"> Rpl_semi_sync_source_no_tx </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_status"> Rpl_semi_sync_source_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_timefunc_failures"> Rpl_semi_sync_source_timefunc_failures </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_tx_avg_wait_time"> Rpl_semi_sync_source_tx_avg_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_tx_wait_time"> Rpl_semi_sync_source_tx_wait_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_tx_waits"> Rpl_semi_sync_source_tx_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_wait_pos_backtraverse"> Rpl_semi_sync_source_wait_pos_backtraverse </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_wait_sessions"> Rpl_semi_sync_source_wait_sessions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rpl_semi_sync_source_yes_tx"> Rpl_semi_sync_source_yes_tx </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Rsa_public_key"> Rsa_public_key </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Secondary_engine_execution_count"> Secondary_engine_execution_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_full_join"> Select_full_join </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_full_range_join"> Select_full_range_join </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_range"> Select_range </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_range_check"> Select_range_check </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Select_scan"> Select_scan </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Slave_open_temp_tables"> Slave_open_temp_tables </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Slave_rows_last_search_algorithm_used"> Slave_rows_last_search_algorithm_used </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Slow_launch_threads"> Slow_launch_threads </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Slow_queries"> Slow_queries </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Sort_merge_passes"> Sort_merge_passes </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Sort_range"> Sort_range </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Sort_rows"> Sort_rows </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Sort_scan"> Sort_scan </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_accept_renegotiates"> Ssl_accept_renegotiates </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_accepts"> Ssl_accepts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_callback_cache_hits"> Ssl_callback_cache_hits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_cipher"> Ssl_cipher </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_cipher_list"> Ssl_cipher_list </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_client_connects"> Ssl_client_connects </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_connect_renegotiates"> Ssl_connect_renegotiates </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_ctx_verify_depth"> Ssl_ctx_verify_depth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_ctx_verify_mode"> Ssl_ctx_verify_mode </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_default_timeout"> Ssl_default_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_finished_accepts"> Ssl_finished_accepts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_finished_connects"> Ssl_finished_connects </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_server_not_after"> Ssl_server_not_after </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_server_not_before"> Ssl_server_not_before </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_hits"> Ssl_session_cache_hits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_misses"> Ssl_session_cache_misses </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_mode"> Ssl_session_cache_mode </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_overflows"> Ssl_session_cache_overflows </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_size"> Ssl_session_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_timeout"> Ssl_session_cache_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_session_cache_timeouts"> Ssl_session_cache_timeouts </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_sessions_reused"> Ssl_sessions_reused </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_used_session_cache_entries"> Ssl_used_session_cache_entries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_verify_depth"> Ssl_verify_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_verify_mode"> Ssl_verify_mode </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Ssl_version"> Ssl_version </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_locks_immediate"> Table_locks_immediate </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_locks_waited"> Table_locks_waited </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_hits"> Table_open_cache_hits </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_misses"> Table_open_cache_misses </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Table_open_cache_overflows"> Table_open_cache_overflows </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tc_log_max_pages_used"> Tc_log_max_pages_used </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tc_log_page_size"> Tc_log_page_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tc_log_page_waits"> Tc_log_page_waits </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Telemetry_metrics_supported"> Telemetry_metrics_supported </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Telemetry_traces_supported"> Telemetry_traces_supported </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_telemetry.live_sessions"> telemetry.live_sessions </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Threads_cached"> Threads_cached </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Threads_connected"> Threads_connected </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Threads_created"> Threads_created </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Threads_running"> Threads_running </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tls_library_version"> Tls_library_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Tls_sni_server_name"> Tls_sni_server_name </a> </th> <td> String </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Uptime"> Uptime </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Uptime_since_flush_status"> Uptime_since_flush_status </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#statvar_validate_password_dictionary_file_last_parsed"> validate_password_dictionary_file_last_parsed </a> </th> <td> Datetime </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#statvar_validate_password_dictionary_file_words_count"> validate_password_dictionary_file_words_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#statvar_validate_password.dictionary_file_last_parsed"> validate_password.dictionary_file_last_parsed </a> </th> <td> Datetime </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#statvar_validate_password.dictionary_file_words_count"> validate_password.dictionary_file_words_count </a> </th> <td> Integer </td> <td> Global </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th scope="col" style="width: 430.609px;"> Variable Name </th> <th scope="col" style="width: 153.688px;"> Variable Type </th> <th scope="col" style="width: 153.703px;"> Variable Scope </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/general-tablespaces.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="general-tablespaces"> </a> 17.6.3.3 General Tablespaces </h4> </div> </div> </div> <p> A general tablespace is a shared <code class="literal"> InnoDB </code> tablespace that is created using <a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> <code class="literal"> CREATE TABLESPACE </code> </a> syntax. General tablespace capabilities and features are described under the following topics in this section: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-capabilities" title="General Tablespace Capabilities"> General Tablespace Capabilities </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-creating" title="Creating a General Tablespace"> Creating a General Tablespace </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-adding-tables" title="Adding Tables to a General Tablespace"> Adding Tables to a General Tablespace </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-row-format-support" title="General Tablespace Row Format Support"> General Tablespace Row Format Support </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-moving-non-partitioned-tables" title="Moving Tables Between Tablespaces Using ALTER TABLE"> Moving Tables Between Tablespaces Using ALTER TABLE </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-renaming" title="Renaming a General Tablespace"> Renaming a General Tablespace </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-dropping" title="Dropping a General Tablespace"> Dropping a General Tablespace </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="general-tablespaces.html#general-tablespaces-limitations" title="General Tablespace Limitations"> General Tablespace Limitations </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-capabilities"> </a> General Tablespace Capabilities </h5> </div> </div> </div> <p> General tablespaces provide the following capabilities: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Similar to the system tablespace, general tablespaces are shared tablespaces capable of storing data for multiple tables. </p> </li> <li class="listitem"> <p> General tablespaces have a potential memory advantage over <a class="link" href="innodb-file-per-table-tablespaces.html" title="17.6.3.2 File-Per-Table Tablespaces"> file-per-table tablespaces </a> . The server keeps tablespace metadata in memory for the lifetime of a tablespace. Multiple tables in fewer general tablespaces consume less memory for tablespace metadata than the same number of tables in separate file-per-table tablespaces. </p> </li> <li class="listitem"> <p> General tablespace data files can be placed in a directory relative to or independent of the MySQL data directory, which provides you with many of the data file and storage management capabilities of <a class="link" href="innodb-file-per-table-tablespaces.html" title="17.6.3.2 File-Per-Table Tablespaces"> file-per-table tablespaces </a> . As with file-per-table tablespaces, the ability to place data files outside of the MySQL data directory allows you to manage performance of critical tables separately, setup RAID or DRBD for specific tables, or bind tables to particular disks, for example. </p> </li> <li class="listitem"> <p> General tablespaces support all table row formats and associated features. </p> </li> <li class="listitem"> <p> The <code class="literal"> TABLESPACE </code> option can be used with <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> to create tables in a general tablespaces, file-per-table tablespace, or in the system tablespace. </p> </li> <li class="listitem"> <p> The <code class="literal"> TABLESPACE </code> option can be used with <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> to move tables between general tablespaces, file-per-table tablespaces, and the system tablespace. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-creating"> </a> Creating a General Tablespace </h5> </div> </div> </div> <p> General tablespaces are created using <a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> <code class="literal"> CREATE TABLESPACE </code> </a> syntax. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa22223263"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <em class="replaceable">tablespace_name</em> <span class="token punctuation">[</span><span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'<em class="replaceable">file_name</em>'</span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">FILE_BLOCK_SIZE</span> <span class="token operator">=</span> <span class="token keyword"><em class="replaceable">value</em></span><span class="token punctuation">]</span> <span class="token punctuation">[</span><span class="token keyword">ENGINE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <em class="replaceable">engine_name</em><span class="token punctuation">]</span></code></pre> </div> <p> A general tablespace can be created in the data directory or outside of it. To avoid conflicts with implicitly created file-per-table tablespaces, creating a general tablespace in a subdirectory under the data directory is not supported. When creating a general tablespace outside of the data directory, the directory must exist and must be known to <code class="literal"> InnoDB </code> prior to creating the tablespace. To make an unknown directory known to <code class="literal"> InnoDB </code> , add the directory to the <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> argument value. <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> is a read-only startup option. Configuring it requires restarting the server. </p> <p> Examples: </p> <p> Creating a general tablespace in the data directory: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa90744458"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts1.ibd'</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span></code></pre> </div> <p> or </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa34549756"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span></code></pre> </div> <p> The <code class="literal"> ADD DATAFILE </code> clause is optional. If the <code class="literal"> ADD DATAFILE </code> clause is not specified when creating a tablespace, a tablespace data file with a unique file name is created implicitly. The unique file name is a 128 bit UUID formatted into five groups of hexadecimal numbers separated by dashes ( <em class="replaceable"> <code> aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee </code> </em> ). General tablespace data files include an <code class="filename"> .ibd </code> file extension. In a replication environment, the data file name created on the source is not the same as the data file name created on the replica. </p> <p> Creating a general tablespace in a directory outside of the data directory: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa77995652"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'/my/tablespace/directory/ts1.ibd'</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span></code></pre> </div> <p> You can specify a path that is relative to the data directory as long as the tablespace directory is not under the data directory. In this example, the <code class="filename"> my_tablespace </code> directory is at the same level as the data directory: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa48485064"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'../my_tablespace/ts1.ibd'</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The <code class="literal"> ENGINE = InnoDB </code> clause must be defined as part of the <a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> <code class="literal"> CREATE TABLESPACE </code> </a> statement, or <code class="literal"> InnoDB </code> must be defined as the default storage engine ( <a class="link" href="server-system-variables.html#sysvar_default_storage_engine"> <code class="literal"> default_storage_engine=InnoDB </code> </a> ). </p> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-adding-tables"> </a> Adding Tables to a General Tablespace </h5> </div> </div> </div> <p> After creating a general tablespace, <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE <em class="replaceable"> <code> tbl_name </code> </em> ... TABLESPACE [=] <em class="replaceable"> <code> tablespace_name </code> </em> </code> </a> or <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE <em class="replaceable"> <code> tbl_name </code> </em> TABLESPACE [=] <em class="replaceable"> <code> tablespace_name </code> </em> </code> </a> statements can be used to add tables to the tablespace, as shown in the following examples: </p> <p> <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa7562109"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts1<span class="token punctuation">;</span></code></pre> </div> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa69231378"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t2 <span class="token keyword">TABLESPACE</span> ts1<span class="token punctuation">;</span></code></pre> </div> <p> Adding table partitions to shared tablespaces is not supported. Shared tablespaces include the <code class="literal"> InnoDB </code> system tablespace and general tablespaces. </p> <p> For detailed syntax information, see <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> and <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-row-format-support"> </a> General Tablespace Row Format Support </h5> </div> </div> </div> <p> General tablespaces support all table row formats ( <code class="literal"> REDUNDANT </code> , <code class="literal"> COMPACT </code> , <code class="literal"> DYNAMIC </code> , <code class="literal"> COMPRESSED </code> ) with the caveat that compressed and uncompressed tables cannot coexist in the same general tablespace due to different physical page sizes. </p> <p> For a general tablespace to contain compressed tables ( <code class="literal"> ROW_FORMAT=COMPRESSED </code> ), the <code class="literal"> FILE_BLOCK_SIZE </code> option must be specified, and the <code class="literal"> FILE_BLOCK_SIZE </code> value must be a valid compressed page size in relation to the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value. Also, the physical page size of the compressed table ( <code class="literal"> KEY_BLOCK_SIZE </code> ) must be equal to <code class="literal"> FILE_BLOCK_SIZE/1024 </code> . For example, if <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size=16KB </code> </a> and <code class="literal"> FILE_BLOCK_SIZE=8K </code> , the <code class="literal"> KEY_BLOCK_SIZE </code> of the table must be 8. </p> <p> The following table shows permitted <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> , <code class="literal"> FILE_BLOCK_SIZE </code> , and <code class="literal"> KEY_BLOCK_SIZE </code> combinations. <code class="literal"> FILE_BLOCK_SIZE </code> values may also be specified in bytes. To determine a valid <code class="literal"> KEY_BLOCK_SIZE </code> value for a given <code class="literal"> FILE_BLOCK_SIZE </code> , divide the <code class="literal"> FILE_BLOCK_SIZE </code> value by 1024. Table compression is not support for 32K and 64K <code class="literal"> InnoDB </code> page sizes. For more information about <code class="literal"> KEY_BLOCK_SIZE </code> , see <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> , and <a class="xref" href="innodb-compression-usage.html" title="17.9.1.2 Creating Compressed Tables"> Section 17.9.1.2, “Creating Compressed Tables” </a> . </p> <div class="table"> <a name="idm46045165437104"> </a> <p class="title"> <b> Table 17.3 Permitted Page Size, FILE_BLOCK_SIZE, and KEY_BLOCK_SIZE Combinations for Compressed Tables </b> </p> <div class="table-contents"> <table frame="all"> <colgroup> <col style="width: 33%"/> <col style="width: 33%"/> <col style="width: 34%"/> </colgroup> <thead> <tr> <th scope="col"> InnoDB Page Size (innodb_page_size) </th> <th scope="col"> Permitted FILE_BLOCK_SIZE Value </th> <th scope="col"> Permitted KEY_BLOCK_SIZE Value </th> </tr> </thead> <tbody> <tr> <th scope="row"> 64KB </th> <td> 64K (65536) </td> <td> Compression is not supported </td> </tr> <tr> <th scope="row"> 32KB </th> <td> 32K (32768) </td> <td> Compression is not supported </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 16K (16384) </td> <td> None. If <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> is equal to <code class="literal"> FILE_BLOCK_SIZE </code> , the tablespace cannot contain a compressed table. </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 8K (8192) </td> <td> 8 </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 4K (4096) </td> <td> 4 </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 2K (2048) </td> <td> 2 </td> </tr> <tr> <th scope="row"> 16KB </th> <td> 1K (1024) </td> <td> 1 </td> </tr> <tr> <th scope="row"> 8KB </th> <td> 8K (8192) </td> <td> None. If <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> is equal to <code class="literal"> FILE_BLOCK_SIZE </code> , the tablespace cannot contain a compressed table. </td> </tr> <tr> <th scope="row"> 8KB </th> <td> 4K (4096) </td> <td> 4 </td> </tr> <tr> <th scope="row"> 8KB </th> <td> 2K (2048) </td> <td> 2 </td> </tr> <tr> <th scope="row"> 8KB </th> <td> 1K (1024) </td> <td> 1 </td> </tr> <tr> <th scope="row"> 4KB </th> <td> 4K (4096) </td> <td> None. If <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> is equal to <code class="literal"> FILE_BLOCK_SIZE </code> , the tablespace cannot contain a compressed table. </td> </tr> <tr> <th scope="row"> 4KB </th> <td> 2K (2048) </td> <td> 2 </td> </tr> <tr> <th scope="row"> 4KB </th> <td> 1K (1024) </td> <td> 1 </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th scope="col" style="width: 243.531px;"> InnoDB Page Size (innodb_page_size) </th> <th scope="col" style="width: 243.531px;"> Permitted FILE_BLOCK_SIZE Value </th> <th scope="col" style="width: 250.938px;"> Permitted KEY_BLOCK_SIZE Value </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> <p> This example demonstrates creating a general tablespace and adding a compressed table. The example assumes a default <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> of 16KB. The <code class="literal"> FILE_BLOCK_SIZE </code> of 8192 requires that the compressed table have a <code class="literal"> KEY_BLOCK_SIZE </code> of 8. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa46936737"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts2<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts2.ibd'</span> <span class="token keyword">FILE_BLOCK_SIZE</span> <span class="token operator">=</span> <span class="token number">8192</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t4 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts2 <span class="token keyword">ROW_FORMAT</span><span class="token operator">=</span><span class="token keyword">COMPRESSED</span> <span class="token keyword">KEY_BLOCK_SIZE</span><span class="token operator">=</span><span class="token number">8</span><span class="token punctuation">;</span></code></pre> </div> <p> If you do not specify <code class="literal"> FILE_BLOCK_SIZE </code> when creating a general tablespace, <code class="literal"> FILE_BLOCK_SIZE </code> defaults to <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> . When <code class="literal"> FILE_BLOCK_SIZE </code> is equal to <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> , the tablespace may only contain tables with an uncompressed row format ( <code class="literal"> COMPACT </code> , <code class="literal"> REDUNDANT </code> , and <code class="literal"> DYNAMIC </code> row formats). </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-moving-non-partitioned-tables"> </a> Moving Tables Between Tablespaces Using ALTER TABLE </h5> </div> </div> </div> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> with the <code class="literal"> TABLESPACE </code> option can be used to move a table to an existing general tablespace, to a new file-per-table tablespace, or to the system tablespace. </p> <p> Adding table partitions to shared tablespaces is not supported. Shared tablespaces include the <code class="literal"> InnoDB </code> system tablespace and general tablespaces. </p> <p> To move a table from a file-per-table tablespace or from the system tablespace to a general tablespace, specify the name of the general tablespace. The general tablespace must exist. See <a class="link" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement"> <code class="literal"> ALTER TABLESPACE </code> </a> for more information. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa26357229"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> tbl_name <span class="token keyword">TABLESPACE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> <em class="replaceable">tablespace_name</em><span class="token punctuation">;</span></code></pre> </div> <p> To move a table from a general tablespace or file-per-table tablespace to the system tablespace, specify <code class="literal"> innodb_system </code> as the tablespace name. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa76237607"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> tbl_name <span class="token keyword">TABLESPACE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> innodb_system<span class="token punctuation">;</span></code></pre> </div> <p> To move a table from the system tablespace or a general tablespace to a file-per-table tablespace, specify <code class="literal"> innodb_file_per_table </code> as the tablespace name. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa81104879"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> tbl_name <span class="token keyword">TABLESPACE</span> <span class="token punctuation">[</span><span class="token operator">=</span><span class="token punctuation">]</span> innodb_file_per_table<span class="token punctuation">;</span></code></pre> </div> <p> <code class="literal"> ALTER TABLE ... TABLESPACE </code> operations cause a full table rebuild, even if the <code class="literal"> TABLESPACE </code> attribute has not changed from its previous value. </p> <p> <code class="literal"> ALTER TABLE ... TABLESPACE </code> syntax does not support moving a table from a temporary tablespace to a persistent tablespace. </p> <p> The <code class="literal"> DATA DIRECTORY </code> clause is permitted with <code class="literal"> CREATE TABLE ... TABLESPACE=innodb_file_per_table </code> but is otherwise not supported for use in combination with the <code class="literal"> TABLESPACE </code> option. The directory specified in a <code class="literal"> DATA DIRECTORY </code> clause must be known to <code class="literal"> InnoDB </code> . For more information, see <a class="xref" href="innodb-create-table-external.html#innodb-create-table-external-data-directory" title="Using the DATA DIRECTORY Clause"> Using the DATA DIRECTORY Clause </a> . </p> <p> Restrictions apply when moving tables from encrypted tablespaces. See <a class="xref" href="innodb-data-encryption.html#innodb-data-encryption-limitations" title="Encryption Limitations"> Encryption Limitations </a> . </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-renaming"> </a> Renaming a General Tablespace </h5> </div> </div> </div> <p> Renaming a general tablespace is supported using <a class="link" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement"> <code class="literal"> ALTER TABLESPACE ... RENAME TO </code> </a> syntax. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa67453619"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLESPACE</span> s1 <span class="token keyword">RENAME</span> <span class="token keyword">TO</span> s2<span class="token punctuation">;</span></code></pre> </div> <p> The <a class="link" href="privileges-provided.html#priv_create-tablespace"> <code class="literal"> CREATE TABLESPACE </code> </a> privilege is required to rename a general tablespace. </p> <p> <code class="literal"> RENAME TO </code> operations are implicitly performed in <a class="link" href="server-system-variables.html#sysvar_autocommit"> <code class="literal"> autocommit </code> </a> mode regardless of the <a class="link" href="server-system-variables.html#sysvar_autocommit"> <code class="literal"> autocommit </code> </a> setting. </p> <p> A <code class="literal"> RENAME TO </code> operation cannot be performed while <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES </code> </a> or <a class="link" href="flush.html" title="15.7.8.3 FLUSH Statement"> <code class="literal"> FLUSH TABLES WITH READ LOCK </code> </a> is in effect for tables that reside in the tablespace. </p> <p> Exclusive <a class="link" href="glossary.html#glos_metadata_lock" title="metadata lock"> metadata locks </a> are taken on tables within a general tablespace while the tablespace is renamed, which prevents concurrent DDL. Concurrent DML is supported. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-dropping"> </a> Dropping a General Tablespace </h5> </div> </div> </div> <p> The <a class="link" href="drop-tablespace.html" title="15.1.33 DROP TABLESPACE Statement"> <code class="literal"> DROP TABLESPACE </code> </a> statement is used to drop an <code class="literal"> InnoDB </code> general tablespace. </p> <p> All tables must be dropped from the tablespace prior to a <a class="link" href="drop-tablespace.html" title="15.1.33 DROP TABLESPACE Statement"> <code class="literal"> DROP TABLESPACE </code> </a> operation. If the tablespace is not empty, <a class="link" href="drop-tablespace.html" title="15.1.33 DROP TABLESPACE Statement"> <code class="literal"> DROP TABLESPACE </code> </a> returns an error. </p> <p> Use a query similar to the following to identify tables in a general tablespace. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa28439679"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> a<span class="token punctuation">.</span><span class="token keyword">NAME</span> <span class="token keyword">AS</span> space_name<span class="token punctuation">,</span> b<span class="token punctuation">.</span><span class="token keyword">NAME</span> <span class="token keyword">AS</span> <span class="token keyword">table_name</span> <span class="token keyword">FROM</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_TABLESPACES a<span class="token punctuation">,</span> INFORMATION_SCHEMA<span class="token punctuation">.</span>INNODB_TABLES b <span class="token keyword">WHERE</span> a<span class="token punctuation">.</span>SPACE<span class="token operator">=</span>b<span class="token punctuation">.</span>SPACE <span class="token operator">AND</span> a<span class="token punctuation">.</span><span class="token keyword">NAME</span> <span class="token operator">LIKE</span> <span class="token string">'ts1'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> space_name <span class="token punctuation">|</span> table_name <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> ts1 <span class="token punctuation">|</span> test/t1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> ts1 <span class="token punctuation">|</span> test/t2 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> ts1 <span class="token punctuation">|</span> test/t3 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> A general <code class="literal"> InnoDB </code> tablespace is not deleted automatically when the last table in the tablespace is dropped. The tablespace must be dropped explicitly using <a class="link" href="drop-tablespace.html" title="15.1.33 DROP TABLESPACE Statement"> <code class="literal"> DROP TABLESPACE <em class="replaceable"> <code> tablespace_name </code> </em> </code> </a> . </p> <p> A general tablespace does not belong to any particular database. A <a class="link" href="drop-database.html" title="15.1.24 DROP DATABASE Statement"> <code class="literal"> DROP DATABASE </code> </a> operation can drop tables that belong to a general tablespace but it cannot drop the tablespace, even if the <a class="link" href="drop-database.html" title="15.1.24 DROP DATABASE Statement"> <code class="literal"> DROP DATABASE </code> </a> operation drops all tables that belong to the tablespace. </p> <p> Similar to the system tablespace, truncating or dropping tables stored in a general tablespace creates free space internally in the general tablespace <a class="link" href="glossary.html#glos_ibd_file" title=".ibd file"> .ibd data file </a> which can only be used for new <code class="literal"> InnoDB </code> data. Space is not released back to the operating system as it is when a file-per-table tablespace is deleted during a <a class="link" href="drop-table.html" title="15.1.32 DROP TABLE Statement"> <code class="literal"> DROP TABLE </code> </a> operation. </p> <p> This example demonstrates how to drop an <code class="literal"> InnoDB </code> general tablespace. The general tablespace <code class="literal"> ts1 </code> is created with a single table. The table must be dropped before dropping the tablespace. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa34621784"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLESPACE</span> <span class="token punctuation">`</span>ts1<span class="token punctuation">`</span> <span class="token keyword">ADD</span> <span class="token keyword">DATAFILE</span> <span class="token string">'ts1.ibd'</span> <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> t1 <span class="token punctuation">(</span>c1 <span class="token datatype">INT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span> <span class="token keyword">TABLESPACE</span> ts1 <span class="token keyword">Engine</span><span class="token operator">=</span>InnoDB<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">DROP</span> <span class="token keyword">TABLE</span> t1<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">DROP</span> <span class="token keyword">TABLESPACE</span> ts1<span class="token punctuation">;</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <code class="literal"> <em class="replaceable"> <code> tablespace_name </code> </em> </code> is a case-sensitive identifier in MySQL. </p> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="general-tablespaces-limitations"> </a> General Tablespace Limitations </h5> </div> </div> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A generated or existing tablespace cannot be changed to a general tablespace. </p> </li> <li class="listitem"> <p> Creation of temporary general tablespaces is not supported. </p> </li> <li class="listitem"> <p> General tablespaces do not support temporary tables. </p> </li> <li class="listitem"> <p> Similar to the system tablespace, truncating or dropping tables stored in a general tablespace creates free space internally in the general tablespace <a class="link" href="glossary.html#glos_ibd_file" title=".ibd file"> .ibd data file </a> which can only be used for new <code class="literal"> InnoDB </code> data. Space is not released back to the operating system as it is for <a class="link" href="glossary.html#glos_file_per_table" title="file-per-table"> file-per-table </a> tablespaces. </p> <p> Additionally, a table-copying <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operation on table that resides in a shared tablespace (a general tablespace or the system tablespace) can increase the amount of space used by the tablespace. Such operations require as much additional space as the data in the table plus indexes. The additional space required for the table-copying <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operation is not released back to the operating system as it is for file-per-table tablespaces. </p> </li> <li class="listitem"> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE ... DISCARD TABLESPACE </code> </a> and <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE ...IMPORT TABLESPACE </code> </a> are not supported for tables that belong to a general tablespace. </p> </li> <li class="listitem"> <p> Placing table partitions in general tablespaces is not supported. </p> </li> <li class="listitem"> <p> The <code class="literal"> ADD DATAFILE </code> clause is not supported in a replication environment where the source and replica reside on the same host, as it would cause the source and replica to create a tablespace of the same name in the same location, which is not supported. However, if the <code class="literal"> ADD DATAFILE </code> clause is omitted, the tablespace is created in the data directory with a generated file name that is unique, which is permitted. </p> </li> <li class="listitem"> <p> General tablespaces cannot be created in the undo tablespace directory ( <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> ) unless that directly is known to <code class="literal"> InnoDB </code> . Known directories are those defined by the <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="literal"> datadir </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> , and <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> variables. </p> </li> </ul> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/x-plugin-sha2-cache-plugin.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="x-plugin-sha2-cache-plugin"> </a> 22.5.4 Using X Plugin with the Caching SHA-2 Authentication Plugin </h3> </div> </div> </div> <p> X Plugin supports MySQL user accounts created with the <code class="literal"> caching_sha2_password </code> authentication plugin. For more information on this plugin, see <a class="xref" href="caching-sha2-pluggable-authentication.html" title="8.4.1.2 Caching SHA-2 Pluggable Authentication"> Section 8.4.1.2, “Caching SHA-2 Pluggable Authentication” </a> . You can use X Plugin to authenticate against such accounts using non-SSL connections with <code class="literal"> SHA256_MEMORY </code> authentication and SSL connections with <code class="literal"> PLAIN </code> authentication. </p> <p> Although the <code class="literal"> caching_sha2_password </code> authentication plugin holds an authentication cache, this cache is not shared with X Plugin, so X Plugin uses its own authentication cache for <code class="literal"> SHA256_MEMORY </code> authentication. The X Plugin authentication cache stores hashes of user account passwords, and cannot be accessed using SQL. If a user account is modified or removed, the relevant entries are removed from the cache. The X Plugin authentication cache is maintained by the <code class="literal"> mysqlx_cache_cleaner </code> plugin, which is enabled by default, and has no related system variables or status variables. </p> <p> Before you can use non-SSL X Protocol connections to authenticate an account that uses the <code class="literal"> caching_sha2_password </code> authentication plugin, the account must have authenticated at least once over an X Protocol connection with SSL, to supply the password to the X Plugin authentication cache. Once this initial authentication over SSL has succeeded, non-SSL X Protocol connections can be used. </p> <p> It is possible to disable the <code class="literal"> mysqlx_cache_cleaner </code> plugin by starting the MySQL server with the option <code class="literal"> --mysqlx_cache_cleaner=0 </code> . If you do this, the X Plugin authentication cache is disabled, and therefore SSL must always be used for X Protocol connections when authenticating with <code class="literal"> SHA256_MEMORY </code> authentication. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/charset-introducer.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="charset-introducer"> </a> 12.3.8 Character Set Introducers </h3> </div> </div> </div> <a class="indexterm" name="idm46045217606656"> </a> <a class="indexterm" name="idm46045217605200"> </a> <p> A character string literal, hexadecimal literal, or bit-value literal may have an optional character set introducer and <code class="literal"> COLLATE </code> clause, to designate it as a string that uses a particular character set and collation: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa58358720"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">[</span>_<em class="replaceable">charset_name</em><span class="token punctuation">]</span> <em class="replaceable">literal</em> <span class="token punctuation">[</span><span class="token keyword">COLLATE</span> <em class="replaceable">collation_name</em><span class="token punctuation">]</span></code></pre> </div> <p> The <code class="literal"> _ <em class="replaceable"> <code> charset_name </code> </em> </code> expression is formally called an <span class="emphasis"> <em> introducer </em> </span> . It tells the parser, <span class="quote"> “ <span class="quote"> the string that follows uses character set <em class="replaceable"> <code> charset_name </code> </em> . </span> ” </span> An introducer does not change the string to the introducer character set like <a class="link" href="cast-functions.html#function_convert"> <code class="literal"> CONVERT() </code> </a> would do. It does not change the string value, although padding may occur. The introducer is just a signal. </p> <p> For character string literals, space between the introducer and the string is permitted but optional. </p> <p> For character set literals, an introducer indicates the character set for the following string, but does not change how the parser performs escape processing within the string. Escapes are always interpreted by the parser according to the character set given by <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> <code class="literal"> character_set_connection </code> </a> . For additional discussion and examples, see <a class="xref" href="charset-literal.html" title="12.3.6 Character String Literal Character Set and Collation"> Section 12.3.6, “Character String Literal Character Set and Collation” </a> . </p> <p> Examples: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa78023428"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token string">'abc'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1<span class="token string">'abc'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _binary<span class="token string">'abc'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4<span class="token string">'abc'</span> <span class="token keyword">COLLATE</span> utf8mb4_danish_ci<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1 X<span class="token string">'4D7953514C'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4 <span class="token number">0x4D7953514C</span> <span class="token keyword">COLLATE</span> utf8mb4_danish_ci<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1 b<span class="token string">'1000001'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4 <span class="token number">0b1000001</span> <span class="token keyword">COLLATE</span> utf8mb4_danish_ci<span class="token punctuation">;</span></code></pre> </div> <p> Character set introducers and the <code class="literal"> COLLATE </code> clause are implemented according to standard SQL specifications. </p> <p> Character string literals can be designated as binary strings by using the <code class="literal"> _binary </code> introducer. Hexadecimal literals and bit-value literals are binary strings by default, so <code class="literal"> _binary </code> is permitted, but normally unnecessary. <code class="literal"> _binary </code> may be useful to preserve a hexadecimal or bit literal as a binary string in contexts for which the literal is otherwise treated as a number. For example, bit operations permit numeric or binary string arguments in MySQL 8.4 and higher, but treat hexadecimal and bit literals as numbers by default. To explicitly specify binary string context for such literals, use a <code class="literal"> _binary </code> introducer for at least one of the arguments: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa66025281"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@v1</span> <span class="token operator">=</span> X<span class="token string">'000D'</span> <span class="token operator">|</span> X<span class="token string">'0BC0'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@v2</span> <span class="token operator">=</span> _binary X<span class="token string">'000D'</span> <span class="token operator">|</span> X<span class="token string">'0BC0'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">HEX</span><span class="token punctuation">(</span><span class="token variable">@v1</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token function">HEX</span><span class="token punctuation">(</span><span class="token variable">@v2</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> HEX(@v1) <span class="token punctuation">|</span> HEX(@v2) <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> BCD <span class="token punctuation">|</span> 0BCD <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> The displayed result appears similar for both bit operations, but the result without <code class="literal"> _binary </code> is a <code class="literal"> BIGINT </code> value, whereas the result with <code class="literal"> _binary </code> is a binary string. Due to the difference in result types, the displayed values differ: High-order 0 digits are not displayed for the numeric result. </p> <p> MySQL determines the character set and collation of a character string literal, hexadecimal literal, or bit-value literal in the following manner: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If both <em class="replaceable"> <code> _charset_name </code> </em> and <code class="literal"> COLLATE <em class="replaceable"> <code> collation_name </code> </em> </code> are specified, character set <em class="replaceable"> <code> charset_name </code> </em> and collation <em class="replaceable"> <code> collation_name </code> </em> are used. <em class="replaceable"> <code> collation_name </code> </em> must be a permitted collation for <em class="replaceable"> <code> charset_name </code> </em> . </p> </li> <li class="listitem"> <p> If <em class="replaceable"> <code> _charset_name </code> </em> is specified but <code class="literal"> COLLATE </code> is not specified, character set <em class="replaceable"> <code> charset_name </code> </em> and its default collation are used. To see the default collation for each character set, use the <a class="link" href="show-character-set.html" title="15.7.7.4 SHOW CHARACTER SET Statement"> <code class="literal"> SHOW CHARACTER SET </code> </a> statement or query the <code class="literal"> INFORMATION_SCHEMA </code> <a class="link" href="information-schema-character-sets-table.html" title="28.3.4 The INFORMATION_SCHEMA CHARACTER_SETS Table"> <code class="literal"> CHARACTER_SETS </code> </a> table. </p> </li> <li class="listitem"> <p> If <em class="replaceable"> <code> _charset_name </code> </em> is not specified but <code class="literal"> COLLATE <em class="replaceable"> <code> collation_name </code> </em> </code> is specified: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> For a character string literal, the connection default character set given by the <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> <code class="literal"> character_set_connection </code> </a> system variable and collation <em class="replaceable"> <code> collation_name </code> </em> are used. <em class="replaceable"> <code> collation_name </code> </em> must be a permitted collation for the connection default character set. </p> </li> <li class="listitem"> <p> For a hexadecimal literal or bit-value literal, the only permitted collation is <code class="literal"> binary </code> because these types of literals are binary strings by default. </p> </li> </ul> </div> </li> <li class="listitem"> <p> Otherwise (neither <em class="replaceable"> <code> _charset_name </code> </em> nor <code class="literal"> COLLATE <em class="replaceable"> <code> collation_name </code> </em> </code> is specified): </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> For a character string literal, the connection default character set and collation given by the <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> <code class="literal"> character_set_connection </code> </a> and <a class="link" href="server-system-variables.html#sysvar_collation_connection"> <code class="literal"> collation_connection </code> </a> system variables are used. </p> </li> <li class="listitem"> <p> For a hexadecimal literal or bit-value literal, the character set and collation are <code class="literal"> binary </code> . </p> </li> </ul> </div> </li> </ul> </div> <p> Examples: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Nonbinary strings with <code class="literal"> latin1 </code> character set and <code class="literal"> latin1_german1_ci </code> collation: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa91008324"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> _latin1<span class="token string">'Müller'</span> <span class="token keyword">COLLATE</span> latin1_german1_ci<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1 X<span class="token string">'0A0D'</span> <span class="token keyword">COLLATE</span> latin1_german1_ci<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _latin1 b<span class="token string">'0110'</span> <span class="token keyword">COLLATE</span> latin1_german1_ci<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> Nonbinary strings with <code class="literal"> utf8mb4 </code> character set and its default collation (that is, <code class="literal"> utf8mb4_0900_ai_ci </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa39178445"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> _utf8mb4<span class="token string">'Müller'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4 X<span class="token string">'0A0D'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> _utf8mb4 b<span class="token string">'0110'</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> Binary strings with <code class="literal"> binary </code> character set and its default collation (that is, <code class="literal"> binary </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa39233732"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> _binary<span class="token string">'Müller'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> X<span class="token string">'0A0D'</span><span class="token punctuation">;</span> <span class="token keyword">SELECT</span> b<span class="token string">'0110'</span><span class="token punctuation">;</span></code></pre> </div> <p> The hexadecimal literal and bit-value literal need no introducer because they are binary strings by default. </p> </li> <li class="listitem"> <p> A nonbinary string with the connection default character set and <code class="literal"> utf8mb4_0900_ai_ci </code> collation (fails if the connection character set is not <code class="literal"> utf8mb4 </code> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa13055279"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token string">'Müller'</span> <span class="token keyword">COLLATE</span> utf8mb4_0900_ai_ci<span class="token punctuation">;</span></code></pre> </div> <p> This construction ( <code class="literal"> COLLATE </code> only) does not work for hexadecimal literals or bit literals because their character set is <code class="literal"> binary </code> no matter the connection character set, and <code class="literal"> binary </code> is not compatible with the <code class="literal"> utf8mb4_0900_ai_ci </code> collation. The only permitted <code class="literal"> COLLATE </code> clause in the absence of an introducer is <code class="literal"> COLLATE binary </code> . </p> </li> <li class="listitem"> <p> A string with the connection default character set and collation: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa12154941"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token string">'Müller'</span><span class="token punctuation">;</span></code></pre> </div> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/ipv6-system-support.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="ipv6-system-support"> </a> 7.1.13.1 Verifying System Support for IPv6 </h4> </div> </div> </div> <p> Before MySQL Server can accept IPv6 connections, the operating system on your server host must support IPv6. As a simple test to determine whether that is true, try this command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa79199387"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">ping6</span> <span class="token punctuation">:</span><span class="token punctuation">:</span>1 16 bytes from <span class="token punctuation">:</span><span class="token punctuation">:</span>1<span class="token punctuation">,</span> icmp_seq<span class="token attr-value"><span class="token punctuation">=</span>0</span> hlim<span class="token attr-value"><span class="token punctuation">=</span>64</span> time<span class="token attr-value"><span class="token punctuation">=</span>0.171</span> ms 16 bytes from <span class="token punctuation">:</span><span class="token punctuation">:</span>1<span class="token punctuation">,</span> icmp_seq<span class="token attr-value"><span class="token punctuation">=</span>1</span> hlim<span class="token attr-value"><span class="token punctuation">=</span>64</span> time<span class="token attr-value"><span class="token punctuation">=</span>0.077</span> ms <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span></code></pre> </div> <p> To produce a description of your system's network interfaces, invoke <span class="command"> <strong> ifconfig -a </strong> </span> and look for IPv6 addresses in the output. </p> <p> If your host does not support IPv6, consult your system documentation for instructions on enabling it. It might be that you need only reconfigure an existing network interface to add an IPv6 address. Or a more extensive change might be needed, such as rebuilding the kernel with IPv6 options enabled. </p> <p> These links may be helpful in setting up IPv6 on various platforms: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="ulink" href="https://msdn.microsoft.com/en-us/library/dd163569.aspx" target="_blank"> Windows </a> </p> </li> <li class="listitem"> <p> <a class="ulink" href="http://www.gentoo.org/doc/en/ipv6.xml" target="_blank"> Gentoo Linux </a> </p> </li> <li class="listitem"> <p> <a class="ulink" href="https://wiki.ubuntu.com/IPv6" target="_blank"> Ubuntu Linux </a> </p> </li> <li class="listitem"> <p> <a class="ulink" href="http://www.tldp.org/HOWTO/Linux+IPv6-HOWTO/" target="_blank"> Linux (Generic) </a> </p> </li> <li class="listitem"> <p> <a class="ulink" href="https://support.apple.com/en-us/HT202237" target="_blank"> macOS </a> </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/linux-installation-docker.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="linux-installation-docker"> </a> 2.5.6 Deploying MySQL on Linux with Docker Containers </h3> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="docker-mysql-getting-started.html"> 2.5.6.1 Basic Steps for MySQL Server Deployment with Docker </a> </span> </dt> <dt> <span class="section"> <a href="docker-mysql-more-topics.html"> 2.5.6.2 More Topics on Deploying MySQL Server with Docker </a> </span> </dt> <dt> <span class="section"> <a href="deploy-mysql-nonlinux-docker.html"> 2.5.6.3 Deploying MySQL on Windows and Other Non-Linux Platforms with Docker </a> </span> </dt> </dl> </div> <p> This section explains how to deploy MySQL Server using Docker containers. </p> <p> While the <code class="literal"> docker </code> client is used in the following instructions for demonstration purposes, in general, the MySQL container images provided by Oracle work with any container tools that are compliant with the <a class="ulink" href="https://opencontainers.org/posts/announcements/2021-05-04-oci-dist-spec-v1/" target="_blank"> OCI 1.0 specification </a> . </p> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> Before deploying MySQL with Docker containers, make sure you understand the security risks of running containers and mitigate them properly. </p> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/data-directory-initialization.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="data-directory-initialization"> </a> 2.9.1 Initializing the Data Directory </h3> </div> </div> </div> <p> After MySQL is installed, the data directory must be initialized, including the tables in the <code class="literal"> mysql </code> system schema: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> For some MySQL installation methods, data directory initialization is automatic, as described in <a class="xref" href="postinstallation.html" title="2.9 Postinstallation Setup and Testing"> Section 2.9, “Postinstallation Setup and Testing” </a> . </p> </li> <li class="listitem"> <p> For other installation methods, you must initialize the data directory manually. These include installation from generic binary and source distributions on Unix and Unix-like systems, and installation from a ZIP Archive package on Windows. </p> </li> </ul> </div> <p> This section describes how to initialize the data directory manually for MySQL installation methods for which data directory initialization is not automatic. For some suggested commands that enable testing whether the server is accessible and working properly, see <a class="xref" href="testing-server.html" title="2.9.3 Testing the Server"> Section 2.9.3, “Testing the Server” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The default authentication plugin is <code class="literal"> caching_sha2_password </code> , and the <code class="literal"> 'root'@'localhost' </code> administrative account uses <code class="literal"> caching_sha2_password </code> by default. </p> <p> <a class="link" href="native-pluggable-authentication.html" title="8.4.1.1 Native Pluggable Authentication"> mysql_native_password </a> (the default authentication plugin prior to MySQL 8.0) is still supported but disabled by default as of MySQL 8.4.0 and removed as of MySQL 9.0.0. </p> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="data-directory-initialization.html#data-directory-initialization-overview" title="Data Directory Initialization Overview"> Data Directory Initialization Overview </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="data-directory-initialization.html#data-directory-initialization-procedure" title="Data Directory Initialization Procedure"> Data Directory Initialization Procedure </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="data-directory-initialization.html#data-directory-initialization-server-actions" title="Server Actions During Data Directory Initialization"> Server Actions During Data Directory Initialization </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="data-directory-initialization.html#data-directory-initialization-password-assignment" title="Post-Initialization root Password Assignment"> Post-Initialization root Password Assignment </a> </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="data-directory-initialization-overview"> </a> Data Directory Initialization Overview </h4> </div> </div> </div> <p> In the examples shown here, the server is intended to run under the user ID of the <code class="literal"> mysql </code> login account. Either create the account if it does not exist (see <a class="xref" href="binary-installation.html#binary-installation-createsysuser" title="Create a mysql User and Group"> Create a mysql User and Group </a> ), or substitute the name of a different existing login account that you plan to use for running the server. </p> <a class="indexterm" name="idm46045327073952"> </a> <a class="indexterm" name="idm46045327072464"> </a> <a class="indexterm" name="idm46045327070976"> </a> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Change location to the top-level directory of your MySQL installation, which is typically <code class="filename"> /usr/local/mysql </code> (adjust the path name for your system as necessary): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa90223312"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cd /usr/local/mysql</code></pre> </div> <p> Within this directory you can find several files and subdirectories, including the <code class="filename"> bin </code> subdirectory that contains the server, as well as client and utility programs. </p> </li> <li class="listitem"> <p> The <a class="link" href="server-system-variables.html#sysvar_secure_file_priv"> <code class="literal"> secure_file_priv </code> </a> system variable limits import and export operations to a specific directory. Create a directory whose location can be specified as the value of that variable: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa23812799"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mkdir mysql-files</code></pre> </div> <p> Grant directory user and group ownership to the <code class="literal"> mysql </code> user and <code class="literal"> mysql </code> group, and set the directory permissions appropriately: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa47169968"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">chown mysql<span class="token punctuation">:</span>mysql mysql-files chmod 750 mysql-files</code></pre> </div> </li> <li class="listitem"> <p> Use the server to initialize the data directory, including the <code class="literal"> mysql </code> schema containing the initial MySQL grant tables that determine how users are permitted to connect to the server. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa12273579"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld <span class="token property">--initialize</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span></code></pre> </div> <p> For important information about the command, especially regarding command options you might use, see <a class="xref" href="data-directory-initialization.html#data-directory-initialization-procedure" title="Data Directory Initialization Procedure"> Data Directory Initialization Procedure </a> . For details about how the server performs initialization, see <a class="xref" href="data-directory-initialization.html#data-directory-initialization-server-actions" title="Server Actions During Data Directory Initialization"> Server Actions During Data Directory Initialization </a> . </p> <p> Typically, data directory initialization need be done only after you first install MySQL. (For upgrades to an existing installation, perform the upgrade procedure instead; see <a class="xref" href="upgrading.html" title="Chapter 3 Upgrading MySQL"> Chapter 3, <i> Upgrading MySQL </i> </a> .) However, the command that initializes the data directory does not overwrite any existing <code class="literal"> mysql </code> schema tables, so it is safe to run in any circumstances. </p> </li> <li class="listitem"> <p> In the absence of any option files, the server starts with its default settings. (See <a class="xref" href="server-configuration-defaults.html" title="7.1.2 Server Configuration Defaults"> Section 7.1.2, “Server Configuration Defaults” </a> .) To explicitly specify options that the MySQL server should use at startup, put them in an option file such as <code class="filename"> /etc/my.cnf </code> or <code class="filename"> /etc/mysql/my.cnf </code> . (See <a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files"> Section 6.2.2.2, “Using Option Files” </a> .) For example, you can use an option file to set the <a class="link" href="server-system-variables.html#sysvar_secure_file_priv"> <code class="literal"> secure_file_priv </code> </a> system variable. </p> </li> <li class="listitem"> <p> To arrange for MySQL to start without manual intervention at system boot time, see <a class="xref" href="automatic-start.html" title="2.9.5 Starting and Stopping MySQL Automatically"> Section 2.9.5, “Starting and Stopping MySQL Automatically” </a> . </p> </li> <li class="listitem"> <p> Data directory initialization creates time zone tables in the <code class="literal"> mysql </code> schema but does not populate them. To do so, use the instructions in <a class="xref" href="time-zone-support.html" title="7.1.15 MySQL Server Time Zone Support"> Section 7.1.15, “MySQL Server Time Zone Support” </a> . </p> </li> </ol> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="data-directory-initialization-procedure"> </a> Data Directory Initialization Procedure </h4> </div> </div> </div> <p> Change location to the top-level directory of your MySQL installation, which is typically <code class="filename"> /usr/local/mysql </code> (adjust the path name for your system as necessary): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa63496349"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">cd /usr/local/mysql</code></pre> </div> <p> To initialize the data directory, invoke <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> with the <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> or <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> option, depending on whether you want the server to generate a random initial password for the <code class="literal"> 'root'@'localhost' </code> account, or to create that account with no password: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Use <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> for <span class="quote"> “ <span class="quote"> secure by default </span> ” </span> installation (that is, including generation of a random initial <code class="literal"> root </code> password). In this case, the password is marked as expired and you must choose a new one. </p> </li> <li class="listitem"> <p> With <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> , no <code class="literal"> root </code> password is generated. This is insecure; it is assumed that you intend to assign a password to the account in a timely fashion before putting the server into production use. </p> </li> </ul> </div> <p> For instructions on assigning a new <code class="literal"> 'root'@'localhost' </code> password, see <a class="xref" href="data-directory-initialization.html#data-directory-initialization-password-assignment" title="Post-Initialization root Password Assignment"> Post-Initialization root Password Assignment </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The server writes any messages (including any initial password) to its standard error output. This may be redirected to the error log, so look there if you do not see the messages on your screen. For information about the error log, including where it is located, see <a class="xref" href="error-log.html" title="7.4.2 The Error Log"> Section 7.4.2, “The Error Log” </a> . </p> <p> On Windows, use the <a class="link" href="server-options.html#option_mysqld_console"> <code class="option"> --console </code> </a> option to direct messages to the console. </p> </div> <p> On Unix and Unix-like systems, it is important for the database directories and files to be owned by the <code class="literal"> mysql </code> login account so that the server has read and write access to them when you run it later. To ensure this, start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> from the system <code class="literal"> root </code> account and include the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user </code> </a> option as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa69089509"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld <span class="token property">--initialize</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span> bin/mysqld <span class="token property">--initialize-insecure</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span></code></pre> </div> <p> Alternatively, execute <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> while logged in as <code class="literal"> mysql </code> , in which case you can omit the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user </code> </a> option from the command. </p> <p> On Windows, use one of these commands: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa83067570"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin\mysqld <span class="token property">--initialize</span> <span class="token property">--console</span> bin\mysqld <span class="token property">--initialize-insecure</span> <span class="token property">--console</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Data directory initialization might fail if required system libraries are missing. For example, you might see an error like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa55693411"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld<span class="token punctuation">:</span> error while loading shared libraries<span class="token punctuation">:</span> libnuma<span class="token punctuation">.</span>so<span class="token punctuation">.</span>1<span class="token punctuation">:</span> cannot open shared object file<span class="token punctuation">:</span> No such file or directory</code></pre> </div> <p> If this happens, you must install the missing libraries manually or with your system's package manager. Then retry the data directory initialization command. </p> </div> <p> It might be necessary to specify other options such as <a class="link" href="server-system-variables.html#sysvar_basedir"> <code class="option"> --basedir </code> </a> or <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="option"> --datadir </code> </a> if <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> cannot identify the correct locations for the installation directory or data directory. For example (enter the command on a single line): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa80670114"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld <span class="token property">--initialize</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span> <span class="token constant">--basedir</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql</span> <span class="token constant">--datadir</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql/data</span></code></pre> </div> <p> Alternatively, put the relevant option settings in an option file and pass the name of that file to <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . For Unix and Unix-like systems, suppose that the option file name is <code class="filename"> /opt/mysql/mysql/etc/my.cnf </code> . Put these lines in the file: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa73864818"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">basedir</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql</span> <span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql/data</span></code></pre> </div> <p> Then invoke <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as follows (enter the command on a single line, with the <a class="link" href="option-file-options.html#option_general_defaults-file"> <code class="option"> --defaults-file </code> </a> option first): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa83307501"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin/mysqld <span class="token constant">--defaults-file</span><span class="token attr-value"><span class="token punctuation">=</span>/opt/mysql/mysql/etc/my.cnf</span> <span class="token property">--initialize</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span></code></pre> </div> <p> On Windows, suppose that <code class="filename"> C:\my.ini </code> contains these lines: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa43791165"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">basedir</span><span class="token attr-value"><span class="token punctuation">=</span>C:\\Program Files\\MySQL\\MySQL Server 8.4</span> <span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>D:\\MySQLdata</span></code></pre> </div> <p> Then invoke <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as follows (again, you should enter the command on a single line, with the <a class="link" href="option-file-options.html#option_general_defaults-file"> <code class="option"> --defaults-file </code> </a> option first): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa35560823"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">bin\mysqld <span class="token constant">--defaults-file</span><span class="token attr-value"><span class="token punctuation">=</span>C:\my.ini</span> <span class="token property">--initialize</span> <span class="token property">--console</span></code></pre> </div> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> When initializing the data directory, you should not specify any options other than those used for setting directory locations such as <a class="link" href="server-system-variables.html#sysvar_basedir"> <code class="option"> --basedir </code> </a> or <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="option"> --datadir </code> </a> , and the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user </code> </a> option if needed. Options to be employed by the MySQL server during normal use can be set when restarting it following initialization. See the description of the <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> option for further information. </p> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="data-directory-initialization-server-actions"> </a> Server Actions During Data Directory Initialization </h4> </div> </div> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The data directory initialization sequence performed by the server does not substitute for the actions performed by <a class="link" href="mysql-secure-installation.html" title="6.4.2 mysql_secure_installation — Improve MySQL Installation Security"> <span class="command"> <strong> mysql_secure_installation </strong> </span> </a> . </p> </div> <p> When invoked with the <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> or <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> option, <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> performs the following actions during the data directory initialization sequence: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> The server checks for the existence of the data directory as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If no data directory exists, the server creates it. </p> </li> <li class="listitem"> <p> If the data directory exists but is not empty (that is, it contains files or subdirectories), the server exits after producing an error message: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa4231181"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[ERROR] --initialize specified but the data directory exists. Aborting.</code></pre> </div> <p> In this case, remove or rename the data directory and try again. </p> <p> An existing data directory is permitted to be nonempty if every entry has a name that begins with a period ( <code class="literal"> . </code> ). </p> </li> </ul> </div> </li> <li class="listitem"> <p> Within the data directory, the server creates the <code class="literal"> mysql </code> system schema and its tables, including the data dictionary tables, grant tables, time zone tables, and server-side help tables. See <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> . </p> </li> <li class="listitem"> <p> The server initializes the <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> and related data structures needed to manage <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> tables. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> After <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> sets up the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> , certain changes to tablespace characteristics require setting up a whole new <a class="link" href="glossary.html#glos_instance" title="instance"> instance </a> . Qualifying changes include the file name of the first file in the system tablespace and the number of undo logs. If you do not want to use the default values, make sure that the settings for the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> configuration parameters are in place in the MySQL <a class="link" href="glossary.html#glos_configuration_file" title="configuration file"> configuration file </a> <span class="emphasis"> <em> before </em> </span> running <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . Also make sure to specify as necessary other parameters that affect the creation and location of <code class="literal"> InnoDB </code> files, such as <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> <code class="literal"> innodb_log_group_home_dir </code> </a> . </p> <p> If those options are in your configuration file but that file is not in a location that MySQL reads by default, specify the file location using the <a class="link" href="server-options.html#option_mysqld_defaults-extra-file"> <code class="option"> --defaults-extra-file </code> </a> option when you run <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . </p> </div> </li> <li class="listitem"> <p> The server creates a <code class="literal"> 'root'@'localhost' </code> superuser account and other reserved accounts (see <a class="xref" href="reserved-accounts.html" title="8.2.9 Reserved Accounts"> Section 8.2.9, “Reserved Accounts” </a> ). Some reserved accounts are locked and cannot be used by clients, but <code class="literal"> 'root'@'localhost' </code> is intended for administrative use and you should assign it a password. </p> <p> Server actions with respect to a password for the <code class="literal"> 'root'@'localhost' </code> account depend on how you invoke it: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> With <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> but not <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> , the server generates a random password, marks it as expired, and writes a message displaying the password: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa62666523"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[Warning] A temporary password is generated for root@localhost: iTag*AfrH5ej</code></pre> </div> </li> <li class="listitem"> <p> With <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> , (either with or without <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> because <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> implies <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> ), the server does not generate a password or mark it expired, and writes a warning message: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa3187855"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[Warning] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option.</code></pre> </div> </li> </ul> </div> <p> For instructions on assigning a new <code class="literal"> 'root'@'localhost' </code> password, see <a class="xref" href="data-directory-initialization.html#data-directory-initialization-password-assignment" title="Post-Initialization root Password Assignment"> Post-Initialization root Password Assignment </a> . </p> </li> <li class="listitem"> <p> The server populates the server-side help tables used for the <a class="link" href="help.html" title="15.8.3 HELP Statement"> <code class="literal"> HELP </code> </a> statement (see <a class="xref" href="help.html" title="15.8.3 HELP Statement"> Section 15.8.3, “HELP Statement” </a> ). The server does not populate the time zone tables. To do so manually, see <a class="xref" href="time-zone-support.html" title="7.1.15 MySQL Server Time Zone Support"> Section 7.1.15, “MySQL Server Time Zone Support” </a> . </p> </li> <li class="listitem"> <p> If the <a class="link" href="server-system-variables.html#sysvar_init_file"> <code class="literal"> init_file </code> </a> system variable was given to name a file of SQL statements, the server executes the statements in the file. This option enables you to perform custom bootstrapping sequences. </p> <p> When the server operates in bootstrap mode, some functionality is unavailable that limits the statements permitted in the file. These include statements that relate to account management (such as <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> or <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> ), replication, and global transaction identifiers. </p> </li> <li class="listitem"> <p> The server exits. </p> </li> </ol> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="data-directory-initialization-password-assignment"> </a> Post-Initialization root Password Assignment </h4> </div> </div> </div> <p> After you initialize the data directory by starting the server with <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> or <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> , start the server normally (that is, without either of those options) and assign the <code class="literal"> 'root'@'localhost' </code> account a new password: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Start the server. For instructions, see <a class="xref" href="starting-server.html" title="2.9.2 Starting the Server"> Section 2.9.2, “Starting the Server” </a> . </p> </li> <li class="listitem"> <p> Connect to the server: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If you used <a class="link" href="server-options.html#option_mysqld_initialize"> <code class="option"> --initialize </code> </a> but not <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> to initialize the data directory, connect to the server as <code class="literal"> root </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa63561512"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token property">-u</span> root <span class="token property">-p</span></code></pre> </div> <p> Then, at the password prompt, enter the random password that the server generated during the initialization sequence: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa6595132"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">Enter password: <em class="replaceable">(enter the random root password here)</em></code></pre> </div> <p> Look in the server error log if you do not know this password. </p> </li> <li class="listitem"> <p> If you used <a class="link" href="server-options.html#option_mysqld_initialize-insecure"> <code class="option"> --initialize-insecure </code> </a> to initialize the data directory, connect to the server as <code class="literal"> root </code> without a password: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa45198081"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysql <span class="token property">-u</span> root <span class="token property">--skip-password</span></code></pre> </div> </li> </ul> </div> </li> <li class="listitem"> <p> After connecting, use an <a class="link" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> <code class="literal"> ALTER USER </code> </a> statement to assign a new <code class="literal"> root </code> password: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa71794246"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">USER</span> <span class="token string">'root'</span>@<span class="token string">'localhost'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">root-password'</em></span><span class="token punctuation">;</span></code></pre> </div> </li> </ol> </div> <p> See also <a class="xref" href="default-privileges.html" title="2.9.4 Securing the Initial MySQL Account"> Section 2.9.4, “Securing the Initial MySQL Account” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Attempts to connect to the host <code class="literal"> 127.0.0.1 </code> normally resolve to the <code class="literal"> localhost </code> account. However, this fails if the server is run with <a class="link" href="server-system-variables.html#sysvar_skip_name_resolve"> <code class="literal"> skip_name_resolve </code> </a> enabled. If you plan to do that, make sure that an account exists that can accept a connection. For example, to be able to connect as <code class="literal"> root </code> using <code class="option"> --host=127.0.0.1 </code> or <code class="option"> --host=::1 </code> , create these accounts: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa46116313"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'root'</span>@<span class="token string">'127.0.0.1'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">root-password</em>'</span><span class="token punctuation">;</span> <span class="token keyword">CREATE</span> <span class="token keyword">USER</span> <span class="token string">'root'</span>@<span class="token string">'::1'</span> <span class="token keyword">IDENTIFIED</span> <span class="token keyword">BY</span> <span class="token string">'<em class="replaceable">root-password</em>'</span><span class="token punctuation">;</span></code></pre> </div> <p> It is possible to put those statements in a file to be executed using the <a class="link" href="server-system-variables.html#sysvar_init_file"> <code class="literal"> init_file </code> </a> system variable, as discussed in <a class="xref" href="data-directory-initialization.html#data-directory-initialization-server-actions" title="Server Actions During Data Directory Initialization"> Server Actions During Data Directory Initialization </a> . </p> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-oci-marketplace-prereqs.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="mysql-oci-marketplace-prereqs"> </a> 34.1 Prerequisites to Deploying MySQL EE on Oracle Cloud Infrastructure </h2> </div> </div> </div> <p> The following assumptions are made: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> You are familiar with OCI terminology. If you are new to OCI, see <a class="ulink" href="https://docs.cloud.oracle.com/iaas/Content/GSG/Concepts/baremetalintro.htm" target="_blank"> Getting Started </a> . </p> </li> <li class="listitem"> <p> You have access to a properly configured Virtual Cloud Network (VCN) and subnet. For more information, see <a class="ulink" href="https://docs.cloud.oracle.com/iaas/Content/Network/Tasks/quickstartnetworking.htm" target="_blank"> Virtual Networking </a> . </p> </li> <li class="listitem"> <p> You have the permissions required to deploy OCI Marketplace applications in a compartment of your tenancy. For more information, see <a class="ulink" href="https://docs.cloud.oracle.com/iaas/Content/Identity/Concepts/policies.htm" target="_blank"> How Policies Work </a> . </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/request-access.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="request-access"> </a> 8.2.7 Access Control, Stage 2: Request Verification </h3> </div> </div> </div> <p> After the server accepts a connection, it enters Stage 2 of access control. For each request that you issue through the connection, the server determines what operation you want to perform, then checks whether your privileges are sufficient. This is where the privilege columns in the grant tables come into play. These privileges can come from any of the <code class="literal"> user </code> , <code class="literal"> global_grants </code> , <code class="literal"> db </code> , <code class="literal"> tables_priv </code> , <code class="literal"> columns_priv </code> , or <code class="literal"> procs_priv </code> tables. (You may find it helpful to refer to <a class="xref" href="grant-tables.html" title="8.2.3 Grant Tables"> Section 8.2.3, “Grant Tables” </a> , which lists the columns present in each grant table.) </p> <a class="indexterm" name="idm46045249694096"> </a> <p> The <code class="literal"> user </code> and <code class="literal"> global_grants </code> tables grant global privileges. The rows in these tables for a given account indicate the account privileges that apply on a global basis no matter what the default database is. For example, if the <code class="literal"> user </code> table grants you the <a class="link" href="privileges-provided.html#priv_delete"> <code class="literal"> DELETE </code> </a> privilege, you can delete rows from any table in any database on the server host. It is wise to grant privileges in the <code class="literal"> user </code> table only to people who need them, such as database administrators. For other users, leave all privileges in the <code class="literal"> user </code> table set to <code class="literal"> 'N' </code> and grant privileges at more specific levels only (for particular databases, tables, columns, or routines). It is also possible to grant database privileges globally but use partial revokes to restrict them from being exercised on specific databases (see <a class="xref" href="partial-revokes.html" title="8.2.12 Privilege Restriction Using Partial Revokes"> Section 8.2.12, “Privilege Restriction Using Partial Revokes” </a> ). </p> <a class="indexterm" name="idm46045249685728"> </a> <a class="indexterm" name="idm46045249684656"> </a> <p> The <code class="literal"> db </code> table grants database-specific privileges. Values in the scope columns of this table can take the following forms: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A blank <code class="literal"> User </code> value matches the anonymous user. A nonblank value matches literally; there are no wildcards in user names. </p> </li> <li class="listitem"> <p> The wildcard characters <code class="literal"> % </code> and <code class="literal"> _ </code> can be used in the <code class="literal"> Host </code> and <code class="literal"> Db </code> columns. These have the same meaning as for pattern-matching operations performed with the <a class="link" href="string-comparison-functions.html#operator_like"> <code class="literal"> LIKE </code> </a> operator. If you want to use either character literally when granting privileges, you must escape it with a backslash. For example, to include the underscore character ( <code class="literal"> _ </code> ) as part of a database name, specify it as <code class="literal"> \_ </code> in the <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> statement. </p> </li> <li class="listitem"> <p> A <code class="literal"> '%' </code> or blank <code class="literal"> Host </code> value means <span class="quote"> “ <span class="quote"> any host. </span> ” </span> </p> </li> <li class="listitem"> <p> A <code class="literal"> '%' </code> or blank <code class="literal"> Db </code> value means <span class="quote"> “ <span class="quote"> any database. </span> ” </span> </p> </li> </ul> </div> <a class="indexterm" name="idm46045249666928"> </a> <a class="indexterm" name="idm46045249665440"> </a> <a class="indexterm" name="idm46045249663952"> </a> <p> The server reads the <code class="literal"> db </code> table into memory and sorts it at the same time that it reads the <code class="literal"> user </code> table. The server sorts the <code class="literal"> db </code> table based on the <code class="literal"> Host </code> , <code class="literal"> Db </code> , and <code class="literal"> User </code> scope columns. As with the <code class="literal"> user </code> table, sorting puts the most-specific values first and least-specific values last, and when the server looks for matching rows, it uses the first match that it finds. </p> <a class="indexterm" name="idm46045249656816"> </a> <a class="indexterm" name="idm46045249655312"> </a> <a class="indexterm" name="idm46045249653808"> </a> <p> The <code class="literal"> tables_priv </code> , <code class="literal"> columns_priv </code> , and <code class="literal"> procs_priv </code> tables grant table-specific, column-specific, and routine-specific privileges. Values in the scope columns of these tables can take the following forms: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The wildcard characters <code class="literal"> % </code> and <code class="literal"> _ </code> can be used in the <code class="literal"> Host </code> column. These have the same meaning as for pattern-matching operations performed with the <a class="link" href="string-comparison-functions.html#operator_like"> <code class="literal"> LIKE </code> </a> operator. </p> </li> <li class="listitem"> <p> A <code class="literal"> '%' </code> or blank <code class="literal"> Host </code> value means <span class="quote"> “ <span class="quote"> any host. </span> ” </span> </p> </li> <li class="listitem"> <p> The <code class="literal"> Db </code> , <code class="literal"> Table_name </code> , <code class="literal"> Column_name </code> , and <code class="literal"> Routine_name </code> columns cannot contain wildcards or be blank. </p> </li> </ul> </div> <p> The server sorts the <code class="literal"> tables_priv </code> , <code class="literal"> columns_priv </code> , and <code class="literal"> procs_priv </code> tables based on the <code class="literal"> Host </code> , <code class="literal"> Db </code> , and <code class="literal"> User </code> columns. This is similar to <code class="literal"> db </code> table sorting, but simpler because only the <code class="literal"> Host </code> column can contain wildcards. </p> <p> The server uses the sorted tables to verify each request that it receives. For requests that require administrative privileges such as <a class="link" href="privileges-provided.html#priv_shutdown"> <code class="literal"> SHUTDOWN </code> </a> or <a class="link" href="privileges-provided.html#priv_reload"> <code class="literal"> RELOAD </code> </a> , the server checks only the <code class="literal"> user </code> and <code class="literal"> global_privilege </code> tables because those are the only tables that specify administrative privileges. The server grants access if a row for the account in those tables permits the requested operation and denies access otherwise. For example, if you want to execute <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin shutdown </strong> </span> </a> but your <code class="literal"> user </code> table row does not grant the <a class="link" href="privileges-provided.html#priv_shutdown"> <code class="literal"> SHUTDOWN </code> </a> privilege to you, the server denies access without even checking the <code class="literal"> db </code> table. (The latter table contains no <code class="literal"> Shutdown_priv </code> column, so there is no need to check it.) </p> <p> For database-related requests ( <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , and so on), the server first checks the user's global privileges in the <code class="literal"> user </code> table row (less any privilege restrictions imposed by partial revokes). If the row permits the requested operation, access is granted. If the global privileges in the <code class="literal"> user </code> table are insufficient, the server determines the user's database-specific privileges from the <code class="literal"> db </code> table: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The server looks in the <code class="literal"> db </code> table for a match on the <code class="literal"> Host </code> , <code class="literal"> Db </code> , and <code class="literal"> User </code> columns. </p> </li> <li class="listitem"> <p> The <code class="literal"> Host </code> and <code class="literal"> User </code> columns are matched to the connecting user's host name and MySQL user name. </p> </li> <li class="listitem"> <p> The <code class="literal"> Db </code> column is matched to the database that the user wants to access. </p> </li> <li class="listitem"> <p> If there is no row for the <code class="literal"> Host </code> and <code class="literal"> User </code> , access is denied. </p> </li> </ul> </div> <p> After determining the database-specific privileges granted by the <code class="literal"> db </code> table rows, the server adds them to the global privileges granted by the <code class="literal"> user </code> table. If the result permits the requested operation, access is granted. Otherwise, the server successively checks the user's table and column privileges in the <code class="literal"> tables_priv </code> and <code class="literal"> columns_priv </code> tables, adds those to the user's privileges, and permits or denies access based on the result. For stored-routine operations, the server uses the <code class="literal"> procs_priv </code> table rather than <code class="literal"> tables_priv </code> and <code class="literal"> columns_priv </code> . </p> <p> Expressed in boolean terms, the preceding description of how a user's privileges are calculated may be summarized like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa72483520"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">global</span> <span class="token keyword">privileges</span> <span class="token operator">OR</span> <span class="token keyword">database</span> <span class="token keyword">privileges</span> <span class="token operator">OR</span> <span class="token keyword">table</span> <span class="token keyword">privileges</span> <span class="token operator">OR</span> <span class="token keyword">column</span> <span class="token keyword">privileges</span> <span class="token operator">OR</span> <span class="token keyword">routine</span> <span class="token keyword">privileges</span></code></pre> </div> <p> It may not be apparent why, if the global privileges are initially found to be insufficient for the requested operation, the server adds those privileges to the database, table, and column privileges later. The reason is that a request might require more than one type of privilege. For example, if you execute an <a class="link" href="insert-select.html" title="15.2.7.1 INSERT ... SELECT Statement"> <code class="literal"> INSERT INTO ... SELECT </code> </a> statement, you need both the <a class="link" href="privileges-provided.html#priv_insert"> <code class="literal"> INSERT </code> </a> and the <a class="link" href="privileges-provided.html#priv_select"> <code class="literal"> SELECT </code> </a> privileges. Your privileges might be such that the <code class="literal"> user </code> table row grants one privilege global and the <code class="literal"> db </code> table row grants the other specifically for the relevant database. In this case, you have the necessary privileges to perform the request, but the server cannot tell that from either your global or database privileges alone. It must make an access-control decision based on the combined privileges. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/sys-statements-with-full-table-scans.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-statements-with-full-table-scans"> </a> 30.4.3.37 The statements_with_full_table_scans and x$statements_with_full_table_scans Views </h4> </div> </div> </div> <a class="indexterm" name="idm46045062134736"> </a> <a class="indexterm" name="idm46045062133280"> </a> <a class="indexterm" name="idm46045062131776"> </a> <a class="indexterm" name="idm46045062130272"> </a> <p> These views display normalized statements that have done full table scans. By default, rows are sorted by descending percentage of time a full scan was done and descending total latency. </p> <p> The <a class="link" href="sys-statements-with-full-table-scans.html" title="30.4.3.37 The statements_with_full_table_scans and x$statements_with_full_table_scans Views"> <code class="literal"> statements_with_full_table_scans </code> </a> and <a class="link" href="sys-statements-with-full-table-scans.html" title="30.4.3.37 The statements_with_full_table_scans and x$statements_with_full_table_scans Views"> <code class="literal"> x$statements_with_full_table_scans </code> </a> views have these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> query </code> </p> <p> The normalized statement string. </p> </li> <li class="listitem"> <p> <code class="literal"> db </code> </p> <p> The default database for the statement, or <code class="literal"> NULL </code> if there is none. </p> </li> <li class="listitem"> <p> <code class="literal"> exec_count </code> </p> <p> The total number of times the statement has executed. </p> </li> <li class="listitem"> <p> <code class="literal"> total_latency </code> </p> <p> The total wait time of timed statement events for the statement. </p> </li> <li class="listitem"> <p> <code class="literal"> no_index_used_count </code> </p> <p> The total number of times no index was used to scan the table. </p> </li> <li class="listitem"> <p> <code class="literal"> no_good_index_used_count </code> </p> <p> The total number of times no good index was used to scan the table. </p> </li> <li class="listitem"> <p> <code class="literal"> no_index_used_pct </code> </p> <p> The percentage of the time no index was used to scan the table. </p> </li> <li class="listitem"> <p> <code class="literal"> rows_sent </code> </p> <p> The total number of rows returned from the table. </p> </li> <li class="listitem"> <p> <code class="literal"> rows_examined </code> </p> <p> The total number of rows read from the storage engine for the table. </p> </li> <li class="listitem"> <p> <code class="literal"> rows_sent_avg </code> </p> <p> The average number of rows returned from the table. </p> </li> <li class="listitem"> <p> <code class="literal"> rows_examined_avg </code> </p> <p> The average number of rows read from the storage engine for the table. </p> </li> <li class="listitem"> <p> <code class="literal"> first_seen </code> </p> <p> The time at which the statement was first seen. </p> </li> <li class="listitem"> <p> <code class="literal"> last_seen </code> </p> <p> The time at which the statement was most recently seen. </p> </li> <li class="listitem"> <p> <code class="literal"> digest </code> </p> <p> The statement digest. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/foreign-key-optimization.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="foreign-key-optimization"> </a> 10.3.4 Foreign Key Optimization </h3> </div> </div> </div> <a class="indexterm" name="idm46045227474336"> </a> <p> If a table has many columns, and you query many different combinations of columns, it might be efficient to split the less-frequently used data into separate tables with a few columns each, and relate them back to the main table by duplicating the numeric ID column from the main table. That way, each small table can have a primary key for fast lookups of its data, and you can query just the set of columns that you need using a join operation. Depending on how the data is distributed, the queries might perform less I/O and take up less cache memory because the relevant columns are packed together on disk. (To maximize performance, queries try to read as few data blocks as possible from disk; tables with only a few columns can fit more rows in each data block.) </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/index-statistics.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="index-statistics"> </a> 10.3.8 InnoDB and MyISAM Index Statistics Collection </h3> </div> </div> </div> <p> Storage engines collect statistics about tables for use by the optimizer. Table statistics are based on value groups, where a value group is a set of rows with the same key prefix value. For optimizer purposes, an important statistic is the average value group size. </p> <p> MySQL uses the average value group size in the following ways: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> To estimate how many rows must be read for each <a class="link" href="explain-output.html#jointype_ref"> <code class="literal"> ref </code> </a> access </p> </li> <li class="listitem"> <p> To estimate how many rows a partial join produces, that is, the number of rows produced by an operation of the form </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa538586"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">(</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">)</span> <span class="token keyword">JOIN</span> <em class="replaceable">tbl_name</em> <span class="token keyword">ON</span> <em class="replaceable">tbl_name</em><span class="token punctuation">.</span><span class="token keyword"><em class="replaceable">key</em></span> <span class="token operator">=</span> <em class="replaceable">expr</em></code></pre> </div> </li> </ul> </div> <p> As the average value group size for an index increases, the index is less useful for those two purposes because the average number of rows per lookup increases: For the index to be good for optimization purposes, it is best that each index value target a small number of rows in the table. When a given index value yields a large number of rows, the index is less useful and MySQL is less likely to use it. </p> <p> The average value group size is related to table cardinality, which is the number of value groups. The <a class="link" href="show-index.html" title="15.7.7.23 SHOW INDEX Statement"> <code class="literal"> SHOW INDEX </code> </a> statement displays a cardinality value based on <em class="replaceable"> <code> N/S </code> </em> , where <em class="replaceable"> <code> N </code> </em> is the number of rows in the table and <em class="replaceable"> <code> S </code> </em> is the average value group size. That ratio yields an approximate number of value groups in the table. </p> <p> For a join based on the <code class="literal"> <=> </code> comparison operator, <code class="literal"> NULL </code> is not treated differently from any other value: <code class="literal"> NULL <=> NULL </code> , just as <code class="literal"> <em class="replaceable"> <code> N </code> </em> <=> <em class="replaceable"> <code> N </code> </em> </code> for any other <em class="replaceable"> <code> N </code> </em> . </p> <p> However, for a join based on the <code class="literal"> = </code> operator, <code class="literal"> NULL </code> is different from non- <code class="literal"> NULL </code> values: <code class="literal"> <em class="replaceable"> <code> expr1 </code> </em> = <em class="replaceable"> <code> expr2 </code> </em> </code> is not true when <em class="replaceable"> <code> expr1 </code> </em> or <em class="replaceable"> <code> expr2 </code> </em> (or both) are <code class="literal"> NULL </code> . This affects <a class="link" href="explain-output.html#jointype_ref"> <code class="literal"> ref </code> </a> accesses for comparisons of the form <code class="literal"> <em class="replaceable"> <code> tbl_name.key </code> </em> = <em class="replaceable"> <code> expr </code> </em> </code> : MySQL does not access the table if the current value of <em class="replaceable"> <code> expr </code> </em> is <code class="literal"> NULL </code> , because the comparison cannot be true. </p> <p> For <code class="literal"> = </code> comparisons, it does not matter how many <code class="literal"> NULL </code> values are in the table. For optimization purposes, the relevant value is the average size of the non- <code class="literal"> NULL </code> value groups. However, MySQL does not currently enable that average size to be collected or used. </p> <p> For <code class="literal"> InnoDB </code> and <code class="literal"> MyISAM </code> tables, you have some control over collection of table statistics by means of the <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> and <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> system variables, respectively. These variables have three possible values, which differ as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> When the variable is set to <code class="literal"> nulls_equal </code> , all <code class="literal"> NULL </code> values are treated as identical (that is, they all form a single value group). </p> <p> If the <code class="literal"> NULL </code> value group size is much higher than the average non- <code class="literal"> NULL </code> value group size, this method skews the average value group size upward. This makes index appear to the optimizer to be less useful than it really is for joins that look for non- <code class="literal"> NULL </code> values. Consequently, the <code class="literal"> nulls_equal </code> method may cause the optimizer not to use the index for <a class="link" href="explain-output.html#jointype_ref"> <code class="literal"> ref </code> </a> accesses when it should. </p> </li> <li class="listitem"> <p> When the variable is set to <code class="literal"> nulls_unequal </code> , <code class="literal"> NULL </code> values are not considered the same. Instead, each <code class="literal"> NULL </code> value forms a separate value group of size 1. </p> <p> If you have many <code class="literal"> NULL </code> values, this method skews the average value group size downward. If the average non- <code class="literal"> NULL </code> value group size is large, counting <code class="literal"> NULL </code> values each as a group of size 1 causes the optimizer to overestimate the value of the index for joins that look for non- <code class="literal"> NULL </code> values. Consequently, the <code class="literal"> nulls_unequal </code> method may cause the optimizer to use this index for <a class="link" href="explain-output.html#jointype_ref"> <code class="literal"> ref </code> </a> lookups when other methods may be better. </p> </li> <li class="listitem"> <p> When the variable is set to <code class="literal"> nulls_ignored </code> , <code class="literal"> NULL </code> values are ignored. </p> </li> </ul> </div> <p> If you tend to use many joins that use <code class="literal"> <=> </code> rather than <code class="literal"> = </code> , <code class="literal"> NULL </code> values are not special in comparisons and one <code class="literal"> NULL </code> is equal to another. In this case, <code class="literal"> nulls_equal </code> is the appropriate statistics method. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> system variable has a global value; the <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> system variable has both global and session values. Setting the global value affects statistics collection for tables from the corresponding storage engine. Setting the session value affects statistics collection only for the current client connection. This means that you can force a table's statistics to be regenerated with a given method without affecting other clients by setting the session value of <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> . </p> <p> To regenerate <code class="literal"> MyISAM </code> table statistics, you can use any of the following methods: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Execute <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --stats_method= <em class="replaceable"> <code> method_name </code> </em> --analyze </strong> </span> </a> </p> </li> <li class="listitem"> <p> Change the table to cause its statistics to go out of date (for example, insert a row and then delete it), and then set <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> and issue an <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> statement </p> </li> </ul> </div> <p> Some caveats regarding the use of <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> and <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> : </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> You can force table statistics to be collected explicitly, as just described. However, MySQL may also collect statistics automatically. For example, if during the course of executing statements for a table, some of those statements modify the table, MySQL may collect statistics. (This may occur for bulk inserts or deletes, or some <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements, for example.) If this happens, the statistics are collected using whatever value <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> or <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> <code class="literal"> myisam_stats_method </code> </a> has at the time. Thus, if you collect statistics using one method, but the system variable is set to the other method when a table's statistics are collected automatically later, the other method is used. </p> </li> <li class="listitem"> <p> There is no way to tell which method was used to generate statistics for a given table. </p> </li> <li class="listitem"> <p> These variables apply only to <code class="literal"> InnoDB </code> and <code class="literal"> MyISAM </code> tables. Other storage engines have only one method for collecting table statistics. Usually it is closer to the <code class="literal"> nulls_equal </code> method. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/spatial-function-argument-handling.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="spatial-function-argument-handling"> </a> 14.16.2 Argument Handling by Spatial Functions </h3> </div> </div> </div> <p> Spatial values, or geometries, have the properties described in <a class="xref" href="gis-class-geometry.html" title="13.4.2.2 Geometry Class"> Section 13.4.2.2, “Geometry Class” </a> . The following discussion lists general spatial function argument-handling characteristics. Specific functions or groups of functions may have additional or different argument-handling characteristics, as discussed in the sections where those function descriptions occur. Where that is true, those descriptions take precedence over the general discussion here. </p> <p> Spatial functions are defined only for valid geometry values. See <a class="xref" href="geometry-well-formedness-validity.html" title="13.4.4 Geometry Well-Formedness and Validity"> Section 13.4.4, “Geometry Well-Formedness and Validity” </a> . </p> <p> Each geometry value is associated with a spatial reference system (SRS), which is a coordinate-based system for geographic locations. See <a class="xref" href="spatial-reference-systems.html" title="13.4.5 Spatial Reference System Support"> Section 13.4.5, “Spatial Reference System Support” </a> . </p> <a class="indexterm" name="idm46045198057408"> </a> <p> The spatial reference identifier (SRID) of a geometry identifies the SRS in which the geometry is defined. In MySQL, the SRID value is an integer associated with the geometry value. The maximum usable SRID value is 2 <sup> 32 </sup> −1. If a larger value is given, only the lower 32 bits are used. </p> <p> SRID 0 represents an infinite flat Cartesian plane with no units assigned to its axes. To ensure SRID 0 behavior, create geometry values using SRID 0. SRID 0 is the default for new geometry values if no SRID is specified. </p> <p> For computations on multiple geometry values, all values must be in the same SRS or an error occurs. Thus, spatial functions that take multiple geometry arguments require those arguments to be in the same SRS. If a spatial function returns <a class="ulink" href="/doc/mysql-errors/8.4/en/server-error-reference.html#error_er_gis_different_srids" target="_top"> <code class="literal"> ER_GIS_DIFFERENT_SRIDS </code> </a> , it means that the geometry arguments were not all in the same SRS. You must modify them to have the same SRS. </p> <p> A geometry returned by a spatial function is in the SRS of the geometry arguments because geometry values produced by any spatial function inherit the SRID of the geometry arguments. </p> <p> The <a class="ulink" href="http://www.opengeospatial.org" target="_blank"> Open Geospatial Consortium </a> guidelines require that input polygons already be closed, so unclosed polygons are rejected as invalid rather than being closed. </p> <p> In MySQL, the only valid empty geometry is represented in the form of an empty geometry collection. Empty geometry collection handling is as follows: An empty WKT input geometry collection may be specified as <code class="literal"> 'GEOMETRYCOLLECTION()' </code> . This is also the output WKT resulting from a spatial operation that produces an empty geometry collection. </p> <p> During parsing of a nested geometry collection, the collection is flattened and its basic components are used in various GIS operations to compute results. This provides additional flexibility to users because it is unnecessary to be concerned about the uniqueness of geometry data. Nested geometry collections may be produced from nested GIS function calls without having to be explicitly flattened first. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/faqs-mysql-cluster.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="faqs-mysql-cluster"> </a> A.10 MySQL 8.4 FAQ: NDB Cluster </h2> </div> </div> </div> <a class="indexterm" name="idm46045056063952"> </a> <a class="indexterm" name="idm46045056062480"> </a> <a class="indexterm" name="idm46045056061024"> </a> <p> In the following section, we answer questions that are frequently asked about MySQL NDB Cluster and the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine. </p> <div class="qandaset"> <a name="idm46045056057808"> </a> <dl> <dt> A.10.1. <a href="faqs-mysql-cluster.html#faq-cluster-which-versions-support-cluster"> Which versions of the MySQL software support NDB Cluster? Do I have to compile from source? </a> </dt> <dt> A.10.2. <a href="faqs-mysql-cluster.html#faq-cluster-what-is-ndb"> What do “NDB” and “NDBCLUSTER” mean? </a> </dt> <dt> A.10.3. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-vs-replication"> What is the difference between using NDB Cluster versus using MySQL Replication? </a> </dt> <dt> A.10.4. <a href="faqs-mysql-cluster.html#faq-cluster-how-cluster-network-need"> Do I need any special networking to run NDB Cluster? How do computers in a cluster communicate? </a> </dt> <dt> A.10.5. <a href="faqs-mysql-cluster.html#faq-cluster-what-min-hosts-cluster"> How many computers do I need to run an NDB Cluster, and why? </a> </dt> <dt> A.10.6. <a href="faqs-mysql-cluster.html#faq-cluster-what-hosts-do-clustering"> What do the different computers do in an NDB Cluster? </a> </dt> <dt> A.10.7. <a href="faqs-mysql-cluster.html#faq-cluster-what-show-nodegroup-star"> When I run the SHOW command in the NDB Cluster management client, I see a line of output that looks like this: </a> </dt> <dt> A.10.8. <a href="faqs-mysql-cluster.html#faq-cluster-which-os-clustering"> With which operating systems can I use NDB Cluster? </a> </dt> <dt> A.10.9. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-requirements"> What are the hardware requirements for running NDB Cluster? </a> </dt> <dt> A.10.10. <a href="faqs-mysql-cluster.html#faq-cluster-what-memory-needed-cluster"> How much RAM do I need to use NDB Cluster? Is it possible to use disk memory at all? </a> </dt> <dt> A.10.11. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-file-systems"> What file systems can I use with NDB Cluster? What about network file systems or network shares? </a> </dt> <dt> A.10.12. <a href="faqs-mysql-cluster.html#faq-cluster-can-cluster-vm"> Can I run NDB Cluster nodes inside virtual machines (such as those created by VMWare, VirtualBox, Parallels, or Xen)? </a> </dt> <dt> A.10.13. <a href="faqs-mysql-cluster.html#faq-cluster-why-error-1114"> I am trying to populate an NDB Cluster database. The loading process terminates prematurely and I get an error message like this one: </a> </dt> <dt> A.10.14. <a href="faqs-mysql-cluster.html#faq-cluster-can-cluster-remote-network"> NDB Cluster uses TCP/IP. Does this mean that I can run it over the Internet, with one or more nodes in remote locations? </a> </dt> <dt> A.10.15. <a href="faqs-mysql-cluster.html#faq-cluster-what-language-needed-cluster"> Do I have to learn a new programming or query language to use NDB Cluster? </a> </dt> <dt> A.10.16. <a href="faqs-mysql-cluster.html#faq-cluster-what-api-cluster-support"> What programming languages and APIs are supported by NDB Cluster? </a> </dt> <dt> A.10.17. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-management-tools"> Does NDB Cluster include any management tools? </a> </dt> <dt> A.10.18. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-errors-are"> How do I find out what an error or warning message means when using NDB Cluster? </a> </dt> <dt> A.10.19. <a href="faqs-mysql-cluster.html#faq-cluster-is-cluster-transaction-safe"> Is NDB Cluster transaction-safe? What isolation levels are supported? </a> </dt> <dt> A.10.20. <a href="faqs-mysql-cluster.html#faq-cluster-what-storage-engines-cluster"> What storage engines are supported by NDB Cluster? </a> </dt> <dt> A.10.21. <a href="faqs-mysql-cluster.html#faq-cluster-is-data-loss-no-power"> In the event of a catastrophic failure— for example, the whole city loses power and my UPS fails—would I lose all my data? </a> </dt> <dt> A.10.22. <a href="faqs-mysql-cluster.html#faq-cluster-can-cluster-fullindex"> Is it possible to use FULLTEXT indexes with NDB Cluster? </a> </dt> <dt> A.10.23. <a href="faqs-mysql-cluster.html#faq-cluster-can-multinode-cluster-one-host"> Can I run multiple nodes on a single computer? </a> </dt> <dt> A.10.24. <a href="faqs-mysql-cluster.html#faq-cluster-how-add-nodes-no-restart"> Can I add data nodes to an NDB Cluster without restarting it? </a> </dt> <dt> A.10.25. <a href="faqs-mysql-cluster.html#faq-cluster-what-cluster-limitations"> Are there any limitations that I should be aware of when using NDB Cluster? </a> </dt> <dt> A.10.26. <a href="faqs-mysql-cluster.html#faq-cluster-have-foreign-keys-cluster"> Does NDB Cluster support foreign keys? </a> </dt> <dt> A.10.27. <a href="faqs-mysql-cluster.html#faq-cluster-how-import-db-cluster"> How do I import an existing MySQL database into an NDB Cluster? </a> </dt> <dt> A.10.28. <a href="faqs-mysql-cluster.html#faq-cluster-how-nodes-communicate"> How do NDB Cluster nodes communicate with one another? </a> </dt> <dt> A.10.29. <a href="faqs-mysql-cluster.html#faq-cluster-what-is-arbitrator"> What is an arbitrator? </a> </dt> <dt> A.10.30. <a href="faqs-mysql-cluster.html#faq-cluster-what-types-cluster-support"> What data types are supported by NDB Cluster? </a> </dt> <dt> A.10.31. <a href="faqs-mysql-cluster.html#faq-cluster-how-start-stop-cluster"> How do I start and stop NDB Cluster? </a> </dt> <dt> A.10.32. <a href="faqs-mysql-cluster.html#faq-cluster-what-shutdown-do-data"> What happens to NDB Cluster data when the cluster is shut down? </a> </dt> <dt> A.10.33. <a href="faqs-mysql-cluster.html#faq-cluster-have-multiple-node-managers"> Is it a good idea to have more than one management node for an NDB Cluster? </a> </dt> <dt> A.10.34. <a href="faqs-mysql-cluster.html#faq-cluster-have-different-cluster-hosts"> Can I mix different kinds of hardware and operating systems in one NDB Cluster? </a> </dt> <dt> A.10.35. <a href="faqs-mysql-cluster.html#faq-cluster-have-multiple-nodes-one-host"> Can I run two data nodes on a single host? Two SQL nodes? </a> </dt> <dt> A.10.36. <a href="faqs-mysql-cluster.html#faq-cluster-have-host-names-cluster"> Can I use host names with NDB Cluster? </a> </dt> <dt> A.10.37. <a href="faqs-mysql-cluster.html#faq-cluster-have-ipv6-support-cluster"> Does NDB Cluster support IPv6? </a> </dt> <dt> A.10.38. <a href="faqs-mysql-cluster.html#faq-cluster-have-multiple-users-servers-cluster"> How do I handle MySQL users in an NDB Cluster having multiple MySQL servers? </a> </dt> <dt> A.10.39. <a href="faqs-mysql-cluster.html#faq-cluster-how-continue-after-node-error"> How do I continue to send queries in the event that one of the SQL nodes fails? </a> </dt> <dt> A.10.40. <a href="faqs-mysql-cluster.html#faq-cluster-how-backup-restore-cluster"> How do I back up and restore an NDB Cluster? </a> </dt> <dt> A.10.41. <a href="faqs-mysql-cluster.html#faq-cluster-what-angel-process"> What is an “angel process”? </a> </dt> </dl> <table border="0" style="width: 100%;"> <colgroup> <col align="left" width="1%"/> <col/> </colgroup> <tbody> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-which-versions-support-cluster"> </a> <a name="idm46045056057008"> </a> <p> <b> A.10.1. </b> </p> </td> <td align="left" valign="top"> <p> Which versions of the MySQL software support NDB Cluster? Do I have to compile from source? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster is not supported in standard MySQL Server releases. Instead, MySQL NDB Cluster is provided as a separate product. Available NDB Cluster release series include the following: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <b> NDB Cluster 7.3 / NDB Cluster 7.4. </b> These two series are no longer maintained or supported for new deployments. Users of NDB Cluster 7.3 or 7.4 should upgrade to NDB 7.5 or newer as soon as possible. We recommend that new deployments use the latest NDB Cluster 8.0 release. </p> </li> <li class="listitem"> <p> <b> NDB Cluster 7.5. </b> This series is a previous General Availability (GA) version of NDB Cluster, still available for production use, although we recommend that new deployments use the latest NDB Cluster 8.0 release. The latest NDB Cluster 7.5 releases can be obtained from <a class="ulink" href="https://dev.mysql.com/downloads/cluster/" target="_top"> https://dev.mysql.com/downloads/cluster/ </a> . </p> </li> <li class="listitem"> <p> <b> NDB Cluster 7.6. </b> This series is a previous General Availability (GA) version of NDB Cluster, still available for production use, although we recommend that new deployments use the latest NDB Cluster 8.0 release. The latest NDB Cluster 7.6 releases can be obtained from <a class="ulink" href="https://dev.mysql.com/downloads/cluster/" target="_top"> https://dev.mysql.com/downloads/cluster/ </a> . </p> </li> <li class="listitem"> <p> <b> NDB Cluster 8.0. </b> This series is the most recent General Availability (GA) version of NDB Cluster, based on version 8.0 of the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine and MySQL Server 8.0. NDB Cluster 8.0 is available for production use; new deployments intended for production should use the latest GA release in this series, which is currently NDB Cluster 8.0.41. You can obtain the most recent NDB Cluster 8.0 release from <a class="ulink" href="https://dev.mysql.com/downloads/cluster/" target="_top"> https://dev.mysql.com/downloads/cluster/ </a> . For information about new features and other important changes in this series, see <a class="ulink" href="/doc/refman/8.0/en/mysql-cluster-what-is-new.html" target="_top"> What is New in MySQL NDB Cluster 8.0 </a> . </p> </li> </ul> </div> <p> You can obtain and compile NDB Cluster from source (see <a class="xref" href="mysql-cluster-install-linux-source.html" title="25.3.1.4 Building NDB Cluster from Source on Linux"> Section 25.3.1.4, “Building NDB Cluster from Source on Linux” </a> , and <a class="xref" href="mysql-cluster-install-windows-source.html" title="25.3.2.2 Compiling and Installing NDB Cluster from Source on Windows"> Section 25.3.2.2, “Compiling and Installing NDB Cluster from Source on Windows” </a> ), but for all but the most specialized cases, we recommend using one of the following installers provided by Oracle that is appropriate to your operating platform and circumstances: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Linux <a class="link" href="mysql-cluster-install-linux-binary.html" title="25.3.1.1 Installing an NDB Cluster Binary Release on Linux"> binary release </a> ( <code class="filename"> tar.gz </code> file) </p> </li> <li class="listitem"> <p> Linux <a class="link" href="mysql-cluster-install-linux-rpm.html" title="25.3.1.2 Installing NDB Cluster from RPM"> RPM package </a> </p> </li> <li class="listitem"> <p> Linux <a class="link" href="mysql-cluster-install-debian.html" title="25.3.1.3 Installing NDB Cluster Using .deb Files"> <code class="filename"> .deb </code> file </a> </p> </li> <li class="listitem"> <p> Windows <a class="link" href="mysql-cluster-install-windows-binary.html" title="25.3.2.1 Installing NDB Cluster on Windows from a Binary Release"> binary <span class="quote"> “ <span class="quote"> no-install </span> ” </span> release </a> </p> </li> <li class="listitem"> <p> Windows <a class="ulink" href="/doc/refman/8.0/en/mysql-installer.html" target="_top"> MSI Installer </a> </p> </li> </ul> </div> <p> Installation packages may also be available from your platform's package management system. </p> <p> You can determine whether your MySQL Server has <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> support using one of the statements <code class="literal"> SHOW VARIABLES LIKE 'have_%' </code> , <a class="link" href="show-engines.html" title="15.7.7.17 SHOW ENGINES Statement"> <code class="literal"> SHOW ENGINES </code> </a> , or <a class="link" href="show-plugins.html" title="15.7.7.27 SHOW PLUGINS Statement"> <code class="literal"> SHOW PLUGINS </code> </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-is-ndb"> </a> <a name="idm46045056024704"> </a> <p> <b> A.10.2. </b> </p> </td> <td align="left" valign="top"> <p> What do <span class="quote"> “ <span class="quote"> NDB </span> ” </span> and <span class="quote"> “ <span class="quote"> NDBCLUSTER </span> ” </span> mean? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> <span class="quote"> “ <span class="quote"> NDB </span> ” </span> stands for <span class="quote"> “ <span class="quote"> <span class="bold"> <strong> N </strong> </span> etwork <span class="bold"> <strong> D </strong> </span> ata <span class="bold"> <strong> b </strong> </span> ase </span> ” </span> . <code class="literal"> NDB </code> and <code class="literal"> NDBCLUSTER </code> are both names for the storage engine that enables clustering support with MySQL. <code class="literal"> NDB </code> is preferred, but either name is correct. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-vs-replication"> </a> <a name="idm46045056017008"> </a> <p> <b> A.10.3. </b> </p> </td> <td align="left" valign="top"> <p> What is the difference between using NDB Cluster versus using MySQL Replication? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> In traditional MySQL replication, a source MySQL server updates one or more replicas. Transactions are committed sequentially, and a slow transaction can cause the replica to lag behind the source. This means that if the source fails, it is possible that the replica might not have recorded the last few transactions. If a transaction-safe engine such as <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> is being used, a transaction is either completed on the replica or not applied at all, but replication does not guarantee that all data on the source and the replica remains consistent at all times. In NDB Cluster, all data nodes are kept in synchrony, and a transaction committed by any one data node is committed for all data nodes. In the event of a data node failure, all remaining data nodes remain in a consistent state. </p> <p> In short, whereas standard MySQL replication is <span class="firstterm"> asynchronous </span> , NDB Cluster is <span class="firstterm"> synchronous </span> . </p> <p> Asynchronous replication is also available in NDB Cluster. <span class="firstterm"> NDB Cluster Replication </span> (also sometimes known as <span class="quote"> “ <span class="quote"> geo-replication </span> ” </span> ) includes the capability to replicate both between two NDB Clusters, and from an NDB Cluster to a non-Cluster MySQL server. See <a class="xref" href="mysql-cluster-replication.html" title="25.7 NDB Cluster Replication"> Section 25.7, “NDB Cluster Replication” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-cluster-network-need"> </a> <a name="idm46045056008384"> </a> <p> <b> A.10.4. </b> </p> </td> <td align="left" valign="top"> <p> Do I need any special networking to run NDB Cluster? How do computers in a cluster communicate? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster is intended to be used in a high-bandwidth environment, with computers connecting using TCP/IP. Its performance depends directly upon the connection speed between the cluster's computers. The minimum connectivity requirements for NDB Cluster include a typical 100-megabit Ethernet network or the equivalent. We recommend you use gigabit Ethernet whenever available. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-min-hosts-cluster"> </a> <a name="idm46045056005872"> </a> <p> <b> A.10.5. </b> </p> </td> <td align="left" valign="top"> <p> How many computers do I need to run an NDB Cluster, and why? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> A minimum of three computers is required to run a viable cluster. However, the minimum <span class="emphasis"> <em> recommended </em> </span> number of computers in an NDB Cluster is four: one each to run the management and SQL nodes, and two computers to serve as data nodes. The purpose of the two data nodes is to provide redundancy; the management node must run on a separate machine to guarantee continued arbitration services in the event that one of the data nodes fails. </p> <p> To provide increased throughput and high availability, you should use multiple SQL nodes (MySQL Servers connected to the cluster). It is also possible (although not strictly necessary) to run multiple management servers. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-hosts-do-clustering"> </a> <a name="idm46045056002304"> </a> <p> <b> A.10.6. </b> </p> </td> <td align="left" valign="top"> <p> What do the different computers do in an NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> An NDB Cluster has both a physical and logical organization, with computers being the physical elements. The logical or functional elements of a cluster are referred to as <span class="firstterm"> nodes </span> , and a computer housing a cluster node is sometimes referred to as a <span class="firstterm"> cluster host </span> . There are three types of nodes, each corresponding to a specific role within the cluster. These are: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <b> Management node. </b> This node provides management services for the cluster as a whole, including startup, shutdown, backups, and configuration data for the other nodes. The management node server is implemented as the application <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> ; the management client used to control NDB Cluster is <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> . See <a class="xref" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> Section 25.5.4, “ndb_mgmd — The NDB Cluster Management Server Daemon” </a> , and <a class="xref" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> Section 25.5.5, “ndb_mgm — The NDB Cluster Management Client” </a> , for information about these programs. </p> </li> <li class="listitem"> <p> <b> Data node. </b> This type of node stores and replicates data. Data node functionality is handled by instances of the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> data node process <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> . For more information, see <a class="xref" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> Section 25.5.1, “ndbd — The NDB Cluster Data Node Daemon” </a> . </p> </li> <li class="listitem"> <p> <b> SQL node. </b> This is simply an instance of MySQL Server ( <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> ) that is built with support for the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> storage engine and started with the <code class="option"> --ndb-cluster </code> option to enable the engine and the <code class="option"> --ndb-connectstring </code> option to enable it to connect to an NDB Cluster management server. For more about these options, see <a class="xref" href="mysql-cluster-options-variables.html#mysql-cluster-program-options-mysqld" title="25.4.3.9.1 MySQL Server Options for NDB Cluster"> Section 25.4.3.9.1, “MySQL Server Options for NDB Cluster” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> An <span class="firstterm"> API node </span> is any application that makes direct use of Cluster data nodes for data storage and retrieval. An SQL node can thus be considered a type of API node that uses a MySQL Server to provide an SQL interface to the Cluster. You can write such applications (that do not depend on a MySQL Server) using the NDB API, which supplies a direct, object-oriented transaction and scanning interface to NDB Cluster data; see <a class="ulink" href="/doc/ndbapi/en/overview-ndb-api.html" target="_top"> NDB Cluster API Overview: The NDB API </a> , for more information. </p> </div> </li> </ul> </div> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-show-nodegroup-star"> </a> <a name="idm46045055978416"> </a> <p> <b> A.10.7. </b> </p> </td> <td align="left" valign="top"> <p> When I run the <code class="literal"> SHOW </code> command in the NDB Cluster management client, I see a line of output that looks like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa77586617"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">id=2 @10.100.10.32 (Version: 8.0.41-ndb-8.0.41 Nodegroup: 0, *)</code></pre> </div> <p> What does the <code class="literal"> * </code> mean? How is this node different from the others? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> The simplest answer is, <span class="quote"> “ <span class="quote"> It's not something you can control, and it's nothing that you need to worry about in any case, unless you're a software engineer writing or analyzing the NDB Cluster source code </span> ” </span> . </p> <p> If you don't find that answer satisfactory, here's a longer and more technical version: </p> <p> A number of mechanisms in NDB Cluster require distributed coordination among the data nodes. These distributed algorithms and protocols include global checkpointing, DDL (schema) changes, and node restart handling. To make this coordination simpler, the data nodes <span class="quote"> “ <span class="quote"> elect </span> ” </span> one of their number to act as leader. There is no user-facing mechanism for influencing this selection, which is completely automatic; the fact that it <span class="emphasis"> <em> is </em> </span> automatic is a key part of NDB Cluster's internal architecture. </p> <p> When a node acts as the <span class="quote"> “ <span class="quote"> leader </span> ” </span> for any of these mechanisms, it is usually the point of coordination for the activity, and the other nodes act as <span class="quote"> “ <span class="quote"> followers </span> ” </span> , carrying out their parts of the activity as directed by the leader. If the node acting as leader fails, then the remaining nodes elect a new leader. Tasks in progress that were being coordinated by the old leader may either fail or be continued by the new leader, depending on the actual mechanism involved. </p> <p> It is possible for some of these different mechanisms and protocols to have different leader nodes, but in general the same leader is chosen for all of them. The node indicated as the leader in the output of <a class="link" href="mysql-cluster-mgm-client-commands.html#ndbclient-show"> <code class="literal"> SHOW </code> </a> in the management client is known internally as the <a class="ulink" href="/doc/ndb-internals/en/ndb-internals-kernel-blocks-dbdict.html" target="_top"> <code class="literal"> DICT </code> </a> manager, responsible for coordinating DDL and metadata activity. </p> <p> NDB Cluster is designed in such a way that the choice of leader has no discernible effect outside the cluster itself. For example, the current leader does not have significantly higher CPU or resource usage than the other data nodes, and failure of the leader should not have a significantly different impact on the cluster than the failure of any other data node. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-which-os-clustering"> </a> <a name="idm46045055964784"> </a> <p> <b> A.10.8. </b> </p> </td> <td align="left" valign="top"> <p> With which operating systems can I use NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster is supported on most Unix-like operating systems. NDB Cluster is also supported in production settings on Microsoft Windows operating systems. </p> <p> For more detailed information concerning the level of support which is offered for NDB Cluster on various operating system versions, operating system distributions, and hardware platforms, please refer to <a class="ulink" href="https://www.mysql.com/support/supportedplatforms/cluster.html" target="_blank"> https://www.mysql.com/support/supportedplatforms/cluster.html </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-requirements"> </a> <a name="idm46045055961392"> </a> <p> <b> A.10.9. </b> </p> </td> <td align="left" valign="top"> <p> What are the hardware requirements for running NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster should run on any platform for which <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> -enabled binaries are available. For data nodes and API nodes, faster CPUs and more memory are likely to improve performance, and 64-bit CPUs are likely to be more effective than 32-bit processors. There must be sufficient memory on machines used for data nodes to hold each node's share of the database (see <span class="emphasis"> <em> How much RAM do I Need? </em> </span> for more information). For a computer which is used only for running the NDB Cluster management server, the requirements are minimal; a common desktop PC (or the equivalent) is generally sufficient for this task. Nodes can communicate through the standard TCP/IP network and hardware. They can also use the high-speed SCI protocol; however, special networking hardware and software are required to use SCI (see <a class="xref" href="mysql-cluster-interconnects.html" title="25.4.4 Using High-Speed Interconnects with NDB Cluster"> Section 25.4.4, “Using High-Speed Interconnects with NDB Cluster” </a> ). </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-memory-needed-cluster"> </a> <a name="idm46045055956080"> </a> <p> <b> A.10.10. </b> </p> </td> <td align="left" valign="top"> <p> How much RAM do I need to use NDB Cluster? Is it possible to use disk memory at all? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster was originally implemented as in-memory only, but all versions currently available also provide the ability to store NDB Cluster on disk. See <a class="xref" href="mysql-cluster-disk-data.html" title="25.6.11 NDB Cluster Disk Data Tables"> Section 25.6.11, “NDB Cluster Disk Data Tables” </a> , for more information. </p> <p> For in-memory <code class="literal"> NDB </code> tables, you can use the following formula for obtaining a rough estimate of how much RAM is needed for each data node in the cluster: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa30747490"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple"><span class="token punctuation">(</span>SizeofDatabase × NumberOfReplicas × 1<span class="token punctuation">.</span>1 <span class="token punctuation">)</span> <span class="token operator">/</span> NumberOfDataNodes</code></pre> </div> <p> To calculate the memory requirements more exactly requires determining, for each table in the cluster database, the storage space required per row (see <a class="xref" href="storage-requirements.html" title="13.7 Data Type Storage Requirements"> Section 13.7, “Data Type Storage Requirements” </a> , for details), and multiplying this by the number of rows. You must also remember to account for any column indexes as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Each primary key or hash index created for an <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> table requires 21−25 bytes per record. These indexes use <code class="literal"> IndexMemory </code> . </p> </li> <li class="listitem"> <p> Each ordered index requires 10 bytes storage per record, using <code class="literal"> DataMemory </code> . </p> </li> <li class="listitem"> <p> Creating a primary key or unique index also creates an ordered index, unless this index is created with <code class="literal"> USING HASH </code> . In other words: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> A primary key or unique index on a Cluster table normally takes up 31 to 35 bytes per record. </p> </li> <li class="listitem"> <p> However, if the primary key or unique index is created with <code class="literal"> USING HASH </code> , then it requires only 21 to 25 bytes per record. </p> </li> </ul> </div> </li> </ul> </div> <p> Creating NDB Cluster tables with <code class="literal"> USING HASH </code> for all primary keys and unique indexes generally causes table updates to run more quickly—in some cases by a much as 20 to 30 percent faster than updates on tables where <code class="literal"> USING HASH </code> was not used in creating primary and unique keys. This is due to the fact that less memory is required (because no ordered indexes are created), and that less CPU must be utilized (because fewer indexes must be read and possibly updated). However, it also means that queries that could otherwise use range scans must be satisfied by other means, which can result in slower selects. </p> <p> When calculating Cluster memory requirements, you may find useful the <a class="link" href="mysql-cluster-programs-ndb-size-pl.html" title="25.5.29 ndb_size.pl — NDBCLUSTER Size Requirement Estimator"> <span class="command"> <strong> ndb_size.pl </strong> </span> </a> utility which is available in recent MySQL 8.4 releases. This Perl script connects to a current (non-Cluster) MySQL database and creates a report on how much space that database would require if it used the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> storage engine. For more information, see <a class="xref" href="mysql-cluster-programs-ndb-size-pl.html" title="25.5.29 ndb_size.pl — NDBCLUSTER Size Requirement Estimator"> Section 25.5.29, “ndb_size.pl — NDBCLUSTER Size Requirement Estimator” </a> . </p> <p> It is especially important to keep in mind that <span class="emphasis"> <em> every NDB Cluster table must have a primary key </em> </span> . The <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine creates a primary key automatically if none is defined; this primary key is created without <code class="literal"> USING HASH </code> . </p> <p> You can determine how much memory is being used for storage of NDB Cluster data and indexes at any given time using the <code class="literal"> REPORT MEMORYUSAGE </code> command in the <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> client; see <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> , for more information. In addition, warnings are written to the cluster log when 80% of available <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> or (prior to NDB 7.6) <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-indexmemory"> <code class="literal"> IndexMemory </code> </a> is in use, and again when usage reaches 90%, 99%, and 100%. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-file-systems"> </a> <a name="idm46045055924320"> </a> <p> <b> A.10.11. </b> </p> </td> <td align="left" valign="top"> <p> What file systems can I use with NDB Cluster? What about network file systems or network shares? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Generally, any file system that is native to the host operating system should work well with NDB Cluster. If you find that a given file system works particularly well (or not so especially well) with NDB Cluster, we invite you to discuss your findings in the <a class="ulink" href="https://forums.mysql.com/list.php?25" target="_blank"> NDB Cluster Forums </a> . </p> <p> For Windows, we recommend that you use <code class="literal"> NTFS </code> file systems for NDB Cluster, just as we do for standard MySQL. We do not test NDB Cluster with <code class="literal"> FAT </code> or <code class="literal"> VFAT </code> file systems. Because of this, we do not recommend their use with MySQL or NDB Cluster. </p> <p> NDB Cluster is implemented as a shared-nothing solution; the idea behind this is that the failure of a single piece of hardware should not cause the failure of multiple cluster nodes, or possibly even the failure of the cluster as a whole. For this reason, the use of network shares or network file systems is not supported for NDB Cluster. This also applies to shared storage devices such as SANs. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-can-cluster-vm"> </a> <a name="idm46045055917584"> </a> <p> <b> A.10.12. </b> </p> </td> <td align="left" valign="top"> <p> Can I run NDB Cluster nodes inside virtual machines (such as those created by VMWare, VirtualBox, Parallels, or Xen)? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster is supported for use in virtual machines. We currently support and test using <a class="ulink" href="http://www.oracle.com/technetwork/server-storage/vm/index.html" target="_blank"> Oracle VM </a> . </p> <p> Some NDB Cluster users have successfully deployed NDB Cluster using other virtualization products; in such cases, Oracle can provide NDB Cluster support, but issues specific to the virtual environment must be referred to that product's vendor. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-why-error-1114"> </a> <a name="idm46045055913984"> </a> <p> <b> A.10.13. </b> </p> </td> <td align="left" valign="top"> <p> I am trying to populate an NDB Cluster database. The loading process terminates prematurely and I get an error message like this one: </p> <p> <code class="literal"> <span class="errortext"> ERROR 1114: The table 'my_cluster_table' is full </span> </code> </p> <p> Why is this happening? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> The cause is very likely to be that your setup does not provide sufficient RAM for all table data and all indexes, <span class="emphasis"> <em> including the primary key required by the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine and automatically created in the event that the table definition does not include the definition of a primary key </em> </span> . </p> <p> It is also worth noting that all data nodes should have the same amount of RAM, since no data node in a cluster can use more memory than the least amount available to any individual data node. For example, if there are four computers hosting Cluster data nodes, and three of these have 3GB of RAM available to store Cluster data while the remaining data node has only 1GB RAM, then each data node can devote at most 1GB to NDB Cluster data and indexes. </p> <p> In some cases it is possible to get <span class="errortext"> Table is full </span> errors in MySQL client applications even when <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm -e "ALL REPORT MEMORYUSAGE" </strong> </span> </a> shows significant free <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> . You can force <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> to create extra partitions for NDB Cluster tables and thus have more memory available for hash indexes by using the <code class="literal"> MAX_ROWS </code> option for <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> . In general, setting <code class="literal"> MAX_ROWS </code> to twice the number of rows that you expect to store in the table should be sufficient. </p> <p> For similar reasons, you can also sometimes encounter problems with data node restarts on nodes that are heavily loaded with data. The <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-minfreepct" title="MinFreePct"> <code class="literal"> MinFreePct </code> </a> parameter can help with this issue by reserving a portion (5% by default) of <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-datamemory"> <code class="literal"> DataMemory </code> </a> and (prior to NDB 7.6) <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-indexmemory"> <code class="literal"> IndexMemory </code> </a> for use in restarts. This reserved memory is not available for storing <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables or data. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-can-cluster-remote-network"> </a> <a name="idm46045055893952"> </a> <p> <b> A.10.14. </b> </p> </td> <td align="left" valign="top"> <p> NDB Cluster uses TCP/IP. Does this mean that I can run it over the Internet, with one or more nodes in remote locations? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It is <span class="emphasis"> <em> very </em> </span> unlikely that a cluster would perform reliably under such conditions, as NDB Cluster was designed and implemented with the assumption that it would be run under conditions guaranteeing dedicated high-speed connectivity such as that found in a LAN setting using 100 Mbps or gigabit Ethernet—preferably the latter. We neither test nor warrant its performance using anything slower than this. </p> <p> Also, it is extremely important to keep in mind that communications between the nodes in an NDB Cluster are not secure; they are neither encrypted nor safeguarded by any other protective mechanism. The most secure configuration for a cluster is in a private network behind a firewall, with no direct access to any Cluster data or management nodes from outside. (For SQL nodes, you should take the same precautions as you would with any other instance of the MySQL server.) For more information, see <a class="xref" href="mysql-cluster-security.html" title="25.6.21 NDB Cluster Security Issues"> Section 25.6.21, “NDB Cluster Security Issues” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-language-needed-cluster"> </a> <a name="idm46045055888880"> </a> <p> <b> A.10.15. </b> </p> </td> <td align="left" valign="top"> <p> Do I have to learn a new programming or query language to use NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> <span class="emphasis"> <em> No </em> </span> . Although some specialized commands are used to manage and configure the cluster itself, only standard (My)SQL statements are required for the following operations: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Creating, altering, and dropping tables </p> </li> <li class="listitem"> <p> Inserting, updating, and deleting table data </p> </li> <li class="listitem"> <p> Creating, changing, and dropping primary and unique indexes </p> </li> </ul> </div> <p> Some specialized configuration parameters and files are required to set up an NDB Cluster—see <a class="xref" href="mysql-cluster-config-file.html" title="25.4.3 NDB Cluster Configuration Files"> Section 25.4.3, “NDB Cluster Configuration Files” </a> , for information about these. </p> <p> A few simple commands are used in the NDB Cluster management client ( <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> ) for tasks such as starting and stopping cluster nodes. See <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-api-cluster-support"> </a> <a name="idm46045055879440"> </a> <p> <b> A.10.16. </b> </p> </td> <td align="left" valign="top"> <p> What programming languages and APIs are supported by NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster supports the same programming APIs and languages as the standard MySQL Server, including ODBC, .Net, the MySQL C API, and numerous drivers for popular scripting languages such as PHP, Perl, and Python. NDB Cluster applications written using these APIs behave similarly to other MySQL applications; they transmit SQL statements to a MySQL Server (in the case of NDB Cluster, an SQL node), and receive responses containing rows of data. For more information about these APIs, see <a class="xref" href="connectors-apis.html" title="Chapter 31 Connectors and APIs"> Chapter 31, <i> Connectors and APIs </i> </a> . </p> <p> NDB Cluster also supports application programming using the NDB API, which provides a low-level C++ interface to NDB Cluster data without needing to go through a MySQL Server. See <a class="ulink" href="/doc/ndbapi/en/ndbapi.html" target="_top"> The NDB API </a> . In addition, many <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> management functions are exposed by the C-language MGM API; see <a class="ulink" href="/doc/ndbapi/en/mgm-api.html" target="_top"> The MGM API </a> , for more information. </p> <p> NDB Cluster also supports Java application programming using ClusterJ, which supports a domain object model of data using sessions and transactions. See <a class="ulink" href="/doc/ndbapi/en/mccj-overview-java.html" target="_top"> Java and NDB Cluster </a> , for more information. </p> <p> NDB Cluster 8.0 also includes adapters supporting NoSQL applications written against <code class="literal"> Node.js </code> , with NDB Cluster as the data store. See <a class="ulink" href="/doc/ndbapi/en/ndb-nodejs.html" target="_top"> MySQL NoSQL Connector for JavaScript </a> , for more information. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-management-tools"> </a> <a name="idm46045055869328"> </a> <p> <b> A.10.17. </b> </p> </td> <td align="left" valign="top"> <p> Does NDB Cluster include any management tools? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster includes a command line client for performing basic management functions. See <a class="xref" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> Section 25.5.5, “ndb_mgm — The NDB Cluster Management Client” </a> , and <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> . </p> <p> NDB Cluster is also supported by MySQL Cluster Manager, a separate product providing an advanced command line interface that can automate many NDB Cluster management tasks such as rolling restarts and configuration changes. For more information about MySQL Cluster Manager, see <a class="ulink" href="/doc/mysql-cluster-manager/8.4/en/" target="_top"> MySQL Cluster Manager 8.4.3 User Manual </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-errors-are"> </a> <a name="idm46045055864320"> </a> <p> <b> A.10.18. </b> </p> </td> <td align="left" valign="top"> <p> How do I find out what an error or warning message means when using NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> There are two ways in which this can be done: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> From within the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client, use <span class="command"> <strong> SHOW ERRORS </strong> </span> or <span class="command"> <strong> SHOW WARNINGS </strong> </span> immediately upon being notified of the error or warning condition. </p> </li> <li class="listitem"> <p> From a system shell prompt, use <a class="link" href="perror.html" title="6.8.1 perror — Display MySQL Error Message Information"> <span class="command"> <strong> perror --ndb <em class="replaceable"> <code> error_code </code> </em> </strong> </span> </a> . </p> </li> </ul> </div> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-is-cluster-transaction-safe"> </a> <a name="idm46045055855840"> </a> <p> <b> A.10.19. </b> </p> </td> <td align="left" valign="top"> <p> Is NDB Cluster transaction-safe? What isolation levels are supported? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> <span class="emphasis"> <em> Yes </em> </span> . For tables created with the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine, transactions are supported. Currently, NDB Cluster supports only the <a class="link" href="innodb-transaction-isolation-levels.html#isolevel_read-committed"> <code class="literal"> READ COMMITTED </code> </a> transaction isolation level. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-storage-engines-cluster"> </a> <a name="idm46045055850784"> </a> <p> <b> A.10.20. </b> </p> </td> <td align="left" valign="top"> <p> What storage engines are supported by NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster requires the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine. That is, in order for a table to be shared between nodes in an NDB Cluster, the table must be created using <code class="literal"> ENGINE=NDB </code> (or the equivalent option <code class="literal"> ENGINE=NDBCLUSTER </code> ). </p> <p> It is possible to create tables using other storage engines (such as <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> or <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> ) on a MySQL server being used with NDB Cluster, but since these tables do not use <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> , they do not participate in clustering; each such table is strictly local to the individual MySQL server instance on which it is created. </p> <p> NDB Cluster is quite different from <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> clustering with regard to architecture, requirements, and implementation; despite any similarity in their names, the two are not compatible. For more information about <code class="literal"> InnoDB </code> clustering, see <a class="ulink" href="/doc/mysql-shell/8.4/en/admin-api-userguide.html" target="_top"> MySQL AdminAPI </a> . See also <a class="xref" href="mysql-cluster-compared.html" title="25.2.6 MySQL Server Using InnoDB Compared with NDB Cluster"> Section 25.2.6, “MySQL Server Using InnoDB Compared with NDB Cluster” </a> , for information about the differences between the <code class="literal"> NDB </code> and <code class="literal"> InnoDB </code> storage engines. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-is-data-loss-no-power"> </a> <a name="idm46045055836096"> </a> <p> <b> A.10.21. </b> </p> </td> <td align="left" valign="top"> <p> In the event of a catastrophic failure— for example, the whole city loses power <span class="emphasis"> <em> and </em> </span> my UPS fails—would I lose all my data? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> All committed transactions are logged. Therefore, although it is possible that some data could be lost in the event of a catastrophe, this should be quite limited. Data loss can be further reduced by minimizing the number of operations per transaction. (It is not a good idea to perform large numbers of operations per transaction in any case.) </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-can-cluster-fullindex"> </a> <a name="idm46045055833040"> </a> <p> <b> A.10.22. </b> </p> </td> <td align="left" valign="top"> <p> Is it possible to use <code class="literal"> FULLTEXT </code> indexes with NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> <code class="literal"> FULLTEXT </code> indexing is currently supported only by the <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> and <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> storage engines. See <a class="xref" href="fulltext-search.html" title="14.9 Full-Text Search Functions"> Section 14.9, “Full-Text Search Functions” </a> , for more information. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-can-multinode-cluster-one-host"> </a> <a name="idm46045055826320"> </a> <p> <b> A.10.23. </b> </p> </td> <td align="left" valign="top"> <p> Can I run multiple nodes on a single computer? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It is possible but not always advisable. One of the chief reasons to run a cluster is to provide redundancy. To obtain the full benefits of this redundancy, each node should reside on a separate machine. If you place multiple nodes on a single machine and that machine fails, you lose all of those nodes. For this reason, if you do run multiple data nodes on a single machine, it is <span class="emphasis"> <em> extremely </em> </span> important that they be set up in such a way that the failure of this machine does not cause the loss of all the data nodes in a given node group. </p> <p> Given that NDB Cluster can be run on commodity hardware loaded with a low-cost (or even no-cost) operating system, the expense of an extra machine or two is well worth it to safeguard mission-critical data. It also worth noting that the requirements for a cluster host running a management node are minimal. This task can be accomplished with a 300 MHz Pentium or equivalent CPU and sufficient RAM for the operating system, plus a small amount of overhead for the <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> and <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> processes. </p> <p> It is acceptable to run multiple cluster data nodes on a single host that has multiple CPUs, cores, or both. The NDB Cluster distribution also provides a multithreaded version of the data node binary intended for use on such systems. For more information, see <a class="xref" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> Section 25.5.3, “ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)” </a> . </p> <p> It is also possible in some cases to run data nodes and SQL nodes concurrently on the same machine; how well such an arrangement performs is dependent on a number of factors such as number of cores and CPUs as well as the amount of disk and memory available to the data node and SQL node processes, and you must take these factors into account when planning such a configuration. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-add-nodes-no-restart"> </a> <a name="idm46045055817584"> </a> <p> <b> A.10.24. </b> </p> </td> <td align="left" valign="top"> <p> Can I add data nodes to an NDB Cluster without restarting it? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It is possible to add new data nodes to a running NDB Cluster without taking the cluster offline. For more information, see <a class="xref" href="mysql-cluster-online-add-node.html" title="25.6.7 Adding NDB Cluster Data Nodes Online"> Section 25.6.7, “Adding NDB Cluster Data Nodes Online” </a> . </p> <p> For other types of NDB Cluster nodes, a rolling restart is all that is required (see <a class="xref" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster"> Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster” </a> ). </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-cluster-limitations"> </a> <a name="idm46045055813488"> </a> <p> <b> A.10.25. </b> </p> </td> <td align="left" valign="top"> <p> Are there any limitations that I should be aware of when using NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Limitations on <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables in MySQL NDB Cluster include the following: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Temporary tables are not supported; a <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TEMPORARY TABLE </code> </a> statement using <code class="literal"> ENGINE=NDB </code> or <code class="literal"> ENGINE=NDBCLUSTER </code> fails with an error. </p> </li> <li class="listitem"> <p> The only types of user-defined partitioning supported for <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> tables are <code class="literal"> KEY </code> and <code class="literal"> LINEAR KEY </code> . Trying to create an <code class="literal"> NDB </code> table using any other partitioning type fails with an error. </p> </li> <li class="listitem"> <p> <code class="literal"> FULLTEXT </code> indexes are not supported. </p> </li> <li class="listitem"> <p> Index prefixes are not supported. Only complete columns may be indexed. </p> </li> <li class="listitem"> <p> Spatial indexes are not supported (although spatial columns can be used). See <a class="xref" href="spatial-types.html" title="13.4 Spatial Data Types"> Section 13.4, “Spatial Data Types” </a> . </p> </li> <li class="listitem"> <p> Support for partial transactions and partial rollbacks is comparable to that of other transactional storage engines such as <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> that can roll back individual statements. </p> </li> <li class="listitem"> <p> The maximum number of attributes allowed per table is 512. Attribute names cannot be any longer than 31 characters. For each table, the maximum combined length of the table and database names is 122 characters. </p> </li> <li class="listitem"> <p> Priot to NDB 8.0, the maximum size for a table row is 14 kilobytes, not counting <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> values. In NDB 8.0, this maximum is increased to 30000 bytes. See <a class="xref" href="mysql-cluster-limitations-database-objects.html" title="25.2.7.5 Limits Associated with Database Objects in NDB Cluster"> Section 25.2.7.5, “Limits Associated with Database Objects in NDB Cluster” </a> , for more information. </p> <p> There is no set limit for the number of rows per <code class="literal"> NDB </code> table. Limits on table size depend on a number of factors, in particular on the amount of RAM available to each data node. </p> </li> </ul> </div> <p> For a complete listing of limitations in NDB Cluster, see <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> . See also <a class="xref" href="mysql-cluster-limitations-resolved.html" title="25.2.7.11 Previous NDB Cluster Issues Resolved in NDB Cluster 8.4"> Section 25.2.7.11, “Previous NDB Cluster Issues Resolved in NDB Cluster 8.4” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-foreign-keys-cluster"> </a> <a name="idm46045055788576"> </a> <p> <b> A.10.26. </b> </p> </td> <td align="left" valign="top"> <p> Does NDB Cluster support foreign keys? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster provides support for foreign key constraints which is comparable to that found in the <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> storage engine; see <a class="xref" href="constraint-foreign-key.html" title="1.7.3.2 FOREIGN KEY Constraints"> Section 1.7.3.2, “FOREIGN KEY Constraints” </a> , for more detailed information, as well as <a class="xref" href="create-table-foreign-keys.html" title="15.1.20.5 FOREIGN KEY Constraints"> Section 15.1.20.5, “FOREIGN KEY Constraints” </a> . Applications requiring foreign key support should use NDB Cluster 7.3, 7.4, 7.5, or later. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-import-db-cluster"> </a> <a name="idm46045055783744"> </a> <p> <b> A.10.27. </b> </p> </td> <td align="left" valign="top"> <p> How do I import an existing MySQL database into an NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> You can import databases into NDB Cluster much as you would with any other version of MySQL. Other than the limitations mentioned elsewhere in this FAQ, the only other special requirement is that any tables to be included in the cluster must use the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine. This means that the tables must be created with <code class="literal"> ENGINE=NDB </code> or <code class="literal"> ENGINE=NDBCLUSTER </code> . </p> <p> It is also possible to convert existing tables that use other storage engines to <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> using one or more <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statement. However, the definition of the table must be compatible with the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> storage engine prior to making the conversion. In MySQL 8.4, an additional workaround is also required; see <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> , for details. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-nodes-communicate"> </a> <a name="idm46045055773680"> </a> <p> <b> A.10.28. </b> </p> </td> <td align="left" valign="top"> <p> How do NDB Cluster nodes communicate with one another? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Cluster nodes can communicate through any of three different transport mechanisms: TCP/IP, SHM (shared memory), and SCI (Scalable Coherent Interface). Where available, SHM is used by default between nodes residing on the same cluster host; however, this is considered experimental. SCI is a high-speed (1 gigabit per second and higher), high-availability protocol used in building scalable multi-processor systems; it requires special hardware and drivers. See <a class="xref" href="mysql-cluster-interconnects.html" title="25.4.4 Using High-Speed Interconnects with NDB Cluster"> Section 25.4.4, “Using High-Speed Interconnects with NDB Cluster” </a> , for more about using SCI as a transport mechanism for NDB Cluster. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-is-arbitrator"> </a> <a name="idm46045055770432"> </a> <p> <b> A.10.29. </b> </p> </td> <td align="left" valign="top"> <p> What is an <span class="firstterm"> arbitrator </span> ? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> If one or more data nodes in a cluster fail, it is possible that not all cluster data nodes are able to <span class="quote"> “ <span class="quote"> see </span> ” </span> one another. In fact, it is possible that two sets of data nodes might become isolated from one another in a network partitioning, also known as a <span class="quote"> “ <span class="quote"> split-brain </span> ” </span> scenario. This type of situation is undesirable because each set of data nodes tries to behave as though it is the entire cluster. An arbitrator is required to decide between the competing sets of data nodes. </p> <p> When all data nodes in at least one node group are alive, network partitioning is not an issue, because no single subset of the cluster can form a functional cluster on its own. The real problem arises when no single node group has all its nodes alive, in which case network partitioning (the <span class="quote"> “ <span class="quote"> split-brain </span> ” </span> scenario) becomes possible. Then an arbitrator is required. All cluster nodes recognize the same node as the arbitrator, which is normally the management server; however, it is possible to configure any of the MySQL Servers in the cluster to act as the arbitrator instead. The arbitrator accepts the first set of cluster nodes to contact it, and tells the remaining set to shut down. Arbitrator selection is controlled by the <code class="literal"> ArbitrationRank </code> configuration parameter for MySQL Server and management server nodes. You can also use the <code class="literal"> ArbitrationRank </code> configuration parameter to control the arbitrator selection process. For more information about these parameters, see <a class="xref" href="mysql-cluster-mgm-definition.html" title="25.4.3.5 Defining an NDB Cluster Management Server"> Section 25.4.3.5, “Defining an NDB Cluster Management Server” </a> . </p> <p> The role of arbitrator does not in and of itself impose any heavy demands upon the host so designated, and thus the arbitrator host does not need to be particularly fast or to have extra memory especially for this purpose. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-types-cluster-support"> </a> <a name="idm46045055761744"> </a> <p> <b> A.10.30. </b> </p> </td> <td align="left" valign="top"> <p> What data types are supported by NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> NDB Cluster supports all of the usual MySQL data types, including those associated with MySQL's spatial extensions; however, the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> storage engine does not support spatial indexes. (Spatial indexes are supported only by <a class="link" href="myisam-storage-engine.html" title="18.2 The MyISAM Storage Engine"> <code class="literal"> MyISAM </code> </a> ; see <a class="xref" href="spatial-types.html" title="13.4 Spatial Data Types"> Section 13.4, “Spatial Data Types” </a> , for more information.) In addition, there are some differences with regard to indexes when used with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> NDB Cluster Disk Data tables (that is, tables created with <code class="literal"> TABLESPACE ... STORAGE DISK ENGINE=NDB </code> or <code class="literal"> TABLESPACE ... STORAGE DISK ENGINE=NDBCLUSTER </code> ) have only fixed-width rows. This means that (for example) each Disk Data table record containing a <a class="link" href="char.html" title="13.3.2 The CHAR and VARCHAR Types"> <code class="literal"> VARCHAR(255) </code> </a> column requires space for 255 characters (as required for the character set and collation being used for the table), regardless of the actual number of characters stored therein. </p> </div> <p> See <a class="xref" href="mysql-cluster-limitations.html" title="25.2.7 Known Limitations of NDB Cluster"> Section 25.2.7, “Known Limitations of NDB Cluster” </a> , for more information about these issues. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-start-stop-cluster"> </a> <a name="idm46045055750000"> </a> <p> <b> A.10.31. </b> </p> </td> <td align="left" valign="top"> <p> How do I start and stop NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It is necessary to start each node in the cluster separately, in the following order: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Start the management node, using the <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> command. </p> <p> When starting the cluster for the first time, you must include the <a class="link" href="mysql-cluster-programs-ndb-mgmd.html#option_ndb_mgmd_config-file"> <code class="option"> -f </code> </a> or <a class="link" href="mysql-cluster-programs-ndb-mgmd.html#option_ndb_mgmd_config-file"> <code class="option"> --config-file </code> </a> option to tell the management node where its configuration file can be found. </p> </li> <li class="listitem"> <p> Start each data node with the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> command. </p> <p> Each data node must be started with the <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> -c </code> </a> or <a class="link" href="mysql-cluster-programs-ndbd.html#option_ndbd_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> option so that the data node knows how to connect to the management server. </p> </li> <li class="listitem"> <p> Start each MySQL Server (SQL node) using your preferred startup script, such as <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> . </p> <p> Each MySQL Server must be started with the <a class="link" href="mysql-cluster-options-variables.html#option_mysqld_ndbcluster"> <code class="option"> --ndbcluster </code> </a> and <a class="link" href="mysql-cluster-options-variables.html#option_mysqld_ndb-connectstring"> <code class="option"> --ndb-connectstring </code> </a> options. These options cause <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> to enable <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDBCLUSTER </code> </a> storage engine support and how to connect to the management server. </p> </li> </ol> </div> <p> Each of these commands must be run from a system shell on the machine housing the affected node. (You do not have to be physically present at the machine—a remote login shell can be used for this purpose.) You can verify that the cluster is running by starting the <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> management client <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> on the machine housing the management node and issuing the <code class="literal"> SHOW </code> or <code class="literal"> ALL STATUS </code> command. </p> <p> To shut down a running cluster, issue the command <code class="literal"> SHUTDOWN </code> in the management client. Alternatively, you may enter the following command in a system shell: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa71880820"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">ndb_mgm</span> <span class="token property">-e</span> <span class="token atrule">"SHUTDOWN"</span></code></pre> </div> <p> (The quotation marks in this example are optional, since there are no spaces in the command string following the <code class="option"> -e </code> option; in addition, the <code class="literal"> SHUTDOWN </code> command, like other management client commands, is not case-sensitive.) </p> <p> Either of these commands causes the <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> , <a class="link" href="mysql-cluster-programs-ndb-mgm.html" title="25.5.5 ndb_mgm — The NDB Cluster Management Client"> <span class="command"> <strong> ndb_mgm </strong> </span> </a> , and any <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> processes to terminate gracefully. MySQL servers running as SQL nodes can be stopped using <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin shutdown </strong> </span> </a> . </p> <p> For more information, see <a class="xref" href="mysql-cluster-mgm-client-commands.html" title="25.6.1 Commands in the NDB Cluster Management Client"> Section 25.6.1, “Commands in the NDB Cluster Management Client” </a> , and <a class="xref" href="mysql-cluster-install-shutdown-restart.html" title="25.3.6 Safe Shutdown and Restart of NDB Cluster"> Section 25.3.6, “Safe Shutdown and Restart of NDB Cluster” </a> . </p> <p> MySQL Cluster Manager provides additional ways to handle starting ansd stopping of NDB Cluster nodes. See <a class="ulink" href="/doc/mysql-cluster-manager/8.4/en/" target="_top"> MySQL Cluster Manager 8.4.3 User Manual </a> , for more information about this tool. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-shutdown-do-data"> </a> <a name="idm46045055712032"> </a> <p> <b> A.10.32. </b> </p> </td> <td align="left" valign="top"> <p> What happens to NDB Cluster data when the cluster is shut down? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> The data that was held in memory by the cluster's data nodes is written to disk, and is reloaded into memory the next time that the cluster is started. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-multiple-node-managers"> </a> <a name="idm46045055709824"> </a> <p> <b> A.10.33. </b> </p> </td> <td align="left" valign="top"> <p> Is it a good idea to have more than one management node for an NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> It can be helpful as a fail-safe. Only one management node controls the cluster at any given time, but it is possible to configure one management node as primary, and one or more additional management nodes to take over in the event that the primary management node fails. </p> <p> See <a class="xref" href="mysql-cluster-config-file.html" title="25.4.3 NDB Cluster Configuration Files"> Section 25.4.3, “NDB Cluster Configuration Files” </a> , for information on how to configure NDB Cluster management nodes. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-different-cluster-hosts"> </a> <a name="idm46045055706288"> </a> <p> <b> A.10.34. </b> </p> </td> <td align="left" valign="top"> <p> Can I mix different kinds of hardware and operating systems in one NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Yes, as long as all machines and operating systems have the same <span class="quote"> “ <span class="quote"> endianness </span> ” </span> (all big-endian or all little-endian). </p> <p> It is also possible to use software from different NDB Cluster releases on different nodes. However, we support such use only as part of a rolling upgrade procedure (see <a class="xref" href="mysql-cluster-rolling-restart.html" title="25.6.5 Performing a Rolling Restart of an NDB Cluster"> Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster” </a> ). </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-multiple-nodes-one-host"> </a> <a name="idm46045055702336"> </a> <p> <b> A.10.35. </b> </p> </td> <td align="left" valign="top"> <p> Can I run two data nodes on a single host? Two SQL nodes? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Yes, it is possible to do this. In the case of multiple data nodes, it is advisable (but not required) for each node to use a different data directory. If you want to run multiple SQL nodes on one machine, each instance of <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> must use a different TCP/IP port. </p> <p> Running data nodes and SQL nodes together on the same host is possible, but you should be aware that the <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> processes may compete for memory with <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-host-names-cluster"> </a> <a name="idm46045055694544"> </a> <p> <b> A.10.36. </b> </p> </td> <td align="left" valign="top"> <p> Can I use host names with NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> Yes, it is possible to use DNS and DHCP for cluster hosts. However, if your application requires <span class="quote"> “ <span class="quote"> five nines </span> ” </span> availability, you should use fixed (numeric) IP addresses, since making communication between Cluster hosts dependent on services such as DNS and DHCP introduces additional potential points of failure. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-ipv6-support-cluster"> </a> <a name="idm46045055691824"> </a> <p> <b> A.10.37. </b> </p> </td> <td align="left" valign="top"> <p> Does NDB Cluster support IPv6? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> IPv6 is supported for connections between SQL nodes (MySQL servers), but connections between all other types of NDB Cluster nodes must use IPv4. </p> <p> In practical terms, this means that you can use IPv6 for replication between NDB Clusters, but connections between nodes in the same NDB Cluster must use IPv4. For more information, see <a class="xref" href="mysql-cluster-replication-issues.html" title="25.7.3 Known Issues in NDB Cluster Replication"> Section 25.7.3, “Known Issues in NDB Cluster Replication” </a> . </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-have-multiple-users-servers-cluster"> </a> <a name="idm46045055688336"> </a> <p> <b> A.10.38. </b> </p> </td> <td align="left" valign="top"> <p> How do I handle MySQL users in an NDB Cluster having multiple MySQL servers? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> MySQL user accounts and privileges are normally not automatically propagated between different MySQL servers accessing the same NDB Cluster. MySQL NDB Cluster provides support for shared and synchronized users and privileges using the <a class="link" href="privileges-provided.html#priv_ndb-stored-user"> <code class="literal"> NDB_STORED_USER </code> </a> privilege; see <a class="ulink" href="/doc/refman/5.7/en/mysql-cluster-privilege-distribution.html" target="_top"> Distributed Privileges Using Shared Grant Tables </a> , for more information. You should be aware that this implementation was introduced in NDB 8.0, and is not compatible with the shared privileges mechanism employed in earlier versions of NDB Cluster. The older implementation is no longer supported in NDB 8.0. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-continue-after-node-error"> </a> <a name="idm46045055683632"> </a> <p> <b> A.10.39. </b> </p> </td> <td align="left" valign="top"> <p> How do I continue to send queries in the event that one of the SQL nodes fails? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> MySQL NDB Cluster does not provide any sort of automatic failover between SQL nodes. Your application must be prepared to handle the loss of SQL nodes and to fail over between them. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-how-backup-restore-cluster"> </a> <a name="idm46045055681440"> </a> <p> <b> A.10.40. </b> </p> </td> <td align="left" valign="top"> <p> How do I back up and restore an NDB Cluster? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> You can use the NDB Cluster native backup and restore functionality in the NDB management client and the <a class="link" href="mysql-cluster-programs-ndb-restore.html" title="25.5.23 ndb_restore — Restore an NDB Cluster Backup"> <span class="command"> <strong> ndb_restore </strong> </span> </a> program. See <a class="xref" href="mysql-cluster-backup.html" title="25.6.8 Online Backup of NDB Cluster"> Section 25.6.8, “Online Backup of NDB Cluster” </a> , and <a class="xref" href="mysql-cluster-programs-ndb-restore.html" title="25.5.23 ndb_restore — Restore an NDB Cluster Backup"> Section 25.5.23, “ndb_restore — Restore an NDB Cluster Backup” </a> . </p> <p> You can also use the traditional functionality provided for this purpose in <a class="link" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program"> <span class="command"> <strong> mysqldump </strong> </span> </a> and the MySQL server. See <a class="xref" href="mysqldump.html" title="6.5.4 mysqldump — A Database Backup Program"> Section 6.5.4, “mysqldump — A Database Backup Program” </a> , for more information. </p> </td> </tr> <tr class="question"> <td align="left" valign="top"> <a name="faq-cluster-what-angel-process"> </a> <a name="idm46045055674256"> </a> <p> <b> A.10.41. </b> </p> </td> <td align="left" valign="top"> <p> What is an <span class="quote"> “ <span class="quote"> angel process </span> ” </span> ? </p> </td> </tr> <tr class="answer"> <td align="left" valign="top"> </td> <td align="left" valign="top"> <p> This process monitors and, if necessary, attempts to restart the data node process. If you check the list of active processes on your system after starting <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> , you can see that there are actually 2 processes running by that name, as shown here (we omit the output from <a class="link" href="mysql-cluster-programs-ndb-mgmd.html" title="25.5.4 ndb_mgmd — The NDB Cluster Management Server Daemon"> <span class="command"> <strong> ndb_mgmd </strong> </span> </a> and <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> for brevity): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa98953940"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">./ndb_mgmd</span> <span class="token prompt">$> </span><span class="token command">ps</span> aux | grep ndb me 23002 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 122948 3104 ? Ssl 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 <span class="token punctuation">.</span>/ndb_mgmd me 23025 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 5284 820 pts/2 S+ 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 grep ndb <span class="token prompt">$> </span><span class="token command">./ndbd</span> <span class="token property">-c</span> 127<span class="token punctuation">.</span>0<span class="token punctuation">.</span>0<span class="token punctuation">.</span>1 <span class="token property">--initial</span> <span class="token prompt">$> </span><span class="token command">ps</span> aux | grep ndb me 23002 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 123080 3356 ? Ssl 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 <span class="token punctuation">.</span>/ndb_mgmd me 23096 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 35876 2036 ? Ss 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 <span class="token punctuation">.</span>/ndbmtd <span class="token property">-c</span> 127<span class="token punctuation">.</span>0<span class="token punctuation">.</span>0<span class="token punctuation">.</span>1 <span class="token property">--initial</span> me 23097 1<span class="token punctuation">.</span>0 2<span class="token punctuation">.</span>4 524116 91096 ? Sl 14<span class="token punctuation">:</span>14 0<span class="token punctuation">:</span>00 <span class="token punctuation">.</span>/ndbmtd <span class="token property">-c</span> 127<span class="token punctuation">.</span>0<span class="token punctuation">.</span>0<span class="token punctuation">.</span>1 <span class="token property">--initial</span> me 23168 0<span class="token punctuation">.</span>0 0<span class="token punctuation">.</span>0 5284 812 pts/2 R+ 14<span class="token punctuation">:</span>15 0<span class="token punctuation">:</span>00 grep ndb</code></pre> </div> <p> The <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> process showing <code class="literal"> 0.0 </code> for both memory and CPU usage is the angel process (although it actually does use a very small amount of each). This process merely checks to see if the main <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> or <a class="link" href="mysql-cluster-programs-ndbmtd.html" title="25.5.3 ndbmtd — The NDB Cluster Data Node Daemon (Multi-Threaded)"> <span class="command"> <strong> ndbmtd </strong> </span> </a> process (the primary data node process which actually handles the data) is running. If permitted to do so (for example, if the <a class="link" href="mysql-cluster-ndbd-definition.html#ndbparam-ndbd-stoponerror"> <code class="literal"> StopOnError </code> </a> configuration parameter is set to <code class="literal"> false </code> ), the angel process tries to restart the primary data node process. </p> </td> </tr> </tbody> </table> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/group-replication-offline-upgrade.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="group-replication-offline-upgrade"> </a> 20.8.2 Group Replication Offline Upgrade </h3> </div> </div> </div> <a class="indexterm" name="idm46045131618032"> </a> <p> To perform an offline upgrade of a Group Replication group, you remove each member from the group, perform an upgrade of the member and then restart the group as usual. In a multi-primary group you can shutdown the members in any order. In a single-primary group, shutdown each secondary first and then finally the primary. See <a class="xref" href="group-replication-upgrading-member.html" title="20.8.3.2 Upgrading a Group Replication Member"> Section 20.8.3.2, “Upgrading a Group Replication Member” </a> for how to remove members from a group and shutdown MySQL. </p> <p> Once the group is offline, upgrade all of the members. See <a class="xref" href="upgrading.html" title="Chapter 3 Upgrading MySQL"> Chapter 3, <i> Upgrading MySQL </i> </a> for how to perform an upgrade. When all members have been upgraded, restart the members. </p> <p> If you upgrade all the members of a replication group when they are offline and then restart the group, the members join using the new release's Group Replication communication protocol version, so that becomes the group's communication protocol version. If you have a requirement to allow members at earlier releases to join, you can use the <a class="link" href="group-replication-functions-for-communication-protocol.html#function_group-replication-set-communication-protocol"> <code class="literal"> group_replication_set_communication_protocol() </code> </a> function to downgrade the communication protocol version, specifying the MySQL Server version of the prospective group member that has the oldest installed server version. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/audit-log-file-reading.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="audit-log-file-reading"> </a> 8.4.5.6 Reading Audit Log Files </h4> </div> </div> </div> <p> The audit log plugin supports functions that provide an SQL interface for reading JSON-format audit log files. (This capability does not apply to log files written in other formats.) </p> <p> When the audit log plugin initializes and is configured for JSON logging, it uses the directory containing the current audit log file as the location to search for readable audit log files. The plugin determines the file location, base name, and suffix from the value of the <a class="link" href="audit-log-reference.html#sysvar_audit_log_file"> <code class="literal"> audit_log_file </code> </a> system variable, then looks for files with names that match the following pattern, where <code class="literal"> [...] </code> indicates optional file name parts: </p> <a class="indexterm" name="idm46045237488976"> </a> <a class="indexterm" name="idm46045237487888"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa96385302"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none"><em class="replaceable">basename</em>[.<em class="replaceable">timestamp</em>].<em class="replaceable">suffix</em>[.gz][[.<em class="replaceable">pwd_id</em>].enc]</code></pre> </div> <p> If a file name ends with <code class="filename"> .enc </code> , the file is encrypted and reading its unencrypted contents requires a decryption password obtained from the keyring. The audit log plugin determines the keyring ID of the decryption password as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> If <code class="filename"> .enc </code> is preceded by <em class="replaceable"> <code> pwd_id </code> </em> , the keyring ID is <code class="literal"> audit_log- <em class="replaceable"> <code> pwd_id </code> </em> </code> . </p> </li> <li class="listitem"> <p> If <code class="filename"> .enc </code> is not preceded by <em class="replaceable"> <code> pwd_id </code> </em> , the file has an old name from before audit log encryption password history was implemented. The keyring ID is <code class="literal"> audit_log </code> . </p> </li> </ul> </div> <p> For more information about encrypted audit log files, see <a class="xref" href="audit-log-logging-configuration.html#audit-log-file-encryption" title="Encrypting Audit Log Files"> Encrypting Audit Log Files </a> . </p> <p> The plugin ignores files that have been renamed manually and do not match the pattern, and files that were encrypted with a password no longer available in the keyring. The plugin opens each remaining candidate file, verifies that the file actually contains <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> audit events, and sorts the files using the timestamps from the first event of each file. The result is a sequence of files that are subject to access using the log-reading functions: </p> <a class="indexterm" name="idm46045237472912"> </a> <a class="indexterm" name="idm46045237471808"> </a> <a class="indexterm" name="idm46045237470304"> </a> <a class="indexterm" name="idm46045237469200"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> reads events from the audit log or closes the reading process. </p> </li> <li class="listitem"> <p> <a class="link" href="audit-log-reference.html#function_audit-log-read-bookmark"> <code class="literal"> audit_log_read_bookmark() </code> </a> returns a bookmark for the most recently written audit log event. This bookmark is suitable for passing to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> to indicate where to begin reading. </p> </li> </ul> </div> <p> <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> takes an optional <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> string argument, and the result returned from a successful call to either function is a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> string. </p> <p> To use the functions to read the audit log, follow these principles: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Call <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> to read events beginning from a given position or the current position, or to close reading: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> To initialize an audit log read sequence, pass an argument that indicates the position at which to begin. One way to do so is to pass the bookmark returned by <a class="link" href="audit-log-reference.html#function_audit-log-read-bookmark"> <code class="literal"> audit_log_read_bookmark() </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa5892792"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> audit_log_read<span class="token punctuation">(</span>audit_log_read_bookmark<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> To continue reading from the current position in the sequence, call <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> with no position specified: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa96699573"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> audit_log_read<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> To explicitly close the read sequence, pass a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> argument: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa68600731"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> audit_log_read<span class="token punctuation">(</span><span class="token string">'null'</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> It is unnecessary to close reading explicitly. Reading is closed implicitly when the session ends or a new read sequence is initialized by calling <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> with an argument that indicates the position at which to begin. </p> </li> </ul> </div> </li> <li class="listitem"> <p> A successful call to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> to read events returns a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> string containing an array of audit events: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If the final value of the returned array is not a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value, there are more events following those just read and <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> can be called again to read more of them. </p> </li> <li class="listitem"> <p> If the final value of the returned array is a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value, there are no more events left to be read in the current read sequence. </p> </li> </ul> </div> <p> Each non- <code class="literal"> null </code> array element is an event represented as a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> hash. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-json"><div class="docs-select-all right" id="sa78882737"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-json"><span class="token punctuation">[</span> <span class="token punctuation">{</span> <span class="token property">"timestamp"</span><span class="token operator">:</span> <span class="token string">"2020-05-18 13:39:33"</span><span class="token punctuation">,</span> <span class="token property">"id"</span><span class="token operator">:</span> <span class="token number">0</span><span class="token punctuation">,</span> <span class="token property">"class"</span><span class="token operator">:</span> <span class="token string">"connection"</span><span class="token punctuation">,</span> <span class="token property">"event"</span><span class="token operator">:</span> <span class="token string">"connect"</span><span class="token punctuation">,</span> ... <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span> <span class="token property">"timestamp"</span><span class="token operator">:</span> <span class="token string">"2020-05-18 13:39:33"</span><span class="token punctuation">,</span> <span class="token property">"id"</span><span class="token operator">:</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token property">"class"</span><span class="token operator">:</span> <span class="token string">"general"</span><span class="token punctuation">,</span> <span class="token property">"event"</span><span class="token operator">:</span> <span class="token string">"status"</span><span class="token punctuation">,</span> ... <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span> <span class="token property">"timestamp"</span><span class="token operator">:</span> <span class="token string">"2020-05-18 13:39:33"</span><span class="token punctuation">,</span> <span class="token property">"id"</span><span class="token operator">:</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token property">"class"</span><span class="token operator">:</span> <span class="token string">"connection"</span><span class="token punctuation">,</span> <span class="token property">"event"</span><span class="token operator">:</span> <span class="token string">"disconnect"</span><span class="token punctuation">,</span> ... <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token null">null</span> <span class="token punctuation">]</span></code></pre> </div> <p> For more information about the content of JSON-format audit events, see <a class="xref" href="audit-log-file-formats.html#audit-log-file-json-format" title="JSON Audit Log File Format"> JSON Audit Log File Format </a> . </p> </li> <li class="listitem"> <p> An <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> call to read events that does not specify a position produces an error under any of these conditions: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> A read sequence has not yet been initialized by passing a position to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> . </p> </li> <li class="listitem"> <p> There are no more events left to be read in the current read sequence; that is, <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> previously returned an array ending with a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value. </p> </li> <li class="listitem"> <p> The most recent read sequence has been closed by passing a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> . </p> </li> </ul> </div> <p> To read events under those conditions, it is necessary to first initialize a read sequence by calling <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> with an argument that specifies a position. </p> </li> </ul> </div> <p> To specify a position to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> , include an argument that indicates where to begin reading. For example, pass a bookmark, which is a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> hash containing <code class="literal"> timestamp </code> and <code class="literal"> id </code> elements that uniquely identify a particular event. Here is an example bookmark, obtained by calling the <a class="link" href="audit-log-reference.html#function_audit-log-read-bookmark"> <code class="literal"> audit_log_read_bookmark() </code> </a> function: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa85144958"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> audit_log_read_bookmark<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> audit_log_read_bookmark() <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> { "timestamp": "2020<span class="token punctuation">-</span>05<span class="token punctuation">-</span>18 21:03:44", "id": 0 } <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> Passing the current bookmark to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> initializes event reading beginning at the bookmark position: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa25164799"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> audit_log_read<span class="token punctuation">(</span>audit_log_read_bookmark<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> audit_log_read(audit_log_read_bookmark()) <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> [ {"timestamp":"2020<span class="token punctuation">-</span>05<span class="token punctuation">-</span>18 22:41:24","id":0,"class":"connection", ... <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> The argument to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> is optional. If present, it can be a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> <code class="literal"> null </code> value to close the read sequence, or a <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> hash. </p> <p> Within a hash argument to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> , items are optional and control aspects of the read operation such as the position at which to begin reading or how many events to read. The following items are significant (other items are ignored): </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> start </code> : The position within the audit log of the first event to read. The position is given as a timestamp and the read starts from the first event that occurs on or after the timestamp value. The <code class="literal"> start </code> item has this format, where <em class="replaceable"> <code> value </code> </em> is a literal timestamp value: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-json"><div class="docs-select-all right" id="sa24668904"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-json"><span class="token property">"start"</span><span class="token operator">:</span> <span class="token punctuation">{</span> <span class="token property">"timestamp"</span><span class="token operator">:</span> <span class="token string">"<em class="replaceable">value</em>"</span> <span class="token punctuation">}</span></code></pre> </div> </li> <li class="listitem"> <p> <code class="literal"> timestamp </code> , <code class="literal"> id </code> : The position within the audit log of the first event to read. The <code class="literal"> timestamp </code> and <code class="literal"> id </code> items together comprise a bookmark that uniquely identify a particular event. If an <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> argument includes either item, it must include both to completely specify a position or an error occurs. </p> </li> <li class="listitem"> <p> <code class="literal"> max_array_length </code> : The maximum number of events to read from the log. If this item is omitted, the default is to read to the end of the log or until the read buffer is full, whichever comes first. </p> </li> </ul> </div> <p> To specify a starting position to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> , pass a hash argument that includes either a <code class="literal"> start </code> item or a bookmark consisting of <code class="literal"> timestamp </code> and <code class="literal"> id </code> items. If a hash argument includes both a <code class="literal"> start </code> item and a bookmark, an error occurs. </p> <p> If a hash argument specifies no starting position, reading continues from the current position. </p> <p> If a timestamp value includes no time part, a time part of <code class="literal"> 00:00:00 </code> is assumed. </p> <p> Example arguments accepted by <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> : </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Read events starting with the first event that occurs on or after the given timestamp: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa82908806"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "start": { "timestamp": "2020-05-24 12:30:00" } }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Like the previous example, but read at most 3 events: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa8352805"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "start": { "timestamp": "2020-05-24 12:30:00" }, "max_array_length": 3 }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Read events starting with the first event that occurs on or after <code class="literal"> 2020-05-24 00:00:00 </code> (the timestamp includes no time part, so <code class="literal"> 00:00:00 </code> is assumed): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa15585267"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "start": { "timestamp": "2020-05-24" } }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Read events starting with the event that has the exact timestamp and event ID: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa41723971"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "timestamp": "2020-05-24 12:30:00", "id": 0 }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Like the previous example, but read at most 3 events: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa53440569"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "timestamp": "2020-05-24 12:30:00", "id": 0, "max_array_length": 3 }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Read events from the current position in the read sequence: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa3992450"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Read at most 5 events beginning at the current position in the read sequence: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa37238954"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'{ "max_array_length": 5 }'</span><span class="token punctuation">)</span></code></pre> </div> </li> <li class="listitem"> <p> Close the current read sequence: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa45503142"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql">audit_log_read<span class="token punctuation">(</span><span class="token string">'null'</span><span class="token punctuation">)</span></code></pre> </div> </li> </ul> </div> <p> A <a class="link" href="json.html" title="13.5 The JSON Data Type"> <code class="literal"> JSON </code> </a> string returned from either log-reading function can be manipulated as necessary. Suppose that a call to obtain a bookmark produces this value: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa6428293"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@mark</span> <span class="token operator">:=</span> audit_log_read_bookmark<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token variable">@mark</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> @mark <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> { "timestamp": "2020<span class="token punctuation">-</span>05<span class="token punctuation">-</span>18 16:10:28", "id": 2 } <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> Calling <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> with that argument can return multiple events. To limit <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> to reading at most <em class="replaceable"> <code> N </code> </em> events, add to the string a <code class="literal"> max_array_length </code> item with that value. For example, to read a single event, modify the string as follows: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa18444196"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@mark</span> <span class="token operator">:=</span> <span class="token function">JSON_SET</span><span class="token punctuation">(</span><span class="token variable">@mark</span><span class="token punctuation">,</span> <span class="token string">'$.max_array_length'</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token variable">@mark</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> @mark <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> {"id": 2, "timestamp": "2020<span class="token punctuation">-</span>05<span class="token punctuation">-</span>18 16:10:28", "max_array_length": 1} <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> <p> The modified string, when passed to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> , produces a result containing at most one event, no matter how many are available. </p> <p> If an audit log function is invoked from within the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> client, binary string results display using hexadecimal notation, depending on the value of the <a class="link" href="mysql-command-options.html#option_mysql_binary-as-hex"> <code class="option"> --binary-as-hex </code> </a> . For more information about that option, see <a class="xref" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> Section 6.5.1, “mysql — The MySQL Command-Line Client” </a> . </p> <p> To set a limit on the number of bytes that <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> reads, set the <a class="link" href="audit-log-reference.html#sysvar_audit_log_read_buffer_size"> <code class="literal"> audit_log_read_buffer_size </code> </a> system variable. This variable has a default of 32KB and can be set at runtime. Each client should set its session value of <a class="link" href="audit-log-reference.html#sysvar_audit_log_read_buffer_size"> <code class="literal"> audit_log_read_buffer_size </code> </a> appropriately for its use of <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> . </p> <a class="indexterm" name="idm46045237334768"> </a> <a class="indexterm" name="idm46045237333664"> </a> <p> Each call to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> returns as many available events as fit within the buffer size. Events that do not fit within the buffer size are skipped and generate warnings. Given this behavior, consider these factors when assessing the proper buffer size for an application: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> There is a tradeoff between number of calls to <a class="link" href="audit-log-reference.html#function_audit-log-read"> <code class="literal"> audit_log_read() </code> </a> and events returned per call: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> With a smaller buffer size, calls return fewer events, so more calls are needed. </p> </li> <li class="listitem"> <p> With a larger buffer size, calls return more events, so fewer calls are needed. </p> </li> </ul> </div> </li> <li class="listitem"> <p> With a smaller buffer size, such as the default size of 32KB, there is a greater chance for events to exceed the buffer size and thus to be skipped. </p> </li> </ul> </div> <p> For additional information about audit log-reading functions, see <a class="xref" href="audit-log-reference.html#audit-log-routines" title="Audit Log Functions"> Audit Log Functions </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/optimizer-trace-implementation.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="optimizer-trace-implementation"> </a> 10.15.16 Optimizer Trace Implementation </h3> </div> </div> </div> <p> See the files <code class="filename"> sql/opt_trace* </code> , starting with <code class="filename"> sql/opt_trace.h </code> . A trace is started by creating an instance of <code class="literal"> Opt_trace_start </code> ; information is added to this trace by creating instances of <code class="literal"> Opt_trace_object </code> and <code class="literal"> Opt_trace_array </code> , and by using the <code class="literal"> add() </code> methods of these classes. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/replication-options-source.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-options-source"> </a> 19.1.6.2 Replication Source Options and Variables </h4> </div> </div> </div> <p> This section describes the server options and system variables that you can use on replication source servers. You can specify the options either on the <a class="link" href="command-line-options.html" title="6.2.2.1 Using Options on the Command Line"> command line </a> or in an <a class="link" href="option-files.html" title="6.2.2.2 Using Option Files"> option file </a> . You can specify system variable values using <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> . </p> <p> On the source and each replica, you must set the <a class="link" href="replication-options.html#sysvar_server_id"> <code class="literal"> server_id </code> </a> system variable to establish a unique replication ID. For each server, you should pick a unique positive integer in the range from 1 to 2 <sup> 32 </sup> − 1, and each ID must be different from every other ID in use by any other source or replica in the replication topology. Example: <code class="literal"> server-id=3 </code> . </p> <p> For options used on the source for controlling binary logging, see <a class="xref" href="replication-options-binary-log.html" title="19.1.6.4 Binary Logging Options and Variables"> Section 19.1.6.4, “Binary Logging Options and Variables” </a> . </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="replication-optvars-masters"> </a> Startup Options for Replication Source Servers </h5> </div> </div> </div> <p> The following list describes startup options for controlling replication source servers. Replication-related system variables are discussed later in this section. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_mysqld_show-replica-auth-info"> </a> <a class="link" href="replication-options-source.html#option_mysqld_show-replica-auth-info"> <code class="option"> --show-replica-auth-info </code> </a> </p> <a class="indexterm" name="idm46045144569168"> </a> <a class="indexterm" name="idm46045144567664"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for show-replica-auth-info"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --show-replica-auth-info[={OFF|ON}] </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Use <a class="link" href="replication-options-source.html#option_mysqld_show-replica-auth-info"> <code class="option"> --show-replica-auth-info </code> </a> , which displays replication user names and passwords in the output of <a class="link" href="show-replicas.html" title="15.7.7.36 SHOW REPLICAS Statement"> <code class="literal"> SHOW REPLICAS </code> </a> on the source for replicas started with the <a class="link" href="replication-options-replica.html#sysvar_report_user"> <code class="option"> --report-user </code> </a> and <a class="link" href="replication-options-replica.html#sysvar_report_password"> <code class="option"> --report-password </code> </a> options. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_show-slave-auth-info"> </a> <a class="link" href="replication-options-source.html#option_mysqld_show-slave-auth-info"> <code class="option"> --show-slave-auth-info </code> </a> </p> <a class="indexterm" name="idm46045144549280"> </a> <a class="indexterm" name="idm46045144547824"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for show-slave-auth-info"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --show-slave-auth-info[={OFF|ON}] </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Deprecated alias for <a class="link" href="replication-options-source.html#option_mysqld_show-replica-auth-info"> <code class="option"> --show-replica-auth-info </code> </a> . </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="replication-sysvars-masters"> </a> System Variables Used on Replication Source Servers </h5> </div> </div> </div> <p> The following system variables are used for or by replication source servers: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="sysvar_auto_increment_increment"> </a> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> </p> <a class="indexterm" name="idm46045144528208"> </a> <a class="indexterm" name="idm46045144527104"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for auto_increment_increment"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --auto-increment-increment=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> auto_increment_increment </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> Yes </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> and <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> are intended for use with circular (source-to-source) replication, and can be used to control the operation of <code class="literal"> AUTO_INCREMENT </code> columns. Both variables have global and session values, and each can assume an integer value between 1 and 65,535 inclusive. Setting the value of either of these two variables to 0 causes its value to be set to 1 instead. Attempting to set the value of either of these two variables to an integer greater than 65,535 or less than 0 causes its value to be set to 65,535 instead. Attempting to set the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> or <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> to a noninteger value produces an error, and the actual value of the variable remains unchanged. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> is also supported for use with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables. </p> </div> <p> When Group Replication is started on a server, the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> is changed to the value of <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_auto_increment_increment"> <code class="literal"> group_replication_auto_increment_increment </code> </a> , which defaults to 7, and the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> is changed to the server ID. The changes are reverted when Group Replication is stopped. These changes are only made and reverted if <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> and <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> each have their default value of 1. If their values have already been modified from the default, Group Replication does not alter them. These system variables are also not modified when Group Replication is in single-primary mode, where only one server writes. </p> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> and <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> affect <code class="literal"> AUTO_INCREMENT </code> column behavior as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> controls the interval between successive column values. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa12559337"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'auto_inc%'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Variable_name <span class="token punctuation">|</span> Value <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> auto_increment_increment <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> auto_increment_offset <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">2 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> autoinc1 <span class="token prompt"> -></span> <span class="token punctuation">(</span>col <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">Query</span> OK<span class="token punctuation">,</span> <span class="token number">0</span> <span class="token keyword">rows</span> affected <span class="token punctuation">(</span><span class="token number">0.04</span> sec<span class="token punctuation">)</span> <span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@@auto_increment_increment</span><span class="token operator">=</span><span class="token number">10</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'auto_inc%'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Variable_name <span class="token punctuation">|</span> Value <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> auto_increment_increment <span class="token punctuation">|</span> 10 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> auto_increment_offset <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">2 rows in set (0.01 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> autoinc1 <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 4 rows affected (0.00 sec)</span> <span class="token output">Records: 4 Duplicates: 0 Warnings: 0</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> col <span class="token keyword">FROM</span> autoinc1<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> col <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 21 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 31 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">4 rows in set (0.00 sec)</span></code></pre> </div> </li> <li class="listitem"> <p> <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> determines the starting point for the <code class="literal"> AUTO_INCREMENT </code> column value. Consider the following, assuming that these statements are executed during the same session as the example given in the description for <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa65560444"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SET</span> <span class="token variable">@@auto_increment_offset</span><span class="token operator">=</span><span class="token number">5</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'auto_inc%'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Variable_name <span class="token punctuation">|</span> Value <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> auto_increment_increment <span class="token punctuation">|</span> 10 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> auto_increment_offset <span class="token punctuation">|</span> 5 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">2 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> autoinc2 <span class="token prompt"> -></span> <span class="token punctuation">(</span>col <span class="token datatype">INT</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 0 rows affected (0.06 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> autoinc2 <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 4 rows affected (0.00 sec)</span> <span class="token output">Records: 4 Duplicates: 0 Warnings: 0</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> col <span class="token keyword">FROM</span> autoinc2<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> col <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 5 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 15 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 25 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 35 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">4 rows in set (0.02 sec)</span></code></pre> </div> <p> When the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> is greater than that of <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> , the value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> is ignored. </p> </li> </ul> </div> <p> If either of these variables is changed, and then new rows inserted into a table containing an <code class="literal"> AUTO_INCREMENT </code> column, the results may seem counterintuitive because the series of <code class="literal"> AUTO_INCREMENT </code> values is calculated without regard to any values already present in the column, and the next value inserted is the least value in the series that is greater than the maximum existing value in the <code class="literal"> AUTO_INCREMENT </code> column. The series is calculated like this: </p> <p> <code class="literal"> auto_increment_offset </code> + <em class="replaceable"> <code> N </code> </em> × <code class="literal"> auto_increment_increment </code> </p> <p> where <em class="replaceable"> <code> N </code> </em> is a positive integer value in the series [1, 2, 3, ...]. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa24423883"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SHOW</span> <span class="token keyword">VARIABLES</span> <span class="token operator">LIKE</span> <span class="token string">'auto_inc%'</span><span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> Variable_name <span class="token punctuation">|</span> Value <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> auto_increment_increment <span class="token punctuation">|</span> 10 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> auto_increment_offset <span class="token punctuation">|</span> 5 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">2 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> col <span class="token keyword">FROM</span> autoinc1<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> col <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 21 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 31 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">4 rows in set (0.00 sec)</span> <span class="token prompt">mysql></span> <span class="token keyword">INSERT</span> <span class="token keyword">INTO</span> autoinc1 <span class="token keyword">VALUES</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token output">Query OK, 4 rows affected (0.00 sec)</span> <span class="token output">Records: 4 Duplicates: 0 Warnings: 0</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> col <span class="token keyword">FROM</span> autoinc1<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> col <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> 1 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 11 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 21 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 31 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 35 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 45 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 55 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> 65 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output">8 rows in set (0.00 sec)</span></code></pre> </div> <p> The values shown for <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> and <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> generate the series 5 + <em class="replaceable"> <code> N </code> </em> × 10, that is, [5, 15, 25, 35, 45, ...]. The highest value present in the <code class="literal"> col </code> column prior to the <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> is 31, and the next available value in the <code class="literal"> AUTO_INCREMENT </code> series is 35, so the inserted values for <code class="literal"> col </code> begin at that point and the results are as shown for the <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> query. </p> <p> It is not possible to restrict the effects of these two variables to a single table; these variables control the behavior of all <code class="literal"> AUTO_INCREMENT </code> columns in <span class="emphasis"> <em> all </em> </span> tables on the MySQL server. If the global value of either variable is set, its effects persist until the global value is changed or overridden by setting the session value, or until <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> is restarted. If the local value is set, the new value affects <code class="literal"> AUTO_INCREMENT </code> columns for all tables into which new rows are inserted by the current user for the duration of the session, unless the values are changed during that session. </p> <p> The default value of <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> is 1. See <a class="xref" href="replication-features-auto-increment.html" title="19.5.1.1 Replication and AUTO_INCREMENT"> Section 19.5.1.1, “Replication and AUTO_INCREMENT” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_auto_increment_offset"> </a> <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> <code class="literal"> auto_increment_offset </code> </a> </p> <a class="indexterm" name="idm46045144425840"> </a> <a class="indexterm" name="idm46045144424800"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for auto_increment_offset"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --auto-increment-offset=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> auto_increment_offset </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> Yes </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> This variable has a default value of 1. If it is left with its default value, and Group Replication is started on the server in multi-primary mode, it is changed to the server ID. For more information, see the description for <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> <code class="literal"> auto_increment_increment </code> </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <code class="literal"> auto_increment_offset </code> is also supported for use with <a class="link" href="mysql-cluster.html" title="Chapter 25 MySQL NDB Cluster 8.4"> <code class="literal"> NDB </code> </a> tables. </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_immediate_server_version"> </a> <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> <code class="literal"> immediate_server_version </code> </a> </p> <a class="indexterm" name="idm46045144391200"> </a> <a class="indexterm" name="idm46045144390096"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for immediate_server_version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> immediate_server_version </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 999999 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 999999 </code> </td> </tr> </tbody> </table> </div> <p> For internal use by replication. This session system variable holds the MySQL Server release number of the server that is the immediate source in a replication topology (for example, <code class="literal"> 80403 </code> for a MySQL 8.4.4 server instance). If this immediate server is at a release that does not support the session system variable, the value of the variable is set to 0 ( <code class="literal"> UNKNOWN_SERVER_VERSION </code> ). </p> <p> The value of the variable is replicated from a source to a replica. With this information the replica can correctly process data originating from a source at an older release, by recognizing where syntax changes or semantic changes have occurred between the releases involved and handling these appropriately. The information can also be used in a Group Replication environment where one or more members of the replication group is at a newer release than the others. The value of the variable can be viewed in the binary log for each transaction (as part of the <code class="literal"> Gtid_log_event </code> , or <code class="literal"> Anonymous_gtid_log_event </code> if GTIDs are not in use on the server), and could be helpful in debugging cross-version replication issues. </p> <p> Setting the session value of this system variable is a restricted operation. The session user must have either the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege (see <a class="xref" href="replication-privilege-checks.html" title="19.3.3 Replication Privilege Checks"> Section 19.3.3, “Replication Privilege Checks” </a> ), or privileges sufficient to set restricted session variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ). However, note that the variable is not intended for users to set; it is set automatically by the replication infrastructure. </p> </li> <li class="listitem"> <p> <a name="sysvar_original_server_version"> </a> <a class="link" href="replication-options-source.html#sysvar_original_server_version"> <code class="literal"> original_server_version </code> </a> </p> <a class="indexterm" name="idm46045144355760"> </a> <a class="indexterm" name="idm46045144354720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for original_server_version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_original_server_version"> original_server_version </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 999999 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 999999 </code> </td> </tr> </tbody> </table> </div> <p> For internal use by replication. This session system variable holds the MySQL Server release number of the server where a transaction was originally committed (for example, <code class="literal"> 80403 </code> for a MySQL 8.4.3 server instance). If this original server is at a release that does not support the session system variable, the value of the variable is set to 0 ( <code class="literal"> UNKNOWN_SERVER_VERSION </code> ). Note that when a release number is set by the original server, the value of the variable is reset to 0 if the immediate server or any other intervening server in the replication topology does not support the session system variable, and so does not replicate its value. </p> <p> The value of the variable is set and used in the same ways as for the <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> <code class="literal"> immediate_server_version </code> </a> system variable. If the value of the variable is the same as that for the <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> <code class="literal"> immediate_server_version </code> </a> system variable, only the latter is recorded in the binary log, with an indicator that the original server version is the same. </p> <p> In a Group Replication environment, view change log events, which are special transactions queued by each group member when a new member joins the group, are tagged with the server version of the group member queuing the transaction. This ensures that the server version of the original donor is known to the joining member. Because the view change log events queued for a particular view change have the same GTID on all members, for this case only, instances of the same GTID might have a different original server version. </p> <p> Setting the session value of this system variable is a restricted operation. The session user must have either the <a class="link" href="privileges-provided.html#priv_replication-applier"> <code class="literal"> REPLICATION_APPLIER </code> </a> privilege (see <a class="xref" href="replication-privilege-checks.html" title="19.3.3 Replication Privilege Checks"> Section 19.3.3, “Replication Privilege Checks” </a> ), or privileges sufficient to set restricted session variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ). However, note that the variable is not intended for users to set; it is set automatically by the replication infrastructure. </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_enabled"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_enabled"> <code class="literal"> rpl_semi_sync_master_enabled </code> </a> </p> <a class="indexterm" name="idm46045144317824"> </a> <a class="indexterm" name="idm46045144316720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_enabled"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-enabled[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_enabled"> rpl_semi_sync_master_enabled </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> <code class="literal"> rpl_semi_sync_source_enabled </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_timeout"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_timeout"> <code class="literal"> rpl_semi_sync_master_timeout </code> </a> </p> <a class="indexterm" name="idm46045144290880"> </a> <a class="indexterm" name="idm46045144289776"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-timeout=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_timeout"> rpl_semi_sync_master_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> <tr> <th> Unit </th> <td> milliseconds </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_trace_level"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_trace_level"> <code class="literal"> rpl_semi_sync_master_trace_level </code> </a> </p> <a class="indexterm" name="idm46045144257008"> </a> <a class="indexterm" name="idm46045144255904"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_trace_level"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-trace-level=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_trace_level"> rpl_semi_sync_master_trace_level </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 32 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> <code class="literal"> rpl_semi_sync_source_trace_level </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_wait_for_slave_count"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_for_slave_count"> <code class="literal"> rpl_semi_sync_master_wait_for_slave_count </code> </a> </p> <a class="indexterm" name="idm46045144225136"> </a> <a class="indexterm" name="idm46045144224016"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_wait_for_slave_count"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-wait-for-slave-count=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_for_slave_count"> rpl_semi_sync_master_wait_for_slave_count </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_wait_no_slave"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_no_slave"> <code class="literal"> rpl_semi_sync_master_wait_no_slave </code> </a> </p> <a class="indexterm" name="idm46045144193056"> </a> <a class="indexterm" name="idm46045144192016"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_wait_no_slave"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-wait-no-slave[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_no_slave"> rpl_semi_sync_master_wait_no_slave </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_master_wait_point"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_point"> <code class="literal"> rpl_semi_sync_master_wait_point </code> </a> </p> <a class="indexterm" name="idm46045144166112"> </a> <a class="indexterm" name="idm46045144165008"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_master_wait_point"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-master-wait-point=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_point"> rpl_semi_sync_master_wait_point </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> AFTER_SYNC </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> AFTER_SYNC </code> </p> <p class="valid-value"> <code class="literal"> AFTER_COMMIT </code> </p> </td> </tr> </tbody> </table> </div> <p> Deprecated synonym for <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> <code class="literal"> rpl_semi_sync_source_wait_point </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_enabled"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> <code class="literal"> rpl_semi_sync_source_enabled </code> </a> </p> <a class="indexterm" name="idm46045144135344"> </a> <a class="indexterm" name="idm46045144134240"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_enabled"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-enabled[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> rpl_semi_sync_source_enabled </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> <code class="literal"> rpl_semi_sync_source_enabled </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="literal"> semisync_source.so </code> library) plugin was installed on the replica to set up semisynchronous replication. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> <code class="literal"> rpl_semi_sync_source_enabled </code> </a> controls whether semisynchronous replication is enabled on the source server. To enable or disable the plugin, set this variable to <code class="literal"> ON </code> or <code class="literal"> OFF </code> (or 1 or 0), respectively. The default is <code class="literal"> OFF </code> . </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_timeout"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> </p> <a class="indexterm" name="idm46045144102960"> </a> <a class="indexterm" name="idm46045144101856"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-timeout=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> rpl_semi_sync_source_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> <tr> <th> Unit </th> <td> milliseconds </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="filename"> semisync_source.so </code> library) plugin is installed on the replica. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> controls how long the source waits on a commit for acknowledgment from a replica before timing out and reverting to asynchronous replication. The value is specified in milliseconds, and the default value is 10000 (10 seconds). </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_trace_level"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> <code class="literal"> rpl_semi_sync_source_trace_level </code> </a> </p> <a class="indexterm" name="idm46045144065616"> </a> <a class="indexterm" name="idm46045144064512"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_trace_level"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-trace-level=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> rpl_semi_sync_source_trace_level </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 32 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> <code class="literal"> rpl_semi_sync_source_trace_level </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="filename"> semisync_source.so </code> library) plugin is installed on the replica. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> <code class="literal"> rpl_semi_sync_source_trace_level </code> </a> specifies the semisynchronous replication debug trace level on the source server. Four levels are defined: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> 1 = general level (for example, time function failures) </p> </li> <li class="listitem"> <p> 16 = detail level (more verbose information) </p> </li> <li class="listitem"> <p> 32 = net wait level (more information about network waits) </p> </li> <li class="listitem"> <p> 64 = function level (information about function entry and exit) </p> </li> </ul> </div> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_wait_for_replica_count"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> </p> <a class="indexterm" name="idm46045144026592"> </a> <a class="indexterm" name="idm46045144025472"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_wait_for_replica_count"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-wait-for-replica-count=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> rpl_semi_sync_source_wait_for_replica_count </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 65535 </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="literal"> semisync_source.so </code> library) plugin is installed on the replica to set up semisynchronous replication. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> specifies the number of replica acknowledgments the source must receive per transaction before proceeding. By default <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> is <code class="literal"> 1 </code> , meaning that semisynchronous replication proceeds after receiving a single replica acknowledgment. Performance is best for small values of this variable. </p> <p> For example, if <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> is <code class="literal"> 2 </code> , then 2 replicas must acknowledge receipt of the transaction before the timeout period configured by <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> for semisynchronous replication to proceed. If fewer replicas acknowledge receipt of the transaction during the timeout period, the source reverts to normal replication. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> This behavior also depends on <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> . </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_wait_no_replica"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> </p> <a class="indexterm" name="idm46045143983856"> </a> <a class="indexterm" name="idm46045143982816"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_wait_no_replica"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-wait-no-replica[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> rpl_semi_sync_source_wait_no_replica </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="filename"> semisync_source.so </code> library) plugin is installed on the replica. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> </a> controls whether the source waits for the timeout period configured by <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> to expire, even if the replica count drops to less than the number of replicas configured by <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> during the timeout period. </p> <p> When the value of <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> is <code class="literal"> ON </code> (the default), it is permissible for the replica count to drop to less than <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> during the timeout period. As long as enough replicas acknowledge the transaction before the timeout period expires, semisynchronous replication continues. </p> <p> When the value of <code class="literal"> rpl_semi_sync_source_wait_no_replica </code> is <code class="literal"> OFF </code> , if the replica count drops to less than the number configured in <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> <code class="literal"> rpl_semi_sync_source_wait_for_replica_count </code> </a> at any time during the timeout period configured by <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> <code class="literal"> rpl_semi_sync_source_timeout </code> </a> , the source reverts to normal replication. </p> </li> <li class="listitem"> <p> <a name="sysvar_rpl_semi_sync_source_wait_point"> </a> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> <code class="literal"> rpl_semi_sync_source_wait_point </code> </a> </p> <a class="indexterm" name="idm46045143942704"> </a> <a class="indexterm" name="idm46045143941600"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for rpl_semi_sync_source_wait_point"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --rpl-semi-sync-source-wait-point=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> rpl_semi_sync_source_wait_point </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> AFTER_SYNC </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> AFTER_SYNC </code> </p> <p class="valid-value"> <code class="literal"> AFTER_COMMIT </code> </p> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> <code class="literal"> rpl_semi_sync_source_wait_point </code> </a> is available when the <code class="literal"> rpl_semi_sync_source </code> ( <code class="filename"> semisync_source.so </code> library) plugin is installed on the replica. </p> <p> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> <code class="literal"> rpl_semi_sync_source_wait_point </code> </a> controls the point at which a semisynchronous replication source server waits for replica acknowledgment of transaction receipt before returning a status to the client that committed the transaction. These values are permitted: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> AFTER_SYNC </code> (the default): The source writes each transaction to its binary log and the replica, and syncs the binary log to disk. The source waits for replica acknowledgment of transaction receipt after the sync. Upon receiving acknowledgment, the source commits the transaction to the storage engine and returns a result to the client, which then can proceed. </p> </li> <li class="listitem"> <p> <code class="literal"> AFTER_COMMIT </code> : The source writes each transaction to its binary log and the replica, syncs the binary log, and commits the transaction to the storage engine. The source waits for replica acknowledgment of transaction receipt after the commit. Upon receiving acknowledgment, the source returns a result to the client, which then can proceed. </p> </li> </ul> </div> <p> The replication characteristics of these settings differ as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> With <code class="literal"> AFTER_SYNC </code> , all clients see the committed transaction at the same time: After it has been acknowledged by the replica and committed to the storage engine on the source. Thus, all clients see the same data on the source. </p> <p> In the event of source failure, all transactions committed on the source have been replicated to the replica (saved to its relay log). An unexpected exit of the source server and failover to the replica is lossless because the replica is up to date. Note, however, that the source cannot be restarted in this scenario and must be discarded, because its binary log might contain uncommitted transactions that would cause a conflict with the replica when externalized after binary log recovery. </p> </li> <li class="listitem"> <p> With <code class="literal"> AFTER_COMMIT </code> , the client issuing the transaction gets a return status only after the server commits to the storage engine and receives replica acknowledgment. After the commit and before replica acknowledgment, other clients can see the committed transaction before the committing client. </p> <p> If something goes wrong such that the replica does not process the transaction, then in the event of an unexpected source server exit and failover to the replica, it is possible for such clients to see a loss of data relative to what they saw on the source. </p> </li> </ul> </div> </li> </ul> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/charset-collation-coercibility.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="charset-collation-coercibility"> </a> 12.8.4 Collation Coercibility in Expressions </h3> </div> </div> </div> <a class="indexterm" name="idm46045217092592"> </a> <a class="indexterm" name="idm46045217091104"> </a> <p> In the great majority of statements, it is obvious what collation MySQL uses to resolve a comparison operation. For example, in the following cases, it should be clear that the collation is the collation of column <code class="literal"> x </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa92754765"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> x <span class="token keyword">FROM</span> T <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> x<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> x <span class="token keyword">FROM</span> T <span class="token keyword">WHERE</span> x <span class="token operator">=</span> x<span class="token punctuation">;</span> <span class="token keyword">SELECT</span> <span class="token keyword">DISTINCT</span> x <span class="token keyword">FROM</span> T<span class="token punctuation">;</span></code></pre> </div> <p> However, with multiple operands, there can be ambiguity. For example, this statement performs a comparison between the column <code class="literal"> x </code> and the string literal <code class="literal"> 'Y' </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa92406400"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> x <span class="token keyword">FROM</span> T <span class="token keyword">WHERE</span> x <span class="token operator">=</span> <span class="token string">'Y'</span><span class="token punctuation">;</span></code></pre> </div> <p> If <code class="literal"> x </code> and <code class="literal"> 'Y' </code> have the same collation, there is no ambiguity about the collation to use for the comparison. But if they have different collations, should the comparison use the collation of <code class="literal"> x </code> , or of <code class="literal"> 'Y' </code> ? Both <code class="literal"> x </code> and <code class="literal"> 'Y' </code> have collations, so which collation takes precedence? </p> <p> A mix of collations may also occur in contexts other than comparison. For example, a multiple-argument concatenation operation such as <a class="link" href="string-functions.html#function_concat"> <code class="literal"> CONCAT(x,'Y') </code> </a> combines its arguments to produce a single string. What collation should the result have? </p> <p> To resolve questions like these, MySQL checks whether the collation of one item can be coerced to the collation of the other. MySQL assigns coercibility values as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> An explicit <code class="literal"> COLLATE </code> clause has a coercibility of 0 (not coercible at all). </p> </li> <li class="listitem"> <p> The concatenation of two strings with different collations has a coercibility of 1. </p> </li> <li class="listitem"> <p> The collation of a column or a stored routine parameter or local variable has a coercibility of 2. </p> </li> <li class="listitem"> <p> A <span class="quote"> “ <span class="quote"> system constant </span> ” </span> (the string returned by functions such as <a class="link" href="information-functions.html#function_user"> <code class="literal"> USER() </code> </a> or <a class="link" href="information-functions.html#function_version"> <code class="literal"> VERSION() </code> </a> ) has a coercibility of 3. </p> </li> <li class="listitem"> <p> The collation of a literal has a coercibility of 4. </p> </li> <li class="listitem"> <p> The collation of a numeric or temporal value has a coercibility of 5. </p> </li> <li class="listitem"> <p> <code class="literal"> NULL </code> or an expression that is derived from <code class="literal"> NULL </code> has a coercibility of 6. </p> </li> </ul> </div> <p> MySQL uses coercibility values with the following rules to resolve ambiguities: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Use the collation with the lowest coercibility value. </p> </li> <li class="listitem"> <p> If both sides have the same coercibility, then: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If both sides are Unicode, or both sides are not Unicode, it is an error. </p> </li> <li class="listitem"> <p> If one of the sides has a Unicode character set, and another side has a non-Unicode character set, the side with Unicode character set wins, and automatic character set conversion is applied to the non-Unicode side. For example, the following statement does not return an error: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa73424587"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SELECT</span> <span class="token function">CONCAT</span><span class="token punctuation">(</span>utf8mb4_column<span class="token punctuation">,</span> latin1_column<span class="token punctuation">)</span> <span class="token keyword">FROM</span> t1<span class="token punctuation">;</span></code></pre> </div> <p> It returns a result that has a character set of <code class="literal"> utf8mb4 </code> and the same collation as <code class="literal"> utf8mb4_column </code> . Values of <code class="literal"> latin1_column </code> are automatically converted to <code class="literal"> utf8mb4 </code> before concatenating. </p> </li> <li class="listitem"> <p> For an operation with operands from the same character set but that mix a <code class="literal"> _bin </code> collation and a <code class="literal"> _ci </code> or <code class="literal"> _cs </code> collation, the <code class="literal"> _bin </code> collation is used. This is similar to how operations that mix nonbinary and binary strings evaluate the operands as binary strings, applied to collations rather than data types. </p> </li> </ul> </div> </li> </ul> </div> <p> Although automatic conversion is not in the SQL standard, the standard does say that every character set is (in terms of supported characters) a <span class="quote"> “ <span class="quote"> subset </span> ” </span> of Unicode. Because it is a well-known principle that <span class="quote"> “ <span class="quote"> what applies to a superset can apply to a subset, </span> ” </span> we believe that a collation for Unicode can apply for comparisons with non-Unicode strings. More generally, MySQL uses the concept of character set repertoire, which can sometimes be used to determine subset relationships among character sets and enable conversion of operands in operations that would otherwise produce an error. See <a class="xref" href="charset-repertoire.html" title="12.2.1 Character Set Repertoire"> Section 12.2.1, “Character Set Repertoire” </a> . </p> <p> The following table illustrates some applications of the preceding rules. </p> <div class="informaltable"> <table summary="Comparisons and the collation used for each comparison."> <colgroup> <col style="width: 50%"/> <col style="width: 50%"/> </colgroup> <thead> <tr> <th> Comparison </th> <th> Collation Used </th> </tr> </thead> <tbody> <tr> <td> <code class="literal"> column1 = 'A' </code> </td> <td> Use collation of <code class="literal"> column1 </code> </td> </tr> <tr> <td> <code class="literal"> column1 = 'A' COLLATE x </code> </td> <td> Use collation of <code class="literal"> 'A' COLLATE x </code> </td> </tr> <tr> <td> <code class="literal"> column1 COLLATE x = 'A' COLLATE y </code> </td> <td> Error </td> </tr> </tbody> </table> </div> <p> To determine the coercibility of a string expression, use the <a class="link" href="information-functions.html#function_coercibility"> <code class="literal"> COERCIBILITY() </code> </a> function (see <a class="xref" href="information-functions.html" title="14.15 Information Functions"> Section 14.15, “Information Functions” </a> ): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa24199754"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span>_utf8mb4<span class="token string">'A'</span> <span class="token keyword">COLLATE</span> utf8mb4_bin<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">0</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span><span class="token function">VERSION</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">3</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span><span class="token string">'A'</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">4</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">5</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token function">COERCIBILITY</span><span class="token punctuation">(</span><span class="token boolean">NULL</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token prompt"> -></span> <span class="token number">6</span></code></pre> </div> <p> For implicit conversion of a numeric or temporal value to a string, such as occurs for the argument <code class="literal"> 1 </code> in the expression <a class="link" href="string-functions.html#function_concat"> <code class="literal"> CONCAT(1, 'abc') </code> </a> , the result is a character (nonbinary) string that has a character set and collation determined by the <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> <code class="literal"> character_set_connection </code> </a> and <a class="link" href="server-system-variables.html#sysvar_collation_connection"> <code class="literal"> collation_connection </code> </a> system variables. See <a class="xref" href="type-conversion.html" title="14.3 Type Conversion in Expression Evaluation"> Section 14.3, “Type Conversion in Expression Evaluation” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/windows-restrictions.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="windows-restrictions"> </a> 2.3.6 Windows Platform Restrictions </h3> </div> </div> </div> <a class="indexterm" name="idm46045331758656"> </a> <p> The following restrictions apply to use of MySQL on the Windows platform: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <span class="bold"> <strong> Process memory </strong> </span> </p> <p> On Windows 32-bit platforms, it is not possible by default to use more than 2GB of RAM within a single process, including MySQL. This is because the physical address limit on Windows 32-bit is 4GB and the default setting within Windows is to split the virtual address space between kernel (2GB) and user/applications (2GB). </p> <p> Some versions of Windows have a boot time setting to enable larger applications by reducing the kernel application. Alternatively, to use more than 2GB, use a 64-bit version of Windows. </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> File system aliases </strong> </span> </p> <p> When using <code class="literal"> MyISAM </code> tables, you cannot use aliases within Windows link to the data files on another volume and then link back to the main MySQL <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="option"> datadir </code> </a> location. </p> <p> This facility is often used to move the data and index files to a RAID or other fast solution. </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> Limited number of ports </strong> </span> </p> <p> Windows systems have about 4,000 ports available for client connections, and after a connection on a port closes, it takes two to four minutes before the port can be reused. In situations where clients connect to and disconnect from the server at a high rate, it is possible for all available ports to be used up before closed ports become available again. If this happens, the MySQL server appears to be unresponsive even though it is running. Ports may be used by other applications running on the machine as well, in which case the number of ports available to MySQL is lower. </p> <p> For more information about this problem, see <a class="ulink" href="https://support.microsoft.com/kb/196271" target="_blank"> https://support.microsoft.com/kb/196271 </a> . </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> <code class="literal"> DATA DIRECTORY </code> and <code class="literal"> INDEX DIRECTORY </code> </strong> </span> </p> <p> The <code class="literal"> DATA DIRECTORY </code> clause of the <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> statement is supported on Windows for <code class="literal"> InnoDB </code> tables only, as described in <a class="xref" href="innodb-create-table-external.html" title="17.6.1.2 Creating Tables Externally"> Section 17.6.1.2, “Creating Tables Externally” </a> . For <code class="literal"> MyISAM </code> and other storage engines, the <code class="literal"> DATA DIRECTORY </code> and <code class="literal"> INDEX DIRECTORY </code> clauses for <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> are ignored on Windows and any other platforms with a nonfunctional <code class="literal"> realpath() </code> call. </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> <a class="link" href="drop-database.html" title="15.1.24 DROP DATABASE Statement"> <code class="literal"> DROP DATABASE </code> </a> </strong> </span> </p> <p> You cannot drop a database that is in use by another session. </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> Case-insensitive names </strong> </span> </p> <p> File names are not case-sensitive on Windows, so MySQL database and table names are also not case-sensitive on Windows. The only restriction is that database and table names must be specified using the same case throughout a given statement. See <a class="xref" href="identifier-case-sensitivity.html" title="11.2.3 Identifier Case Sensitivity"> Section 11.2.3, “Identifier Case Sensitivity” </a> . </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> Directory and file names </strong> </span> </p> <p> On Windows, MySQL Server supports only directory and file names that are compatible with the current ANSI code pages. For example, the following Japanese directory name does not work in the Western locale (code page 1252): </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa84914064"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">datadir</span><span class="token attr-value"><span class="token punctuation">=</span>"C:/私たちのプロジェクトのデータ"</span></code></pre> </div> <p> The same limitation applies to directory and file names referred to in SQL statements, such as the data file path name in <a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement"> <code class="literal"> LOAD DATA </code> </a> . </p> </li> <li class="listitem"> <p> <span class="bold"> <strong> The <code class="literal"> \ </code> path name separator character </strong> </span> </p> <p> Path name components in Windows are separated by the <code class="literal"> \ </code> character, which is also the escape character in MySQL. If you are using <a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement"> <code class="literal"> LOAD DATA </code> </a> or <a class="link" href="select-into.html" title="15.2.13.1 SELECT ... INTO Statement"> <code class="literal"> SELECT ... INTO OUTFILE </code> </a> , use Unix-style file names with <code class="literal"> / </code> characters: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa98652142"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">DATA</span> <span class="token keyword">INFILE</span> <span class="token string">'C:/tmp/skr.txt'</span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> skr<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">INTO</span> <span class="token keyword">OUTFILE</span> <span class="token string">'C:/tmp/skr.txt'</span> <span class="token keyword">FROM</span> skr<span class="token punctuation">;</span></code></pre> </div> <p> Alternatively, you must double the <code class="literal"> \ </code> character: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59595940"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">LOAD</span> <span class="token keyword">DATA</span> <span class="token keyword">INFILE</span> <span class="token string">'C:\\tmp\\skr.txt'</span> <span class="token keyword">INTO</span> <span class="token keyword">TABLE</span> skr<span class="token punctuation">;</span> <span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">INTO</span> <span class="token keyword">OUTFILE</span> <span class="token string">'C:\\tmp\\skr.txt'</span> <span class="token keyword">FROM</span> skr<span class="token punctuation">;</span></code></pre> </div> </li> <li class="listitem"> <p> <span class="bold"> <strong> Problems with pipes </strong> </span> </p> <p> Pipes do not work reliably from the Windows command-line prompt. If the pipe includes the character <code class="literal"> ^Z </code> / <code class="literal"> CHAR(24) </code> , Windows thinks that it has encountered end-of-file and aborts the program. </p> <p> This is mainly a problem when you try to apply a binary log as follows: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa75711259"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> mysqlbinlog</span> <em class="replaceable">binary_log_file</em> | mysql <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>root</span></code></pre> </div> <p> If you have a problem applying the log and suspect that it is because of a <code class="literal"> ^Z </code> / <code class="literal"> CHAR(24) </code> character, you can use the following workaround: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa21360665"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span><span class="token command"> mysqlbinlog</span> <em class="replaceable">binary_log_file</em> <span class="token constant">--result-file</span><span class="token attr-value"><span class="token punctuation">=</span>/tmp/bin.sql</span> <span class="token prompt">C:\></span><span class="token command"> mysql</span> <span class="token constant">--user</span><span class="token attr-value"><span class="token punctuation">=</span>root</span> <span class="token property">--execute</span> <span class="token atrule">"source /tmp/bin.sql"</span></code></pre> </div> <p> The latter command also can be used to reliably read any SQL file that may contain binary data. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/innodb-online-ddl-single-multi.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="innodb-online-ddl-single-multi"> </a> 17.12.6 Simplifying DDL Statements with Online DDL </h3> </div> </div> </div> <p> Before the introduction of <a class="link" href="glossary.html#glos_online_ddl" title="online DDL"> online DDL </a> , it was common practice to combine many DDL operations into a single <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statement. Because each <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statement involved copying and rebuilding the table, it was more efficient to make several changes to the same table at once, since those changes could all be done with a single rebuild operation for the table. The downside was that SQL code involving DDL operations was harder to maintain and to reuse in different scripts. If the specific changes were different each time, you might have to construct a new complex <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> for each slightly different scenario. </p> <p> For DDL operations that can be done online, you can separate them into individual <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements for easier scripting and maintenance, without sacrificing efficiency. For example, you might take a complicated statement such as: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa5246341"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ADD</span> <span class="token keyword">INDEX</span> i1<span class="token punctuation">(</span>c1<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">ADD</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">INDEX</span> i2<span class="token punctuation">(</span>c2<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">CHANGE</span> c4_old_name c4_new_name <span class="token datatype">INTEGER</span> <span class="token keyword">UNSIGNED</span><span class="token punctuation">;</span></code></pre> </div> <p> and break it down into simpler parts that can be tested and performed independently, such as: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa47106219"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ADD</span> <span class="token keyword">INDEX</span> i1<span class="token punctuation">(</span>c1<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">ADD</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">INDEX</span> i2<span class="token punctuation">(</span>c2<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token keyword">ALTER</span> <span class="token keyword">TABLE</span> t1 <span class="token keyword">CHANGE</span> c4_old_name c4_new_name <span class="token datatype">INTEGER</span> <span class="token keyword">UNSIGNED</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span><span class="token punctuation">;</span></code></pre> </div> <p> You might still use multi-part <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements for: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Operations that must be performed in a specific sequence, such as creating an index followed by a foreign key constraint that uses that index. </p> </li> <li class="listitem"> <p> Operations all using the same specific <code class="literal"> LOCK </code> clause, that you want to either succeed or fail as a group. </p> </li> <li class="listitem"> <p> Operations that cannot be performed online, that is, that still use the table-copy method. </p> </li> <li class="listitem"> <p> Operations for which you specify <code class="literal"> ALGORITHM=COPY </code> or <a class="link" href="server-system-variables.html#sysvar_old_alter_table"> <code class="literal"> old_alter_table=1 </code> </a> , to force the table-copying behavior if needed for precise backward-compatibility in specialized scenarios. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/performance-schema-variables-info-table.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="performance-schema-variables-info-table"> </a> 29.12.14.2 Performance Schema variables_info Table </h4> </div> </div> </div> <p> The <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table shows, for each system variable, the source from which it was most recently set, and its range of values. </p> <p> The <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table has these columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> VARIABLE_NAME </code> </p> <p> The variable name. </p> </li> <li class="listitem"> <p> <code class="literal"> VARIABLE_SOURCE </code> </p> <p> The source from which the variable was most recently set: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> COMMAND_LINE </code> </p> <p> The variable was set on the command line. </p> </li> <li class="listitem"> <p> <code class="literal"> COMPILED </code> </p> <p> The variable has its compiled-in default value. <code class="literal"> COMPILED </code> is the value used for variables not set any other way. </p> </li> <li class="listitem"> <p> <code class="literal"> DYNAMIC </code> </p> <p> The variable was set at runtime. This includes variables set within files specified using the <a class="link" href="server-system-variables.html#sysvar_init_file"> <code class="literal"> init_file </code> </a> system variable. </p> </li> <li class="listitem"> <p> <code class="literal"> EXPLICIT </code> </p> <p> The variable was set from an option file named with the <a class="link" href="server-options.html#option_mysqld_defaults-file"> <code class="option"> --defaults-file </code> </a> option. </p> </li> <li class="listitem"> <p> <code class="literal"> EXTRA </code> </p> <p> The variable was set from an option file named with the <a class="link" href="server-options.html#option_mysqld_defaults-extra-file"> <code class="option"> --defaults-extra-file </code> </a> option. </p> </li> <li class="listitem"> <p> <code class="literal"> GLOBAL </code> </p> <p> The variable was set from a global option file. This includes option files not covered by <code class="literal"> EXPLICIT </code> , <code class="literal"> EXTRA </code> , <code class="literal"> LOGIN </code> , <code class="literal"> PERSISTED </code> , <code class="literal"> SERVER </code> , or <code class="literal"> USER </code> . </p> </li> <li class="listitem"> <p> <code class="literal"> LOGIN </code> </p> <p> The variable was set from a user-specific login path file ( <code class="filename"> ~/.mylogin.cnf </code> ). </p> </li> <li class="listitem"> <p> <code class="literal"> PERSISTED </code> </p> <p> The variable was set from a server-specific <code class="filename"> mysqld-auto.cnf </code> option file. No row has this value if the server was started with <a class="link" href="server-system-variables.html#sysvar_persisted_globals_load"> <code class="literal"> persisted_globals_load </code> </a> disabled. </p> </li> <li class="listitem"> <p> <code class="literal"> SERVER </code> </p> <p> The variable was set from a server-specific <code class="filename"> <code class="literal"> $MYSQL_HOME </code> /my.cnf </code> option file. For details about how <code class="literal"> MYSQL_HOME </code> is set, see <a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files"> Section 6.2.2.2, “Using Option Files” </a> . </p> </li> <li class="listitem"> <p> <code class="literal"> USER </code> </p> <p> The variable was set from a user-specific <code class="filename"> ~/.my.cnf </code> option file. </p> </li> </ul> </div> </li> <li class="listitem"> <p> <code class="literal"> VARIABLE_PATH </code> </p> <p> If the variable was set from an option file, <code class="literal"> VARIABLE_PATH </code> is the path name of that file. Otherwise, the value is the empty string. </p> </li> <li class="listitem"> <p> <code class="literal"> MIN_VALUE </code> </p> <p> The minimum permitted value for the variable. For a variable whose type is not numeric, this is always 0. </p> </li> <li class="listitem"> <p> <code class="literal"> MAX_VALUE </code> </p> <p> The maximum permitted value for the variable. For a variable whose type is not numeric, this is always 0. </p> </li> <li class="listitem"> <p> <code class="literal"> SET_TIME </code> </p> <p> The time at which the variable was most recently set. The default is the time at which the server initialized global system variables during startup. </p> </li> <li class="listitem"> <p> <code class="literal"> SET_USER </code> , <code class="literal"> SET_HOST </code> </p> <p> The user name and host name of the client user that most recently set the variable. If a client connects as <code class="literal"> user17 </code> from host <code class="literal"> host34.example.com </code> using the account <code class="literal"> 'user17'@'%.example.com </code> , <code class="literal"> SET_USER </code> and <code class="literal"> SET_HOST </code> are <code class="literal"> user17 </code> and <code class="literal"> host34.example.com </code> , respectively. For proxy user connections, these values correspond to the external (proxy) user, not the proxied user against which privilege checking is performed. The default for each column is the empty string, indicating that the variable has not been set since server startup. </p> </li> </ul> </div> <p> The <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table has no indexes. </p> <p> <a class="link" href="truncate-table.html" title="15.1.37 TRUNCATE TABLE Statement"> <code class="literal"> TRUNCATE TABLE </code> </a> is not permitted for the <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table. </p> <p> If a variable with a <code class="literal"> VARIABLE_SOURCE </code> value other than <code class="literal"> DYNAMIC </code> is set at runtime, <code class="literal"> VARIABLE_SOURCE </code> becomes <code class="literal"> DYNAMIC </code> and <code class="literal"> VARIABLE_PATH </code> becomes the empty string. </p> <p> A system variable that has only a session value (such as <a class="link" href="server-system-variables.html#sysvar_debug_sync"> <code class="literal"> debug_sync </code> </a> ) cannot be set at startup or persisted. For session-only system variables, <code class="literal"> VARIABLE_SOURCE </code> can be only <code class="literal"> COMPILED </code> or <code class="literal"> DYNAMIC </code> . </p> <p> If a system variable has an unexpected <code class="literal"> VARIABLE_SOURCE </code> value, consider your server startup method. For example, <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> reads option files and passes certain options it finds there as part of the command line that it uses to start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . Consequently, some system variables that you set in option files might display in <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> as <code class="literal"> COMMAND_LINE </code> , rather than as <code class="literal"> GLOBAL </code> or <code class="literal"> SERVER </code> as you might otherwise expect. </p> <p> Some sample queries that use the <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> table, with representative output: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Display variables set on the command line: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa67978398"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> VARIABLE_NAME <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>variables_info <span class="token keyword">WHERE</span> VARIABLE_SOURCE <span class="token operator">=</span> <span class="token string">'COMMAND_LINE'</span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> VARIABLE_NAME<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> VARIABLE_NAME <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> basedir <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> datadir <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> log_error <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> pid_file <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> plugin_dir <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> port <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </li> <li class="listitem"> <p> Display variables set from persistent storage: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa21616866"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> VARIABLE_NAME <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>variables_info <span class="token keyword">WHERE</span> VARIABLE_SOURCE <span class="token operator">=</span> <span class="token string">'PERSISTED'</span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> VARIABLE_NAME<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> VARIABLE_NAME <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> event_scheduler <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> max_connections <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> validate_password.policy <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </li> <li class="listitem"> <p> Join <a class="link" href="performance-schema-variables-info-table.html" title="29.12.14.2 Performance Schema variables_info Table"> <code class="literal"> variables_info </code> </a> with the <a class="link" href="performance-schema-system-variable-tables.html" title="29.12.14 Performance Schema System Variable Tables"> <code class="literal"> global_variables </code> </a> table to display the current values of persisted variables, together with their range of values: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59996176"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> VI<span class="token punctuation">.</span>VARIABLE_NAME<span class="token punctuation">,</span> GV<span class="token punctuation">.</span>VARIABLE_VALUE<span class="token punctuation">,</span> VI<span class="token punctuation">.</span>MIN_VALUE<span class="token punctuation">,</span>VI<span class="token punctuation">.</span>MAX_VALUE <span class="token keyword">FROM</span> performance_schema<span class="token punctuation">.</span>variables_info <span class="token keyword">AS</span> VI <span class="token keyword">INNER</span> <span class="token keyword">JOIN</span> performance_schema<span class="token punctuation">.</span>global_variables <span class="token keyword">AS</span> GV <span class="token keyword">USING</span><span class="token punctuation">(</span>VARIABLE_NAME<span class="token punctuation">)</span> <span class="token keyword">WHERE</span> VI<span class="token punctuation">.</span>VARIABLE_SOURCE <span class="token operator">=</span> <span class="token string">'PERSISTED'</span> <span class="token keyword">ORDER</span> <span class="token keyword">BY</span> VARIABLE_NAME<span class="token punctuation">;</span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> VARIABLE_NAME <span class="token punctuation">|</span> VARIABLE_VALUE <span class="token punctuation">|</span> MIN_VALUE <span class="token punctuation">|</span> MAX_VALUE <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span> <span class="token output"><span class="token punctuation">|</span> event_scheduler <span class="token punctuation">|</span> ON <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> max_connections <span class="token punctuation">|</span> 200 <span class="token punctuation">|</span> 1 <span class="token punctuation">|</span> 100000 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">|</span> validate_password.policy <span class="token punctuation">|</span> STRONG <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span> 0 <span class="token punctuation">|</span></span> <span class="token output"><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">-</span><span class="token punctuation">+</span></span></code></pre> </div> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysqld-multi.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysqld-multi"> </a> 6.3.4 mysqld_multi — Manage Multiple MySQL Servers </h3> </div> </div> </div> <a class="indexterm" name="idm46045321240832"> </a> <a class="indexterm" name="idm46045321239920"> </a> <a class="indexterm" name="idm46045321238560"> </a> <a class="indexterm" name="idm46045321237616"> </a> <p> <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> is designed to manage several <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> processes that listen for connections on different Unix socket files and TCP/IP ports. It can start or stop servers, or report their current status. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> For some Linux platforms, MySQL installation from RPM or Debian packages includes systemd support for managing MySQL server startup and shutdown. On these platforms, <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> is not installed because it is unnecessary. For information about using systemd to handle multiple MySQL instances, see <a class="xref" href="using-systemd.html" title="2.5.9 Managing MySQL Server with systemd"> Section 2.5.9, “Managing MySQL Server with systemd” </a> . </p> </div> <p> <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> searches for groups named <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> in <code class="filename"> my.cnf </code> (or in the file named by the <a class="link" href="mysqld-multi.html#option_mysqld_multi_defaults-file"> <code class="option"> --defaults-file </code> </a> option). <em class="replaceable"> <code> N </code> </em> can be any positive integer. This number is referred to in the following discussion as the option group number, or <em class="replaceable"> <code> GNR </code> </em> . Group numbers distinguish option groups from one another and are used as arguments to <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> to specify which servers you want to start, stop, or obtain a status report for. Options listed in these groups are the same that you would use in the <code class="literal"> [mysqld] </code> group used for starting <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . (See, for example, <a class="xref" href="automatic-start.html" title="2.9.5 Starting and Stopping MySQL Automatically"> Section 2.9.5, “Starting and Stopping MySQL Automatically” </a> .) However, when using multiple servers, it is necessary that each one use its own value for options such as the Unix socket file and TCP/IP port number. For more information on which options must be unique per server in a multiple-server environment, see <a class="xref" href="multiple-servers.html" title="7.8 Running Multiple MySQL Instances on One Machine"> Section 7.8, “Running Multiple MySQL Instances on One Machine” </a> . </p> <p> To invoke <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> , use the following syntax: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa20955579"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld_multi <span class="token punctuation">[</span><em class="replaceable">options</em><span class="token punctuation">]</span> <span class="token punctuation">{</span>start|stop|reload|report<span class="token punctuation">}</span> <span class="token punctuation">[</span><em class="replaceable">GNR</em><span class="token punctuation">[</span><span class="token punctuation">,</span><em class="replaceable">GNR</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">]</span></code></pre> </div> <p> <code class="literal"> start </code> , <code class="literal"> stop </code> , <code class="literal"> reload </code> (stop and restart), and <code class="literal"> report </code> indicate which operation to perform. You can perform the designated operation for a single server or multiple servers, depending on the <em class="replaceable"> <code> GNR </code> </em> list that follows the option name. If there is no list, <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> performs the operation for all servers in the option file. </p> <p> Each <em class="replaceable"> <code> GNR </code> </em> value represents an option group number or range of group numbers. The value should be the number at the end of the group name in the option file. For example, the <em class="replaceable"> <code> GNR </code> </em> for a group named <code class="literal"> [mysqld17] </code> is <code class="literal"> 17 </code> . To specify a range of numbers, separate the first and last numbers by a dash. The <em class="replaceable"> <code> GNR </code> </em> value <code class="literal"> 10-13 </code> represents groups <code class="literal"> [mysqld10] </code> through <code class="literal"> [mysqld13] </code> . Multiple groups or group ranges can be specified on the command line, separated by commas. There must be no whitespace characters (spaces or tabs) in the <em class="replaceable"> <code> GNR </code> </em> list; anything after a whitespace character is ignored. </p> <p> This command starts a single server using option group <code class="literal"> [mysqld17] </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa155460"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld_multi start 17</code></pre> </div> <p> This command stops several servers, using option groups <code class="literal"> [mysqld8] </code> and <code class="literal"> [mysqld10] </code> through <code class="literal"> [mysqld13] </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa87031173"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld_multi stop 8<span class="token punctuation">,</span>10-13</code></pre> </div> <p> For an example of how you might set up an option file, use this command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa2113699"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld_multi <span class="token property">--example</span></code></pre> </div> <p> <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> searches for option files as follows: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_mysqld_multi_no-defaults"> </a> With <a class="link" href="mysqld-multi.html#option_mysqld_multi_no-defaults"> <code class="option"> --no-defaults </code> </a> , no option files are read. </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-defaults"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-defaults </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321183152"> </a> <a class="indexterm" name="idm46045321181664"> </a> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_defaults-file"> </a> With <a class="link" href="mysqld-multi.html#option_mysqld_multi_defaults-file"> <code class="option"> --defaults-file= <em class="replaceable"> <code> file_name </code> </em> </code> </a> , only the named file is read. </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-file=filename </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321167552"> </a> <a class="indexterm" name="idm46045321166064"> </a> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_defaults-extra-file"> </a> Otherwise, option files in the standard list of locations are read, including any file named by the <a class="link" href="mysqld-multi.html#option_mysqld_multi_defaults-extra-file"> <code class="option"> --defaults-extra-file= <em class="replaceable"> <code> file_name </code> </em> </code> </a> option, if one is given. (If the option is given multiple times, the last value is used.) </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for defaults-extra-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --defaults-extra-file=filename </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321151648"> </a> <a class="indexterm" name="idm46045321150144"> </a> </li> </ul> </div> <p> For additional information about these and other option-file options, see <a class="xref" href="option-file-options.html" title="6.2.2.3 Command-Line Options that Affect Option-File Handling"> Section 6.2.2.3, “Command-Line Options that Affect Option-File Handling” </a> . </p> <p> Option files read are searched for <code class="literal"> [mysqld_multi] </code> and <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> option groups. The <code class="literal"> [mysqld_multi] </code> group can be used for options to <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> itself. <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> groups can be used for options passed to specific <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> instances. </p> <p> The <code class="literal"> [mysqld] </code> or <code class="literal"> [mysqld_safe] </code> groups can be used for common options read by all instances of <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> or <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> . You can specify a <a class="link" href="server-options.html#option_mysqld_defaults-file"> <code class="option"> --defaults-file= <em class="replaceable"> <code> file_name </code> </em> </code> </a> option to use a different configuration file for that instance, in which case the <code class="literal"> [mysqld] </code> or <code class="literal"> [mysqld_safe] </code> groups from that file are used for that instance. </p> <p> <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> supports the following options. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_mysqld_multi_help"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_help"> <code class="option"> --help </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for help"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --help </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321119200"> </a> <a class="indexterm" name="idm46045321117712"> </a> <p> Display a help message and exit. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_example"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_example"> <code class="option"> --example </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for example"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --example </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321103456"> </a> <a class="indexterm" name="idm46045321101968"> </a> <p> Display a sample option file. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_log"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_log"> <code class="option"> --log= <em class="replaceable"> <code> file_name </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for log"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --log=path </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> /var/log/mysqld_multi.log </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321087472"> </a> <a class="indexterm" name="idm46045321085984"> </a> <p> Specify the name of the log file. If the file exists, log output is appended to it. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_mysqladmin"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_mysqladmin"> <code class="option"> --mysqladmin= <em class="replaceable"> <code> prog_name </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for mysqladmin"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --mysqladmin=file </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321071424"> </a> <a class="indexterm" name="idm46045321069936"> </a> <p> The <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin </strong> </span> </a> binary to be used to stop servers. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_mysqld"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_mysqld"> <code class="option"> --mysqld= <em class="replaceable"> <code> prog_name </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for mysqld"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --mysqld=file </code> </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321054160"> </a> <a class="indexterm" name="idm46045321052672"> </a> <p> The <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> binary to be used. Note that you can specify <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> as the value for this option also. If you use <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> to start the server, you can include the <code class="literal"> mysqld </code> or <code class="literal"> ledir </code> options in the corresponding <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> option group. These options indicate the name of the server that <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> should start and the path name of the directory where the server is located. (See the descriptions for these options in <a class="xref" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> Section 6.3.2, “mysqld_safe — MySQL Server Startup Script” </a> .) Example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa74266999"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld38]</span> <span class="token constant">mysqld</span> <span class="token attr-value"><span class="token punctuation">=</span> mysqld-debug</span> <span class="token constant">ledir</span> <span class="token attr-value"><span class="token punctuation">=</span> /opt/local/mysql/libexec</span></code></pre> </div> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_no-log"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_no-log"> <code class="option"> --no-log </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for no-log"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --no-log </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321028960"> </a> <a class="indexterm" name="idm46045321027472"> </a> <p> Print log information to <code class="literal"> stdout </code> rather than to the log file. By default, output goes to the log file. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_password"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_password"> <code class="option"> --password= <em class="replaceable"> <code> password </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for password"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --password=string </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> [none] </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045321012144"> </a> <a class="indexterm" name="idm46045321010656"> </a> <p> The password of the MySQL account to use when invoking <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin </strong> </span> </a> . Note that the password value is not optional for this option, unlike for other MySQL programs. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_silent"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_silent"> <code class="option"> --silent </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for silent"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --silent </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320995104"> </a> <a class="indexterm" name="idm46045320993616"> </a> <p> Silent mode; disable warnings. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_tcp-ip"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_tcp-ip"> <code class="option"> --tcp-ip </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for tcp-ip"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --tcp-ip </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320979424"> </a> <a class="indexterm" name="idm46045320977936"> </a> <p> Connect to each MySQL server through the TCP/IP port instead of the Unix socket file. (If a socket file is missing, the server might still be running, but accessible only through the TCP/IP port.) By default, connections are made using the Unix socket file. This option affects <code class="literal"> stop </code> and <code class="literal"> report </code> operations. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_user"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_user"> <code class="option"> --user= <em class="replaceable"> <code> user_name </code> </em> </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for user"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --user=name </code> </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> root </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320961648"> </a> <a class="indexterm" name="idm46045320960160"> </a> <p> The user name of the MySQL account to use when invoking <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin </strong> </span> </a> . </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_verbose"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_verbose"> <code class="option"> --verbose </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for verbose"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --verbose </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320944656"> </a> <a class="indexterm" name="idm46045320943168"> </a> <p> Be more verbose. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_multi_version"> </a> <a class="link" href="mysqld-multi.html#option_mysqld_multi_version"> <code class="option"> --version </code> </a> </p> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for version"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --version </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> false </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045320928928"> </a> <a class="indexterm" name="idm46045320927440"> </a> <p> Display version information and exit. </p> </li> </ul> </div> <p> Some notes about <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> : </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <span class="bold"> <strong> Most important </strong> </span> : Before using <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> be sure that you understand the meanings of the options that are passed to the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> servers and <span class="emphasis"> <em> why </em> </span> you would want to have separate <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> processes. Beware of the dangers of using multiple <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> servers with the same data directory. Use separate data directories, unless you <span class="emphasis"> <em> know </em> </span> what you are doing. Starting multiple servers with the same data directory does <span class="emphasis"> <em> not </em> </span> give you extra performance in a threaded system. See <a class="xref" href="multiple-servers.html" title="7.8 Running Multiple MySQL Instances on One Machine"> Section 7.8, “Running Multiple MySQL Instances on One Machine” </a> . </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> Make sure that the data directory for each server is fully accessible to the Unix account that the specific <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process is started as. <span class="emphasis"> <em> Do not </em> </span> use the Unix <em class="replaceable"> <code> root </code> </em> account for this, unless you <span class="emphasis"> <em> know </em> </span> what you are doing. See <a class="xref" href="changing-mysql-user.html" title="8.1.5 How to Run MySQL as a Normal User"> Section 8.1.5, “How to Run MySQL as a Normal User” </a> . </p> </div> </li> <li class="listitem"> <p> Make sure that the MySQL account used for stopping the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> servers (with the <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin </strong> </span> </a> program) has the same user name and password for each server. Also, make sure that the account has the <a class="link" href="privileges-provided.html#priv_shutdown"> <code class="literal"> SHUTDOWN </code> </a> privilege. If the servers that you want to manage have different user names or passwords for the administrative accounts, you might want to create an account on each server that has the same user name and password. For example, you might set up a common <code class="literal"> multi_admin </code> account by executing the following commands for each server: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa99522857"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> root <span class="token property">-S</span> /tmp/mysql<span class="token punctuation">.</span>sock <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> <span class="token prompt">mysql></span><span class="token command"> CREATE</span> USER <span class="token atrule">'multi_admin'</span>@<span class="token atrule">'localhost'</span> IDENTIFIED BY <span class="token atrule">'multipass'</span><span class="token punctuation">;</span> <span class="token prompt">mysql></span><span class="token command"> GRANT</span> SHUTDOWN ON *<span class="token punctuation">.</span>* TO <span class="token atrule">'multi_admin'</span>@<span class="token atrule">'localhost'</span><span class="token punctuation">;</span></code></pre> </div> <p> See <a class="xref" href="access-control.html" title="8.2 Access Control and Account Management"> Section 8.2, “Access Control and Account Management” </a> . You have to do this for each <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> server. Change the connection parameters appropriately when connecting to each one. Note that the host name part of the account name must permit you to connect as <code class="literal"> multi_admin </code> from the host where you want to run <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> . </p> </li> <li class="listitem"> <p> The Unix socket file and the TCP/IP port number must be different for every <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . (Alternatively, if the host has multiple network addresses, you can set the <a class="link" href="server-system-variables.html#sysvar_bind_address"> <code class="literal"> bind_address </code> </a> system variable to cause different servers to listen to different interfaces.) </p> </li> <li class="listitem"> <p> The <a class="link" href="mysqld-safe.html#option_mysqld_safe_pid-file"> <code class="option"> --pid-file </code> </a> option is very important if you are using <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> to start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> (for example, <a class="link" href="mysqld-safe.html#option_mysqld_safe_mysqld"> <code class="option"> --mysqld=mysqld_safe </code> </a> ) Every <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> should have its own process ID file. The advantage of using <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> instead of <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> is that <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> monitors its <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process and restarts it if the process terminates due to a signal sent using <code class="literal"> kill -9 </code> or for other reasons, such as a segmentation fault. </p> </li> <li class="listitem"> <p> You might want to use the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user </code> </a> option for <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> , but to do this you need to run the <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> script as the Unix superuser ( <code class="literal"> root </code> ). Having the option in the option file doesn't matter; you just get a warning if you are not the superuser and the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> processes are started under your own Unix account. </p> </li> </ul> </div> <p> The following example shows how you might set up an option file for use with <a class="link" href="mysqld-multi.html" title="6.3.4 mysqld_multi — Manage Multiple MySQL Servers"> <span class="command"> <strong> mysqld_multi </strong> </span> </a> . The order in which the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> programs are started or stopped depends on the order in which they appear in the option file. Group numbers need not form an unbroken sequence. The first and fifth <code class="literal"> [mysqld <em class="replaceable"> <code> N </code> </em> ] </code> groups were intentionally omitted from the example to illustrate that you can have <span class="quote"> “ <span class="quote"> gaps </span> ” </span> in the option file. This gives you more flexibility. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa46676424"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># This is an example of a my.cnf file for mysqld_multi.</span> <span class="token comment" spellcheck="true"># Usually this file is located in home dir ~/.my.cnf or /etc/my.cnf</span> <span class="token selector">[mysqld_multi]</span> <span class="token constant">mysqld</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/bin/mysqld_safe</span> <span class="token constant">mysqladmin</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/bin/mysqladmin</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> multi_admin</span> <span class="token constant">password</span> <span class="token attr-value"><span class="token punctuation">=</span> my_password</span> <span class="token selector">[mysqld2]</span> <span class="token constant">socket</span> <span class="token attr-value"><span class="token punctuation">=</span> /tmp/mysql.sock2</span> <span class="token constant">port</span> <span class="token attr-value"><span class="token punctuation">=</span> 3307</span> <span class="token constant">pid-file</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data2/hostname.pid2</span> <span class="token constant">datadir</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data2</span> <span class="token constant">language</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/share/mysql/english</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> unix_user1</span> <span class="token selector">[mysqld3]</span> <span class="token constant">mysqld</span> <span class="token attr-value"><span class="token punctuation">=</span> /path/to/mysqld_safe</span> <span class="token constant">ledir</span> <span class="token attr-value"><span class="token punctuation">=</span> /path/to/mysqld-binary/</span> <span class="token constant">mysqladmin</span> <span class="token attr-value"><span class="token punctuation">=</span> /path/to/mysqladmin</span> <span class="token constant">socket</span> <span class="token attr-value"><span class="token punctuation">=</span> /tmp/mysql.sock3</span> <span class="token constant">port</span> <span class="token attr-value"><span class="token punctuation">=</span> 3308</span> <span class="token constant">pid-file</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data3/hostname.pid3</span> <span class="token constant">datadir</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data3</span> <span class="token constant">language</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/share/mysql/swedish</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> unix_user2</span> <span class="token selector">[mysqld4]</span> <span class="token constant">socket</span> <span class="token attr-value"><span class="token punctuation">=</span> /tmp/mysql.sock4</span> <span class="token constant">port</span> <span class="token attr-value"><span class="token punctuation">=</span> 3309</span> <span class="token constant">pid-file</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data4/hostname.pid4</span> <span class="token constant">datadir</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data4</span> <span class="token constant">language</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/share/mysql/estonia</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> unix_user3</span> <span class="token selector">[mysqld6]</span> <span class="token constant">socket</span> <span class="token attr-value"><span class="token punctuation">=</span> /tmp/mysql.sock6</span> <span class="token constant">port</span> <span class="token attr-value"><span class="token punctuation">=</span> 3311</span> <span class="token constant">pid-file</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data6/hostname.pid6</span> <span class="token constant">datadir</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/data6</span> <span class="token constant">language</span> <span class="token attr-value"><span class="token punctuation">=</span> /usr/local/mysql/share/mysql/japanese</span> <span class="token constant">user</span> <span class="token attr-value"><span class="token punctuation">=</span> unix_user4</span></code></pre> </div> <p> See <a class="xref" href="option-files.html" title="6.2.2.2 Using Option Files"> Section 6.2.2.2, “Using Option Files” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/security-against-attack.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="security-against-attack"> </a> 8.1.3 Making MySQL Secure Against Attackers </h3> </div> </div> </div> <a class="indexterm" name="idm46045252803024"> </a> <a class="indexterm" name="idm46045252801568"> </a> <a class="indexterm" name="idm46045252800080"> </a> <a class="indexterm" name="idm46045252799008"> </a> <a class="indexterm" name="idm46045252797968"> </a> <p> When you connect to a MySQL server, you should use a password. The password is not transmitted as cleartext over the connection. </p> <p> All other information is transferred as text, and can be read by anyone who is able to watch the connection. If the connection between the client and the server goes through an untrusted network, and you are concerned about this, you can use the compressed protocol to make traffic much more difficult to decipher. You can also use MySQL's internal SSL support to make the connection even more secure. See <a class="xref" href="encrypted-connections.html" title="8.3 Using Encrypted Connections"> Section 8.3, “Using Encrypted Connections” </a> . Alternatively, use SSH to get an encrypted TCP/IP connection between a MySQL server and a MySQL client. You can find an Open Source SSH client at <a class="ulink" href="http://www.openssh.org/" target="_blank"> http://www.openssh.org/ </a> , and a comparison of both Open Source and Commercial SSH clients at <a class="ulink" href="http://en.wikipedia.org/wiki/Comparison_of_SSH_clients" target="_blank"> http://en.wikipedia.org/wiki/Comparison_of_SSH_clients </a> . </p> <p> To make a MySQL system secure, you should strongly consider the following suggestions: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Require all MySQL accounts to have a password. A client program does not necessarily know the identity of the person running it. It is common for client/server applications that the user can specify any user name to the client program. For example, anyone can use the <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> program to connect as any other person simply by invoking it as <code class="literal"> mysql -u <em class="replaceable"> <code> other_user </code> </em> <em class="replaceable"> <code> db_name </code> </em> </code> if <em class="replaceable"> <code> other_user </code> </em> has no password. If all accounts have a password, connecting using another user's account becomes much more difficult. </p> <p> For a discussion of methods for setting passwords, see <a class="xref" href="assigning-passwords.html" title="8.2.14 Assigning Account Passwords"> Section 8.2.14, “Assigning Account Passwords” </a> . </p> </li> <li class="listitem"> <p> Make sure that the only Unix user account with read or write privileges in the database directories is the account that is used for running <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . </p> </li> <li class="listitem"> <p> Never run the MySQL server as the Unix <code class="literal"> root </code> user. This is extremely dangerous, because any user with the <a class="link" href="privileges-provided.html#priv_file"> <code class="literal"> FILE </code> </a> privilege is able to cause the server to create files as <code class="literal"> root </code> (for example, <code class="literal"> ~root/.bashrc </code> ). To prevent this, <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> refuses to run as <code class="literal"> root </code> unless that is specified explicitly using the <a class="link" href="server-options.html#option_mysqld_user"> <code class="option"> --user=root </code> </a> option. </p> <p> <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> can (and should) be run as an ordinary, unprivileged user instead. You can create a separate Unix account named <code class="literal"> mysql </code> to make everything even more secure. Use this account only for administering MySQL. To start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as a different Unix user, add a <code class="literal"> user </code> option that specifies the user name in the <code class="literal"> [mysqld] </code> group of the <code class="filename"> my.cnf </code> option file where you specify server options. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa75167223"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">user</span><span class="token attr-value"><span class="token punctuation">=</span>mysql</span></code></pre> </div> <p> This causes the server to start as the designated user whether you start it manually or by using <a class="link" href="mysqld-safe.html" title="6.3.2 mysqld_safe — MySQL Server Startup Script"> <span class="command"> <strong> mysqld_safe </strong> </span> </a> or <a class="link" href="mysql-server.html" title="6.3.3 mysql.server — MySQL Server Startup Script"> <span class="command"> <strong> mysql.server </strong> </span> </a> . For more details, see <a class="xref" href="changing-mysql-user.html" title="8.1.5 How to Run MySQL as a Normal User"> Section 8.1.5, “How to Run MySQL as a Normal User” </a> . </p> <p> Running <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as a Unix user other than <code class="literal"> root </code> does not mean that you need to change the <code class="literal"> root </code> user name in the <code class="literal"> user </code> table. <span class="emphasis"> <em> User names for MySQL accounts have nothing to do with user names for Unix accounts </em> </span> . </p> </li> <li class="listitem"> <p> Do not grant the <a class="link" href="privileges-provided.html#priv_file"> <code class="literal"> FILE </code> </a> privilege to nonadministrative users. Any user that has this privilege can write a file anywhere in the file system with the privileges of the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> daemon. This includes the server's data directory containing the files that implement the privilege tables. To make <a class="link" href="privileges-provided.html#priv_file"> <code class="literal"> FILE </code> </a> -privilege operations a bit safer, files generated with <a class="link" href="select-into.html" title="15.2.13.1 SELECT ... INTO Statement"> <code class="literal"> SELECT ... INTO OUTFILE </code> </a> do not overwrite existing files and are writable by everyone. </p> <a class="indexterm" name="idm46045252756304"> </a> <p> The <a class="link" href="privileges-provided.html#priv_file"> <code class="literal"> FILE </code> </a> privilege may also be used to read any file that is world-readable or accessible to the Unix user that the server runs as. With this privilege, you can read any file into a database table. This could be abused, for example, by using <a class="link" href="load-data.html" title="15.2.9 LOAD DATA Statement"> <code class="literal"> LOAD DATA </code> </a> to load <code class="filename"> /etc/passwd </code> into a table, which then can be displayed with <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> . </p> <p> To limit the location in which files can be read and written, set the <a class="link" href="server-system-variables.html#sysvar_secure_file_priv"> <code class="literal"> secure_file_priv </code> </a> system to a specific directory. See <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> . </p> </li> <li class="listitem"> <p> Encrypt binary log files and relay log files. Encryption helps to protect these files and the potentially sensitive data contained in them from being misused by outside attackers, and also from unauthorized viewing by users of the operating system where they are stored. You enable encryption on a MySQL server by setting the <a class="link" href="replication-options-binary-log.html#sysvar_binlog_encryption"> <code class="literal"> binlog_encryption </code> </a> system variable to <code class="literal"> ON </code> . For more information, see <a class="xref" href="replication-binlog-encryption.html" title="19.3.2 Encrypting Binary Log Files and Relay Log Files"> Section 19.3.2, “Encrypting Binary Log Files and Relay Log Files” </a> . </p> </li> <li class="listitem"> <p> Do not grant the <a class="link" href="privileges-provided.html#priv_process"> <code class="literal"> PROCESS </code> </a> or <a class="link" href="privileges-provided.html#priv_super"> <code class="literal"> SUPER </code> </a> privilege to nonadministrative users. The output of <a class="link" href="mysqladmin.html" title="6.5.2 mysqladmin — A MySQL Server Administration Program"> <span class="command"> <strong> mysqladmin processlist </strong> </span> </a> and <a class="link" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement"> <code class="literal"> SHOW PROCESSLIST </code> </a> shows the text of any statements currently being executed, so any user who is permitted to see the server process list might be able to see statements issued by other users. </p> <p> <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> reserves an extra connection for users who have the <a class="link" href="privileges-provided.html#priv_connection-admin"> <code class="literal"> CONNECTION_ADMIN </code> </a> or <a class="link" href="privileges-provided.html#priv_super"> <code class="literal"> SUPER </code> </a> privilege, so that a MySQL <code class="literal"> root </code> user can log in and check server activity even if all normal connections are in use. </p> <p> The <a class="link" href="privileges-provided.html#priv_super"> <code class="literal"> SUPER </code> </a> privilege can be used to terminate client connections, change server operation by changing the value of system variables, and control replication servers. </p> </li> <li class="listitem"> <p> Do not permit the use of symlinks to tables. (This capability can be disabled with the <a class="link" href="server-options.html#option_mysqld_symbolic-links"> <code class="option"> --skip-symbolic-links </code> </a> option.) This is especially important if you run <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> as <code class="literal"> root </code> , because anyone that has write access to the server's data directory then could delete any file in the system! See <a class="xref" href="symbolic-links-to-tables.html" title="10.12.2.2 Using Symbolic Links for MyISAM Tables on Unix"> Section 10.12.2.2, “Using Symbolic Links for MyISAM Tables on Unix” </a> . </p> </li> <li class="listitem"> <p> Stored programs and views should be written using the security guidelines discussed in <a class="xref" href="stored-objects-security.html" title="27.6 Stored Object Access Control"> Section 27.6, “Stored Object Access Control” </a> . </p> </li> <li class="listitem"> <p> If you do not trust your DNS, you should use IP addresses rather than host names in the grant tables. In any case, you should be very careful about creating grant table entries using host name values that contain wildcards. </p> </li> <li class="listitem"> <p> If you want to restrict the number of connections permitted to a single account, you can do so by setting the <a class="link" href="server-system-variables.html#sysvar_max_user_connections"> <code class="literal"> max_user_connections </code> </a> variable in <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> . The <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> and <a class="link" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> <code class="literal"> ALTER USER </code> </a> statements also support resource control options for limiting the extent of server use permitted to an account. See <a class="xref" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> Section 15.7.1.3, “CREATE USER Statement” </a> , and <a class="xref" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> Section 15.7.1.1, “ALTER USER Statement” </a> . </p> </li> <li class="listitem"> <p> If the plugin directory is writable by the server, it may be possible for a user to write executable code to a file in the directory using <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT ... INTO DUMPFILE </code> </a> . This can be prevented by making <a class="link" href="server-system-variables.html#sysvar_plugin_dir"> <code class="literal"> plugin_dir </code> </a> read only to the server or by setting <a class="link" href="server-system-variables.html#sysvar_secure_file_priv"> <code class="literal"> secure_file_priv </code> </a> to a directory where <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> writes can be made safely. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/windows-server-first-start.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="windows-server-first-start"> </a> 2.3.3.5 Starting the Server for the First Time </h4> </div> </div> </div> <p> This section gives a general overview of starting the MySQL server. The following sections provide more specific information for starting the MySQL server from the command line or as a Windows service. </p> <p> The information here applies primarily if you installed MySQL using the <code class="literal"> noinstall </code> version, or if you wish to configure and test MySQL manually rather than using MySQL Configurator. </p> <p> The examples in these sections assume that MySQL is installed under the default location of <code class="filename"> C:\Program Files\MySQL\MySQL Server 8.4 </code> . Adjust the path names shown in the examples if you have MySQL installed in a different location. </p> <p> Clients have two options. They can use TCP/IP, or they can use a named pipe if the server supports named-pipe connections. </p> <p> MySQL for Windows also supports shared-memory connections if the server is started with the <a class="link" href="server-system-variables.html#sysvar_shared_memory"> <code class="literal"> shared_memory </code> </a> system variable enabled. Clients can connect through shared memory by using the <a class="link" href="connection-options.html#option_general_protocol"> <code class="option"> --protocol=MEMORY </code> </a> option. </p> <p> For information about which server binary to run, see <a class="xref" href="windows-select-server.html" title="2.3.3.3 Selecting a MySQL Server Type"> Section 2.3.3.3, “Selecting a MySQL Server Type” </a> . </p> <p> Testing is best done from a command prompt in a console window (or <span class="quote"> “ <span class="quote"> DOS window </span> ” </span> ). In this way you can have the server display status messages in the window where they are easy to see. If something is wrong with your configuration, these messages make it easier for you to identify and fix any problems. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The database must be initialized before MySQL can be started. For additional information about the initialization process, see <a class="xref" href="data-directory-initialization.html" title="2.9.1 Initializing the Data Directory"> Section 2.9.1, “Initializing the Data Directory” </a> . </p> </div> <p> To start the server, enter this command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa25924138"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">C:\></span> <span class="token atrule">"C:\Program Files\MySQL\MySQL Server 8.4\bin\mysqld"</span> <span class="token property">--console</span></code></pre> </div> <p> You should see messages similar to those following as it starts (the path names and sizes may differ). The <code class="literal"> ready for connections </code> messages indicate that the server is ready to service client connections. </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-none"><div class="docs-select-all right" id="sa94118152"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none">[Server] C:\mysql\bin\mysqld.exe (mysqld 8.0.30) starting as process 21236 [InnoDB] InnoDB initialization has started. [InnoDB] InnoDB initialization has ended. [Server] CA certificate ca.pem is self signed. [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel. [Server] X Plugin ready for connections. Bind-address: '::' port: 33060 [Server] C:\mysql\bin\mysqld.exe: ready for connections. Version: '8.0.30' socket: '' port: 3306 MySQL Community Server - GPL.</code></pre> </div> <p> You can now open a new console window in which to run client programs. </p> <p> If you omit the <a class="link" href="server-options.html#option_mysqld_console"> <code class="option"> --console </code> </a> option, the server writes diagnostic output to the error log in the data directory ( <code class="filename"> C:\Program Files\MySQL\MySQL Server 8.4\data </code> by default). The error log is the file with the <code class="filename"> .err </code> extension, and may be set using the <a class="link" href="server-options.html#option_mysqld_log-error"> <code class="option"> --log-error </code> </a> option. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The initial <code class="literal"> root </code> account in the MySQL grant tables has no password. After starting the server, you should set up a password for it using the instructions in <a class="xref" href="default-privileges.html" title="2.9.4 Securing the Initial MySQL Account"> Section 2.9.4, “Securing the Initial MySQL Account” </a> . </p> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-locks-per-fragment.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-ndbinfo-locks-per-fragment"> </a> 25.6.17.42 The ndbinfo locks_per_fragment Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045089088032"> </a> <p> The <code class="literal"> locks_per_fragment </code> table provides information about counts of lock claim requests, and the outcomes of these requests on a per-fragment basis, serving as a companion table to <a class="link" href="mysql-cluster-ndbinfo-operations-per-fragment.html" title="25.6.17.49 The ndbinfo operations_per_fragment Table"> <code class="literal"> operations_per_fragment </code> </a> and <a class="link" href="mysql-cluster-ndbinfo-memory-per-fragment.html" title="25.6.17.47 The ndbinfo memory_per_fragment Table"> <code class="literal"> memory_per_fragment </code> </a> . This table also shows the total time spent waiting for locks successfully and unsuccessfully since fragment or table creation, or since the most recent restart. </p> <p> The <code class="literal"> locks_per_fragment </code> table contains the following columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> fq_name </code> </p> <p> Fully qualified table name </p> </li> <li class="listitem"> <p> <code class="literal"> parent_fq_name </code> </p> <p> Fully qualified name of parent object </p> </li> <li class="listitem"> <p> <code class="literal"> type </code> </p> <p> Table type; see text for possible values </p> </li> <li class="listitem"> <p> <code class="literal"> table_id </code> </p> <p> Table ID </p> </li> <li class="listitem"> <p> <code class="literal"> node_id </code> </p> <p> Reporting node ID </p> </li> <li class="listitem"> <p> <code class="literal"> block_instance </code> </p> <p> LDM instance ID </p> </li> <li class="listitem"> <p> <code class="literal"> fragment_num </code> </p> <p> Fragment identifier </p> </li> <li class="listitem"> <p> <code class="literal"> ex_req </code> </p> <p> Exclusive lock requests started </p> </li> <li class="listitem"> <p> <code class="literal"> ex_imm_ok </code> </p> <p> Exclusive lock requests immediately granted </p> </li> <li class="listitem"> <p> <code class="literal"> ex_wait_ok </code> </p> <p> Exclusive lock requests granted following wait </p> </li> <li class="listitem"> <p> <code class="literal"> ex_wait_fail </code> </p> <p> Exclusive lock requests not granted </p> </li> <li class="listitem"> <p> <code class="literal"> sh_req </code> </p> <p> Shared lock requests started </p> </li> <li class="listitem"> <p> <code class="literal"> sh_imm_ok </code> </p> <p> Shared lock requests immediately granted </p> </li> <li class="listitem"> <p> <code class="literal"> sh_wait_ok </code> </p> <p> Shared lock requests granted following wait </p> </li> <li class="listitem"> <p> <code class="literal"> sh_wait_fail </code> </p> <p> Shared lock requests not granted </p> </li> <li class="listitem"> <p> <code class="literal"> wait_ok_millis </code> </p> <p> Time spent waiting for lock requests that were granted, in milliseconds </p> </li> <li class="listitem"> <p> <code class="literal"> wait_fail_millis </code> </p> <p> Time spent waiting for lock requests that failed, in milliseconds </p> </li> </ul> </div> <h5> <a name="idm46045089048400"> </a> Notes </h5> <p> <code class="literal"> block_instance </code> refers to an instance of a kernel block. Together with the block name, this number can be used to look up a given instance in the <a class="link" href="mysql-cluster-ndbinfo-threadblocks.html" title="25.6.17.62 The ndbinfo threadblocks Table"> <code class="literal"> threadblocks </code> </a> table. </p> <p> <code class="literal"> fq_name </code> is a fully qualified database object name in <em class="replaceable"> <code> database </code> </em> / <em class="replaceable"> <code> schema </code> </em> / <em class="replaceable"> <code> name </code> </em> format, such as <code class="literal"> test/def/t1 </code> or <code class="literal"> sys/def/10/b$unique </code> . </p> <p> <code class="literal"> parent_fq_name </code> is the fully qualified name of this object's parent object (table). </p> <p> <code class="literal"> table_id </code> is the table's internal ID generated by <code class="literal"> NDB </code> . This is the same internal table ID shown in other <code class="literal"> ndbinfo </code> tables; it is also visible in the output of <a class="link" href="mysql-cluster-programs-ndb-show-tables.html" title="25.5.27 ndb_show_tables — Display List of NDB Tables"> <span class="command"> <strong> ndb_show_tables </strong> </span> </a> . </p> <p> The <code class="literal"> type </code> column shows the type of table. This is always one of <code class="literal"> System table </code> , <code class="literal"> User table </code> , <code class="literal"> Unique hash index </code> , <code class="literal"> Hash index </code> , <code class="literal"> Unique ordered index </code> , <code class="literal"> Ordered index </code> , <code class="literal"> Hash index trigger </code> , <code class="literal"> Subscription trigger </code> , <code class="literal"> Read only constraint </code> , <code class="literal"> Index trigger </code> , <code class="literal"> Reorganize trigger </code> , <code class="literal"> Tablespace </code> , <code class="literal"> Log file group </code> , <code class="literal"> Data file </code> , <code class="literal"> Undo file </code> , <code class="literal"> Hash map </code> , <code class="literal"> Foreign key definition </code> , <code class="literal"> Foreign key parent trigger </code> , <code class="literal"> Foreign key child trigger </code> , or <code class="literal"> Schema transaction </code> . </p> <p> The values shown in all of the columns <code class="literal"> ex_req </code> , <code class="literal"> ex_req_imm_ok </code> , <code class="literal"> ex_wait_ok </code> , <code class="literal"> ex_wait_fail </code> , <code class="literal"> sh_req </code> , <code class="literal"> sh_req_imm_ok </code> , <code class="literal"> sh_wait_ok </code> , and <code class="literal"> sh_wait_fail </code> represent cumulative numbers of requests since the table or fragment was created, or since the last restart of this node, whichever of these occurred later. This is also true for the time values shown in the <code class="literal"> wait_ok_millis </code> and <code class="literal"> wait_fail_millis </code> columns. </p> <p> Every lock request is considered either to be in progress, or to have completed in some way (that is, to have succeeded or failed). This means that the following relationships are true: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa55878428"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">ex_req <span class="token operator">>=</span> <span class="token punctuation">(</span>ex_req_imm_ok <span class="token operator">+</span> ex_wait_ok <span class="token operator">+</span> ex_wait_fail<span class="token punctuation">)</span> sh_req <span class="token operator">>=</span> <span class="token punctuation">(</span>sh_req_imm_ok <span class="token operator">+</span> sh_wait_ok <span class="token operator">+</span> sh_wait_fail<span class="token punctuation">)</span></code></pre> </div> <p> The number of requests currently in progress is the current number of incomplete requests, which can be found as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-simple"><div class="docs-select-all right" id="sa40026695"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple"><span class="token punctuation">[</span>exclusive lock requests in progress<span class="token punctuation">]</span> <span class="token operator">=</span> ex_req <span class="token operator">-</span> <span class="token punctuation">(</span>ex_req_imm_ok <span class="token operator">+</span> ex_wait_ok <span class="token operator">+</span> ex_wait_fail<span class="token punctuation">)</span> <span class="token punctuation">[</span>shared lock requests in progress<span class="token punctuation">]</span> <span class="token operator">=</span> sh_req <span class="token operator">-</span> <span class="token punctuation">(</span>sh_req_imm_ok <span class="token operator">+</span> sh_wait_ok <span class="token operator">+</span> sh_wait_fail<span class="token punctuation">)</span></code></pre> </div> <p> A failed wait indicates an aborted transaction, but the abort may or may not be caused by a lock wait timeout. You can obtain the total number of aborts while waiting for locks as shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa91462517"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple"><span class="token punctuation">[</span>aborts while waiting for locks<span class="token punctuation">]</span> <span class="token operator">=</span> ex_wait_fail <span class="token operator">+</span> sh_wait_fail</code></pre> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/myisamlog.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="myisamlog"> </a> 6.6.5 myisamlog — Display MyISAM Log File Contents </h3> </div> </div> </div> <a class="indexterm" name="idm46045306541792"> </a> <p> <a class="link" href="myisamlog.html" title="6.6.5 myisamlog — Display MyISAM Log File Contents"> <span class="command"> <strong> myisamlog </strong> </span> </a> processes the contents of a <code class="literal"> MyISAM </code> log file. To create such a file, start the server with a <a class="link" href="server-options.html#option_mysqld_log-isam"> <code class="option"> --log-isam= <code class="filename"> log_file </code> </code> </a> option. </p> <p> Invoke <a class="link" href="myisamlog.html" title="6.6.5 myisamlog — Display MyISAM Log File Contents"> <span class="command"> <strong> myisamlog </strong> </span> </a> like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa46382698"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">myisamlog <span class="token punctuation">[</span><em class="replaceable">options</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><em class="replaceable">file_name</em> <span class="token punctuation">[</span><em class="replaceable">tbl_name</em><span class="token punctuation">]</span> <span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">.</span><span class="token punctuation">]</span></code></pre> </div> <p> The default operation is update ( <code class="option"> -u </code> ). If a recovery is done ( <code class="option"> -r </code> ), all writes and possibly updates and deletes are done and errors are only counted. The default log file name is <code class="filename"> myisam.log </code> if no <em class="replaceable"> <code> log_file </code> </em> argument is given. If tables are named on the command line, only those tables are updated. </p> <p> <a class="link" href="myisamlog.html" title="6.6.5 myisamlog — Display MyISAM Log File Contents"> <span class="command"> <strong> myisamlog </strong> </span> </a> supports the following options: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_myisamlog_help"> </a> <code class="option"> -? </code> , <code class="option"> -I </code> </p> <p> Display a help message and exit. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_commands"> </a> <code class="option"> -c <em class="replaceable"> <code> N </code> </em> </code> </p> <p> Execute only <em class="replaceable"> <code> N </code> </em> commands. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_files"> </a> <code class="option"> -f <em class="replaceable"> <code> N </code> </em> </code> </p> <p> Specify the maximum number of open files. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_filepath"> </a> <code class="option"> -F <em class="replaceable"> <code> filepath/ </code> </em> </code> </p> <p> Specify the file path with a trailing slash. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_information"> </a> <code class="option"> -i </code> </p> <p> Display extra information before exiting. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_offset"> </a> <code class="option"> -o <em class="replaceable"> <code> offset </code> </em> </code> </p> <p> Specify the starting offset. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_path"> </a> <code class="option"> -p <em class="replaceable"> <code> N </code> </em> </code> </p> <p> Remove <em class="replaceable"> <code> N </code> </em> components from path. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_recovery"> </a> <code class="option"> -r </code> </p> <p> Perform a recovery operation. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_record-position"> </a> <code class="option"> -R <em class="replaceable"> <code> record_pos_file record_pos </code> </em> </code> </p> <p> Specify record position file and record position. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_update"> </a> <code class="option"> -u </code> </p> <p> Perform an update operation. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_verbose"> </a> <code class="option"> -v </code> </p> <p> Verbose mode. Print more output about what the program does. This option can be given multiple times to produce more and more output. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_write"> </a> <code class="option"> -w <em class="replaceable"> <code> write_file </code> </em> </code> </p> <p> Specify the write file. </p> </li> <li class="listitem"> <p> <a name="option_myisamlog_version"> </a> <code class="option"> -V </code> </p> <p> Display version information. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/federated-create-connection.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="federated-create-connection"> </a> 18.8.2.1 Creating a FEDERATED Table Using CONNECTION </h4> </div> </div> </div> <p> To use the first method, you must specify the <code class="literal"> CONNECTION </code> string after the engine type in a <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> statement. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa81982638"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">TABLE</span> federated_table <span class="token punctuation">(</span> id <span class="token datatype">INT</span><span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">AUTO_INCREMENT</span><span class="token punctuation">,</span> <span class="token keyword">name</span> <span class="token datatype">VARCHAR</span><span class="token punctuation">(</span><span class="token number">32</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">DEFAULT</span> <span class="token string">''</span><span class="token punctuation">,</span> other <span class="token datatype">INT</span><span class="token punctuation">(</span><span class="token number">20</span><span class="token punctuation">)</span> <span class="token operator">NOT</span> <span class="token boolean">NULL</span> <span class="token keyword">DEFAULT</span> <span class="token string">'0'</span><span class="token punctuation">,</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> <span class="token punctuation">(</span>id<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">INDEX</span> <span class="token keyword">name</span> <span class="token punctuation">(</span><span class="token keyword">name</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token keyword">INDEX</span> other_key <span class="token punctuation">(</span>other<span class="token punctuation">)</span> <span class="token punctuation">)</span> <span class="token keyword">ENGINE</span><span class="token operator">=</span>FEDERATED <span class="token keyword">DEFAULT</span> <span class="token keyword">CHARSET</span><span class="token operator">=</span>utf8mb4 <span class="token keyword">CONNECTION</span><span class="token operator">=</span><span class="token string">'mysql://fed_user@remote_host:9306/federated/test_table'</span><span class="token punctuation">;</span></code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <code class="literal"> CONNECTION </code> replaces the <code class="literal"> COMMENT </code> used in some previous versions of MySQL. </p> </div> <p> The <code class="literal"> CONNECTION </code> string contains the information required to connect to the remote server containing the table in which the data physically resides. The connection string specifies the server name, login credentials, port number and database/table information. In the example, the remote table is on the server <code class="literal"> remote_host </code> , using port 9306. The name and port number should match the host name (or IP address) and port number of the remote MySQL server instance you want to use as your remote table. </p> <p> The format of the connection string is as follows: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa31285325"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none"><em class="replaceable">scheme</em>://<em class="replaceable">user_name</em>[:<em class="replaceable">password</em>]@<em class="replaceable">host_name</em>[:<em class="replaceable">port_num</em>]/<em class="replaceable">db_name</em>/<em class="replaceable">tbl_name</em></code></pre> </div> <p> Where: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <em class="replaceable"> <code> scheme </code> </em> : A recognized connection protocol. Only <code class="literal"> mysql </code> is supported as the <em class="replaceable"> <code> scheme </code> </em> value at this point. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> user_name </code> </em> : The user name for the connection. This user must have been created on the remote server, and must have suitable privileges to perform the required actions ( <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> , <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , and so forth) on the remote table. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> password </code> </em> : (Optional) The corresponding password for <em class="replaceable"> <code> user_name </code> </em> . </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> host_name </code> </em> : The host name or IP address of the remote server. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> port_num </code> </em> : (Optional) The port number for the remote server. The default is 3306. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> db_name </code> </em> : The name of the database holding the remote table. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> tbl_name </code> </em> : The name of the remote table. The name of the local and the remote table do not have to match. </p> </li> </ul> </div> <p> Sample connection strings: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa33244394"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CONNECTION</span><span class="token operator">=</span><span class="token string">'mysql://username:password@hostname:port/database/tablename'</span> <span class="token keyword">CONNECTION</span><span class="token operator">=</span><span class="token string">'mysql://username@hostname/database/tablename'</span> <span class="token keyword">CONNECTION</span><span class="token operator">=</span><span class="token string">'mysql://username:password@hostname/database/tablename'</span></code></pre> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-cluster-transactions.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-ndbinfo-cluster-transactions"> </a> 25.6.17.9 The ndbinfo cluster_transactions Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045090279856"> </a> <p> The <code class="literal"> cluster_transactions </code> table shows information about all ongoing transactions in an NDB Cluster. </p> <p> The <code class="literal"> cluster_transactions </code> table contains the following columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> node_id </code> </p> <p> Node ID of transaction coordinator </p> </li> <li class="listitem"> <p> <code class="literal"> block_instance </code> </p> <p> TC block instance </p> </li> <li class="listitem"> <p> <code class="literal"> transid </code> </p> <p> Transaction ID </p> </li> <li class="listitem"> <p> <code class="literal"> state </code> </p> <p> Operation state (see text for possible values) </p> </li> <li class="listitem"> <p> <code class="literal"> count_operations </code> </p> <p> Number of stateful primary key operations in transaction (includes reads with locks, as well as DML operations) </p> </li> <li class="listitem"> <p> <code class="literal"> outstanding_operations </code> </p> <p> Operations still being executed in local data management blocks </p> </li> <li class="listitem"> <p> <code class="literal"> inactive_seconds </code> </p> <p> Time spent waiting for API </p> </li> <li class="listitem"> <p> <code class="literal"> client_node_id </code> </p> <p> Client node ID </p> </li> <li class="listitem"> <p> <code class="literal"> client_block_ref </code> </p> <p> Client block reference </p> </li> </ul> </div> <h5> <a name="idm46045090258384"> </a> Notes </h5> <p> The transaction ID is a unique 64-bit number which can be obtained using the NDB API's <a class="ulink" href="/doc/ndbapi/en/ndb-ndbtransaction.html#ndb-ndbtransaction-gettransactionid" target="_top"> <code class="literal"> getTransactionId() </code> </a> method. (Currently, the MySQL Server does not expose the NDB API transaction ID of an ongoing transaction.) </p> <p> <code class="literal"> block_instance </code> refers to an instance of a kernel block. Together with the block name, this number can be used to look up a given instance in the <a class="link" href="mysql-cluster-ndbinfo-threadblocks.html" title="25.6.17.62 The ndbinfo threadblocks Table"> <code class="literal"> threadblocks </code> </a> table. </p> <p> The <code class="literal"> state </code> column can have any one of the values <code class="literal"> CS_ABORTING </code> , <code class="literal"> CS_COMMITTING </code> , <code class="literal"> CS_COMMIT_SENT </code> , <code class="literal"> CS_COMPLETE_SENT </code> , <code class="literal"> CS_COMPLETING </code> , <code class="literal"> CS_CONNECTED </code> , <code class="literal"> CS_DISCONNECTED </code> , <code class="literal"> CS_FAIL_ABORTED </code> , <code class="literal"> CS_FAIL_ABORTING </code> , <code class="literal"> CS_FAIL_COMMITTED </code> , <code class="literal"> CS_FAIL_COMMITTING </code> , <code class="literal"> CS_FAIL_COMPLETED </code> , <code class="literal"> CS_FAIL_PREPARED </code> , <code class="literal"> CS_PREPARE_TO_COMMIT </code> , <code class="literal"> CS_RECEIVING </code> , <code class="literal"> CS_REC_COMMITTING </code> , <code class="literal"> CS_RESTART </code> , <code class="literal"> CS_SEND_FIRE_TRIG_REQ </code> , <code class="literal"> CS_STARTED </code> , <code class="literal"> CS_START_COMMITTING </code> , <code class="literal"> CS_START_SCAN </code> , <code class="literal"> CS_WAIT_ABORT_CONF </code> , <code class="literal"> CS_WAIT_COMMIT_CONF </code> , <code class="literal"> CS_WAIT_COMPLETE_CONF </code> , <code class="literal"> CS_WAIT_FIRE_TRIG_REQ </code> . (If the MySQL Server is running with <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_show_hidden"> <code class="literal"> ndbinfo_show_hidden </code> </a> enabled, you can view this list of states by selecting from the <code class="literal"> ndb$dbtc_apiconnect_state </code> table, which is normally hidden.) </p> <p> In <code class="literal"> client_node_id </code> and <code class="literal"> client_block_ref </code> , <code class="literal"> client </code> refers to an NDB Cluster API or SQL node (that is, an NDB API client or a MySQL Server attached to the cluster). </p> <p> The <code class="literal"> tc_block_instance </code> column provides the <a class="ulink" href="/doc/ndb-internals/en/ndb-internals-kernel-blocks-dbtc.html" target="_top"> <code class="literal"> DBTC </code> </a> block instance number. You can use this along with the block name to obtain information about specific threads from the <a class="link" href="mysql-cluster-ndbinfo-threadblocks.html" title="25.6.17.62 The ndbinfo threadblocks Table"> <code class="literal"> threadblocks </code> </a> table. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/statement-labels.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="statement-labels"> </a> 15.6.2 Statement Labels </h3> </div> </div> </div> <a class="indexterm" name="idm46045176479376"> </a> <a class="indexterm" name="idm46045176477888"> </a> <a class="indexterm" name="idm46045176476400"> </a> <a class="indexterm" name="idm46045176474912"> </a> <a class="indexterm" name="idm46045176473424"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa459480"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token punctuation">[</span><em class="replaceable">begin_label</em>:<span class="token punctuation">]</span> <span class="token keyword">BEGIN</span> <span class="token punctuation">[</span><em class="replaceable">statement_list</em><span class="token punctuation">]</span> <span class="token keyword">END</span> <span class="token punctuation">[</span><em class="replaceable">end_label</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><em class="replaceable">begin_label</em>:<span class="token punctuation">]</span> <span class="token keyword">LOOP</span> <em class="replaceable">statement_list</em> <span class="token keyword">END</span> <span class="token keyword">LOOP</span> <span class="token punctuation">[</span><em class="replaceable">end_label</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><em class="replaceable">begin_label</em>:<span class="token punctuation">]</span> <span class="token keyword">REPEAT</span> <em class="replaceable">statement_list</em> <span class="token keyword">UNTIL</span> <em class="replaceable">search_condition</em> <span class="token keyword">END</span> <span class="token keyword">REPEAT</span> <span class="token punctuation">[</span><em class="replaceable">end_label</em><span class="token punctuation">]</span> <span class="token punctuation">[</span><em class="replaceable">begin_label</em>:<span class="token punctuation">]</span> <span class="token keyword">WHILE</span> <em class="replaceable">search_condition</em> <span class="token keyword">DO</span> <em class="replaceable">statement_list</em> <span class="token keyword">END</span> <span class="token keyword">WHILE</span> <span class="token punctuation">[</span><em class="replaceable">end_label</em><span class="token punctuation">]</span></code></pre> </div> <p> Labels are permitted for <a class="link" href="begin-end.html" title="15.6.1 BEGIN ... END Compound Statement"> <code class="literal"> BEGIN ... END </code> </a> blocks and for the <a class="link" href="loop.html" title="15.6.5.5 LOOP Statement"> <code class="literal"> LOOP </code> </a> , <a class="link" href="repeat.html" title="15.6.5.6 REPEAT Statement"> <code class="literal"> REPEAT </code> </a> , and <a class="link" href="while.html" title="15.6.5.8 WHILE Statement"> <code class="literal"> WHILE </code> </a> statements. Label use for those statements follows these rules: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <em class="replaceable"> <code> begin_label </code> </em> must be followed by a colon. </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> begin_label </code> </em> can be given without <em class="replaceable"> <code> end_label </code> </em> . If <em class="replaceable"> <code> end_label </code> </em> is present, it must be the same as <em class="replaceable"> <code> begin_label </code> </em> . </p> </li> <li class="listitem"> <p> <em class="replaceable"> <code> end_label </code> </em> cannot be given without <em class="replaceable"> <code> begin_label </code> </em> . </p> </li> <li class="listitem"> <p> Labels at the same nesting level must be distinct. </p> </li> <li class="listitem"> <p> Labels can be up to 16 characters long. </p> </li> </ul> </div> <p> To refer to a label within the labeled construct, use an <a class="link" href="iterate.html" title="15.6.5.3 ITERATE Statement"> <code class="literal"> ITERATE </code> </a> or <a class="link" href="leave.html" title="15.6.5.4 LEAVE Statement"> <code class="literal"> LEAVE </code> </a> statement. The following example uses those statements to continue iterating or terminate the loop: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa41440835"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">CREATE</span> <span class="token keyword">PROCEDURE</span> doiterate<span class="token punctuation">(</span>p1 <span class="token datatype">INT</span><span class="token punctuation">)</span> <span class="token keyword">BEGIN</span> label1: <span class="token keyword">LOOP</span> <span class="token keyword">SET</span> p1 <span class="token operator">=</span> p1 <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">;</span> <span class="token keyword">IF</span> p1 <span class="token operator"><</span> <span class="token number">10</span> <span class="token keyword">THEN</span> <span class="token keyword">ITERATE</span> label1<span class="token punctuation">;</span> <span class="token keyword">END</span> <span class="token keyword">IF</span><span class="token punctuation">;</span> <span class="token keyword">LEAVE</span> label1<span class="token punctuation">;</span> <span class="token keyword">END</span> <span class="token keyword">LOOP</span> label1<span class="token punctuation">;</span> <span class="token keyword">END</span><span class="token punctuation">;</span></code></pre> </div> <p> The scope of a block label does not include the code for handlers declared within the block. For details, see <a class="xref" href="declare-handler.html" title="15.6.7.2 DECLARE ... HANDLER Statement"> Section 15.6.7.2, “DECLARE ... HANDLER Statement” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/connection-control.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="connection-control"> </a> 8.4.2 The Connection-Control Plugins </h3> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="connection-control-installation.html"> 8.4.2.1 Connection-Control Plugin Installation </a> </span> </dt> <dt> <span class="section"> <a href="connection-control-variables.html"> 8.4.2.2 Connection-Control System and Status Variables </a> </span> </dt> </dl> </div> <p> MySQL Server includes a plugin library that enables administrators to introduce an increasing delay in server response to connection attempts after a configurable number of consecutive failed attempts. This capability provides a deterrent that slows down brute force attacks against MySQL user accounts. The plugin library contains two plugins: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> CONNECTION_CONTROL </code> checks incoming connection attempts and adds a delay to server responses as necessary. This plugin also exposes system variables that enable its operation to be configured and a status variable that provides rudimentary monitoring information. </p> <p> The <code class="literal"> CONNECTION_CONTROL </code> plugin uses the audit plugin interface (see <a class="ulink" href="/doc/extending-mysql/8.4/en/writing-audit-plugins.html" target="_top"> Writing Audit Plugins </a> ). To collect information, it subscribes to the <code class="literal"> MYSQL_AUDIT_CONNECTION_CLASSMASK </code> event class, and processes <code class="literal"> MYSQL_AUDIT_CONNECTION_CONNECT </code> and <code class="literal"> MYSQL_AUDIT_CONNECTION_CHANGE_USER </code> subevents to check whether the server should introduce a delay before responding to connection attempts. </p> </li> <li class="listitem"> <p> <code class="literal"> CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS </code> implements an <code class="literal"> INFORMATION_SCHEMA </code> table that exposes more detailed monitoring information for failed connection attempts. </p> </li> </ul> </div> <p> The following sections provide information about connection-control plugin installation and configuration. For information about the <a class="link" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table"> <code class="literal"> CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS </code> </a> table, see <a class="xref" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table"> Section 28.6.2, “The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/sys-ps-setup-show-disabled-instruments.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="sys-ps-setup-show-disabled-instruments"> </a> 30.4.4.17 The ps_setup_show_disabled_instruments() Procedure </h4> </div> </div> </div> <a class="indexterm" name="idm46045061350576"> </a> <a class="indexterm" name="idm46045061349056"> </a> <p> Displays all currently disabled Performance Schema instruments. This might be a long list. </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-ps-setup-show-disabled-instruments-parameters"> </a> Parameters </h5> </div> </div> </div> <p> None. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="sys-ps-setup-show-disabled-instruments-example"> </a> Example </h5> </div> </div> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa59732337"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">CALL</span> sys<span class="token punctuation">.</span>ps_setup_show_disabled_instruments<span class="token punctuation">(</span><span class="token punctuation">)</span>\G <span class="token output"><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 1. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> disabled_instruments<span class="token punctuation">:</span> wait/synch/mutex/sql/TC_LOG_MMAP<span class="token punctuation">:</span><span class="token punctuation">:</span>LOCK_tc timed<span class="token punctuation">:</span> NO <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 2. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> disabled_instruments<span class="token punctuation">:</span> wait/synch/mutex/sql/THD<span class="token punctuation">:</span><span class="token punctuation">:</span>LOCK_query_plan timed<span class="token punctuation">:</span> NO <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> 3. row <span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span><span class="token punctuation">*</span> disabled_instruments<span class="token punctuation">:</span> wait/synch/mutex/sql/MYSQL_BIN_LOG<span class="token punctuation">:</span><span class="token punctuation">:</span>LOCK_commit timed<span class="token punctuation">:</span> NO ...</span></code></pre> </div> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/replication-binlog-encryption-key-rotation.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="replication-binlog-encryption-key-rotation"> </a> 19.3.2.3 Binary Log Master Key Rotation </h4> </div> </div> </div> <p> When binary log encryption is enabled, you can rotate the binary log master key at any time while the server is running by issuing <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> . When the binary log master key is rotated manually using this statement, the passwords for the new and subsequent files are encrypted using the new binary log master key, and also the file passwords for existing encrypted binary log files and relay log files are re-encrypted using the new binary log master key, so the encryption is renewed completely. You can rotate the binary log master key on a regular basis to comply with your organization's security policy, and also if you suspect that the current or any of the previous binary log master keys might have been compromised. </p> <p> When you rotate the binary log master key manually, MySQL Server takes the following actions in sequence: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> A new binary log encryption key is generated with the next available sequence number, stored on the keyring, and used as the new binary log master key. </p> </li> <li class="listitem"> <p> The binary log and relay log files are rotated on all channels. </p> </li> <li class="listitem"> <p> The new binary log master key is used to encrypt the file passwords for the new binary log and relay log files, and subsequent files until the key is changed again. </p> </li> <li class="listitem"> <p> The file passwords for existing encrypted binary log files and relay log files on the server are re-encrypted in turn using the new binary log master key, starting with the most recent files. Any unencrypted files are skipped. </p> </li> <li class="listitem"> <p> Binary log encryption keys that are no longer in use for any files after the re-encryption process are removed from the keyring. </p> </li> </ol> </div> <p> The <a class="link" href="privileges-provided.html#priv_binlog-encryption-admin"> <code class="literal"> BINLOG_ENCRYPTION_ADMIN </code> </a> privilege is required to issue <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> , and the statement cannot be used if the <a class="link" href="replication-options-binary-log.html#sysvar_binlog_encryption"> <code class="literal"> binlog_encryption </code> </a> system variable is set to <code class="literal"> OFF </code> . </p> <p> As the final step of the binary log master key rotation process, all binary log encryption keys that no longer apply to any retained binary log files or relay log files are cleaned up from the keyring. If a retained binary log file or relay log file cannot be initialized for re-encryption, the relevant binary log encryption keys are not deleted in case the files can be recovered in the future. For example, this might be the case if a file listed in a binary log index file is currently unreadable, or if a channel fails to initialize. If the server UUID changes, for example because a backup created using MySQL Enterprise Backup is used to set up a new replica, issuing <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> on the new server does not delete any earlier binary log encryption keys that include the original server UUID. </p> <p> If any of the first four steps of the binary log master key rotation process cannot be completed correctly, an error message is issued explaining the situation and the consequences for the encryption status of the binary log files and relay log files. Files that were previously encrypted are always left in an encrypted state, but their file passwords might still be encrypted using an old binary log master key. If you see these errors, first retry the process by issuing <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> again. Then investigate the status of individual files to see what is blocking the process, especially if you suspect that the current or any of the previous binary log master keys might have been compromised. </p> <p> If the final step of the binary log master key rotation process cannot be completed correctly, a warning message is issued explaining the situation. The warning message identifies whether the process could not clean up the auxiliary keys in the keyring for rotating the binary log master key, or could not clean up unused binary log encryption keys. You can choose to ignore the message as the keys are auxiliary keys or no longer in use, or you can issue <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> again to retry the process. </p> <p> If the server stops and is restarted with binary log encryption still set to <code class="literal"> ON </code> during the binary log master key rotation process, new binary log files and relay log files after the restart are encrypted using the new binary log master key. However, the re-encryption of existing files is not continued, so files that did not get re-encrypted before the server stopped are left encrypted using the previous binary log master key. To complete re-encryption and clean up unused binary log encryption keys, issue <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> again after the restart. </p> <p> <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> actions are not written to the binary log and are not executed on replicas. Binary log master key rotation can therefore be carried out in replication environments including a mix of MySQL versions. To schedule regular rotation of the binary log master key on all applicable source and replica servers, you can enable the MySQL Event Scheduler on each server and issue the <a class="link" href="alter-instance.html#alter-instance-rotate-binlog-master-key"> <code class="literal"> ALTER INSTANCE ROTATE BINLOG MASTER KEY </code> </a> statement using a <a class="link" href="create-event.html" title="15.1.13 CREATE EVENT Statement"> <code class="literal"> CREATE EVENT </code> </a> statement. If you rotate the binary log master key because you suspect that the current or any of the previous binary log master keys might have been compromised, issue the statement on every applicable source and replica server. Issuing the statement on individual servers ensures that you can verify immediate compliance, even in the case of replicas that are lagging, belong to multiple replication topologies, or are not currently active in the replication topology but have binary log and relay log files. </p> <p> The <a class="link" href="replication-options-binary-log.html#sysvar_binlog_rotate_encryption_master_key_at_startup"> <code class="literal"> binlog_rotate_encryption_master_key_at_startup </code> </a> system variable controls whether the binary log master key is automatically rotated when the server is restarted. If this system variable is set to <code class="literal"> ON </code> , a new binary log encryption key is generated and used as the new binary log master key whenever the server is restarted. If it is set to <code class="literal"> OFF </code> , which is the default, the existing binary log master key is used again after the restart. When the binary log master key is rotated at startup, the file passwords for the new binary log and relay log files are encrypted using the new key. The file passwords for the existing encrypted binary log files and relay log files are not re-encrypted, so they remain encrypted using the old key, which remains available on the keyring. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/dynamic-system-variables.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="dynamic-system-variables"> </a> 7.1.9.2 Dynamic System Variables </h4> </div> </div> </div> <p> Many server system variables are dynamic and can be set at runtime. See <a class="xref" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> Section 15.7.6.1, “SET Syntax for Variable Assignment” </a> . For a description of the privilege requirements for setting system variables, see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> </p> <p> The following table lists all dynamic system variables applicable within <code class="literal"> mysqld </code> . </p> <p> The table lists each variable's data type and scope. The last column indicates whether the scope for each variable is Global, Session, or both. Please see the corresponding item descriptions for details on setting and using the variables. Where appropriate, direct links to further information about the items are provided. </p> <p> Variables that have a type of <span class="quote"> “ <span class="quote"> string </span> ” </span> take a string value. Variables that have a type of <span class="quote"> “ <span class="quote"> numeric </span> ” </span> take a numeric value. Variables that have a type of <span class="quote"> “ <span class="quote"> boolean </span> ” </span> can be set to 0, 1, <code class="literal"> ON </code> or <code class="literal"> OFF </code> . Variables that are marked as <span class="quote"> “ <span class="quote"> enumeration </span> ” </span> normally should be set to one of the available values for the variable, but can also be set to the number that corresponds to the desired enumeration value. For enumerated system variables, the first enumeration value corresponds to 0. This differs from the <a class="link" href="enum.html" title="13.3.5 The ENUM Type"> <code class="literal"> ENUM </code> </a> data type used for table columns, for which the first enumeration value corresponds to 1. </p> <div class="table"> <a name="idm46045266542144"> </a> <p class="title"> <b> Table 7.5 Dynamic System Variable Summary </b> </p> <div class="table-contents"> <table frame="box" rules="all" summary="Reference for dynamic system variables (variables that can be modified at runtime)."> <colgroup> <col style="width: 40%"/> <col style="width: 20%"/> <col align="center" style="width: 20%"/> </colgroup> <thead> <tr> <th scope="col"> Variable Name </th> <th scope="col"> Variable Type </th> <th scope="col"> Variable Scope </th> </tr> </thead> <tbody> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_activate_all_roles_on_login"> activate_all_roles_on_login </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_ca"> admin_ssl_ca </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_capath"> admin_ssl_capath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_cert"> admin_ssl_cert </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_cipher"> admin_ssl_cipher </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_crl"> admin_ssl_crl </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_crlpath"> admin_ssl_crlpath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_ssl_key"> admin_ssl_key </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_tls_ciphersuites"> admin_tls_ciphersuites </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_admin_tls_version"> admin_tls_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_connection_policy"> audit_log_connection_policy </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_disable"> audit_log_disable </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_exclude_accounts"> audit_log_exclude_accounts </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_flush"> audit_log_flush </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_format_unix_timestamp"> audit_log_format_unix_timestamp </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_include_accounts"> audit_log_include_accounts </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_max_size"> audit_log_max_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_password_history_keep_days"> audit_log_password_history_keep_days </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_prune_seconds"> audit_log_prune_seconds </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_read_buffer_size"> audit_log_read_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_rotate_on_size"> audit_log_rotate_on_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="audit-log-reference.html#sysvar_audit_log_statement_policy"> audit_log_statement_policy </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_kerberos_service_principal"> authentication_kerberos_service_principal </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_auth_method_name"> authentication_ldap_sasl_auth_method_name </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_bind_base_dn"> authentication_ldap_sasl_bind_base_dn </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_bind_root_dn"> authentication_ldap_sasl_bind_root_dn </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_bind_root_pwd"> authentication_ldap_sasl_bind_root_pwd </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_ca_path"> authentication_ldap_sasl_ca_path </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_connect_timeout"> authentication_ldap_sasl_connect_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_group_search_attr"> authentication_ldap_sasl_group_search_attr </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_group_search_filter"> authentication_ldap_sasl_group_search_filter </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_init_pool_size"> authentication_ldap_sasl_init_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_log_status"> authentication_ldap_sasl_log_status </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_max_pool_size"> authentication_ldap_sasl_max_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_referral"> authentication_ldap_sasl_referral </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_response_timeout"> authentication_ldap_sasl_response_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_server_host"> authentication_ldap_sasl_server_host </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_server_port"> authentication_ldap_sasl_server_port </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_tls"> authentication_ldap_sasl_tls </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_sasl_user_search_attr"> authentication_ldap_sasl_user_search_attr </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_auth_method_name"> authentication_ldap_simple_auth_method_name </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_bind_base_dn"> authentication_ldap_simple_bind_base_dn </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_bind_root_dn"> authentication_ldap_simple_bind_root_dn </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_bind_root_pwd"> authentication_ldap_simple_bind_root_pwd </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_ca_path"> authentication_ldap_simple_ca_path </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_connect_timeout"> authentication_ldap_simple_connect_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_group_search_attr"> authentication_ldap_simple_group_search_attr </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_group_search_filter"> authentication_ldap_simple_group_search_filter </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_init_pool_size"> authentication_ldap_simple_init_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_log_status"> authentication_ldap_simple_log_status </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_max_pool_size"> authentication_ldap_simple_max_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_referral"> authentication_ldap_simple_referral </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_response_timeout"> authentication_ldap_simple_response_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_server_host"> authentication_ldap_simple_server_host </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_server_port"> authentication_ldap_simple_server_port </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_tls"> authentication_ldap_simple_tls </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_ldap_simple_user_search_attr"> authentication_ldap_simple_user_search_attr </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_authentication_policy"> authentication_policy </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="pluggable-authentication-system-variables.html#sysvar_authentication_webauthn_rp_id"> authentication_webauthn_rp_id </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_auto_increment_increment"> auto_increment_increment </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_auto_increment_offset"> auto_increment_offset </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_autocommit"> autocommit </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_automatic_sp_privileges"> automatic_sp_privileges </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_big_tables"> big_tables </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_cache_size"> binlog_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_checksum"> binlog_checksum </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_direct_non_transactional_updates"> binlog_direct_non_transactional_updates </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_encryption"> binlog_encryption </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_error_action"> binlog_error_action </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_expire_logs_auto_purge"> binlog_expire_logs_auto_purge </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_expire_logs_seconds"> binlog_expire_logs_seconds </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_format"> binlog_format </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_group_commit_sync_delay"> binlog_group_commit_sync_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_group_commit_sync_no_delay_count"> binlog_group_commit_sync_no_delay_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_max_flush_queue_time"> binlog_max_flush_queue_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_order_commits"> binlog_order_commits </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_row_image"> binlog_row_image </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_row_metadata"> binlog_row_metadata </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_row_value_options"> binlog_row_value_options </a> </th> <td> Set </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_rows_query_log_events"> binlog_rows_query_log_events </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_stmt_cache_size"> binlog_stmt_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_transaction_compression"> binlog_transaction_compression </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_transaction_compression_level_zstd"> binlog_transaction_compression_level_zstd </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_binlog_transaction_dependency_history_size"> binlog_transaction_dependency_history_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_block_encryption_mode"> block_encryption_mode </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_bulk_insert_buffer_size"> bulk_insert_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_client"> character_set_client </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_connection"> character_set_connection </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_database"> character_set_database </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_filesystem"> character_set_filesystem </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_results"> character_set_results </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_character_set_server"> character_set_server </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_check_proxy_users"> check_proxy_users </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_autotune_concurrency"> clone_autotune_concurrency </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_block_ddl"> clone_block_ddl </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_buffer_size"> clone_buffer_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_ddl_timeout"> clone_ddl_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_delay_after_data_drop"> clone_delay_after_data_drop </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_donor_timeout_after_network_failure"> clone_donor_timeout_after_network_failure </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_enable_compression"> clone_enable_compression </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_max_concurrency"> clone_max_concurrency </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_max_data_bandwidth"> clone_max_data_bandwidth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_max_network_bandwidth"> clone_max_network_bandwidth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_ssl_ca"> clone_ssl_ca </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_ssl_cert"> clone_ssl_cert </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_ssl_key"> clone_ssl_key </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="clone-plugin-options-variables.html#sysvar_clone_valid_donor_list"> clone_valid_donor_list </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_collation_connection"> collation_connection </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_collation_database"> collation_database </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_collation_server"> collation_server </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_completion_type"> completion_type </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_component_scheduler.enabled"> component_scheduler.enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_concurrent_insert"> concurrent_insert </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_connect_timeout"> connect_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="connection-control-variables.html#sysvar_connection_control_failed_connections_threshold"> connection_control_failed_connections_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="connection-control-variables.html#sysvar_connection_control_max_connection_delay"> connection_control_max_connection_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="connection-control-variables.html#sysvar_connection_control_min_connection_delay"> connection_control_min_connection_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_connection_memory_chunk_size"> connection_memory_chunk_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_connection_memory_limit"> connection_memory_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_cte_max_recursion_depth"> cte_max_recursion_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_debug"> debug </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_debug_sync"> debug_sync </a> </th> <td> String </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_collation_for_utf8mb4"> default_collation_for_utf8mb4 </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_password_lifetime"> default_password_lifetime </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_storage_engine"> default_storage_engine </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_table_encryption"> default_table_encryption </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_tmp_storage_engine"> default_tmp_storage_engine </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_default_week_format"> default_week_format </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_delay_key_write"> delay_key_write </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_delayed_insert_limit"> delayed_insert_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_delayed_insert_timeout"> delayed_insert_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_delayed_queue_size"> delayed_queue_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_div_precision_increment"> div_precision_increment </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_dragnet.log_error_filter_rules"> dragnet.log_error_filter_rules </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_end_markers_in_json"> end_markers_in_json </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_enforce_gtid_consistency"> enforce_gtid_consistency </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_enterprise_encryption.maximum_rsa_key_size"> enterprise_encryption.maximum_rsa_key_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_enterprise_encryption.rsa_support_legacy_padding"> enterprise_encryption.rsa_support_legacy_padding </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_eq_range_index_dive_limit"> eq_range_index_dive_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_event_scheduler"> event_scheduler </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_explain_format"> explain_format </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_explain_json_format_version"> explain_json_format_version </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_explicit_defaults_for_timestamp"> explicit_defaults_for_timestamp </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_flush"> flush </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_flush_time"> flush_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_foreign_key_checks"> foreign_key_checks </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ft_boolean_syntax"> ft_boolean_syntax </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_general_log"> general_log </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_general_log_file"> general_log_file </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_generated_random_password_length"> generated_random_password_length </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_global_connection_memory_limit"> global_connection_memory_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_global_connection_memory_tracking"> global_connection_memory_tracking </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_group_concat_max_len"> group_concat_max_len </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_advertise_recovery_endpoints"> group_replication_advertise_recovery_endpoints </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_allow_local_lower_version_join"> group_replication_allow_local_lower_version_join </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_auto_increment_increment"> group_replication_auto_increment_increment </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_autorejoin_tries"> group_replication_autorejoin_tries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_bootstrap_group"> group_replication_bootstrap_group </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_clone_threshold"> group_replication_clone_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_communication_debug_options"> group_replication_communication_debug_options </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_communication_max_message_size"> group_replication_communication_max_message_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_communication_stack"> group_replication_communication_stack </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_components_stop_timeout"> group_replication_components_stop_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_compression_threshold"> group_replication_compression_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_consistency"> group_replication_consistency </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_enforce_update_everywhere_checks"> group_replication_enforce_update_everywhere_checks </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_exit_state_action"> group_replication_exit_state_action </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_applier_threshold"> group_replication_flow_control_applier_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_certifier_threshold"> group_replication_flow_control_certifier_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_hold_percent"> group_replication_flow_control_hold_percent </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_max_quota"> group_replication_flow_control_max_quota </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_member_quota_percent"> group_replication_flow_control_member_quota_percent </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_min_quota"> group_replication_flow_control_min_quota </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_min_recovery_quota"> group_replication_flow_control_min_recovery_quota </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_mode"> group_replication_flow_control_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_period"> group_replication_flow_control_period </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_flow_control_release_percent"> group_replication_flow_control_release_percent </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_force_members"> group_replication_force_members </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_group_name"> group_replication_group_name </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_group_seeds"> group_replication_group_seeds </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_gtid_assignment_block_size"> group_replication_gtid_assignment_block_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_ip_allowlist"> group_replication_ip_allowlist </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_local_address"> group_replication_local_address </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_member_expel_timeout"> group_replication_member_expel_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_member_weight"> group_replication_member_weight </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_message_cache_size"> group_replication_message_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_paxos_single_leader"> group_replication_paxos_single_leader </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_poll_spin_loops"> group_replication_poll_spin_loops </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_preemptive_garbage_collection"> group_replication_preemptive_garbage_collection </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_preemptive_garbage_collection_rows_threshold"> group_replication_preemptive_garbage_collection_rows_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_compression_algorithms"> group_replication_recovery_compression_algorithms </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_get_public_key"> group_replication_recovery_get_public_key </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_public_key_path"> group_replication_recovery_public_key_path </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_reconnect_interval"> group_replication_recovery_reconnect_interval </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_retry_count"> group_replication_recovery_retry_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_ca"> group_replication_recovery_ssl_ca </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_capath"> group_replication_recovery_ssl_capath </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_cert"> group_replication_recovery_ssl_cert </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_cipher"> group_replication_recovery_ssl_cipher </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_crl"> group_replication_recovery_ssl_crl </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_crlpath"> group_replication_recovery_ssl_crlpath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_key"> group_replication_recovery_ssl_key </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_ssl_verify_server_cert"> group_replication_recovery_ssl_verify_server_cert </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_ciphersuites"> group_replication_recovery_tls_ciphersuites </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_tls_version"> group_replication_recovery_tls_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_use_ssl"> group_replication_recovery_use_ssl </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_recovery_zstd_compression_level"> group_replication_recovery_zstd_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_single_primary_mode"> group_replication_single_primary_mode </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_ssl_mode"> group_replication_ssl_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_start_on_boot"> group_replication_start_on_boot </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_tls_source"> group_replication_tls_source </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_transaction_size_limit"> group_replication_transaction_size_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_unreachable_majority_timeout"> group_replication_unreachable_majority_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="group-replication-system-variables.html#sysvar_group_replication_view_change_uuid"> group_replication_view_change_uuid </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_gtid_executed_compression_period"> gtid_executed_compression_period </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_gtid_mode"> gtid_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_gtid_next"> gtid_next </a> </th> <td> Enumeration </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-gtids.html#sysvar_gtid_purged"> gtid_purged </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_histogram_generation_max_mem_size"> histogram_generation_max_mem_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_host_cache_size"> host_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_identity"> identity </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_immediate_server_version"> immediate_server_version </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_information_schema_stats_expiry"> information_schema_stats_expiry </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_init_connect"> init_connect </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_init_replica"> init_replica </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_init_slave"> init_slave </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> innodb_adaptive_flushing </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> innodb_adaptive_flushing_lwm </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> innodb_adaptive_hash_index </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> innodb_adaptive_max_sleep_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> innodb_autoextend_increment </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> innodb_background_drop_list_empty </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> innodb_buffer_pool_dump_at_shutdown </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> innodb_buffer_pool_dump_now </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> innodb_buffer_pool_dump_pct </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_filename"> innodb_buffer_pool_filename </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> innodb_buffer_pool_in_core_file </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> innodb_buffer_pool_load_abort </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> innodb_buffer_pool_load_now </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> innodb_buffer_pool_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffer_max_size"> innodb_change_buffer_max_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering"> innodb_change_buffering </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering_debug"> innodb_change_buffering_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checkpoint_disabled"> innodb_checkpoint_disabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> innodb_checksum_algorithm </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_cmp_per_index_enabled"> innodb_cmp_per_index_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> innodb_commit_concurrency </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compress_debug"> innodb_compress_debug </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> innodb_compression_failure_threshold_pct </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_level"> innodb_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> innodb_compression_pad_pct_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> innodb_concurrency_tickets </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> innodb_ddl_buffer_size </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_log_crash_reset_debug"> innodb_ddl_log_crash_reset_debug </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> innodb_ddl_threads </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> innodb_deadlock_detect </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> innodb_default_row_format </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_disable_sort_file_cache"> innodb_disable_sort_file_cache </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> innodb_doublewrite </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_extend_and_initialize"> innodb_extend_and_initialize </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> innodb_fast_shutdown </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> innodb_fil_make_page_dirty_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> innodb_file_per_table </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> innodb_fill_factor </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> innodb_flush_log_at_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> innodb_flush_log_at_trx_commit </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> innodb_flush_neighbors </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> innodb_flush_sync </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> innodb_flushing_avg_loops </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> innodb_fsync_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_aux_table"> innodb_ft_aux_table </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_diag_print"> innodb_ft_enable_diag_print </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> innodb_ft_enable_stopword </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_num_word_optimize"> innodb_ft_num_word_optimize </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> innodb_ft_result_cache_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> innodb_ft_server_stopword_table </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> innodb_ft_user_stopword_table </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> innodb_idle_flush_pct </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> innodb_io_capacity </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> innodb_io_capacity_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_limit_optimistic_insert_debug"> innodb_limit_optimistic_insert_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> innodb_lock_wait_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> innodb_log_buffer_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_fuzzy_now"> innodb_log_checkpoint_fuzzy_now </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_now"> innodb_log_checkpoint_now </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> innodb_log_checksums </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> innodb_log_compressed_pages </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_abs_lwm"> innodb_log_spin_cpu_abs_lwm </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> innodb_log_spin_cpu_pct_hwm </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_wait_for_flush_spin_hwm"> innodb_log_wait_for_flush_spin_hwm </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> innodb_log_write_ahead_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_writer_threads"> innodb_log_writer_threads </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> innodb_lru_scan_depth </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> innodb_max_dirty_pages_pct </a> </th> <td> Numeric </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> innodb_max_dirty_pages_pct_lwm </a> </th> <td> Numeric </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> innodb_max_purge_lag </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> innodb_max_purge_lag_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> innodb_max_undo_log_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_merge_threshold_set_all_debug"> innodb_merge_threshold_set_all_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> innodb_monitor_disable </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> innodb_monitor_enable </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> innodb_monitor_reset </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset_all"> innodb_monitor_reset_all </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> innodb_old_blocks_pct </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> innodb_old_blocks_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> innodb_online_alter_log_max_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> innodb_open_files </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_optimize_fulltext_only"> innodb_optimize_fulltext_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> innodb_parallel_read_threads </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_all_deadlocks"> innodb_print_all_deadlocks </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_ddl_logs"> innodb_print_ddl_logs </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> innodb_purge_batch_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> innodb_purge_rseg_truncate_frequency </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_random_read_ahead"> innodb_random_read_ahead </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> innodb_read_ahead_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_archive_dirs"> innodb_redo_log_archive_dirs </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> innodb_redo_log_capacity </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_encrypt"> innodb_redo_log_encrypt </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_replication_delay"> innodb_replication_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> innodb_rollback_segments </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> innodb_saved_page_number_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> innodb_segment_reserve_factor </a> </th> <td> Numeric </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_delay"> innodb_spin_wait_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> innodb_spin_wait_pause_multiplier </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_auto_recalc"> innodb_stats_auto_recalc </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> innodb_stats_include_delete_marked </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> innodb_stats_method </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> innodb_stats_on_metadata </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> innodb_stats_persistent </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> innodb_stats_persistent_sample_pages </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> innodb_stats_transient_sample_pages </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output"> innodb_status_output </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> innodb_status_output_locks </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> innodb_strict_mode </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_spin_loops"> innodb_sync_spin_loops </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> innodb_table_locks </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> innodb_thread_concurrency </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> innodb_thread_sleep_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> innodb_tmpdir </a> </th> <td> Directory name </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_purge_view_update_only_debug"> innodb_trx_purge_view_update_only_debug </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_rseg_n_slots_debug"> innodb_trx_rseg_n_slots_debug </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_encrypt"> innodb_undo_log_encrypt </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> innodb_undo_log_truncate </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> innodb_undo_tablespaces </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> innodb_use_fdatasync </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_insert_id"> insert_id </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_interactive_timeout"> interactive_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_internal_tmp_mem_storage_engine"> internal_tmp_mem_storage_engine </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_join_buffer_size"> join_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_keep_files_on_create"> keep_files_on_create </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_key_buffer_size"> key_buffer_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_key_cache_age_threshold"> key_cache_age_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_key_cache_block_size"> key_cache_block_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_key_cache_division_limit"> key_cache_division_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_aws_cmk_id"> keyring_aws_cmk_id </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_aws_region"> keyring_aws_region </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_auth_path"> keyring_hashicorp_auth_path </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_ca_path"> keyring_hashicorp_ca_path </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_caching"> keyring_hashicorp_caching </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_role_id"> keyring_hashicorp_role_id </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_secret_id"> keyring_hashicorp_secret_id </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_server_url"> keyring_hashicorp_server_url </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_hashicorp_store_path"> keyring_hashicorp_store_path </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_okv_conf_dir"> keyring_okv_conf_dir </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="keyring-system-variables.html#sysvar_keyring_operations"> keyring_operations </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_last_insert_id"> last_insert_id </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_lc_messages"> lc_messages </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_lc_time_names"> lc_time_names </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_local_infile"> local_infile </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_lock_wait_timeout"> lock_wait_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_log_bin_trust_function_creators"> log_bin_trust_function_creators </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_error_services"> log_error_services </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_error_suppression_list"> log_error_suppression_list </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> log_error_verbosity </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_output"> log_output </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_queries_not_using_indexes"> log_queries_not_using_indexes </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_raw"> log_raw </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_slow_admin_statements"> log_slow_admin_statements </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_slow_extra"> log_slow_extra </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_log_slow_replica_statements"> log_slow_replica_statements </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_log_slow_slave_statements"> log_slow_slave_statements </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_log_statements_unsafe_for_binlog"> log_statements_unsafe_for_binlog </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_throttle_queries_not_using_indexes"> log_throttle_queries_not_using_indexes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_log_timestamps"> log_timestamps </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_long_query_time"> long_query_time </a> </th> <td> Numeric </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_low_priority_updates"> low_priority_updates </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_mandatory_roles"> mandatory_roles </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_master_verify_checksum"> master_verify_checksum </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_allowed_packet"> max_allowed_packet </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_max_binlog_cache_size"> max_binlog_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_max_binlog_size"> max_binlog_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_max_binlog_stmt_cache_size"> max_binlog_stmt_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_connect_errors"> max_connect_errors </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_connections"> max_connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_delayed_threads"> max_delayed_threads </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_error_count"> max_error_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_execution_time"> max_execution_time </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_heap_table_size"> max_heap_table_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_insert_delayed_threads"> max_insert_delayed_threads </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_join_size"> max_join_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_length_for_sort_data"> max_length_for_sort_data </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_points_in_geometry"> max_points_in_geometry </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_prepared_stmt_count"> max_prepared_stmt_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_max_relay_log_size"> max_relay_log_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_seeks_for_key"> max_seeks_for_key </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_sort_length"> max_sort_length </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_sp_recursion_depth"> max_sp_recursion_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_user_connections"> max_user_connections </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_max_write_lock_count"> max_write_lock_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_min_examined_row_limit"> min_examined_row_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_data_pointer_size"> myisam_data_pointer_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_max_sort_file_size"> myisam_max_sort_file_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_sort_buffer_size"> myisam_sort_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_stats_method"> myisam_stats_method </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_myisam_use_mmap"> myisam_use_mmap </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#sysvar_mysql_firewall_mode"> mysql_firewall_mode </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="firewall-reference.html#sysvar_mysql_firewall_trace"> mysql_firewall_trace </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_mysql_native_password_proxy_users"> mysql_native_password_proxy_users </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_compression_algorithms"> mysqlx_compression_algorithms </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_connect_timeout"> mysqlx_connect_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_deflate_default_compression_level"> mysqlx_deflate_default_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_deflate_max_client_compression_level"> mysqlx_deflate_max_client_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_document_id_unique_prefix"> mysqlx_document_id_unique_prefix </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_enable_hello_notice"> mysqlx_enable_hello_notice </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_idle_worker_thread_timeout"> mysqlx_idle_worker_thread_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_interactive_timeout"> mysqlx_interactive_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_lz4_default_compression_level"> mysqlx_lz4_default_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_lz4_max_client_compression_level"> mysqlx_lz4_max_client_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_max_allowed_packet"> mysqlx_max_allowed_packet </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_max_connections"> mysqlx_max_connections </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_min_worker_threads"> mysqlx_min_worker_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_read_timeout"> mysqlx_read_timeout </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_wait_timeout"> mysqlx_wait_timeout </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_write_timeout"> mysqlx_write_timeout </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_zstd_default_compression_level"> mysqlx_zstd_default_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="x-plugin-options-system-variables.html#sysvar_mysqlx_zstd_max_client_compression_level"> mysqlx_zstd_max_client_compression_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_allow_copying_alter_table </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_autoincrement_prefetch_sz"> ndb_autoincrement_prefetch_sz </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> ndb_batch_size </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> ndb_blob_read_batch_bytes </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> ndb_blob_write_batch_bytes </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_clear_apply_status"> ndb_clear_apply_status </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_conflict_role"> ndb_conflict_role </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_data_node_neighbour"> ndb_data_node_neighbour </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_dbg_check_shares"> ndb_dbg_check_shares </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_default_column_format"> ndb_default_column_format </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_default_column_format"> ndb_default_column_format </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_deferred_constraints"> ndb_deferred_constraints </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_deferred_constraints"> ndb_deferred_constraints </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_distribution"> ndb_distribution </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_distribution"> ndb_distribution </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_eventbuffer_free_percent"> ndb_eventbuffer_free_percent </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_eventbuffer_max_alloc"> ndb_eventbuffer_max_alloc </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_extra_logging"> ndb_extra_logging </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_force_send"> ndb_force_send </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_fully_replicated"> ndb_fully_replicated </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_index_stat_enable"> ndb_index_stat_enable </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_index_stat_option"> ndb_index_stat_option </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_join_pushdown"> ndb_join_pushdown </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_binlog_index"> ndb_log_binlog_index </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_cache_size"> ndb_log_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_empty_epochs"> ndb_log_empty_epochs </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_empty_epochs"> ndb_log_empty_epochs </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_empty_update"> ndb_log_empty_update </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_empty_update"> ndb_log_empty_update </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_exclusive_reads"> ndb_log_exclusive_reads </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_exclusive_reads"> ndb_log_exclusive_reads </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_transaction_compression"> ndb_log_transaction_compression </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_log_transaction_compression_level_zstd"> ndb_log_transaction_compression_level_zstd </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_log_update_as_write </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_log_update_minimal </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_log_updated_only </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_metadata_check"> ndb_metadata_check </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_metadata_check_interval"> ndb_metadata_check_interval </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_metadata_sync"> ndb_metadata_sync </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> ndb_optimization_delay </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_read_backup"> ndb_read_backup </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_recv_thread_activation_threshold"> ndb_recv_thread_activation_threshold </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_recv_thread_cpu_mask"> ndb_recv_thread_cpu_mask </a> </th> <td> Bitmap </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_replica_batch_size"> ndb_replica_batch_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_replica_blob_write_batch_bytes"> ndb_replica_blob_write_batch_bytes </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_report_thresh_binlog_epoch_slip"> ndb_report_thresh_binlog_epoch_slip </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_report_thresh_binlog_mem_usage"> ndb_report_thresh_binlog_mem_usage </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_row_checksum"> ndb_row_checksum </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_schema_dist_lock_wait_timeout"> ndb_schema_dist_lock_wait_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_show_foreign_key_mock_tables"> ndb_show_foreign_key_mock_tables </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_slave_conflict_role"> ndb_slave_conflict_role </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_table_no_logging"> ndb_table_no_logging </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_table_temporary"> ndb_table_temporary </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_use_exact_count"> ndb_use_exact_count </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndb_use_transactions"> ndb_use_transactions </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_max_bytes"> ndbinfo_max_bytes </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_max_rows"> ndbinfo_max_rows </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_offline"> ndbinfo_offline </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_ndbinfo_show_hidden"> ndbinfo_show_hidden </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_net_buffer_length"> net_buffer_length </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_net_read_timeout"> net_read_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_net_retry_count"> net_retry_count </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_net_write_timeout"> net_write_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_offline_mode"> offline_mode </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_old_alter_table"> old_alter_table </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_prune_level"> optimizer_prune_level </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_search_depth"> optimizer_search_depth </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_switch"> optimizer_switch </a> </th> <td> Set </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace"> optimizer_trace </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace_features"> optimizer_trace_features </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace_limit"> optimizer_trace_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace_max_mem_size"> optimizer_trace_max_mem_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_optimizer_trace_offset"> optimizer_trace_offset </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_original_commit_timestamp"> original_commit_timestamp </a> </th> <td> Numeric </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_original_server_version"> original_server_version </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_parser_max_mem_size"> parser_max_mem_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_partial_revokes"> partial_revokes </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_password_history"> password_history </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_password_require_current"> password_require_current </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_password_reuse_interval"> password_reuse_interval </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-system-variables.html#sysvar_performance_schema_max_digest_sample_age"> performance_schema_max_digest_sample_age </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="performance-schema-system-variables.html#sysvar_performance_schema_show_processlist"> performance_schema_show_processlist </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_preload_buffer_size"> preload_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_print_identified_with_as_hex"> print_identified_with_as_hex </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_profiling"> profiling </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_profiling_history_size"> profiling_history_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_protocol_compression_algorithms"> protocol_compression_algorithms </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_pseudo_replica_mode"> pseudo_replica_mode </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_pseudo_slave_mode"> pseudo_slave_mode </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_pseudo_thread_id"> pseudo_thread_id </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_query_alloc_block_size"> query_alloc_block_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_query_prealloc_size"> query_prealloc_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_rand_seed1"> rand_seed1 </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_rand_seed2"> rand_seed2 </a> </th> <td> Integer </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_range_alloc_block_size"> range_alloc_block_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_range_optimizer_max_mem_size"> range_optimizer_max_mem_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_rbr_exec_mode"> rbr_exec_mode </a> </th> <td> Enumeration </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_read_buffer_size"> read_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_read_only"> read_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_read_rnd_buffer_size"> read_rnd_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_regexp_stack_limit"> regexp_stack_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_regexp_time_limit"> regexp_time_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_relay_log_purge"> relay_log_purge </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_replica_allow_batching"> replica_allow_batching </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_checkpoint_group"> replica_checkpoint_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_checkpoint_period"> replica_checkpoint_period </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_compressed_protocol"> replica_compressed_protocol </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_exec_mode"> replica_exec_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_max_allowed_packet"> replica_max_allowed_packet </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_net_timeout"> replica_net_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_type"> replica_parallel_type </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_parallel_workers"> replica_parallel_workers </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_pending_jobs_size_max"> replica_pending_jobs_size_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_preserve_commit_order"> replica_preserve_commit_order </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_sql_verify_checksum"> replica_sql_verify_checksum </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_transaction_retries"> replica_transaction_retries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replica_type_conversions"> replica_type_conversions </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replication_optimize_for_static_plugin_config"> replication_optimize_for_static_plugin_config </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_replication_sender_observe_commit_only"> replication_sender_observe_commit_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_require_row_format"> require_row_format </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_require_secure_transport"> require_secure_transport </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_restrict_fk_on_non_standard_key"> restrict_fk_on_non_standard_key </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_resultset_metadata"> resultset_metadata </a> </th> <td> Enumeration </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#sysvar_rewriter_enabled"> rewriter_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#sysvar_rewriter_enabled_for_threads_without_privilege_checks"> rewriter_enabled_for_threads_without_privilege_checks </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="rewriter-query-rewrite-plugin-reference.html#sysvar_rewriter_verbose"> rewriter_verbose </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_read_size"> rpl_read_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_enabled"> rpl_semi_sync_master_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_timeout"> rpl_semi_sync_master_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_trace_level"> rpl_semi_sync_master_trace_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_for_slave_count"> rpl_semi_sync_master_wait_for_slave_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_no_slave"> rpl_semi_sync_master_wait_no_slave </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_master_wait_point"> rpl_semi_sync_master_wait_point </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_semi_sync_replica_enabled"> rpl_semi_sync_replica_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_semi_sync_replica_trace_level"> rpl_semi_sync_replica_trace_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_semi_sync_slave_enabled"> rpl_semi_sync_slave_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_semi_sync_slave_trace_level"> rpl_semi_sync_slave_trace_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_enabled"> rpl_semi_sync_source_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_timeout"> rpl_semi_sync_source_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_trace_level"> rpl_semi_sync_source_trace_level </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_for_replica_count"> rpl_semi_sync_source_wait_for_replica_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_no_replica"> rpl_semi_sync_source_wait_no_replica </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-source.html#sysvar_rpl_semi_sync_source_wait_point"> rpl_semi_sync_source_wait_point </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_stop_replica_timeout"> rpl_stop_replica_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_rpl_stop_slave_timeout"> rpl_stop_slave_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_schema_definition_cache"> schema_definition_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_secondary_engine_cost_threshold"> secondary_engine_cost_threshold </a> </th> <td> Numeric </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_select_into_buffer_size"> select_into_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_select_into_disk_sync"> select_into_disk_sync </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_select_into_disk_sync_delay"> select_into_disk_sync_delay </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options.html#sysvar_server_id"> server_id </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_gtids"> session_track_gtids </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_schema"> session_track_schema </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_state_change"> session_track_state_change </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_system_variables"> session_track_system_variables </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_session_track_transaction_info"> session_track_transaction_info </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_set_operations_buffer_size"> set_operations_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sha256_password_proxy_users"> sha256_password_proxy_users </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_show_create_table_skip_secondary_engine"> show_create_table_skip_secondary_engine </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_show_create_table_verbosity"> show_create_table_verbosity </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_show_gipk_in_create_table_and_information_schema"> show_gipk_in_create_table_and_information_schema </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_slave_allow_batching"> slave_allow_batching </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_checkpoint_group"> slave_checkpoint_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_checkpoint_period"> slave_checkpoint_period </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_compressed_protocol"> slave_compressed_protocol </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_exec_mode"> slave_exec_mode </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_max_allowed_packet"> slave_max_allowed_packet </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_net_timeout"> slave_net_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_parallel_type"> slave_parallel_type </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_parallel_workers"> slave_parallel_workers </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_pending_jobs_size_max"> slave_pending_jobs_size_max </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_preserve_commit_order"> slave_preserve_commit_order </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_sql_verify_checksum"> slave_sql_verify_checksum </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_transaction_retries"> slave_transaction_retries </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_slave_type_conversions"> slave_type_conversions </a> </th> <td> Set </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_slow_launch_time"> slow_launch_time </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_slow_query_log"> slow_query_log </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_slow_query_log_file"> slow_query_log_file </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sort_buffer_size"> sort_buffer_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_source_verify_checksum"> source_verify_checksum </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_auto_is_null"> sql_auto_is_null </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_big_selects"> sql_big_selects </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_buffer_result"> sql_buffer_result </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_generate_invisible_primary_key"> sql_generate_invisible_primary_key </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_sql_log_bin"> sql_log_bin </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_log_off"> sql_log_off </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_mode"> sql_mode </a> </th> <td> Set </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_notes"> sql_notes </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_quote_show_create"> sql_quote_show_create </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sql_replica_skip_counter"> sql_replica_skip_counter </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_require_primary_key"> sql_require_primary_key </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_safe_updates"> sql_safe_updates </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_select_limit"> sql_select_limit </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sql_slave_skip_counter"> sql_slave_skip_counter </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_sql_warnings"> sql_warnings </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_ca"> ssl_ca </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_capath"> ssl_capath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_cert"> ssl_cert </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_cipher"> ssl_cipher </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_crl"> ssl_crl </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_crlpath"> ssl_crlpath </a> </th> <td> Directory name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_key"> ssl_key </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_session_cache_mode"> ssl_session_cache_mode </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_ssl_session_cache_timeout"> ssl_session_cache_timeout </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_stored_program_cache"> stored_program_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_stored_program_definition_cache"> stored_program_definition_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_super_read_only"> super_read_only </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-binary-log.html#sysvar_sync_binlog"> sync_binlog </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sync_master_info"> sync_master_info </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sync_relay_log"> sync_relay_log </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sync_relay_log_info"> sync_relay_log_info </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_sync_source_info"> sync_source_info </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_syseventlog.facility"> syseventlog.facility </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_syseventlog.include_pid"> syseventlog.include_pid </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_syseventlog.tag"> syseventlog.tag </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_table_definition_cache"> table_definition_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_table_encryption_privilege_check"> table_encryption_privilege_check </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_table_open_cache"> table_open_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_tablespace_definition_cache"> tablespace_definition_cache </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="telemetry-trace-configuration.html#sysvar_telemetry.otel_log_level"> telemetry.otel_log_level </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="telemetry-trace-configuration.html#sysvar_telemetry.query_text_enabled"> telemetry.query_text_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="telemetry-trace-configuration.html#sysvar_telemetry.trace_enabled"> telemetry.trace_enabled </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_temptable_max_mmap"> temptable_max_mmap </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_temptable_max_ram"> temptable_max_ram </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_temptable_use_mmap"> temptable_use_mmap </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="replication-options-replica.html#sysvar_terminology_use_previous"> terminology_use_previous </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_cache_size"> thread_cache_size </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_high_priority_connection"> thread_pool_high_priority_connection </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_longrun_trx_limit"> thread_pool_longrun_trx_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_max_active_query_threads"> thread_pool_max_active_query_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_max_transactions_limit"> thread_pool_max_transactions_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_max_unused_threads"> thread_pool_max_unused_threads </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_prio_kickup_timer"> thread_pool_prio_kickup_timer </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_query_threads_per_group"> thread_pool_query_threads_per_group </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_stall_limit"> thread_pool_stall_limit </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_thread_pool_transaction_delay"> thread_pool_transaction_delay </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_time_zone"> time_zone </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_timestamp"> timestamp </a> </th> <td> Numeric </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_tls_ciphersuites"> tls_ciphersuites </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_tls_version"> tls_version </a> </th> <td> String </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_tmp_table_size"> tmp_table_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_transaction_alloc_block_size"> transaction_alloc_block_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="mysql-cluster-options-variables.html#sysvar_transaction_allow_batching"> transaction_allow_batching </a> </th> <td> Boolean </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_transaction_isolation"> transaction_isolation </a> </th> <td> Enumeration </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_transaction_prealloc_size"> transaction_prealloc_size </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_transaction_read_only"> transaction_read_only </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_unique_checks"> unique_checks </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_updatable_views_with_limit"> updatable_views_with_limit </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_use_secondary_engine"> use_secondary_engine </a> </th> <td> Enumeration </td> <td> Session </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_check_user_name"> validate_password_check_user_name </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_dictionary_file"> validate_password_dictionary_file </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_length"> validate_password_length </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_mixed_case_count"> validate_password_mixed_case_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_number_count"> validate_password_number_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_policy"> validate_password_policy </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password_special_char_count"> validate_password_special_char_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.changed_characters_percentage"> validate_password.changed_characters_percentage </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.check_user_name"> validate_password.check_user_name </a> </th> <td> Boolean </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.dictionary_file"> validate_password.dictionary_file </a> </th> <td> File name </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.length"> validate_password.length </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.mixed_case_count"> validate_password.mixed_case_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.number_count"> validate_password.number_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.policy"> validate_password.policy </a> </th> <td> Enumeration </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="validate-password-options-variables.html#sysvar_validate_password.special_char_count"> validate_password.special_char_count </a> </th> <td> Integer </td> <td> Global </td> </tr> <tr> <th scope="row"> <a class="link" href="version-tokens-reference.html#sysvar_version_tokens_session"> version_tokens_session </a> </th> <td> String </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_wait_timeout"> wait_timeout </a> </th> <td> Integer </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_windowing_use_high_precision"> windowing_use_high_precision </a> </th> <td> Boolean </td> <td> Both </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_xa_detach_on_prepare"> xa_detach_on_prepare </a> </th> <td> Boolean </td> <td> Both </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th scope="col" style="width: 472.031px;"> Variable Name </th> <th scope="col" style="width: 135.375px;"> Variable Type </th> <th scope="col" style="width: 130.594px;"> Variable Scope </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/connecting-disconnecting.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="connecting-disconnecting"> </a> 5.1 Connecting to and Disconnecting from the Server </h2> </div> </div> </div> <a class="indexterm" name="idm46045325684192"> </a> <a class="indexterm" name="idm46045325682704"> </a> <a class="indexterm" name="idm46045325681216"> </a> <a class="indexterm" name="idm46045325679728"> </a> <p> To connect to the server, you usually need to provide a MySQL user name when you invoke <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> and, most likely, a password. If the server runs on a machine other than the one where you log in, you must also specify a host name. Contact your administrator to find out what connection parameters you should use to connect (that is, what host, user name, and password to use). Once you know the proper parameters, you should be able to connect like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa83410438"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-h</span> <em class="replaceable">host</em> <span class="token property">-u</span> <em class="replaceable">user</em> <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> ********</code></pre> </div> <p> <em class="replaceable"> <code> host </code> </em> and <em class="replaceable"> <code> user </code> </em> represent the host name where your MySQL server is running and the user name of your MySQL account. Substitute appropriate values for your setup. The <code class="literal"> ******** </code> represents your password; enter it when <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> displays the <code class="literal"> Enter password: </code> prompt. </p> <p> If that works, you should see some introductory information followed by a <code class="literal"> mysql> </code> prompt: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa46609857"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-h</span> <em class="replaceable">host</em> <span class="token property">-u</span> <em class="replaceable">user</em> <span class="token property">-p</span> Enter password<span class="token punctuation">:</span> ******** Welcome to the MySQL monitor<span class="token punctuation">.</span> Commands end with <span class="token punctuation">;</span> or \g<span class="token punctuation">.</span> Your MySQL connection id is 25338 to server version<span class="token punctuation">:</span> 8<span class="token punctuation">.</span>4<span class="token punctuation">.</span>3-standard Type <span class="token atrule">'help;'</span> or <span class="token atrule">'\h'</span> for help<span class="token punctuation">.</span> Type <span class="token atrule">'\c'</span> to clear the buffer<span class="token punctuation">.</span> <span class="token prompt">mysql></span></code></pre> </div> <p> The <code class="literal"> mysql> </code> prompt tells you that <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> is ready for you to enter SQL statements. </p> <p> If you are logging in on the same machine that MySQL is running on, you can omit the host, and simply use the following: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa58352605"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span> <span class="token property">-u</span> <em class="replaceable">user</em> <span class="token property">-p</span></code></pre> </div> <p> If, when you attempt to log in, you get an error message such as <span class="errortext"> ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2) </span> , it means that the MySQL server daemon (Unix) or service (Windows) is not running. Consult the administrator or see the section of <a class="xref" href="installing.html" title="Chapter 2 Installing MySQL"> Chapter 2, <i> Installing MySQL </i> </a> that is appropriate to your operating system. </p> <p> For help with other problems often encountered when trying to log in, see <a class="xref" href="common-errors.html" title="B.3.2 Common Errors When Using MySQL Programs"> Section B.3.2, “Common Errors When Using MySQL Programs” </a> . </p> <p> Some MySQL installations permit users to connect as the anonymous (unnamed) user to the server running on the local host. If this is the case on your machine, you should be able to connect to that server by invoking <a class="link" href="mysql.html" title="6.5.1 mysql — The MySQL Command-Line Client"> <span class="command"> <strong> mysql </strong> </span> </a> without any options: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa74607461"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">mysql</span></code></pre> </div> <p> After you have connected successfully, you can disconnect any time by typing <code class="literal"> QUIT </code> (or <code class="literal"> \q </code> ) at the <code class="literal"> mysql> </code> prompt: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa35101348"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> QUIT Bye</code></pre> </div> <p> On Unix, you can also disconnect by pressing Control+D. </p> <p> Most examples in the following sections assume that you are connected to the server. They indicate this by the <code class="literal"> mysql> </code> prompt. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/optimizing-queries-myisam.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="optimizing-queries-myisam"> </a> 10.6.1 Optimizing MyISAM Queries </h3> </div> </div> </div> <p> Some general tips for speeding up queries on <code class="literal"> MyISAM </code> tables: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> To help MySQL better optimize queries, use <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> or run <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --analyze </strong> </span> </a> on a table after it has been loaded with data. This updates a value for each index part that indicates the average number of rows that have the same value. (For unique indexes, this is always 1.) MySQL uses this to decide which index to choose when you join two tables based on a nonconstant expression. You can check the result from the table analysis by using <code class="literal"> SHOW INDEX FROM <em class="replaceable"> <code> tbl_name </code> </em> </code> and examining the <code class="literal"> Cardinality </code> value. <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --description --verbose </strong> </span> </a> shows index distribution information. </p> </li> <li class="listitem"> <p> To sort an index and data according to an index, use <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk --sort-index --sort-records=1 </strong> </span> </a> (assuming that you want to sort on index 1). This is a good way to make queries faster if you have a unique index from which you want to read all rows in order according to the index. The first time you sort a large table this way, it may take a long time. </p> </li> <li class="listitem"> <p> Try to avoid complex <a class="link" href="select.html" title="15.2.13 SELECT Statement"> <code class="literal"> SELECT </code> </a> queries on <code class="literal"> MyISAM </code> tables that are updated frequently, to avoid problems with table locking that occur due to contention between readers and writers. </p> </li> <li class="listitem"> <p> <code class="literal"> MyISAM </code> supports concurrent inserts: If a table has no free blocks in the middle of the data file, you can <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> new rows into it at the same time that other threads are reading from the table. If it is important to be able to do this, consider using the table in ways that avoid deleting rows. Another possibility is to run <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> to defragment the table after you have deleted a lot of rows from it. This behavior is altered by setting the <a class="link" href="server-system-variables.html#sysvar_concurrent_insert"> <code class="literal"> concurrent_insert </code> </a> variable. You can force new rows to be appended (and therefore permit concurrent inserts), even in tables that have deleted rows. See <a class="xref" href="concurrent-inserts.html" title="10.11.3 Concurrent Inserts"> Section 10.11.3, “Concurrent Inserts” </a> . </p> </li> <li class="listitem"> <p> For <code class="literal"> MyISAM </code> tables that change frequently, try to avoid all variable-length columns ( <a class="link" href="char.html" title="13.3.2 The CHAR and VARCHAR Types"> <code class="literal"> VARCHAR </code> </a> , <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> , and <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> TEXT </code> </a> ). The table uses dynamic row format if it includes even a single variable-length column. See <a class="xref" href="storage-engines.html" title="Chapter 18 Alternative Storage Engines"> Chapter 18, <i> Alternative Storage Engines </i> </a> . </p> </li> <li class="listitem"> <p> It is normally not useful to split a table into different tables just because the rows become large. In accessing a row, the biggest performance hit is the disk seek needed to find the first byte of the row. After finding the data, most modern disks can read the entire row fast enough for most applications. The only cases where splitting up a table makes an appreciable difference is if it is a <code class="literal"> MyISAM </code> table using dynamic row format that you can change to a fixed row size, or if you very often need to scan the table but do not need most of the columns. See <a class="xref" href="storage-engines.html" title="Chapter 18 Alternative Storage Engines"> Chapter 18, <i> Alternative Storage Engines </i> </a> . </p> </li> <li class="listitem"> <p> Use <code class="literal"> ALTER TABLE ... ORDER BY <em class="replaceable"> <code> expr1 </code> </em> , <em class="replaceable"> <code> expr2 </code> </em> , ... </code> if you usually retrieve rows in <code class="literal"> <em class="replaceable"> <code> expr1 </code> </em> , <em class="replaceable"> <code> expr2 </code> </em> , ... </code> order. By using this option after extensive changes to the table, you may be able to get higher performance. </p> </li> <li class="listitem"> <p> If you often need to calculate results such as counts based on information from a lot of rows, it may be preferable to introduce a new table and update the counter in real time. An update of the following form is very fast: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa29818268"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">UPDATE</span> <em class="replaceable">tbl_name</em> <span class="token keyword">SET</span> <em class="replaceable">count_col</em><span class="token operator">=</span><em class="replaceable">count_col</em><span class="token operator">+</span><span class="token number">1</span> <span class="token keyword">WHERE</span> <em class="replaceable">key_col</em><span class="token operator">=</span><em class="replaceable">constant</em><span class="token punctuation">;</span></code></pre> </div> <p> This is very important when you use MySQL storage engines such as <code class="literal"> MyISAM </code> that has only table-level locking (multiple readers with single writers). This also gives better performance with most database systems, because the row locking manager in this case has less to do. </p> </li> <li class="listitem"> <p> Use <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> periodically to avoid fragmentation with dynamic-format <code class="literal"> MyISAM </code> tables. See <a class="xref" href="myisam-table-formats.html" title="18.2.3 MyISAM Table Storage Formats"> Section 18.2.3, “MyISAM Table Storage Formats” </a> . </p> </li> <li class="listitem"> <p> Declaring a <code class="literal"> MyISAM </code> table with the <code class="literal"> DELAY_KEY_WRITE=1 </code> table option makes index updates faster because they are not flushed to disk until the table is closed. The downside is that if something kills the server while such a table is open, you must ensure that the table is okay by running the server with the <a class="link" href="server-system-variables.html#sysvar_myisam_recover_options"> <code class="literal"> myisam_recover_options </code> </a> system variable set, or by running <a class="link" href="myisamchk.html" title="6.6.4 myisamchk — MyISAM Table-Maintenance Utility"> <span class="command"> <strong> myisamchk </strong> </span> </a> before restarting the server. (However, even in this case, you should not lose anything by using <code class="literal"> DELAY_KEY_WRITE </code> , because the key information can always be generated from the data rows.) </p> </li> <li class="listitem"> <p> Strings are automatically prefix- and end-space compressed in <code class="literal"> MyISAM </code> indexes. See <a class="xref" href="create-index.html" title="15.1.15 CREATE INDEX Statement"> Section 15.1.15, “CREATE INDEX Statement” </a> . </p> </li> <li class="listitem"> <p> You can increase performance by caching queries or answers in your application and then executing many inserts or updates together. Locking the table during this operation ensures that the index cache is only flushed once after all updates. </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/error-log-components.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="error-log-components"> </a> 7.5.3 Error Log Components </h3> </div> </div> </div> <p> This section describes the characteristics of individual error log components. For general information about configuring error logging, see <a class="xref" href="error-log.html" title="7.4.2 The Error Log"> Section 7.4.2, “The Error Log” </a> . </p> <p> A log component can be a filter or a sink: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> A filter processes log events, to add, remove, or modify event fields, or to delete events entirely. The resulting events pass to the next log component in the list of enabled components. </p> </li> <li class="listitem"> <p> A sink is a destination (writer) for log events. Typically, a sink processes log events into log messages that have a particular format and writes these messages to its associated output, such as a file or the system log. A sink may also write to the Performance Schema <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table; see <a class="xref" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> Section 29.12.22.2, “The error_log Table” </a> . Events pass unmodified to the next log component in the list of enabled components (that is, although a sink formats events to produce output messages, it does not modify events as they pass internally to the next component). </p> </li> </ul> </div> <p> The <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> system variable lists the enabled log components. Components not named in the list are disabled. <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> also implicitly loads error log components if they are not already loaded. For more information, see <a class="xref" href="error-log-configuration.html" title="7.4.2.1 Error Log Configuration"> Section 7.4.2.1, “Error Log Configuration” </a> . </p> <p> The following sections describe individual log components, grouped by component type: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="error-log-components.html#error-log-filter-components" title="Filter Error Log Components"> Filter Error Log Components </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="error-log-components.html#error-log-sink-components" title="Sink Error Log Components"> Sink Error Log Components </a> </p> </li> </ul> </div> <p> Component descriptions include these types of information: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The component name and intended purpose. </p> </li> <li class="listitem"> <p> Whether the component is built in or must be loaded. For a loadable component, the description specifies the URN to use if explicitly loading or unloading the component with the <a class="link" href="install-component.html" title="15.7.4.3 INSTALL COMPONENT Statement"> <code class="literal"> INSTALL COMPONENT </code> </a> and <a class="link" href="uninstall-component.html" title="15.7.4.5 UNINSTALL COMPONENT Statement"> <code class="literal"> UNINSTALL COMPONENT </code> </a> statements. Implicitly loading error log components requires only the component name. For more information, see <a class="xref" href="error-log-configuration.html" title="7.4.2.1 Error Log Configuration"> Section 7.4.2.1, “Error Log Configuration” </a> . </p> </li> <li class="listitem"> <p> Whether the component can be listed multiple times in the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value. </p> </li> <li class="listitem"> <p> For a sink component, the destination to which the component writes output. </p> </li> <li class="listitem"> <p> For a sink component, whether it supports an interface to the Performance Schema <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table. </p> </li> </ul> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="error-log-filter-components"> </a> Filter Error Log Components </h4> </div> </div> </div> <p> Error log filter components implement filtering of error log events. If no filter component is enabled, no filtering occurs. </p> <p> Any enabled filter component affects log events only for components listed later in the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value. In particular, for any log sink component listed in <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> earlier than any filter component, no log event filtering occurs. </p> <h5> <a name="idm46045257269152"> </a> The log_filter_internal Component </h5> <a class="indexterm" name="idm46045257268480"> </a> <a class="indexterm" name="idm46045257267392"> </a> <a class="indexterm" name="idm46045257265904"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements filtering based on log event priority and error code, in combination with the <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> <code class="literal"> log_error_verbosity </code> </a> and <a class="link" href="server-system-variables.html#sysvar_log_error_suppression_list"> <code class="literal"> log_error_suppression_list </code> </a> system variables. See <a class="xref" href="error-log-priority-based-filtering.html" title="7.4.2.5 Priority-Based Error Log Filtering (log_filter_internal)"> Section 7.4.2.5, “Priority-Based Error Log Filtering (log_filter_internal)” </a> . </p> </li> <li class="listitem"> <p> URN: This component is built in and need not be loaded. </p> </li> <li class="listitem"> <p> Multiple uses permitted: No. </p> </li> </ul> </div> <p> If <code class="literal"> log_filter_internal </code> is disabled, <a class="link" href="server-system-variables.html#sysvar_log_error_verbosity"> <code class="literal"> log_error_verbosity </code> </a> and <a class="link" href="server-system-variables.html#sysvar_log_error_suppression_list"> <code class="literal"> log_error_suppression_list </code> </a> have no effect. </p> <h5> <a name="idm46045257254448"> </a> The log_filter_dragnet Component </h5> <a class="indexterm" name="idm46045257253728"> </a> <a class="indexterm" name="idm46045257252640"> </a> <a class="indexterm" name="idm46045257251152"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements filtering based on the rules defined by the <a class="link" href="server-system-variables.html#sysvar_dragnet.log_error_filter_rules"> <code class="literal"> dragnet.log_error_filter_rules </code> </a> system variable setting. See <a class="xref" href="error-log-rule-based-filtering.html" title="7.4.2.6 Rule-Based Error Log Filtering (log_filter_dragnet)"> Section 7.4.2.6, “Rule-Based Error Log Filtering (log_filter_dragnet)” </a> . </p> </li> <li class="listitem"> <p> URN: <code class="literal"> file://component_log_filter_dragnet </code> </p> </li> <li class="listitem"> <p> Multiple uses permitted: No. </p> </li> </ul> </div> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h4 class="title"> <a name="error-log-sink-components"> </a> Sink Error Log Components </h4> </div> </div> </div> <p> Error log sink components are writers that implement error log output. If no sink component is enabled, no log output occurs. </p> <p> Some sink component descriptions refer to the default error log destination. This is the console or a file and is indicated by the value of the <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> system variable, determined as described in <a class="xref" href="error-log-destination-configuration.html" title="7.4.2.2 Default Error Log Destination Configuration"> Section 7.4.2.2, “Default Error Log Destination Configuration” </a> . </p> <h5> <a name="idm46045257239616"> </a> The log_sink_internal Component </h5> <a class="indexterm" name="idm46045257238944"> </a> <a class="indexterm" name="idm46045257237856"> </a> <a class="indexterm" name="idm46045257236368"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements traditional error log message output format. </p> </li> <li class="listitem"> <p> URN: This component is built in and need not be loaded. </p> </li> <li class="listitem"> <p> Multiple uses permitted: No. </p> </li> <li class="listitem"> <p> Output destination: Writes to the default error log destination. </p> </li> <li class="listitem"> <p> Performance Schema support: Writes to the <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table. Provides a parser for reading error log files created by previous server instances. </p> </li> </ul> </div> <h5> <a name="idm46045257228768"> </a> The log_sink_json Component </h5> <a class="indexterm" name="idm46045257228096"> </a> <a class="indexterm" name="idm46045257227008"> </a> <a class="indexterm" name="idm46045257225520"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements JSON-format error logging. See <a class="xref" href="error-log-json.html" title="7.4.2.7 Error Logging in JSON Format"> Section 7.4.2.7, “Error Logging in JSON Format” </a> . </p> </li> <li class="listitem"> <p> URN: <code class="literal"> file://component_log_sink_json </code> </p> </li> <li class="listitem"> <p> Multiple uses permitted: Yes. </p> </li> <li class="listitem"> <p> Output destination: This sink determines its output destination based on the default error log destination, which is given by the <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> system variable: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> names a file, the sink bases output file naming on that file name, plus a numbered <code class="filename"> . <em class="replaceable"> <code> NN </code> </em> .json </code> suffix, with <em class="replaceable"> <code> NN </code> </em> starting at 00. For example, if <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> is <em class="replaceable"> <code> file_name </code> </em> , successive instances of <code class="literal"> log_sink_json </code> named in the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value write to <code class="filename"> <em class="replaceable"> <code> file_name </code> </em> .00.json </code> , <code class="filename"> <em class="replaceable"> <code> file_name </code> </em> .01.json </code> , and so forth. </p> </li> <li class="listitem"> <p> If <a class="link" href="server-system-variables.html#sysvar_log_error"> <code class="literal"> log_error </code> </a> is <code class="literal"> stderr </code> , the sink writes to the console. If <code class="literal"> log_sink_json </code> is named multiple times in the <a class="link" href="server-system-variables.html#sysvar_log_error_services"> <code class="literal"> log_error_services </code> </a> value, they all write to the console, which is likely not useful. </p> </li> </ul> </div> </li> <li class="listitem"> <p> Performance Schema support: Writes to the <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table. Provides a parser for reading error log files created by previous server instances. </p> </li> </ul> </div> <h5> <a name="idm46045257200480"> </a> The log_sink_syseventlog Component </h5> <a class="indexterm" name="idm46045257199808"> </a> <a class="indexterm" name="idm46045257198720"> </a> <a class="indexterm" name="idm46045257197232"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Implements error logging to the system log. This is the Event Log on Windows, and <code class="literal"> syslog </code> on Unix and Unix-like systems. See <a class="xref" href="error-log-syslog.html" title="7.4.2.8 Error Logging to the System Log"> Section 7.4.2.8, “Error Logging to the System Log” </a> . </p> </li> <li class="listitem"> <p> URN: <code class="literal"> file://component_log_sink_syseventlog </code> </p> </li> <li class="listitem"> <p> Multiple uses permitted: No. </p> </li> <li class="listitem"> <p> Output destination: Writes to the system log. Does not use the default error log destination. </p> </li> <li class="listitem"> <p> Performance Schema support: Does not write to the <a class="link" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> <code class="literal"> error_log </code> </a> table. Does not provide a parser for reading error log files created by previous server instances. </p> </li> </ul> </div> <h5> <a name="idm46045257187472"> </a> The log_sink_test Component </h5> <a class="indexterm" name="idm46045257186800"> </a> <a class="indexterm" name="idm46045257185712"> </a> <a class="indexterm" name="idm46045257184224"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Purpose: Intended for internal use in writing test cases, not for production use. </p> </li> <li class="listitem"> <p> URN: <code class="literal"> file://component_log_sink_test </code> </p> </li> </ul> </div> <p> Sink properties such as whether multiple uses are permitted and the output destination are not specified for <code class="literal"> log_sink_test </code> because, as mentioned, it is for internal use. As such, its behavior is subject to change at any time. </p> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/downgrading.html

<div id="docs-body"> <div class="chapter"> <div class="titlepage"> <div> <div> <h1 class="title"> <a name="downgrading"> </a> Chapter 4 Downgrading MySQL </h1> </div> </div> </div> <a class="indexterm" name="idm46045325743728"> </a> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Notes </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Make sure you understand <a class="link" href="mysql-releases.html" title="1.3 MySQL Releases: Innovation and LTS"> the MySQL release model </a> for MySQL long-term support (LTS) and Innovation releases before proceeding with a downgrade. </p> </li> <li class="listitem"> <p> A replication topology is downgraded by following the rolling downgrade scheme described at <a class="xref" href="replication-upgrade.html" title="19.5.3 Upgrading or Downgrading a Replication Topology"> Section 19.5.3, “Upgrading or Downgrading a Replication Topology” </a> , which uses one of the supported single-server methods for each individual server downgrade. </p> </li> <li class="listitem"> <p> Monthly Rapid Updates (MRUs) and hot fixes also count as releases in this documentation. </p> </li> </ul> </div> </div> <div class="table"> <a name="mysqld-downgrade-paths"> </a> <p class="title"> <b> Table 4.1 Downgrade Paths for MySQL Server </b> </p> <div class="table-contents"> <table width="1062"> <colgroup> <col width="25%"/> <col width="15%"/> <col width="30%"/> <col width="30%"/> </colgroup> <thead> <tr> <th scope="col"> Downgrade Path </th> <th scope="col"> Path Examples </th> <th scope="col"> Supported Downgrade Methods </th> <th scope="col"> Notes </th> </tr> </thead> <tbody> <tr> <th scope="row"> Within an LTS series </th> <td> <p> 8.4.y LTS to 8.4.x LTS </p> </td> <td> In-place, logical dump and load, MySQL Clone, or by using replication </td> <td> </td> </tr> <tr> <th scope="row"> From an LTS or Bugfix series to the previous LTS or Bugfix series </th> <td> 8.4.x LTS to 8.0.y </td> <td> Logical dump and load or by using replication </td> <td> Only supported for rollback purposes (that is, if no new server functionality has been applied to the data) </td> </tr> <tr> <th scope="row"> From an LTS or Bugfix series to an Innovation series <span class="emphasis"> <em> after the previous LTS series </em> </span> </th> <td> 8.4.x LTS to 8.3.0 Innovation </td> <td> Logical dump and load or by using replication </td> <td> Only supported for rollback purposes (that is, if no new server functionality has been applied to the data) </td> </tr> <tr> <th scope="row"> From within an Innovation series </th> <td> 9.1 to 9.0 </td> <td> Logical dump and load or by using replication </td> <td> Only supported for rollback purposes (that is, if no new server functionality has been applied to the data) </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> <p> Downgrading to MySQL 5.7 or earlier is not supported. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/large-page-support.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="large-page-support"> </a> 10.12.3.3 Enabling Large Page Support </h4> </div> </div> </div> <a class="indexterm" name="idm46045222150512"> </a> <p> Some hardware and operating system architectures support memory pages greater than the default (usually 4KB). The actual implementation of this support depends on the underlying hardware and operating system. Applications that perform a lot of memory accesses may obtain performance improvements by using large pages due to reduced Translation Lookaside Buffer (TLB) misses. </p> <p> In MySQL, large pages can be used by <a class="link" href="innodb-storage-engine.html" title="Chapter 17 The InnoDB Storage Engine"> <code class="literal"> InnoDB </code> </a> , to allocate memory for its buffer pool and additional memory pool. </p> <p> Standard use of large pages in MySQL attempts to use the largest size supported, up to 4MB. Under Solaris, a <span class="quote"> “ <span class="quote"> super large pages </span> ” </span> feature enables uses of pages up to 256MB. This feature is available for recent SPARC platforms. It can be enabled or disabled by using the <a class="link" href="server-options.html#option_mysqld_super-large-pages"> <code class="option"> --super-large-pages </code> </a> or <a class="link" href="server-options.html#option_mysqld_super-large-pages"> <code class="option"> --skip-super-large-pages </code> </a> option. </p> <p> MySQL also supports the Linux implementation of large page support (which is called HugeTLB in Linux). </p> <p> Before large pages can be used on Linux, the kernel must be enabled to support them and it is necessary to configure the HugeTLB memory pool. For reference, the HugeTBL API is documented in the <code class="filename"> Documentation/vm/hugetlbpage.txt </code> file of your Linux sources. </p> <p> The kernels for some recent systems such as Red Hat Enterprise Linux may have the large pages feature enabled by default. To check whether this is true for your kernel, use the following command and look for output lines containing <span class="quote"> “ <span class="quote"> huge </span> ” </span> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa90271592"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">grep</span> <span class="token property">-i</span> huge /proc/meminfo AnonHugePages<span class="token punctuation">:</span> 2658304 kB ShmemHugePages<span class="token punctuation">:</span> 0 kB HugePages_Total<span class="token punctuation">:</span> 0 HugePages_Free<span class="token punctuation">:</span> 0 HugePages_Rsvd<span class="token punctuation">:</span> 0 HugePages_Surp<span class="token punctuation">:</span> 0 Hugepagesize<span class="token punctuation">:</span> 2048 kB Hugetlb<span class="token punctuation">:</span> 0 kB</code></pre> </div> <p> The nonempty command output indicates that large page support is present, but the zero values indicate that no pages are configured for use. </p> <p> If your kernel needs to be reconfigured to support large pages, consult the <code class="filename"> hugetlbpage.txt </code> file for instructions. </p> <p> Assuming that your Linux kernel has large page support enabled, configure it for use by MySQL using the following steps: </p> <div class="orderedlist"> <ol class="orderedlist" type="1"> <li class="listitem"> <p> Determine the number of large pages needed. This is the size of the InnoDB buffer pool divided by the large page size, which we can calculate as <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> / <code class="literal"> Hugepagesize </code> . Assuming the default value for the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> (128MB) and using the <code class="literal"> Hugepagesize </code> value obtained from <code class="filename"> /proc/meminfo </code> (2MB), this is 128MB / 2MB, or 64 Huge Pages. We call this value <em class="replaceable"> <code> P </code> </em> . </p> </li> <li class="listitem"> <p> As system root, open the file <code class="filename"> /etc/sysctl.conf </code> in a text editor, and add the line shown here, where <em class="replaceable"> <code> P </code> </em> is the number of large pages obtained in the previous step: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa61463335"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">vm.nr_hugepages</span><span class="token attr-value"><span class="token punctuation">=</span><em class="replaceable">P</em></span></code></pre> </div> <p> Using the actual value obtained previously, the additional line should look like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa3147095"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">vm.nr_hugepages</span><span class="token attr-value"><span class="token punctuation">=</span>66</span></code></pre> </div> <p> Save the updated file. </p> </li> <li class="listitem"> <p> As system root, run the following command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-simple"><div class="docs-select-all right" id="sa31987450"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-simple">$<span class="token operator">></span> sudo sysctl <span class="token operator">-</span>p</code></pre> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> On some systems the large pages file may be named slightly differently; for example, some distributions call it <code class="filename"> nr_hugepages </code> . In the event <span class="command"> <strong> sysctl </strong> </span> returns an error relating to the file name, check the name of the corresponding file in <code class="filename"> /proc/sys/vm </code> and use that instead. </p> </div> <p> To verify the large page configuration, check <code class="filename"> /proc/meminfo </code> again as described previously. Now you should see some additional nonzero values in the output, similar to this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa19754463"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">grep</span> <span class="token property">-i</span> huge /proc/meminfo AnonHugePages<span class="token punctuation">:</span> 2686976 kB ShmemHugePages<span class="token punctuation">:</span> 0 kB HugePages_Total<span class="token punctuation">:</span> 233 HugePages_Free<span class="token punctuation">:</span> 233 HugePages_Rsvd<span class="token punctuation">:</span> 0 HugePages_Surp<span class="token punctuation">:</span> 0 Hugepagesize<span class="token punctuation">:</span> 2048 kB Hugetlb<span class="token punctuation">:</span> 477184 kB</code></pre> </div> </li> <li class="listitem"> <p> Optionally, you may wish to compact the Linux VM. You can do this using a sequence of commands, possibly in a script file, similar to what is shown here: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-bash"><div class="docs-select-all right" id="sa57947087"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-bash"><span class="token function">sync</span> <span class="token function">sync</span> <span class="token function">sync</span> <span class="token keyword">echo</span> 3 <span class="token operator">></span> /proc/sys/vm/drop_caches <span class="token keyword">echo</span> 1 <span class="token operator">></span> /proc/sys/vm/compact_memory</code></pre> </div> <p> See your operating platform documentation for more information about how to do this. </p> </li> <li class="listitem"> <p> Check any configuration files such as <code class="filename"> my.cnf </code> used by the server, and make sure that <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> is set larger than the huge page size. The default for this variable is 128M. </p> </li> <li class="listitem"> <p> Large page support in the MySQL server is disabled by default. To enable it, start the server with <a class="link" href="server-options.html#option_mysqld_large-pages"> <code class="option"> --large-pages </code> </a> . You can also do so by adding the following line to the <code class="literal"> [mysqld] </code> section of the server <code class="filename"> my.cnf </code> file: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa62367466"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">large-pages</span><span class="token attr-value"><span class="token punctuation">=</span>ON</span></code></pre> </div> <p> With this option enabled, <code class="literal"> InnoDB </code> uses large pages automatically for its buffer pool and additional memory pool. If <code class="literal"> InnoDB </code> cannot do this, it falls back to use of traditional memory and writes a warning to the error log: <span class="errortext"> Warning: Using conventional memory pool </span> . </p> </li> </ol> </div> <p> You can verify that MySQL is now using large pages by checking <code class="filename"> /proc/meminfo </code> again after restarting <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> , like this: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa57815047"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">grep</span> <span class="token property">-i</span> huge /proc/meminfo AnonHugePages<span class="token punctuation">:</span> 2516992 kB ShmemHugePages<span class="token punctuation">:</span> 0 kB HugePages_Total<span class="token punctuation">:</span> 233 HugePages_Free<span class="token punctuation">:</span> 222 HugePages_Rsvd<span class="token punctuation">:</span> 55 HugePages_Surp<span class="token punctuation">:</span> 0 Hugepagesize<span class="token punctuation">:</span> 2048 kB Hugetlb<span class="token punctuation">:</span> 477184 kB</code></pre> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-table-distribution-status.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysql-cluster-ndbinfo-table-distribution-status"> </a> 25.6.17.57 The ndbinfo table_distribution_status Table </h4> </div> </div> </div> <a class="indexterm" name="idm46045087785536"> </a> <p> The <code class="literal"> table_distribution_status </code> table provides information about the progress of table distribution for <code class="literal"> NDB </code> tables. </p> <p> The <code class="literal"> table_distribution_status </code> table contains the following columns: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <code class="literal"> node_id </code> </p> <p> Node id </p> </li> <li class="listitem"> <p> <code class="literal"> table_id </code> </p> <p> Table ID </p> </li> <li class="listitem"> <p> <code class="literal"> tab_copy_status </code> </p> <p> Status of copying of table distribution data to disk; one of <code class="literal"> IDLE </code> , <code class="literal"> SR_PHASE1_READ_PAGES </code> , <code class="literal"> SR_PHASE2_READ_TABLE </code> , <code class="literal"> SR_PHASE3_COPY_TABLE </code> , <code class="literal"> REMOVE_NODE </code> , <code class="literal"> LCP_READ_TABLE </code> , <code class="literal"> COPY_TAB_REQ </code> , <code class="literal"> COPY_NODE_STATE </code> , <code class="literal"> ADD_TABLE_COORDINATOR </code> , <code class="literal"> ADD_TABLE_PARTICIPANT </code> , <code class="literal"> INVALIDATE_NODE_LCP </code> , <code class="literal"> ALTER_TABLE </code> , <code class="literal"> COPY_TO_SAVE </code> , or <code class="literal"> GET_TABINFO </code> </p> </li> <li class="listitem"> <p> <code class="literal"> tab_update_status </code> </p> <p> Status of updating of table distribution data; one of <code class="literal"> IDLE </code> , <code class="literal"> LOCAL_CHECKPOINT </code> , <code class="literal"> LOCAL_CHECKPOINT_QUEUED </code> , <code class="literal"> REMOVE_NODE </code> , <code class="literal"> COPY_TAB_REQ </code> , <code class="literal"> ADD_TABLE_MASTER </code> , <code class="literal"> ADD_TABLE_SLAVE </code> , <code class="literal"> INVALIDATE_NODE_LCP </code> , or <code class="literal"> CALLBACK </code> </p> </li> <li class="listitem"> <p> <code class="literal"> tab_lcp_status </code> </p> <p> Status of table LCP; one of <code class="literal"> ACTIVE </code> (waiting for local checkpoint to be performed), <code class="literal"> WRITING_TO_FILE </code> (checkpoint performed but not yet written to disk), or <code class="literal"> COMPLETED </code> (checkpoint performed and persisted to disk) </p> </li> <li class="listitem"> <p> <code class="literal"> tab_status </code> </p> <p> Table internal status; one of <code class="literal"> ACTIVE </code> (table exists), <code class="literal"> CREATING </code> (table is being created), or <code class="literal"> DROPPING </code> (table is being dropped) </p> </li> <li class="listitem"> <p> <code class="literal"> tab_storage </code> </p> <p> Table recoverability; one of <code class="literal"> NORMAL </code> (fully recoverable with redo logging and checkpointing), <code class="literal"> NOLOGGING </code> (recoverable from node crash, empty following cluster crash), or <code class="literal"> TEMPORARY </code> (not recoverable) </p> </li> <li class="listitem"> <p> <code class="literal"> tab_partitions </code> </p> <p> Number of partitions in table </p> </li> <li class="listitem"> <p> <code class="literal"> tab_fragments </code> </p> <p> Number of fragments in table; normally same as <code class="literal"> tab_partitions </code> ; for fully replicated tables equal to <code class="literal"> tab_partitions * [number of node groups] </code> </p> </li> <li class="listitem"> <p> <code class="literal"> current_scan_count </code> </p> <p> Current number of active scans </p> </li> <li class="listitem"> <p> <code class="literal"> scan_count_wait </code> </p> <p> Current number of scans waiting to be performed before <code class="literal"> ALTER TABLE </code> can complete. </p> </li> <li class="listitem"> <p> <code class="literal"> is_reorg_ongoing </code> </p> <p> Whether the table is currently being reorganized (1 if true) </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-information-schema-tables.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="mysql-cluster-information-schema-tables"> </a> 25.6.18 INFORMATION_SCHEMA Tables for NDB Cluster </h3> </div> </div> </div> <p> Two <a class="link" href="information-schema.html" title="Chapter 28 INFORMATION_SCHEMA Tables"> <code class="literal"> INFORMATION_SCHEMA </code> </a> tables provide information that is of particular use when managing an NDB Cluster. The <a class="link" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table"> <code class="literal"> FILES </code> </a> table provides information about NDB Cluster Disk Data files (see <a class="xref" href="mysql-cluster-disk-data-objects.html" title="25.6.11.1 NDB Cluster Disk Data Objects"> Section 25.6.11.1, “NDB Cluster Disk Data Objects” </a> ). The <a class="link" href="information-schema-ndb-transid-mysql-connection-map-table.html" title="28.3.18 The INFORMATION_SCHEMA ndb_transid_mysql_connection_map Table"> <code class="literal"> ndb_transid_mysql_connection_map </code> </a> table provides a mapping between transactions, transaction coordinators, and API nodes. </p> <p> Additional statistical and other data about NDB Cluster transactions, operations, threads, blocks, and other aspects of performance can be obtained from the tables in the <a class="link" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> <code class="literal"> ndbinfo </code> </a> database. For information about these tables, see <a class="xref" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> Section 25.6.17, “ndbinfo: The NDB Cluster Information Database” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/dynindex-is.html

<div id="docs-body"> <div class="index"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="dynindex-is"> </a> INFORMATION_SCHEMA Index </h2> </div> </div> </div> <p> <a name="is-index-top"> </a> <a class="link" href="dynindex-is.html#is-index-A" title="A"> A </a> | <a class="link" href="dynindex-is.html#is-index-C" title="C"> C </a> | <a class="link" href="dynindex-is.html#is-index-E" title="E"> E </a> | <a class="link" href="dynindex-is.html#is-index-F" title="F"> F </a> | <a class="link" href="dynindex-is.html#is-index-I" title="I"> I </a> | <a class="link" href="dynindex-is.html#is-index-K" title="K"> K </a> | <a class="link" href="dynindex-is.html#is-index-M" title="M"> M </a> | <a class="link" href="dynindex-is.html#is-index-N" title="N"> N </a> | <a class="link" href="dynindex-is.html#is-index-O" title="O"> O </a> | <a class="link" href="dynindex-is.html#is-index-P" title="P"> P </a> | <a class="link" href="dynindex-is.html#is-index-R" title="R"> R </a> | <a class="link" href="dynindex-is.html#is-index-S" title="S"> S </a> | <a class="link" href="dynindex-is.html#is-index-T" title="T"> T </a> | <a class="link" href="dynindex-is.html#is-index-U" title="U"> U </a> | <a class="link" href="dynindex-is.html#is-index-V" title="V"> V </a> </p> <div class="indexdiv"> <a name="is-index-A"> </a> <h3 class="title"> A </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ADMINISTRABLE_ROLE_AUTHORIZATIONS </h3> <dl> <dt> <a class="xref" href="information-schema-administrable-role-authorizations-table.html" title="28.3.2 The INFORMATION_SCHEMA ADMINISTRABLE_ROLE_AUTHORIZATIONS Table"> Section 28.3.2, “The INFORMATION_SCHEMA ADMINISTRABLE_ROLE_AUTHORIZATIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> APPLICABLE_ROLES </h3> <dl> <dt> <a class="xref" href="information-schema-applicable-roles-table.html" title="28.3.3 The INFORMATION_SCHEMA APPLICABLE_ROLES Table"> Section 28.3.3, “The INFORMATION_SCHEMA APPLICABLE_ROLES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-C"> </a> <h3 class="title"> C </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> CHARACTER_SETS </h3> <dl> <dt> <a class="xref" href="charset-introducer.html" title="12.3.8 Character Set Introducers"> Section 12.3.8, “Character Set Introducers” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-mysql.html" title="12.2 Character Sets and Collations in MySQL"> Section 12.2, “Character Sets and Collations in MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-literal.html" title="12.3.6 Character String Literal Character Set and Collation"> Section 12.3.6, “Character String Literal Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-column.html" title="12.3.5 Column Character Set and Collation"> Section 12.3.5, “Column Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-database.html" title="12.3.3 Database Character Set and Collation"> Section 12.3.3, “Database Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-character-set.html" title="15.7.7.4 SHOW CHARACTER SET Statement"> Section 15.7.7.4, “SHOW CHARACTER SET Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-charsets.html" title="12.10 Supported Character Sets and Collations"> Section 12.10, “Supported Character Sets and Collations” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-table.html" title="12.3.4 Table Character Set and Collation"> Section 12.3.4, “Table Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-character-sets-table.html" title="28.3.4 The INFORMATION_SCHEMA CHARACTER_SETS Table"> Section 28.3.4, “The INFORMATION_SCHEMA CHARACTER_SETS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> CHECK_CONSTRAINTS </h3> <dl> <dt> <a class="xref" href="create-table-check-constraints.html" title="15.1.20.6 CHECK Constraints"> Section 15.1.20.6, “CHECK Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-check-constraints-table.html" title="28.3.5 The INFORMATION_SCHEMA CHECK_CONSTRAINTS Table"> Section 28.3.5, “The INFORMATION_SCHEMA CHECK_CONSTRAINTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLLATION_CHARACTER_SET_APPLICABILITY </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-optimization.html" title="10.2.3 Optimizing INFORMATION_SCHEMA Queries"> Section 10.2.3, “Optimizing INFORMATION_SCHEMA Queries” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-collation-character-set-applicability-table.html" title="28.3.7 The INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY Table"> Section 28.3.7, “The INFORMATION_SCHEMA COLLATION_CHARACTER_SET_APPLICABILITY Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLLATIONS </h3> <dl> <dt> <a class="xref" href="charset-configuration.html" title="12.15 Character Set Configuration"> Section 12.15, “Character Set Configuration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-mysql.html" title="12.2 Character Sets and Collations in MySQL"> Section 12.2, “Character Sets and Collations in MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="adding-collation-choosing-id.html" title="12.14.2 Choosing a Collation ID"> Section 12.14.2, “Choosing a Collation ID” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-collation.html" title="15.7.7.5 SHOW COLLATION Statement"> Section 15.7.7.5, “SHOW COLLATION Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-binary-collations.html" title="12.8.5 The binary Collation Compared to _bin Collations"> Section 12.8.5, “The binary Collation Compared to _bin Collations” </a> </dt> <dd> </dd> <dt> <a class="xref" href="char.html" title="13.3.2 The CHAR and VARCHAR Types"> Section 13.3.2, “The CHAR and VARCHAR Types” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-collations-table.html" title="28.3.6 The INFORMATION_SCHEMA COLLATIONS Table"> Section 28.3.6, “The INFORMATION_SCHEMA COLLATIONS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-unicode-sets.html" title="12.10.1 Unicode Character Sets"> Section 12.10.1, “Unicode Character Sets” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLUMN_PRIVILEGES </h3> <dl> <dt> <a class="xref" href="information-schema-column-privileges-table.html" title="28.3.10 The INFORMATION_SCHEMA COLUMN_PRIVILEGES Table"> Section 28.3.10, “The INFORMATION_SCHEMA COLUMN_PRIVILEGES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLUMN_STATISTICS </h3> <dl> <dt> <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-column-statistics-table.html" title="28.3.11 The INFORMATION_SCHEMA COLUMN_STATISTICS Table"> Section 28.3.11, “The INFORMATION_SCHEMA COLUMN_STATISTICS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLUMNS </h3> <dl> <dt> <a class="xref" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> Section 15.1.20, “CREATE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-gipks.html" title="15.1.20.11 Generated Invisible Primary Keys"> Section 15.1.20.11, “Generated Invisible Primary Keys” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-introduction.html" title="28.1 Introduction"> Section 28.1, “Introduction” </a> </dt> <dd> </dd> <dt> <a class="xref" href="invisible-columns.html" title="15.1.20.10 Invisible Columns"> Section 15.1.20.10, “Invisible Columns” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-columns.html" title="15.7.7.6 SHOW COLUMNS Statement"> Section 15.7.7.6, “SHOW COLUMNS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> Section 28.3.8, “The INFORMATION_SCHEMA COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table"> Section 28.4.2, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table"> Section 28.4.3, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-pool-stats-table.html" title="28.4.4 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table"> Section 28.4.4, “The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cached-indexes-table.html" title="28.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table"> Section 28.4.5, “The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-table.html" title="28.4.6 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables"> Section 28.4.6, “The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> Section 28.4.8, “The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmpmem-table.html" title="28.4.7 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables"> Section 28.4.7, “The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-columns-table.html" title="28.4.9 The INFORMATION_SCHEMA INNODB_COLUMNS Table"> Section 28.4.9, “The INFORMATION_SCHEMA INNODB_COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-datafiles-table.html" title="28.4.10 The INFORMATION_SCHEMA INNODB_DATAFILES Table"> Section 28.4.10, “The INFORMATION_SCHEMA INNODB_DATAFILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-fields-table.html" title="28.4.11 The INFORMATION_SCHEMA INNODB_FIELDS Table"> Section 28.4.11, “The INFORMATION_SCHEMA INNODB_FIELDS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-foreign-table.html" title="28.4.12 The INFORMATION_SCHEMA INNODB_FOREIGN Table"> Section 28.4.12, “The INFORMATION_SCHEMA INNODB_FOREIGN Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-foreign-cols-table.html" title="28.4.13 The INFORMATION_SCHEMA INNODB_FOREIGN_COLS Table"> Section 28.4.13, “The INFORMATION_SCHEMA INNODB_FOREIGN_COLS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> Section 28.4.14, “The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-config-table.html" title="28.4.15 The INFORMATION_SCHEMA INNODB_FT_CONFIG Table"> Section 28.4.15, “The INFORMATION_SCHEMA INNODB_FT_CONFIG Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-default-stopword-table.html" title="28.4.16 The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table"> Section 28.4.16, “The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-deleted-table.html" title="28.4.17 The INFORMATION_SCHEMA INNODB_FT_DELETED Table"> Section 28.4.17, “The INFORMATION_SCHEMA INNODB_FT_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-index-cache-table.html" title="28.4.18 The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table"> Section 28.4.18, “The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-index-table-table.html" title="28.4.19 The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table"> Section 28.4.19, “The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-indexes-table.html" title="28.4.20 The INFORMATION_SCHEMA INNODB_INDEXES Table"> Section 28.4.20, “The INFORMATION_SCHEMA INNODB_INDEXES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> Section 28.4.21, “The INFORMATION_SCHEMA INNODB_METRICS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-session-temp-tablespaces-table.html" title="28.4.22 The INFORMATION_SCHEMA INNODB_SESSION_TEMP_TABLESPACES Table"> Section 28.4.22, “The INFORMATION_SCHEMA INNODB_SESSION_TEMP_TABLESPACES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tables-table.html" title="28.4.23 The INFORMATION_SCHEMA INNODB_TABLES Table"> Section 28.4.23, “The INFORMATION_SCHEMA INNODB_TABLES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-table.html" title="28.4.24 The INFORMATION_SCHEMA INNODB_TABLESPACES Table"> Section 28.4.24, “The INFORMATION_SCHEMA INNODB_TABLESPACES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> Section 28.4.25, “The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablestats-table.html" title="28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View"> Section 28.4.26, “The INFORMATION_SCHEMA INNODB_TABLESTATS View” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-temp-table-info-table.html" title="28.4.27 The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table"> Section 28.4.27, “The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-trx-table.html" title="28.4.28 The INFORMATION_SCHEMA INNODB_TRX Table"> Section 28.4.28, “The INFORMATION_SCHEMA INNODB_TRX Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-virtual-table.html" title="28.4.29 The INFORMATION_SCHEMA INNODB_VIRTUAL Table"> Section 28.4.29, “The INFORMATION_SCHEMA INNODB_VIRTUAL Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-st-geometry-columns-table.html" title="28.3.35 The INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS Table"> Section 28.3.35, “The INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="upgrade-binary-package.html" title="3.7 Upgrading MySQL Binary or Package-based Installations on Unix/Linux"> Section 3.7, “Upgrading MySQL Binary or Package-based Installations on Unix/Linux” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> COLUMNS_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="information-schema-columns-extensions-table.html" title="28.3.9 The INFORMATION_SCHEMA COLUMNS_EXTENSIONS Table"> Section 28.3.9, “The INFORMATION_SCHEMA COLUMNS_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS </h3> <dl> <dt> <a class="xref" href="connection-control-installation.html" title="8.4.2.1 Connection-Control Plugin Installation"> Section 8.4.2.1, “Connection-Control Plugin Installation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="connection-control-variables.html" title="8.4.2.2 Connection-Control System and Status Variables"> Section 8.4.2.2, “Connection-Control System and Status Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="connection-control.html" title="8.4.2 The Connection-Control Plugins"> Section 8.4.2, “The Connection-Control Plugins” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-connection-control-failed-login-attempts-table.html" title="28.6.2 The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table"> Section 28.6.2, “The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-E"> </a> <h3 class="title"> E </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ENABLED_ROLES </h3> <dl> <dt> <a class="xref" href="information-schema-enabled-roles-table.html" title="28.3.12 The INFORMATION_SCHEMA ENABLED_ROLES Table"> Section 28.3.12, “The INFORMATION_SCHEMA ENABLED_ROLES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ENGINES </h3> <dl> <dt> <a class="xref" href="performance-schema-quick-start.html" title="29.1 Performance Schema Quick Start"> Section 29.1, “Performance Schema Quick Start” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-sql-statements.html" title="25.6.20 Quick Reference: NDB Cluster SQL Statements"> Section 25.6.20, “Quick Reference: NDB Cluster SQL Statements” </a> </dt> <dd> </dd> <dt> <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-engines.html" title="15.7.7.17 SHOW ENGINES Statement"> Section 15.7.7.17, “SHOW ENGINES Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-engines-table.html" title="28.3.13 The INFORMATION_SCHEMA ENGINES Table"> Section 28.3.13, “The INFORMATION_SCHEMA ENGINES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-check-availability.html" title="17.1.3 Verifying that InnoDB is the Default Storage Engine"> Section 17.1.3, “Verifying that InnoDB is the Default Storage Engine” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> EVENTS </h3> <dl> <dt> <a class="xref" href="replication-howto-additionalslaves.html" title="19.1.2.8 Adding Replicas to a Replication Environment"> Section 19.1.2.8, “Adding Replicas to a Replication Environment” </a> </dt> <dd> </dd> <dt> <a class="xref" href="events-metadata.html" title="27.4.4 Event Metadata"> Section 27.4.4, “Event Metadata” </a> </dt> <dd> </dd> <dt> <a class="xref" href="events-configuration.html" title="27.4.2 Event Scheduler Configuration"> Section 27.4.2, “Event Scheduler Configuration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="replication-features-invoked.html" title="19.5.1.16 Replication of Invoked Features"> Section 19.5.1.16, “Replication of Invoked Features” </a> </dt> <dd> </dd> <dt> <a class="xref" href="stored-program-restrictions.html" title="27.8 Restrictions on Stored Programs"> Section 27.8, “Restrictions on Stored Programs” </a> </dt> <dd> </dd> <dt> <a class="xref" href="replication-setup-replicas.html#replication-howto-existingdata" title="19.1.2.6.2 Setting Up Replication with Existing Data"> Section 19.1.2.6.2, “Setting Up Replication with Existing Data” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-events.html" title="15.7.7.19 SHOW EVENTS Statement"> Section 15.7.7.19, “SHOW EVENTS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="events-privileges.html" title="27.4.6 The Event Scheduler and MySQL Privileges"> Section 27.4.6, “The Event Scheduler and MySQL Privileges” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-events-table.html" title="28.3.14 The INFORMATION_SCHEMA EVENTS Table"> Section 28.3.14, “The INFORMATION_SCHEMA EVENTS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-F"> </a> <h3 class="title"> F </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> FILES </h3> <dl> <dt> <a class="xref" href="alter-logfile-group.html" title="15.1.6 ALTER LOGFILE GROUP Statement"> Section 15.1.6, “ALTER LOGFILE GROUP Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="alter-tablespace.html" title="15.1.10 ALTER TABLESPACE Statement"> Section 15.1.10, “ALTER TABLESPACE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="clone-plugin-remote.html" title="7.6.7.3 Cloning Remote Data"> Section 7.6.7.3, “Cloning Remote Data” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-logfile-group.html" title="15.1.16 CREATE LOGFILE GROUP Statement"> Section 15.1.16, “CREATE LOGFILE GROUP Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> Section 15.1.21, “CREATE TABLESPACE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-information-schema-tables.html" title="25.6.18 INFORMATION_SCHEMA Tables for NDB Cluster"> Section 25.6.18, “INFORMATION_SCHEMA Tables for NDB Cluster” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-moving-data-files-offline.html" title="17.6.3.6 Moving Tablespace Files While the Server is Offline"> Section 17.6.3.6, “Moving Tablespace Files While the Server is Offline” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-disk-data-objects.html" title="25.6.11.1 NDB Cluster Disk Data Objects"> Section 25.6.11.1, “NDB Cluster Disk Data Objects” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-disk-data-storage-requirements.html" title="25.6.11.2 NDB Cluster Disk Data Storage Requirements"> Section 25.6.11.2, “NDB Cluster Disk Data Storage Requirements” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-programs-ndb-desc.html" title="25.5.9 ndb_desc — Describe NDB Tables"> Section 25.5.9, “ndb_desc — Describe NDB Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> Section 25.6.17, “ndbinfo: The NDB Cluster Information Database” </a> </dt> <dd> </dd> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-files-table.html" title="17.15.8 Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES"> Section 17.15.8, “Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-temporary-tablespace.html" title="17.6.3.5 Temporary Tablespaces"> Section 17.6.3.5, “Temporary Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table"> Section 28.3.15, “The INFORMATION_SCHEMA FILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-datafiles-table.html" title="28.4.10 The INFORMATION_SCHEMA INNODB_DATAFILES Table"> Section 28.4.10, “The INFORMATION_SCHEMA INNODB_DATAFILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-table.html" title="28.4.24 The INFORMATION_SCHEMA INNODB_TABLESPACES Table"> Section 28.4.24, “The INFORMATION_SCHEMA INNODB_TABLESPACES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-dict-obj-info.html" title="25.6.17.25 The ndbinfo dict_obj_info Table"> Section 25.6.17.25, “The ndbinfo dict_obj_info Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-dict-obj-tree.html" title="25.6.17.26 The ndbinfo dict_obj_tree Table"> Section 25.6.17.26, “The ndbinfo dict_obj_tree Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-logbuffers.html" title="25.6.17.43 The ndbinfo logbuffers Table"> Section 25.6.17.43, “The ndbinfo logbuffers Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-logspaces.html" title="25.6.17.44 The ndbinfo logspaces Table"> Section 25.6.17.44, “The ndbinfo logspaces Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-I"> </a> <h3 class="title"> I </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA </h3> <dl> <dt> <a class="xref" href="data-dictionary-schema.html" title="16.1 Data Dictionary Schema"> Section 16.1, “Data Dictionary Schema” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-information-schema-tables.html" title="25.6.18 INFORMATION_SCHEMA Tables for NDB Cluster"> Section 25.6.18, “INFORMATION_SCHEMA Tables for NDB Cluster” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema.html" title="17.15 InnoDB INFORMATION_SCHEMA Tables"> Section 17.15, “InnoDB INFORMATION_SCHEMA Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary.html" title="Chapter 16 MySQL Data Dictionary"> Chapter 16, <i> MySQL Data Dictionary </i> </a> </dt> <dd> </dd> <dt> <a class="xref" href="glossary.html" title="MySQL Glossary"> MySQL Glossary </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-security-mysql-privileges.html" title="25.6.21.2 NDB Cluster and MySQL Privileges"> Section 25.6.21.2, “NDB Cluster and MySQL Privileges” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-online-ddl-operations.html" title="17.12.1 Online DDL Operations"> Section 17.12.1, “Online DDL Operations” </a> </dt> <dd> </dd> <dt> <a class="xref" href="reserved-accounts.html" title="8.2.9 Reserved Accounts"> Section 8.2.9, “Reserved Accounts” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-directory.html" title="7.2 The MySQL Data Directory"> Section 7.2, “The MySQL Data Directory” </a> </dt> <dd> </dd> <dt> <a class="xref" href="charset-unicode-utf8.html" title="12.9.3 The utf8 Character Set (Deprecated alias for utf8mb3)"> Section 12.9.3, “The utf8 Character Set (Deprecated alias for utf8mb3)” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-schema-usage.html" title="30.2 Using the sys Schema"> Section 30.2, “Using the sys Schema” </a> </dt> <dd> </dd> <dt> <a class="xref" href="upgrading-what-is-upgraded.html" title="3.4 What the MySQL Upgrade Process Upgrades"> Section 3.4, “What the MySQL Upgrade Process Upgrades” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.CHARACTER_SETS </h3> <dl> <dt> <a class="xref" href="faqs-cjk.html" title="A.11 MySQL 8.4 FAQ: MySQL Chinese, Japanese, and Korean Character Sets"> Section A.11, “MySQL 8.4 FAQ: MySQL Chinese, Japanese, and Korean Character Sets” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.COLUMN_STATISTICS </h3> <dl> <dt> <a class="xref" href="controlling-optimizer.html" title="10.9 Controlling the Query Optimizer"> Section 10.9, “Controlling the Query Optimizer” </a> </dt> <dd> </dd> <dt> <a class="xref" href="optimizer-statistics.html" title="10.9.6 Optimizer Statistics"> Section 10.9.6, “Optimizer Statistics” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.COLUMNS </h3> <dl> <dt> <a class="xref" href="mysql-cluster-programs-ndb-index-stat.html" title="25.5.14 ndb_index_stat — NDB Index Statistics Utility"> Section 25.5.14, “ndb_index_stat — NDB Index Statistics Utility” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-quick-start.html" title="29.1 Performance Schema Quick Start"> Section 29.1, “Performance Schema Quick Start” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.EVENTS </h3> <dl> <dt> <a class="xref" href="replication-features-invoked.html" title="19.5.1.16 Replication of Invoked Features"> Section 19.5.1.16, “Replication of Invoked Features” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.FILES </h3> <dl> <dt> <a class="xref" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> Section 15.1.21, “CREATE TABLESPACE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-dict-obj-tree.html" title="25.6.17.26 The ndbinfo dict_obj_tree Table"> Section 25.6.17.26, “The ndbinfo dict_obj_tree Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_CMP </h3> <dl> <dt> <a class="xref" href="glossary.html" title="MySQL Glossary"> MySQL Glossary </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning.html" title="17.9.1.3 Tuning Compression for InnoDB Tables"> Section 17.9.1.3, “Tuning Compression for InnoDB Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_CMP_PER_INDEX </h3> <dl> <dt> <a class="xref" href="innodb-compression-tuning.html" title="17.9.1.3 Tuning Compression for InnoDB Tables"> Section 17.9.1.3, “Tuning Compression for InnoDB Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_CMPMEM </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_TABLES </h3> <dl> <dt> <a class="xref" href="partitioning-management-exchange.html" title="26.3.3 Exchanging Partitions and Subpartitions with Tables"> Section 26.3.3, “Exchanging Partitions and Subpartitions with Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_TABLESPACES </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.INNODB_TABLESTATS </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.OPTIMIZER_TRACE </h3> <dl> <dt> <a class="xref" href="optimizer-tracing.html" title="10.15 Tracing the Optimizer"> Section 10.15, “Tracing the Optimizer” </a> </dt> <dd> </dd> <dt> <a class="xref" href="optimizer-tracing-typical-usage.html" title="10.15.1 Typical Usage"> Section 10.15.1, “Typical Usage” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.PARTITIONS </h3> <dl> <dt> <a class="xref" href="partitioning-handling-nulls.html" title="26.2.7 How MySQL Partitioning Handles NULL"> Section 26.2.7, “How MySQL Partitioning Handles NULL” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.PROCESSLIST </h3> <dl> <dt> <a class="xref" href="information-schema-processlist-table.html" title="28.3.23 The INFORMATION_SCHEMA PROCESSLIST Table"> Section 28.3.23, “The INFORMATION_SCHEMA PROCESSLIST Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> information_schema.processlist </h3> <dl> <dt> <a class="xref" href="server-status-variables.html" title="7.1.10 Server Status Variables"> Section 7.1.10, “Server Status Variables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.ROUTINES </h3> <dl> <dt> <a class="xref" href="faqs-stored-procs.html" title="A.4 MySQL 8.4 FAQ: Stored Procedures and Functions"> Section A.4, “MySQL 8.4 FAQ: Stored Procedures and Functions” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.STATISTICS </h3> <dl> <dt> <a class="xref" href="mysql-cluster-programs-ndb-index-stat.html" title="25.5.14 ndb_index_stat — NDB Index Statistics Utility"> Section 25.5.14, “ndb_index_stat — NDB Index Statistics Utility” </a> </dt> <dd> </dd> <dt> <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.TABLES </h3> <dl> <dt> <a class="xref" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> Section 17.13, “InnoDB Data-at-Rest Encryption” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INFORMATION_SCHEMA.TRIGGERS </h3> <dl> <dt> <a class="xref" href="faqs-triggers.html" title="A.5 MySQL 8.4 FAQ: Triggers"> Section A.5, “MySQL 8.4 FAQ: Triggers” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_BUFFER_PAGE </h3> <dl> <dt> <a class="xref" href="innodb-change-buffer.html" title="17.5.2 Change Buffer"> Section 17.5.2, “Change Buffer” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-buffer-pool-tables.html" title="17.15.5 InnoDB INFORMATION_SCHEMA Buffer Pool Tables"> Section 17.15.5, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-schema-prerequisites.html" title="30.1 Prerequisites for Using the sys Schema"> Section 30.1, “Prerequisites for Using the sys Schema” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-table.html" title="28.4.2 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table"> Section 28.4.2, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table"> Section 28.4.3, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-innodb-buffer-stats-by-schema.html" title="30.4.3.7 The innodb_buffer_stats_by_schema and x$innodb_buffer_stats_by_schema Views"> Section 30.4.3.7, “The innodb_buffer_stats_by_schema and x$innodb_buffer_stats_by_schema Views” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-innodb-buffer-stats-by-table.html" title="30.4.3.8 The innodb_buffer_stats_by_table and x$innodb_buffer_stats_by_table Views"> Section 30.4.3.8, “The innodb_buffer_stats_by_table and x$innodb_buffer_stats_by_table Views” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_BUFFER_PAGE_LRU </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-buffer-pool-tables.html" title="17.15.5 InnoDB INFORMATION_SCHEMA Buffer Pool Tables"> Section 17.15.5, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-page-lru-table.html" title="28.4.3 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table"> Section 28.4.3, “The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_BUFFER_POOL_STATS </h3> <dl> <dt> <a class="xref" href="innodb-buffer-pool.html" title="17.5.1 Buffer Pool"> Section 17.5.1, “Buffer Pool” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-buffer-pool-tables.html" title="17.15.5 InnoDB INFORMATION_SCHEMA Buffer Pool Tables"> Section 17.15.5, “InnoDB INFORMATION_SCHEMA Buffer Pool Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-buffer-pool-stats-table.html" title="28.4.4 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table"> Section 28.4.4, “The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CACHED_INDEXES </h3> <dl> <dt> <a class="xref" href="information-schema-innodb-cached-indexes-table.html" title="28.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table"> Section 28.4.5, “The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMP </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-compression-tables.html" title="17.15.1 InnoDB INFORMATION_SCHEMA Tables about Compression"> Section 17.15.1, “InnoDB INFORMATION_SCHEMA Tables about Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmp.html" title="17.15.1.1 INNODB_CMP and INNODB_CMP_RESET"> Section 17.15.1.1, “INNODB_CMP and INNODB_CMP_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmpmem.html" title="17.15.1.2 INNODB_CMPMEM and INNODB_CMPMEM_RESET"> Section 17.15.1.2, “INNODB_CMPMEM and INNODB_CMPMEM_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning-monitoring.html" title="17.9.1.4 Monitoring InnoDB Table Compression at Runtime"> Section 17.9.1.4, “Monitoring InnoDB Table Compression at Runtime” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-table.html" title="28.4.6 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables"> Section 28.4.6, “The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning.html" title="17.9.1.3 Tuning Compression for InnoDB Tables"> Section 17.9.1.3, “Tuning Compression for InnoDB Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMP_PER_INDEX </h3> <dl> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning-monitoring.html" title="17.9.1.4 Monitoring InnoDB Table Compression at Runtime"> Section 17.9.1.4, “Monitoring InnoDB Table Compression at Runtime” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> Section 28.4.8, “The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-compression-tuning.html" title="17.9.1.3 Tuning Compression for InnoDB Tables"> Section 17.9.1.3, “Tuning Compression for InnoDB Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMP_PER_INDEX_RESET </h3> <dl> <dt> <a class="xref" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> Section 28.4.8, “The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMP_RESET </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-compression-tables.html" title="17.15.1 InnoDB INFORMATION_SCHEMA Tables about Compression"> Section 17.15.1, “InnoDB INFORMATION_SCHEMA Tables about Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmp.html" title="17.15.1.1 INNODB_CMP and INNODB_CMP_RESET"> Section 17.15.1.1, “INNODB_CMP and INNODB_CMP_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmpmem.html" title="17.15.1.2 INNODB_CMPMEM and INNODB_CMPMEM_RESET"> Section 17.15.1.2, “INNODB_CMPMEM and INNODB_CMPMEM_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmp-table.html" title="28.4.6 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables"> Section 28.4.6, “The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMPMEM </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-compression-tables.html" title="17.15.1 InnoDB INFORMATION_SCHEMA Tables about Compression"> Section 17.15.1, “InnoDB INFORMATION_SCHEMA Tables about Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmpmem.html" title="17.15.1.2 INNODB_CMPMEM and INNODB_CMPMEM_RESET"> Section 17.15.1.2, “INNODB_CMPMEM and INNODB_CMPMEM_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmpmem-table.html" title="28.4.7 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables"> Section 28.4.7, “The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples-compression-sect.html" title="17.15.1.3 Using the Compression Information Schema Tables"> Section 17.15.1.3, “Using the Compression Information Schema Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_CMPMEM_RESET </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-compression-tables.html" title="17.15.1 InnoDB INFORMATION_SCHEMA Tables about Compression"> Section 17.15.1, “InnoDB INFORMATION_SCHEMA Tables about Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-innodb_cmpmem.html" title="17.15.1.2 INNODB_CMPMEM and INNODB_CMPMEM_RESET"> Section 17.15.1.2, “INNODB_CMPMEM and INNODB_CMPMEM_RESET” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cmpmem-table.html" title="28.4.7 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables"> Section 28.4.7, “The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_COLUMNS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-columns-table.html" title="28.4.9 The INFORMATION_SCHEMA INNODB_COLUMNS Table"> Section 28.4.9, “The INFORMATION_SCHEMA INNODB_COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-virtual-table.html" title="28.4.29 The INFORMATION_SCHEMA INNODB_VIRTUAL Table"> Section 28.4.29, “The INFORMATION_SCHEMA INNODB_VIRTUAL Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_DATAFILES </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-files-table.html" title="17.15.8 Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES"> Section 17.15.8, “Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table"> Section 28.3.15, “The INFORMATION_SCHEMA FILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-datafiles-table.html" title="28.4.10 The INFORMATION_SCHEMA INNODB_DATAFILES Table"> Section 28.4.10, “The INFORMATION_SCHEMA INNODB_DATAFILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> Section 28.4.25, “The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FIELDS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-fields-table.html" title="28.4.11 The INFORMATION_SCHEMA INNODB_FIELDS Table"> Section 28.4.11, “The INFORMATION_SCHEMA INNODB_FIELDS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FOREIGN </h3> <dl> <dt> <a class="xref" href="constraint-foreign-key.html" title="1.7.3.2 FOREIGN KEY Constraints"> Section 1.7.3.2, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-foreign-keys.html" title="15.1.20.5 FOREIGN KEY Constraints"> Section 15.1.20.5, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-foreign-table.html" title="28.4.12 The INFORMATION_SCHEMA INNODB_FOREIGN Table"> Section 28.4.12, “The INFORMATION_SCHEMA INNODB_FOREIGN Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FOREIGN_COLS </h3> <dl> <dt> <a class="xref" href="constraint-foreign-key.html" title="1.7.3.2 FOREIGN KEY Constraints"> Section 1.7.3.2, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-foreign-keys.html" title="15.1.20.5 FOREIGN KEY Constraints"> Section 15.1.20.5, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-foreign-cols-table.html" title="28.4.13 The INFORMATION_SCHEMA INNODB_FOREIGN_COLS Table"> Section 28.4.13, “The INFORMATION_SCHEMA INNODB_FOREIGN_COLS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_BEING_DELETED </h3> <dl> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> Section 28.4.14, “The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_CONFIG </h3> <dl> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-config-table.html" title="28.4.15 The INFORMATION_SCHEMA INNODB_FT_CONFIG Table"> Section 28.4.15, “The INFORMATION_SCHEMA INNODB_FT_CONFIG Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_DEFAULT_STOPWORD </h3> <dl> <dt> <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-default-stopword-table.html" title="28.4.16 The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table"> Section 28.4.16, “The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_DELETED </h3> <dl> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> Section 28.4.14, “The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-deleted-table.html" title="28.4.17 The INFORMATION_SCHEMA INNODB_FT_DELETED Table"> Section 28.4.17, “The INFORMATION_SCHEMA INNODB_FT_DELETED Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_INDEX_CACHE </h3> <dl> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="fulltext-search-mecab.html" title="14.9.9 MeCab Full-Text Parser Plugin"> Section 14.9.9, “MeCab Full-Text Parser Plugin” </a> </dt> <dd> </dd> <dt> <a class="xref" href="fulltext-search-ngram.html" title="14.9.8 ngram Full-Text Parser"> Section 14.9.8, “ngram Full-Text Parser” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-index-cache-table.html" title="28.4.18 The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table"> Section 28.4.18, “The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_FT_INDEX_TABLE </h3> <dl> <dt> <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> Section 28.4.14, “The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-deleted-table.html" title="28.4.17 The INFORMATION_SCHEMA INNODB_FT_DELETED Table"> Section 28.4.17, “The INFORMATION_SCHEMA INNODB_FT_DELETED Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-ft-index-table-table.html" title="28.4.19 The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table"> Section 28.4.19, “The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_INDEXES </h3> <dl> <dt> <a class="xref" href="index-page-merge-threshold.html" title="17.8.11 Configuring the Merge Threshold for Index Pages"> Section 17.8.11, “Configuring the Merge Threshold for Index Pages” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cached-indexes-table.html" title="28.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table"> Section 28.4.5, “The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-indexes-table.html" title="28.4.20 The INFORMATION_SCHEMA INNODB_INDEXES Table"> Section 28.4.20, “The INFORMATION_SCHEMA INNODB_INDEXES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_METRICS </h3> <dl> <dt> <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-change-buffer.html" title="17.5.2 Change Buffer"> Section 17.5.2, “Change Buffer” </a> </dt> <dd> </dd> <dt> <a class="xref" href="index-page-merge-threshold.html" title="17.8.11 Configuring the Merge Threshold for Index Pages"> Section 17.8.11, “Configuring the Merge Threshold for Index Pages” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="glossary.html" title="MySQL Glossary"> MySQL Glossary </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> Section 28.4.21, “The INFORMATION_SCHEMA INNODB_METRICS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-metrics.html" title="30.4.3.21 The metrics View"> Section 30.4.3.21, “The metrics View” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-transaction-scheduling.html" title="17.7.6 Transaction Scheduling"> Section 17.7.6, “Transaction Scheduling” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_SESSION_TEMP_TABLESPACES </h3> <dl> <dt> <a class="xref" href="innodb-temporary-tablespace.html" title="17.6.3.5 Temporary Tablespaces"> Section 17.6.3.5, “Temporary Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-session-temp-tablespaces-table.html" title="28.4.22 The INFORMATION_SCHEMA INNODB_SESSION_TEMP_TABLESPACES Table"> Section 28.4.22, “The INFORMATION_SCHEMA INNODB_SESSION_TEMP_TABLESPACES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TABLES </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-row-format.html" title="17.10 InnoDB Row Formats"> Section 17.10, “InnoDB Row Formats” </a> </dt> <dd> </dd> <dt> <a class="xref" href="identifier-mapping.html" title="11.2.4 Mapping of Identifiers to File Names"> Section 11.2.4, “Mapping of Identifiers to File Names” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-cached-indexes-table.html" title="28.4.5 The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table"> Section 28.4.5, “The INFORMATION_SCHEMA INNODB_CACHED_INDEXES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tables-table.html" title="28.4.23 The INFORMATION_SCHEMA INNODB_TABLES Table"> Section 28.4.23, “The INFORMATION_SCHEMA INNODB_TABLES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TABLESPACES </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> Section 17.13, “InnoDB Data-at-Rest Encryption” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-page-compression.html" title="17.9.2 InnoDB Page Compression"> Section 17.9.2, “InnoDB Page Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-files-table.html" title="17.15.8 Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES"> Section 17.15.8, “Retrieving InnoDB Tablespace Metadata from INFORMATION_SCHEMA.FILES” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement"> Section 15.7.7.38, “SHOW TABLE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-tablespace-autoextend-size.html" title="17.6.3.9 Tablespace AUTOEXTEND_SIZE Configuration"> Section 17.6.3.9, “Tablespace AUTOEXTEND_SIZE Configuration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-files-table.html" title="28.3.15 The INFORMATION_SCHEMA FILES Table"> Section 28.3.15, “The INFORMATION_SCHEMA FILES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-table.html" title="28.4.24 The INFORMATION_SCHEMA INNODB_TABLESPACES Table"> Section 28.4.24, “The INFORMATION_SCHEMA INNODB_TABLESPACES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> Section 28.4.25, “The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> Section 28.3.38, “The INFORMATION_SCHEMA TABLES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-nutshell.html" title="1.4 What Is New in MySQL 8.4 since MySQL 8.0"> Section 1.4, “What Is New in MySQL 8.4 since MySQL 8.0” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TABLESPACES_BRIEF </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablespaces-brief-table.html" title="28.4.25 The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table"> Section 28.4.25, “The INFORMATION_SCHEMA INNODB_TABLESPACES_BRIEF Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TABLESTATS </h3> <dl> <dt> <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-system-tables.html" title="17.15.3 InnoDB INFORMATION_SCHEMA Schema Object Tables"> Section 17.15.3, “InnoDB INFORMATION_SCHEMA Schema Object Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-tablestats-table.html" title="28.4.26 The INFORMATION_SCHEMA INNODB_TABLESTATS View"> Section 28.4.26, “The INFORMATION_SCHEMA INNODB_TABLESTATS View” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TEMP_TABLE_INFO </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-temp-table-info.html" title="17.15.7 InnoDB INFORMATION_SCHEMA Temporary Table Info Table"> Section 17.15.7, “InnoDB INFORMATION_SCHEMA Temporary Table Info Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-temporary-tablespace.html" title="17.6.3.5 Temporary Tablespaces"> Section 17.6.3.5, “Temporary Tablespaces” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-temp-table-info-table.html" title="28.4.27 The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table"> Section 28.4.27, “The INFORMATION_SCHEMA INNODB_TEMP_TABLE_INFO Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_TRX </h3> <dl> <dt> <a class="xref" href="innodb-information-schema-transactions.html" title="17.15.2 InnoDB INFORMATION_SCHEMA Transaction and Locking Information"> Section 17.15.2, “InnoDB INFORMATION_SCHEMA Transaction and Locking Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-understanding-innodb-locking.html" title="17.15.2.2 InnoDB Lock and Lock-Wait Information"> Section 17.15.2.2, “InnoDB Lock and Lock-Wait Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-internal-data.html" title="17.15.2.3 Persistence and Consistency of InnoDB Transaction and Locking Information"> Section 17.15.2.3, “Persistence and Consistency of InnoDB Transaction and Locking Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-data-locks-table.html" title="29.12.13.1 The data_locks Table"> Section 29.12.13.1, “The data_locks Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-trx-table.html" title="28.4.28 The INFORMATION_SCHEMA INNODB_TRX Table"> Section 28.4.28, “The INFORMATION_SCHEMA INNODB_TRX Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-transaction-scheduling.html" title="17.7.6 Transaction Scheduling"> Section 17.7.6, “Transaction Scheduling” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples.html" title="17.15.2.1 Using InnoDB Transaction and Locking Information"> Section 17.15.2.1, “Using InnoDB Transaction and Locking Information” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> INNODB_VIRTUAL </h3> <dl> <dt> <a class="xref" href="information-schema-innodb-virtual-table.html" title="28.4.29 The INFORMATION_SCHEMA INNODB_VIRTUAL Table"> Section 28.4.29, “The INFORMATION_SCHEMA INNODB_VIRTUAL Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-K"> </a> <h3 class="title"> K </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> KEY_COLUMN_USAGE </h3> <dl> <dt> <a class="xref" href="constraint-foreign-key.html" title="1.7.3.2 FOREIGN KEY Constraints"> Section 1.7.3.2, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-foreign-keys.html" title="15.1.20.5 FOREIGN KEY Constraints"> Section 15.1.20.5, “FOREIGN KEY Constraints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-key-column-usage-table.html" title="28.3.16 The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table"> Section 28.3.16, “The INFORMATION_SCHEMA KEY_COLUMN_USAGE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> KEYWORDS </h3> <dl> <dt> <a class="xref" href="information-schema-keywords-table.html" title="28.3.17 The INFORMATION_SCHEMA KEYWORDS Table"> Section 28.3.17, “The INFORMATION_SCHEMA KEYWORDS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-M"> </a> <h3 class="title"> M </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> MYSQL_FIREWALL_USERS </h3> <dl> <dt> <a class="xref" href="firewall-reference.html" title="8.4.7.4 MySQL Enterprise Firewall Reference"> Section 8.4.7.4, “MySQL Enterprise Firewall Reference” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-mysql-firewall-users-table.html" title="28.7.2 The INFORMATION_SCHEMA MYSQL_FIREWALL_USERS Table"> Section 28.7.2, “The INFORMATION_SCHEMA MYSQL_FIREWALL_USERS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="firewall-usage.html" title="8.4.7.3 Using MySQL Enterprise Firewall"> Section 8.4.7.3, “Using MySQL Enterprise Firewall” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> MYSQL_FIREWALL_WHITELIST </h3> <dl> <dt> <a class="xref" href="firewall-reference.html" title="8.4.7.4 MySQL Enterprise Firewall Reference"> Section 8.4.7.4, “MySQL Enterprise Firewall Reference” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-mysql-firewall-whitelist-table.html" title="28.7.3 The INFORMATION_SCHEMA MYSQL_FIREWALL_WHITELIST Table"> Section 28.7.3, “The INFORMATION_SCHEMA MYSQL_FIREWALL_WHITELIST Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-N"> </a> <h3 class="title"> N </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> NDB_TRANSID_MYSQL_CONNECTION_MAP </h3> <dl> <dt> <a class="xref" href="mysql-cluster-ndbinfo-server-operations.html" title="25.6.17.55 The ndbinfo server_operations Table"> Section 25.6.17.55, “The ndbinfo server_operations Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo-server-transactions.html" title="25.6.17.56 The ndbinfo server_transactions Table"> Section 25.6.17.56, “The ndbinfo server_transactions Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ndb_transid_mysql_connection_map </h3> <dl> <dt> <a class="xref" href="mysql-cluster-information-schema-tables.html" title="25.6.18 INFORMATION_SCHEMA Tables for NDB Cluster"> Section 25.6.18, “INFORMATION_SCHEMA Tables for NDB Cluster” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-options-variables.html#mysql-cluster-program-options-mysqld" title="25.4.3.9.1 MySQL Server Options for NDB Cluster"> Section 25.4.3.9.1, “MySQL Server Options for NDB Cluster” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-ndbinfo.html" title="25.6.17 ndbinfo: The NDB Cluster Information Database"> Section 25.6.17, “ndbinfo: The NDB Cluster Information Database” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-O"> </a> <h3 class="title"> O </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> OPTIMIZER_TRACE </h3> <dl> <dt> <a class="xref" href="range-optimization.html" title="10.2.1.2 Range Optimization"> Section 10.2.1.2, “Range Optimization” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-optimizer-trace-table.html" title="28.3.19 The INFORMATION_SCHEMA OPTIMIZER_TRACE Table"> Section 28.3.19, “The INFORMATION_SCHEMA OPTIMIZER_TRACE Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="tuning-trace-purging.html" title="10.15.4 Tuning Trace Purging"> Section 10.15.4, “Tuning Trace Purging” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-P"> </a> <h3 class="title"> P </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PARAMETERS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="faqs-stored-procs.html" title="A.4 MySQL 8.4 FAQ: Stored Procedures and Functions"> Section A.4, “MySQL 8.4 FAQ: Stored Procedures and Functions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-procedure-status.html" title="15.7.7.30 SHOW PROCEDURE STATUS Statement"> Section 15.7.7.30, “SHOW PROCEDURE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-parameters-table.html" title="28.3.20 The INFORMATION_SCHEMA PARAMETERS Table"> Section 28.3.20, “The INFORMATION_SCHEMA PARAMETERS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-routines-table.html" title="28.3.30 The INFORMATION_SCHEMA ROUTINES Table"> Section 28.3.30, “The INFORMATION_SCHEMA ROUTINES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PARTITIONS </h3> <dl> <dt> <a class="xref" href="partitioning-management-exchange.html" title="26.3.3 Exchanging Partitions and Subpartitions with Tables"> Section 26.3.3, “Exchanging Partitions and Subpartitions with Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning-handling-nulls.html" title="26.2.7 How MySQL Partitioning Handles NULL"> Section 26.2.7, “How MySQL Partitioning Handles NULL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning-key.html" title="26.2.5 KEY Partitioning"> Section 26.2.5, “KEY Partitioning” </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning-info.html" title="26.3.5 Obtaining Information About Partitions"> Section 26.3.5, “Obtaining Information About Partitions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning.html" title="Chapter 26 Partitioning"> Chapter 26, <i> Partitioning </i> </a> </dt> <dd> </dd> <dt> <a class="xref" href="partitioning-columns-range.html" title="26.2.3.1 RANGE COLUMNS partitioning"> Section 26.2.3.1, “RANGE COLUMNS partitioning” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement"> Section 15.7.7.38, “SHOW TABLE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-partitions-table.html" title="28.3.21 The INFORMATION_SCHEMA PARTITIONS Table"> Section 28.3.21, “The INFORMATION_SCHEMA PARTITIONS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> Section 28.3.38, “The INFORMATION_SCHEMA TABLES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PLUGINS </h3> <dl> <dt> <a class="xref" href="clone-plugin-remote.html" title="7.6.7.3 Cloning Remote Data"> Section 7.6.7.3, “Cloning Remote Data” </a> </dt> <dd> </dd> <dt> <a class="xref" href="connection-control-installation.html" title="8.4.2.1 Connection-Control Plugin Installation"> Section 8.4.2.1, “Connection-Control Plugin Installation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> Section 15.7.4.4, “INSTALL PLUGIN Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="plugin-loading.html" title="7.6.1 Installing and Uninstalling Plugins"> Section 7.6.1, “Installing and Uninstalling Plugins” </a> </dt> <dd> </dd> <dt> <a class="xref" href="ddl-rewriter-installation.html" title="7.6.5.1 Installing or Uninstalling ddl_rewriter"> Section 7.6.5.1, “Installing or Uninstalling ddl_rewriter” </a> </dt> <dd> </dd> <dt> <a class="xref" href="audit-log-installation.html" title="8.4.5.2 Installing or Uninstalling MySQL Enterprise Audit"> Section 8.4.5.2, “Installing or Uninstalling MySQL Enterprise Audit” </a> </dt> <dd> </dd> <dt> <a class="xref" href="replication-semisync-installation.html" title="19.4.10.1 Installing Semisynchronous Replication"> Section 19.4.10.1, “Installing Semisynchronous Replication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="clone-plugin-installation.html" title="7.6.7.1 Installing the Clone Plugin"> Section 7.6.7.1, “Installing the Clone Plugin” </a> </dt> <dd> </dd> <dt> <a class="xref" href="kerberos-pluggable-authentication.html" title="8.4.1.8 Kerberos Pluggable Authentication"> Section 8.4.1.8, “Kerberos Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="keyring-metadata.html" title="8.4.4.14 Keyring Metadata"> Section 8.4.4.14, “Keyring Metadata” </a> </dt> <dd> </dd> <dt> <a class="xref" href="keyring-plugin-installation.html" title="8.4.4.3 Keyring Plugin Installation"> Section 8.4.4.3, “Keyring Plugin Installation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="ldap-pluggable-authentication.html" title="8.4.1.7 LDAP Pluggable Authentication"> Section 8.4.1.7, “LDAP Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="no-login-pluggable-authentication.html" title="8.4.1.9 No-Login Pluggable Authentication"> Section 8.4.1.9, “No-Login Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="obtaining-plugin-information.html" title="7.6.2 Obtaining Server Plugin Information"> Section 7.6.2, “Obtaining Server Plugin Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="pam-pluggable-authentication.html" title="8.4.1.5 PAM Pluggable Authentication"> Section 8.4.1.5, “PAM Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-sql-statements.html" title="25.6.20 Quick Reference: NDB Cluster SQL Statements"> Section 25.6.20, “Quick Reference: NDB Cluster SQL Statements” </a> </dt> <dd> </dd> <dt> <a class="xref" href="server-options.html" title="7.1.7 Server Command Options"> Section 7.1.7, “Server Command Options” </a> </dt> <dd> </dd> <dt> <a class="xref" href="socket-pluggable-authentication.html" title="8.4.1.10 Socket Peer-Credential Pluggable Authentication"> Section 8.4.1.10, “Socket Peer-Credential Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="test-pluggable-authentication.html" title="8.4.1.12 Test Pluggable Authentication"> Section 8.4.1.12, “Test Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-plugins-table.html" title="28.3.22 The INFORMATION_SCHEMA PLUGINS Table"> Section 28.3.22, “The INFORMATION_SCHEMA PLUGINS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="thread-pool-installation.html" title="7.6.3.2 Thread Pool Installation"> Section 7.6.3.2, “Thread Pool Installation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="webauthn-pluggable-authentication.html" title="8.4.1.11 WebAuthn Pluggable Authentication"> Section 8.4.1.11, “WebAuthn Pluggable Authentication” </a> </dt> <dd> </dd> <dt> <a class="xref" href="windows-pluggable-authentication.html" title="8.4.1.6 Windows Pluggable Authentication"> Section 8.4.1.6, “Windows Pluggable Authentication” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PROCESSLIST </h3> <dl> <dt> <a class="xref" href="processlist-access.html" title="10.14.1 Accessing the Process List"> Section 10.14.1, “Accessing the Process List” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-functions.html" title="14.15 Information Functions"> Section 14.15, “Information Functions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="kill.html" title="15.7.8.4 KILL Statement"> Section 15.7.8.4, “KILL Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="explain-for-connection.html" title="10.8.4 Obtaining Execution Plan Information for a Named Connection"> Section 10.8.4, “Obtaining Execution Plan Information for a Named Connection” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-instrument-naming.html" title="29.6 Performance Schema Instrument Naming Conventions"> Section 29.6, “Performance Schema Instrument Naming Conventions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-replication-tables.html" title="29.12.11 Performance Schema Replication Tables"> Section 29.12.11, “Performance Schema Replication Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-stage-tables.html" title="29.12.5 Performance Schema Stage Event Tables"> Section 29.12.5, “Performance Schema Stage Event Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-internal-data.html" title="17.15.2.3 Persistence and Consistency of InnoDB Transaction and Locking Information"> Section 17.15.2.3, “Persistence and Consistency of InnoDB Transaction and Locking Information” </a> </dt> <dd> </dd> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-processlist.html" title="15.7.7.31 SHOW PROCESSLIST Statement"> Section 15.7.7.31, “SHOW PROCESSLIST Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="clone-plugin-stop.html" title="7.6.7.11 Stopping a Cloning Operation"> Section 7.6.7.11, “Stopping a Cloning Operation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-error-log-table.html" title="29.12.22.2 The error_log Table"> Section 29.12.22.2, “The error_log Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-innodb-trx-table.html" title="28.4.28 The INFORMATION_SCHEMA INNODB_TRX Table"> Section 28.4.28, “The INFORMATION_SCHEMA INNODB_TRX Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-processlist-table.html" title="28.3.23 The INFORMATION_SCHEMA PROCESSLIST Table"> Section 28.3.23, “The INFORMATION_SCHEMA PROCESSLIST Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-processlist.html" title="30.4.3.22 The processlist and x$processlist Views"> Section 30.4.3.22, “The processlist and x$processlist Views” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-processlist-table.html" title="29.12.22.7 The processlist Table"> Section 29.12.22.7, “The processlist Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="performance-schema-threads-table.html" title="29.12.22.8 The threads Table"> Section 29.12.22.8, “The threads Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-information-schema-examples.html" title="17.15.2.1 Using InnoDB Transaction and Locking Information"> Section 17.15.2.1, “Using InnoDB Transaction and Locking Information” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> PROFILING </h3> <dl> <dt> <a class="xref" href="show-profile.html" title="15.7.7.32 SHOW PROFILE Statement"> Section 15.7.7.32, “SHOW PROFILE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-profiling-table.html" title="28.3.24 The INFORMATION_SCHEMA PROFILING Table"> Section 28.3.24, “The INFORMATION_SCHEMA PROFILING Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-R"> </a> <h3 class="title"> R </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> REFERENTIAL_CONSTRAINTS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-referential-constraints-table.html" title="28.3.25 The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table"> Section 28.3.25, “The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="system-schema.html" title="7.3 The mysql System Schema"> Section 7.3, “The mysql System Schema” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> RESOURCE_GROUPS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="resource-groups.html" title="7.1.16 Resource Groups"> Section 7.1.16, “Resource Groups” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-resource-groups-table.html" title="28.3.26 The INFORMATION_SCHEMA RESOURCE_GROUPS Table"> Section 28.3.26, “The INFORMATION_SCHEMA RESOURCE_GROUPS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ROLE_COLUMN_GRANTS </h3> <dl> <dt> <a class="xref" href="information-schema-role-column-grants-table.html" title="28.3.27 The INFORMATION_SCHEMA ROLE_COLUMN_GRANTS Table"> Section 28.3.27, “The INFORMATION_SCHEMA ROLE_COLUMN_GRANTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ROLE_ROUTINE_GRANTS </h3> <dl> <dt> <a class="xref" href="information-schema-role-routine-grants-table.html" title="28.3.28 The INFORMATION_SCHEMA ROLE_ROUTINE_GRANTS Table"> Section 28.3.28, “The INFORMATION_SCHEMA ROLE_ROUTINE_GRANTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ROLE_TABLE_GRANTS </h3> <dl> <dt> <a class="xref" href="information-schema-role-table-grants-table.html" title="28.3.29 The INFORMATION_SCHEMA ROLE_TABLE_GRANTS Table"> Section 28.3.29, “The INFORMATION_SCHEMA ROLE_TABLE_GRANTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ROUTINES </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-introduction.html" title="28.1 Introduction"> Section 28.1, “Introduction” </a> </dt> <dd> </dd> <dt> <a class="xref" href="faqs-stored-procs.html" title="A.4 MySQL 8.4 FAQ: Stored Procedures and Functions"> Section A.4, “MySQL 8.4 FAQ: Stored Procedures and Functions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-procedure-status.html" title="15.7.7.30 SHOW PROCEDURE STATUS Statement"> Section 15.7.7.30, “SHOW PROCEDURE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="stored-objects-security.html" title="27.6 Stored Object Access Control"> Section 27.6, “Stored Object Access Control” </a> </dt> <dd> </dd> <dt> <a class="xref" href="stored-routines-metadata.html" title="27.2.3 Stored Routine Metadata"> Section 27.2.3, “Stored Routine Metadata” </a> </dt> <dd> </dd> <dt> <a class="xref" href="stored-routines-privileges.html" title="27.2.2 Stored Routines and MySQL Privileges"> Section 27.2.2, “Stored Routines and MySQL Privileges” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-routines-table.html" title="28.3.30 The INFORMATION_SCHEMA ROUTINES Table"> Section 28.3.30, “The INFORMATION_SCHEMA ROUTINES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-S"> </a> <h3 class="title"> S </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> SCHEMA_PRIVILEGES </h3> <dl> <dt> <a class="xref" href="information-schema-schema-privileges-table.html" title="28.3.33 The INFORMATION_SCHEMA SCHEMA_PRIVILEGES Table"> Section 28.3.33, “The INFORMATION_SCHEMA SCHEMA_PRIVILEGES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> SCHEMATA </h3> <dl> <dt> <a class="xref" href="charset-database.html" title="12.3.3 Database Character Set and Collation"> Section 12.3.3, “Database Character Set and Collation” </a> </dt> <dd> </dd> <dt> <a class="xref" href="grant-tables.html" title="8.2.3 Grant Tables"> Section 8.2.3, “Grant Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> Section 17.13, “InnoDB Data-at-Rest Encryption” </a> </dt> <dd> </dd> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="server-system-variables.html" title="7.1.8 Server System Variables"> Section 7.1.8, “Server System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-databases.html" title="15.7.7.15 SHOW DATABASES Statement"> Section 15.7.7.15, “SHOW DATABASES Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-schemata-table.html" title="28.3.31 The INFORMATION_SCHEMA SCHEMATA Table"> Section 28.3.31, “The INFORMATION_SCHEMA SCHEMATA Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-schemata-extensions-table.html" title="28.3.32 The INFORMATION_SCHEMA SCHEMATA_EXTENSIONS Table"> Section 28.3.32, “The INFORMATION_SCHEMA SCHEMATA_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> SCHEMATA_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="alter-database.html" title="15.1.2 ALTER DATABASE Statement"> Section 15.1.2, “ALTER DATABASE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-schemata-table.html" title="28.3.31 The INFORMATION_SCHEMA SCHEMATA Table"> Section 28.3.31, “The INFORMATION_SCHEMA SCHEMATA Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-schemata-extensions-table.html" title="28.3.32 The INFORMATION_SCHEMA SCHEMATA_EXTENSIONS Table"> Section 28.3.32, “The INFORMATION_SCHEMA SCHEMATA_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ST_GEOMETRY_COLUMNS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-columns-table.html" title="28.3.8 The INFORMATION_SCHEMA COLUMNS Table"> Section 28.3.8, “The INFORMATION_SCHEMA COLUMNS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-st-geometry-columns-table.html" title="28.3.35 The INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS Table"> Section 28.3.35, “The INFORMATION_SCHEMA ST_GEOMETRY_COLUMNS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ST_SPATIAL_REFERENCE_SYSTEMS </h3> <dl> <dt> <a class="xref" href="create-spatial-reference-system.html" title="15.1.19 CREATE SPATIAL REFERENCE SYSTEM Statement"> Section 15.1.19, “CREATE SPATIAL REFERENCE SYSTEM Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="spatial-reference-systems.html" title="13.4.5 Spatial Reference System Support"> Section 13.4.5, “Spatial Reference System Support” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-st-spatial-reference-systems-table.html" title="28.3.36 The INFORMATION_SCHEMA ST_SPATIAL_REFERENCE_SYSTEMS Table"> Section 28.3.36, “The INFORMATION_SCHEMA ST_SPATIAL_REFERENCE_SYSTEMS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> ST_UNITS_OF_MEASURE </h3> <dl> <dt> <a class="xref" href="gis-linestring-property-functions.html" title="14.16.7.3 LineString and MultiLineString Property Functions"> Section 14.16.7.3, “LineString and MultiLineString Property Functions” </a> </dt> <dd> </dd> <dt> <a class="xref" href="spatial-relation-functions-object-shapes.html" title="14.16.9.1 Spatial Relation Functions That Use Object Shapes"> Section 14.16.9.1, “Spatial Relation Functions That Use Object Shapes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-st-units-of-measure-table.html" title="28.3.37 The INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table"> Section 28.3.37, “The INFORMATION_SCHEMA ST_UNITS_OF_MEASURE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> STATISTICS </h3> <dl> <dt> <a class="xref" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> Section 15.7.3.1, “ANALYZE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-usage-differences.html" title="16.7 Data Dictionary Usage Differences"> Section 16.7, “Data Dictionary Usage Differences” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-gipks.html" title="15.1.20.11 Generated Invisible Primary Keys"> Section 15.1.20.11, “Generated Invisible Primary Keys” </a> </dt> <dd> </dd> <dt> <a class="xref" href="index-hints.html" title="10.9.4 Index Hints"> Section 10.9.4, “Index Hints” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-introduction.html" title="28.1 Introduction"> Section 28.1, “Introduction” </a> </dt> <dd> </dd> <dt> <a class="xref" href="invisible-indexes.html" title="10.3.12 Invisible Indexes"> Section 10.3.12, “Invisible Indexes” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-index.html" title="15.7.7.23 SHOW INDEX Statement"> Section 15.7.7.23, “SHOW INDEX Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table"> Section 28.3.34, “The INFORMATION_SCHEMA STATISTICS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-T"> </a> <h3 class="title"> T </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLE_CONSTRAINTS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-online-ddl-operations.html" title="17.12.1 Online DDL Operations"> Section 17.12.1, “Online DDL Operations” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-referential-constraints-table.html" title="28.3.25 The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table"> Section 28.3.25, “The INFORMATION_SCHEMA REFERENTIAL_CONSTRAINTS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-table-constraints-table.html" title="28.3.41 The INFORMATION_SCHEMA TABLE_CONSTRAINTS Table"> Section 28.3.41, “The INFORMATION_SCHEMA TABLE_CONSTRAINTS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLE_CONSTRAINTS_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="information-schema-table-constraints-extensions-table.html" title="28.3.42 The INFORMATION_SCHEMA TABLE_CONSTRAINTS_EXTENSIONS Table"> Section 28.3.42, “The INFORMATION_SCHEMA TABLE_CONSTRAINTS_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLE_PRIVILEGES </h3> <dl> <dt> <a class="xref" href="information-schema-table-privileges-table.html" title="28.3.43 The INFORMATION_SCHEMA TABLE_PRIVILEGES Table"> Section 28.3.43, “The INFORMATION_SCHEMA TABLE_PRIVILEGES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLES </h3> <dl> <dt> <a class="xref" href="mysql-cluster-online-add-node-example.html" title="25.6.7.3 Adding NDB Cluster Data Nodes Online: Detailed Example"> Section 25.6.7.3, “Adding NDB Cluster Data Nodes Online: Detailed Example” </a> </dt> <dd> </dd> <dt> <a class="xref" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> Section 15.1.9, “ALTER TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> Section 15.1.20, “CREATE TABLE Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-usage-differences.html" title="16.7 Data Dictionary Usage Differences"> Section 16.7, “Data Dictionary Usage Differences” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-page-compression.html" title="17.9.2 InnoDB Page Compression"> Section 17.9.2, “InnoDB Page Compression” </a> </dt> <dd> </dd> <dt> <a class="xref" href="innodb-parameters.html" title="17.14 InnoDB Startup Options and System Variables"> Section 17.14, “InnoDB Startup Options and System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-introduction.html" title="28.1 Introduction"> Section 28.1, “Introduction” </a> </dt> <dd> </dd> <dt> <a class="xref" href="identifier-mapping.html" title="11.2.4 Mapping of Identifiers to File Names"> Section 11.2.4, “Mapping of Identifiers to File Names” </a> </dt> <dd> </dd> <dt> <a class="xref" href="mysql-cluster-options-variables.html#mysql-cluster-system-variables" title="25.4.3.9.2 NDB Cluster System Variables"> Section 25.4.3.9.2, “NDB Cluster System Variables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="data-dictionary-file-removal.html" title="16.2 Removal of File-based Metadata Storage"> Section 16.2, “Removal of File-based Metadata Storage” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-table-ndb-comment-options.html" title="15.1.20.12 Setting NDB Comment Options"> Section 15.1.20.12, “Setting NDB Comment Options” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement"> Section 15.7.7.38, “SHOW TABLE STATUS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-tables.html" title="15.7.7.39 SHOW TABLES Statement"> Section 15.7.7.39, “SHOW TABLES Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-diagnostics.html" title="30.4.4.2 The diagnostics() Procedure"> Section 30.4.4.2, “The diagnostics() Procedure” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> Section 28.3.38, “The INFORMATION_SCHEMA TABLES Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="sys-sys-config.html" title="30.4.2.1 The sys_config Table"> Section 30.4.2.1, “The sys_config Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="thread-pool-installation.html" title="7.6.3.2 Thread Pool Installation"> Section 7.6.3.2, “Thread Pool Installation” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLES_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="information-schema-tables-extensions-table.html" title="28.3.39 The INFORMATION_SCHEMA TABLES_EXTENSIONS Table"> Section 28.3.39, “The INFORMATION_SCHEMA TABLES_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TABLESPACES_EXTENSIONS </h3> <dl> <dt> <a class="xref" href="information-schema-tablespaces-extensions-table.html" title="28.3.40 The INFORMATION_SCHEMA TABLESPACES_EXTENSIONS Table"> Section 28.3.40, “The INFORMATION_SCHEMA TABLESPACES_EXTENSIONS Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TP_THREAD_GROUP_STATE </h3> <dl> <dt> <a class="xref" href="thread-pool-information-schema-tables.html" title="28.5 INFORMATION_SCHEMA Thread Pool Tables"> Section 28.5, “INFORMATION_SCHEMA Thread Pool Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TP_THREAD_GROUP_STATS </h3> <dl> <dt> <a class="xref" href="thread-pool-information-schema-tables.html" title="28.5 INFORMATION_SCHEMA Thread Pool Tables"> Section 28.5, “INFORMATION_SCHEMA Thread Pool Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TP_THREAD_STATE </h3> <dl> <dt> <a class="xref" href="thread-pool-information-schema-tables.html" title="28.5 INFORMATION_SCHEMA Thread Pool Tables"> Section 28.5, “INFORMATION_SCHEMA Thread Pool Tables” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> TRIGGERS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="upgrade-prerequisites.html" title="3.6 Preparing Your Installation for Upgrade"> Section 3.6, “Preparing Your Installation for Upgrade” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-create-trigger.html" title="15.7.7.12 SHOW CREATE TRIGGER Statement"> Section 15.7.7.12, “SHOW CREATE TRIGGER Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-triggers.html" title="15.7.7.40 SHOW TRIGGERS Statement"> Section 15.7.7.40, “SHOW TRIGGERS Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-triggers-table.html" title="28.3.44 The INFORMATION_SCHEMA TRIGGERS Table"> Section 28.3.44, “The INFORMATION_SCHEMA TRIGGERS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="trigger-metadata.html" title="27.3.2 Trigger Metadata"> Section 27.3.2, “Trigger Metadata” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-U"> </a> <h3 class="title"> U </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> USER_ATTRIBUTES </h3> <dl> <dt> <a class="xref" href="alter-user.html" title="15.7.1.1 ALTER USER Statement"> Section 15.7.1.1, “ALTER USER Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> Section 15.7.1.3, “CREATE USER Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="grant-tables.html" title="8.2.3 Grant Tables"> Section 8.2.3, “Grant Tables” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-user-attributes-table.html" title="28.3.45 The INFORMATION_SCHEMA USER_ATTRIBUTES Table"> Section 28.3.45, “The INFORMATION_SCHEMA USER_ATTRIBUTES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> USER_PRIVILEGES </h3> <dl> <dt> <a class="xref" href="privileges-provided.html" title="8.2.2 Privileges Provided by MySQL"> Section 8.2.2, “Privileges Provided by MySQL” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-user-privileges-table.html" title="28.3.46 The INFORMATION_SCHEMA USER_PRIVILEGES Table"> Section 28.3.46, “The INFORMATION_SCHEMA USER_PRIVILEGES Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <a name="is-index-V"> </a> <h3 class="title"> V </h3> <p> [ <a class="link" href="dynindex-is.html#is-index-top"> index top </a> ] </p> <dl> <dt> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> VIEW_ROUTINE_USAGE </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-view-routine-usage-table.html" title="28.3.48 The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table"> Section 28.3.48, “The INFORMATION_SCHEMA VIEW_ROUTINE_USAGE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> VIEW_TABLE_USAGE </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-view-table-usage-table.html" title="28.3.49 The INFORMATION_SCHEMA VIEW_TABLE_USAGE Table"> Section 28.3.49, “The INFORMATION_SCHEMA VIEW_TABLE_USAGE Table” </a> </dt> <dd> </dd> </dl> </div> <div class="indexdiv"> <h3 class="title"> VIEWS </h3> <dl> <dt> <a class="xref" href="data-dictionary-information-schema.html" title="16.5 INFORMATION_SCHEMA and Data Dictionary Integration"> Section 16.5, “INFORMATION_SCHEMA and Data Dictionary Integration” </a> </dt> <dd> </dd> <dt> <a class="xref" href="upgrade-prerequisites.html" title="3.6 Preparing Your Installation for Upgrade"> Section 3.6, “Preparing Your Installation for Upgrade” </a> </dt> <dd> </dd> <dt> <a class="xref" href="show-create-view.html" title="15.7.7.14 SHOW CREATE VIEW Statement"> Section 15.7.7.14, “SHOW CREATE VIEW Statement” </a> </dt> <dd> </dd> <dt> <a class="xref" href="information-schema-views-table.html" title="28.3.47 The INFORMATION_SCHEMA VIEWS Table"> Section 28.3.47, “The INFORMATION_SCHEMA VIEWS Table” </a> </dt> <dd> </dd> <dt> <a class="xref" href="view-updatability.html" title="27.5.3 Updatable and Insertable Views"> Section 27.5.3, “Updatable and Insertable Views” </a> </dt> <dd> </dd> <dt> <a class="xref" href="view-metadata.html" title="27.5.5 View Metadata"> Section 27.5.5, “View Metadata” </a> </dt> <dd> </dd> </dl> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/innodb-buffer-pool-flushing.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="innodb-buffer-pool-flushing"> </a> 17.8.3.5 Configuring Buffer Pool Flushing </h4> </div> </div> </div> <a class="indexterm" name="idm46045163057584"> </a> <a class="indexterm" name="idm46045163056512"> </a> <p> <code class="literal"> InnoDB </code> performs certain tasks in the background, including flushing of dirty pages from the buffer pool. Dirty pages are those that have been modified but are not yet written to the data files on disk. </p> <p> Buffer pool flushing is performed by page cleaner threads. The number of page cleaner threads is controlled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> <code class="literal"> innodb_page_cleaners </code> </a> variable, which has a default value set to the same value as <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . </p> <p> Buffer pool flushing is initiated when the percentage of dirty pages reaches the low water mark value defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> variable. The default low water mark is 10% of buffer pool pages. A <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> value of 0 disables this early flushing behaviour. </p> <p> The purpose of the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> threshold is to control the percentage dirty pages in the buffer pool and to prevent the amount of dirty pages from reaching the threshold defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> variable, which has a default value of 90. <code class="literal"> InnoDB </code> aggressively flushes buffer pool pages if the percentage of dirty pages in the buffer pool reaches the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> threshold. </p> <p> When configuring <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> , the value should always be lower than the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> value. </p> <p> Additional variables permit fine-tuning of buffer pool flushing behavior: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> variable defines whether flushing a page from the buffer pool also flushes other dirty pages in the same extent. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> The default setting of 0 disables <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> . Dirty pages in the same extent are not flushed. This setting is recommended for non-rotational storage (SSD) devices where seek time is not a significant factor. </p> </li> <li class="listitem"> <p> A setting of 1 flushes contiguous dirty pages in the same extent. </p> </li> <li class="listitem"> <p> A setting of 2 flushes dirty pages in the same extent. </p> </li> </ul> </div> <p> When table data is stored on a traditional <a class="link" href="glossary.html#glos_hdd" title="HDD"> HDD </a> storage device, flushing neighbor pages in one operation reduces I/O overhead (primarily for disk seek operations) compared to flushing individual pages at different times. For table data stored on <a class="link" href="glossary.html#glos_ssd" title="SSD"> SSD </a> , seek time is not a significant factor and you can disable this setting to spread out write operations. </p> </li> <li class="listitem"> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> variable specifies, per buffer pool instance, how far down the buffer pool LRU list the page cleaner thread scans looking for dirty pages to flush. This is a background operation performed by a page cleaner thread once per second. </p> <p> A setting smaller than the default is generally suitable for most workloads. A value that is significantly higher than necessary may impact performance. Only consider increasing the value if you have spare I/O capacity under a typical workload. Conversely, if a write-intensive workload saturates your I/O capacity, decrease the value, especially in the case of a large buffer pool. </p> <p> When tuning <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> , start with a low value and configure the setting upward with the goal of rarely seeing zero free pages. Also, consider adjusting <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> when changing the number of buffer pool instances, since <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> defines the amount of work performed by the page cleaner thread each second. </p> </li> </ul> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> variables are primarily intended for write-intensive workloads. With heavy DML activity, flushing can fall behind if it is not aggressive enough, or disk writes can saturate I/O capacity if flushing is too aggressive. The ideal settings depend on your workload, data access patterns, and storage configuration (for example, whether data is stored on HDD or SSD devices). </p> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="innodb-adaptive-flushing"> </a> Adaptive Flushing </h5> </div> </div> </div> <p> <code class="literal"> InnoDB </code> uses an adaptive flushing algorithm to dynamically adjust the rate of flushing based on the speed of redo log generation and the current rate of flushing. The intent is to smooth overall performance by ensuring that flushing activity keeps pace with the current workload. Automatically adjusting the flushing rate helps avoid sudden dips in throughput that can occur when bursts of I/O activity due to buffer pool flushing affects the I/O capacity available for ordinary read and write activity. </p> <p> Sharp checkpoints, which are typically associated with write-intensive workloads that generate a lot of redo entries, can cause a sudden change in throughput, for example. A sharp checkpoint occurs when <code class="literal"> InnoDB </code> wants to reuse a portion of a log file. Before doing so, all dirty pages with redo entries in that portion of the log file must be flushed. If log files become full, a sharp checkpoint occurs, causing a temporary reduction in throughput. This scenario can occur even if <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> threshold is not reached. </p> <p> The adaptive flushing algorithm helps avoid such scenarios by tracking the number of dirty pages in the buffer pool and the rate at which redo log records are being generated. Based on this information, it decides how many dirty pages to flush from the buffer pool each second, which permits it to manage sudden changes in workload. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> <code class="literal"> innodb_adaptive_flushing_lwm </code> </a> variable defines a low water mark for redo log capacity. When that threshold is crossed, adaptive flushing is enabled, even if the <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> <code class="literal"> innodb_adaptive_flushing </code> </a> variable is disabled. </p> <p> Internal benchmarking has shown that the algorithm not only maintains throughput over time, but can also improve overall throughput significantly. However, adaptive flushing can affect the I/O pattern of a workload significantly and may not be appropriate in all cases. It gives the most benefit when the redo log is in danger of filling up. If adaptive flushing is not appropriate to the characteristics of your workload, you can disable it. Adaptive flushing controlled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> <code class="literal"> innodb_adaptive_flushing </code> </a> variable, which is enabled by default. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> <code class="literal"> innodb_flushing_avg_loops </code> </a> defines the number of iterations that <code class="literal"> InnoDB </code> keeps the previously calculated snapshot of the flushing state, controlling how quickly adaptive flushing responds to foreground workload changes. A high <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> <code class="literal"> innodb_flushing_avg_loops </code> </a> value means that <code class="literal"> InnoDB </code> keeps the previously calculated snapshot longer, so adaptive flushing responds more slowly. When setting a high value it is important to ensure that redo log utilization does not reach 75% (the hardcoded limit at which asynchronous flushing starts), and that the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> threshold keeps the number of dirty pages to a level that is appropriate for the workload. </p> <p> Systems with consistent workloads, a large log file size ( <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> ), and small spikes that do not reach 75% log space utilization should use a high <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> <code class="literal"> innodb_flushing_avg_loops </code> </a> value to keep flushing as smooth as possible. For systems with extreme load spikes or log files that do not provide a lot of space, a smaller value allows flushing to closely track workload changes, and helps to avoid reaching 75% log space utilization. </p> <p> Be aware that if flushing falls behind, the rate of buffer pool flushing can exceed the I/O capacity available to <code class="literal"> InnoDB </code> , as defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> setting. The <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> value defines an upper limit on I/O capacity in such situations, so that a spike in I/O activity does not consume the entire I/O capacity of the server. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> setting is applicable to all buffer pool instances. When dirty pages are flushed, I/O capacity is divided equally among buffer pool instances. </p> </div> <div class="simplesect"> <div class="titlepage"> <div> <div class="simple"> <h5 class="title"> <a name="innodb-limit-flushing-rate"> </a> Limiting Buffer Flushing During Idle Periods </h5> </div> </div> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> <code class="literal"> innodb_idle_flush_pct </code> </a> variable limits the rate of buffer pool flushing during idle periods, which are periods of time that database pages are not modified. Its value is interpreted as a percentage of <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> (which defines the number of I/O operations per second available to <code class="literal"> InnoDB </code> ). The default value is 100, or 100 percent of the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> . To limit flushing during idle periods, set <code class="literal"> innodb_idle_flush_pct </code> to less than 100. </p> <p> Limiting page flushing during idle periods can help extend the life of solid state storage devices. Side effects of limiting page flushing during idle periods may include a longer shutdown time following a lengthy idle period, and a longer recovery period should a server failure occur. </p> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/innodb-parameters.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="innodb-parameters"> </a> 17.14 InnoDB Startup Options and System Variables </h2> </div> </div> </div> <a class="indexterm" name="idm46045159103408"> </a> <a class="indexterm" name="idm46045159101984"> </a> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a class="xref" href="innodb-parameters.html#innodb-parameters-startup" title="InnoDB Startup Options"> InnoDB Startup Options </a> </p> </li> <li class="listitem"> <p> <a class="xref" href="innodb-parameters.html#innodb-parameters-sysvars" title="InnoDB System Variables"> InnoDB System Variables </a> </p> </li> </ul> </div> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> System variables that are true or false can be enabled at server startup by naming them, or disabled by using a <code class="literal"> --skip- </code> prefix. For example, to enable or disable the <code class="literal"> InnoDB </code> adaptive hash index, you can use <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="option"> --innodb-adaptive-hash-index </code> </a> or <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="option"> --skip-innodb-adaptive-hash-index </code> </a> on the command line, or <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="literal"> innodb_adaptive_hash_index </code> </a> or <code class="literal"> skip_innodb_adaptive_hash_index </code> in an option file. </p> </li> <li class="listitem"> <p> Some variable descriptions refer to <span class="quote"> “ <span class="quote"> enabling </span> ” </span> or <span class="quote"> “ <span class="quote"> disabling </span> ” </span> a variable. These variables can be enabled with the <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement by setting them to <code class="literal"> ON </code> or <code class="literal"> 1 </code> , or disabled by setting them to <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . Boolean variables can be set at startup to the values <code class="literal"> ON </code> , <code class="literal"> TRUE </code> , <code class="literal"> OFF </code> , and <code class="literal"> FALSE </code> (not case-sensitive), as well as <code class="literal"> 1 </code> and <code class="literal"> 0 </code> . See <a class="xref" href="option-modifiers.html" title="6.2.2.4 Program Option Modifiers"> Section 6.2.2.4, “Program Option Modifiers” </a> . </p> </li> <li class="listitem"> <p> System variables that take a numeric value can be specified as <code class="option"> -- <em class="replaceable"> <code> var_name </code> </em> = <em class="replaceable"> <code> value </code> </em> </code> on the command line or as <code class="literal"> <em class="replaceable"> <code> var_name </code> </em> = <em class="replaceable"> <code> value </code> </em> </code> in option files. </p> </li> <li class="listitem"> <p> Many system variables can be changed at runtime (see <a class="xref" href="dynamic-system-variables.html" title="7.1.9.2 Dynamic System Variables"> Section 7.1.9.2, “Dynamic System Variables” </a> ). </p> </li> <li class="listitem"> <p> For information about <code class="literal"> GLOBAL </code> and <code class="literal"> SESSION </code> variable scope modifiers, refer to the <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement documentation. </p> </li> <li class="listitem"> <p> Certain options control the locations and layout of the <code class="literal"> InnoDB </code> data files. <a class="xref" href="innodb-init-startup-configuration.html" title="17.8.1 InnoDB Startup Configuration"> Section 17.8.1, “InnoDB Startup Configuration” </a> explains how to use these options. </p> </li> <li class="listitem"> <p> Some options, which you might not use initially, help tune <code class="literal"> InnoDB </code> performance characteristics based on machine capacity and database <a class="link" href="glossary.html#glos_workload" title="workload"> workload </a> . </p> </li> <li class="listitem"> <p> For more information on specifying options and system variables, see <a class="xref" href="program-options.html" title="6.2.2 Specifying Program Options"> Section 6.2.2, “Specifying Program Options” </a> . </p> </li> </ul> </div> <div class="table"> <a name="idm46045159065744"> </a> <p class="title"> <b> Table 17.23 InnoDB Option and Variable Reference </b> </p> <div class="table-contents"> <table frame="box" rules="all" summary="Reference for InnoDB command-line options and system variables."> <colgroup> <col style="width: 20%"/> <col style="width: 15%"/> <col style="width: 15%"/> <col style="width: 15%"/> <col style="width: 15%"/> <col style="width: 15%"/> <col style="width: 15%"/> </colgroup> <thead> <tr> <th scope="col"> Name </th> <th scope="col"> Cmd-Line </th> <th scope="col"> Option File </th> <th scope="col"> System Var </th> <th scope="col"> Status Var </th> <th scope="col"> Var Scope </th> <th scope="col"> Dynamic </th> </tr> </thead> <tbody> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_foreign_key_checks"> foreign_key_checks </a> </th> <td> </td> <td> </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> innodb_adaptive_flushing </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> innodb_adaptive_flushing_lwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> innodb_adaptive_hash_index </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index_parts"> innodb_adaptive_hash_index_parts </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> innodb_adaptive_max_sleep_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> innodb_autoextend_increment </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode"> innodb_autoinc_lock_mode </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> innodb_background_drop_list_empty </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_data"> Innodb_buffer_pool_bytes_data </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_bytes_dirty"> Innodb_buffer_pool_bytes_dirty </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> innodb_buffer_pool_chunk_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_debug"> innodb_buffer_pool_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> innodb_buffer_pool_dump_at_shutdown </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> innodb_buffer_pool_dump_now </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> innodb_buffer_pool_dump_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_dump_status"> Innodb_buffer_pool_dump_status </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_filename"> innodb_buffer_pool_filename </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> innodb_buffer_pool_in_core_file </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> innodb_buffer_pool_instances </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> innodb_buffer_pool_load_abort </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> innodb_buffer_pool_load_at_startup </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> innodb_buffer_pool_load_now </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_load_status"> Innodb_buffer_pool_load_status </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_data"> Innodb_buffer_pool_pages_data </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_dirty"> Innodb_buffer_pool_pages_dirty </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_flushed"> Innodb_buffer_pool_pages_flushed </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_free"> Innodb_buffer_pool_pages_free </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_latched"> Innodb_buffer_pool_pages_latched </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_misc"> Innodb_buffer_pool_pages_misc </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_pages_total"> Innodb_buffer_pool_pages_total </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead"> Innodb_buffer_pool_read_ahead </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_evicted"> Innodb_buffer_pool_read_ahead_evicted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_rnd"> Innodb_buffer_pool_read_ahead_rnd </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_requests"> Innodb_buffer_pool_read_requests </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_reads"> Innodb_buffer_pool_reads </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status"> Innodb_buffer_pool_resize_status </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> innodb_buffer_pool_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_wait_free"> Innodb_buffer_pool_wait_free </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_write_requests"> Innodb_buffer_pool_write_requests </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffer_max_size"> innodb_change_buffer_max_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering"> innodb_change_buffering </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering_debug"> innodb_change_buffering_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checkpoint_disabled"> innodb_checkpoint_disabled </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> innodb_checksum_algorithm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_cmp_per_index_enabled"> innodb_cmp_per_index_enabled </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> innodb_commit_concurrency </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compress_debug"> innodb_compress_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> innodb_compression_failure_threshold_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_level"> innodb_compression_level </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> innodb_compression_pad_pct_max </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> innodb_concurrency_tickets </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> innodb_data_file_path </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_fsyncs"> Innodb_data_fsyncs </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> innodb_data_home_dir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_fsyncs"> Innodb_data_pending_fsyncs </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_reads"> Innodb_data_pending_reads </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_pending_writes"> Innodb_data_pending_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_read"> Innodb_data_read </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_reads"> Innodb_data_reads </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_writes"> Innodb_data_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_data_written"> Innodb_data_written </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_pages_written"> Innodb_dblwr_pages_written </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_dblwr_writes"> Innodb_dblwr_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> innodb_ddl_buffer_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Session </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_log_crash_reset_debug"> innodb_ddl_log_crash_reset_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> innodb_ddl_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Session </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> innodb_deadlock_detect </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> innodb_dedicated_server </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> innodb_default_row_format </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> innodb_directories </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_disable_sort_file_cache"> innodb_disable_sort_file_cache </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> innodb_doublewrite </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_batch_size"> innodb_doublewrite_batch_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_dir"> innodb_doublewrite_dir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_files"> innodb_doublewrite_files </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> innodb_doublewrite_pages </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> innodb_fast_shutdown </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> innodb_fil_make_page_dirty_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> innodb_file_per_table </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> innodb_fill_factor </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> innodb_flush_log_at_timeout </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> innodb_flush_log_at_trx_commit </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> innodb_flush_method </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> innodb_flush_neighbors </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> innodb_flush_sync </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> innodb_flushing_avg_loops </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_load_corrupted"> innodb_force_load_corrupted </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> innodb_force_recovery </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> innodb_fsync_threshold </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_aux_table"> innodb_ft_aux_table </a> </th> <td> </td> <td> </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> innodb_ft_cache_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_diag_print"> innodb_ft_enable_diag_print </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> innodb_ft_enable_stopword </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_max_token_size"> innodb_ft_max_token_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_min_token_size"> innodb_ft_min_token_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_num_word_optimize"> innodb_ft_num_word_optimize </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> innodb_ft_result_cache_limit </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> innodb_ft_server_stopword_table </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_sort_pll_degree"> innodb_ft_sort_pll_degree </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> innodb_ft_total_cache_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> innodb_ft_user_stopword_table </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_have_atomic_builtins"> Innodb_have_atomic_builtins </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> innodb_idle_flush_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> innodb_io_capacity </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> innodb_io_capacity_max </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_limit_optimistic_insert_debug"> innodb_limit_optimistic_insert_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> innodb_lock_wait_timeout </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> innodb_log_buffer_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_fuzzy_now"> innodb_log_checkpoint_fuzzy_now </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_now"> innodb_log_checkpoint_now </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> innodb_log_checksums </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> innodb_log_compressed_pages </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> innodb_log_file_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> innodb_log_files_in_group </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> innodb_log_group_home_dir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_abs_lwm"> innodb_log_spin_cpu_abs_lwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> innodb_log_spin_cpu_pct_hwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_wait_for_flush_spin_hwm"> innodb_log_wait_for_flush_spin_hwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_waits"> Innodb_log_waits </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> innodb_log_write_ahead_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_write_requests"> Innodb_log_write_requests </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_writer_threads"> innodb_log_writer_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_log_writes"> Innodb_log_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> innodb_lru_scan_depth </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> innodb_max_dirty_pages_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> innodb_max_dirty_pages_pct_lwm </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> innodb_max_purge_lag </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> innodb_max_purge_lag_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> innodb_max_undo_log_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_merge_threshold_set_all_debug"> innodb_merge_threshold_set_all_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> innodb_monitor_disable </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> innodb_monitor_enable </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> innodb_monitor_reset </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset_all"> innodb_monitor_reset_all </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_num_open_files"> Innodb_num_open_files </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> innodb_numa_interleave </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> innodb_old_blocks_pct </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> innodb_old_blocks_time </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> innodb_online_alter_log_max_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> innodb_open_files </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_optimize_fulltext_only"> innodb_optimize_fulltext_only </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_fsyncs"> Innodb_os_log_fsyncs </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_fsyncs"> Innodb_os_log_pending_fsyncs </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_pending_writes"> Innodb_os_log_pending_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_written"> Innodb_os_log_written </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> innodb_page_cleaners </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_page_size"> Innodb_page_size </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> innodb_page_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_created"> Innodb_pages_created </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_read"> Innodb_pages_read </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_pages_written"> Innodb_pages_written </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> innodb_parallel_read_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Session </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_all_deadlocks"> innodb_print_all_deadlocks </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_ddl_logs"> innodb_print_ddl_logs </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> innodb_purge_batch_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> innodb_purge_rseg_truncate_frequency </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> innodb_purge_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_random_read_ahead"> innodb_random_read_ahead </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> innodb_read_ahead_threshold </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> innodb_read_io_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> innodb_read_only </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_archive_dirs"> innodb_redo_log_archive_dirs </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> innodb_redo_log_capacity </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_capacity_resized"> Innodb_redo_log_capacity_resized </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_checkpoint_lsn"> Innodb_redo_log_checkpoint_lsn </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_current_lsn"> Innodb_redo_log_current_lsn </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_enabled"> Innodb_redo_log_enabled </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_encrypt"> innodb_redo_log_encrypt </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_flushed_to_disk_lsn"> Innodb_redo_log_flushed_to_disk_lsn </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_logical_size"> Innodb_redo_log_logical_size </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_physical_size"> Innodb_redo_log_physical_size </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_read_only"> Innodb_redo_log_read_only </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_resize_status"> Innodb_redo_log_resize_status </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_uuid"> Innodb_redo_log_uuid </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_replication_delay"> innodb_replication_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> innodb_rollback_on_timeout </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> innodb_rollback_segments </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_current_waits"> Innodb_row_lock_current_waits </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time"> Innodb_row_lock_time </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_avg"> Innodb_row_lock_time_avg </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_time_max"> Innodb_row_lock_time_max </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_row_lock_waits"> Innodb_row_lock_waits </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_deleted"> Innodb_rows_deleted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_inserted"> Innodb_rows_inserted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_read"> Innodb_rows_read </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_rows_updated"> Innodb_rows_updated </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> innodb_saved_page_number_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> innodb_segment_reserve_factor </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> innodb_sort_buffer_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_delay"> innodb_spin_wait_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> innodb_spin_wait_pause_multiplier </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_auto_recalc"> innodb_stats_auto_recalc </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> innodb_stats_include_delete_marked </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> innodb_stats_method </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> innodb_stats_on_metadata </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> innodb_stats_persistent </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> innodb_stats_persistent_sample_pages </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> innodb_stats_transient_sample_pages </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#option_mysqld_innodb-status-file"> innodb-status-file </a> </th> <td> Yes </td> <td> Yes </td> <td> </td> <td> </td> <td> </td> <td> </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output"> innodb_status_output </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> innodb_status_output_locks </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> innodb_strict_mode </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_array_size"> innodb_sync_array_size </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_debug"> innodb_sync_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_spin_loops"> innodb_sync_spin_loops </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_deleted"> Innodb_system_rows_deleted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_inserted"> Innodb_system_rows_inserted </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_read"> Innodb_system_rows_read </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_system_rows_updated"> Innodb_system_rows_updated </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> innodb_table_locks </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> innodb_temp_data_file_path </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_tablespaces_dir"> innodb_temp_tablespaces_dir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> innodb_thread_concurrency </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> innodb_thread_sleep_delay </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> innodb_tmpdir </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_truncated_status_writes"> Innodb_truncated_status_writes </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_purge_view_update_only_debug"> innodb_trx_purge_view_update_only_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_rseg_n_slots_debug"> innodb_trx_rseg_n_slots_debug </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> innodb_undo_directory </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_encrypt"> innodb_undo_log_encrypt </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> innodb_undo_log_truncate </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> innodb_undo_tablespaces </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_active"> Innodb_undo_tablespaces_active </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_explicit"> Innodb_undo_tablespaces_explicit </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_implicit"> Innodb_undo_tablespaces_implicit </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-status-variables.html#statvar_Innodb_undo_tablespaces_total"> Innodb_undo_tablespaces_total </a> </th> <td> </td> <td> </td> <td> </td> <td> Yes </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> innodb_use_fdatasync </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> Yes </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_native_aio"> innodb_use_native_aio </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_validate_tablespace_paths"> innodb_validate_tablespace_paths </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_version"> innodb_version </a> </th> <td> </td> <td> </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> innodb_write_io_threads </a> </th> <td> Yes </td> <td> Yes </td> <td> Yes </td> <td> </td> <td> Global </td> <td> No </td> </tr> <tr> <th scope="row"> <a class="link" href="server-system-variables.html#sysvar_unique_checks"> unique_checks </a> </th> <td> </td> <td> </td> <td> Yes </td> <td> </td> <td> Both </td> <td> Yes </td> </tr> </tbody> </table> </div> <div class="table-contents"> <table cellpadding="0" cellspacing="0" style="position: fixed; top: 0px; display: none; left: 401px; width: 739px;"> <thead> <tr> <th scope="col" style="width: 312.094px;"> Name </th> <th scope="col" style="width: 64.875px;"> Cmd-Line </th> <th scope="col" style="width: 73.3594px;"> Option File </th> <th scope="col" style="width: 75.0938px;"> System Var </th> <th scope="col" style="width: 70.75px;"> Status Var </th> <th scope="col" style="width: 72.5156px;"> Var Scope </th> <th scope="col" style="width: 69.3125px;"> Dynamic </th> </tr> </thead> </table> </div> </div> <br class="table-break"/> <h3> <a name="innodb-parameters-startup"> </a> InnoDB Startup Options </h3> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="option_mysqld_innodb-dedicated-server"> </a> <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> </p> <a class="indexterm" name="idm46045157426144"> </a> <a class="indexterm" name="idm46045157424640"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb-dedicated-server"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-dedicated-server[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> innodb_dedicated_server </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> When this option is set by starting the server with <code class="option"> --innodb-dedicated-server </code> or <code class="option"> --innodb-dedicated-server=ON </code> , either on the command line or in a <code class="filename"> my.cnf </code> file, <code class="literal"> InnoDB </code> automatically calculates and sets the values of the following variables: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> </p> </li> <li class="listitem"> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> </p> </li> </ul> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> In older versions of MySQL 8.0, <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> were also set by <code class="option"> --innodb-dedicated-server </code> . <code class="literal"> innodb_log_file_size </code> and <code class="literal"> innodb_log_files_in_group </code> have since been deprecated, and superseded by <code class="literal"> innodb_redo_log_capacity </code> . See <a class="xref" href="innodb-redo-log.html" title="17.6.5 Redo Log"> Section 17.6.5, “Redo Log” </a> . </p> <p> In MySQL 8.0, <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> was also set automatically by this option, but in MySQL 8.4, this is no longer the case. </p> </div> <p> You should consider using <code class="option"> --innodb-dedicated-server </code> only if the MySQL instance resides on a dedicated server where it can use all available system resources. Using this option is not recommended if the MySQL instance shares system resources with other applications. </p> <p> It is strongly recommended that you read <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> , before using this option in production. </p> </li> <li class="listitem"> <p> <a name="option_mysqld_innodb-status-file"> </a> <a class="link" href="innodb-parameters.html#option_mysqld_innodb-status-file"> <code class="option"> --innodb-status-file </code> </a> </p> <a class="indexterm" name="idm46045157383008"> </a> <a class="indexterm" name="idm46045157381552"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb-status-file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-status-file[={OFF|ON}] </code> </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> The <code class="option"> --innodb-status-file </code> startup option controls whether <code class="literal"> InnoDB </code> creates a file named <code class="filename"> innodb_status. <em class="replaceable"> <code> pid </code> </em> </code> in the data directory and writes <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output to it every 15 seconds, approximately. </p> <p> The <code class="filename"> innodb_status. <em class="replaceable"> <code> pid </code> </em> </code> file is not created by default. To create it, start <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> with the <code class="option"> --innodb-status-file </code> option. <code class="literal"> InnoDB </code> removes the file when the server is shut down normally. If an abnormal shutdown occurs, the status file may have to be removed manually. </p> <p> The <code class="option"> --innodb-status-file </code> option is intended for temporary use, as <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output generation can affect performance, and the <code class="filename"> innodb_status. <em class="replaceable"> <code> pid </code> </em> </code> file can become quite large over time. </p> <p> For related information, see <a class="xref" href="innodb-enabling-monitors.html" title="17.17.2 Enabling InnoDB Monitors"> Section 17.17.2, “Enabling InnoDB Monitors” </a> . </p> </li> </ul> </div> <h3> <a name="innodb-parameters-sysvars"> </a> InnoDB System Variables </h3> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_flushing"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> <code class="literal"> innodb_adaptive_flushing </code> </a> </p> <a class="indexterm" name="idm46045157353568"> </a> <a class="indexterm" name="idm46045157352464"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_flushing"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-flushing[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing"> innodb_adaptive_flushing </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045157330800"> </a> <p> Specifies whether to dynamically adjust the rate of flushing <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> in the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> based on the workload. Adjusting the flush rate dynamically is intended to avoid bursts of I/O activity. This setting is enabled by default. See <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> for more information. For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_flushing_lwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> <code class="literal"> innodb_adaptive_flushing_lwm </code> </a> </p> <a class="indexterm" name="idm46045157322784"> </a> <a class="indexterm" name="idm46045157321680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_flushing_lwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-flushing-lwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_flushing_lwm"> innodb_adaptive_flushing_lwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 70 </code> </td> </tr> </tbody> </table> </div> <p> Defines the low water mark representing percentage of <a class="link" href="glossary.html#glos_redo_log" title="redo log"> redo log </a> capacity at which <a class="link" href="glossary.html#glos_adaptive_flushing" title="adaptive flushing"> adaptive flushing </a> is enabled. For more information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_hash_index"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="literal"> innodb_adaptive_hash_index </code> </a> </p> <a class="indexterm" name="idm46045157289600"> </a> <a class="indexterm" name="idm46045157288496"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_hash_index"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-hash-index[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> innodb_adaptive_hash_index </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Whether the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_adaptive_hash_index" title="adaptive hash index"> adaptive hash index </a> is enabled or disabled. It may be desirable, depending on your workload, to dynamically enable or disable <a class="link" href="glossary.html#glos_adaptive_hash_index" title="adaptive hash index"> adaptive hash indexing </a> to improve query performance. Because the adaptive hash index may not be useful for all workloads, conduct benchmarks with it both enabled and disabled, using realistic workloads. See <a class="xref" href="innodb-adaptive-hash.html" title="17.5.3 Adaptive Hash Index"> Section 17.5.3, “Adaptive Hash Index” </a> for details. </p> <p> This variable is disabled by default. You can modify this parameter using the <code class="literal"> SET GLOBAL </code> statement, without restarting the server. Changing the setting at runtime requires privileges sufficient to set global system variables. See <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> . You can also use <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index"> <code class="option"> --innodb-adaptive-hash-index </code> </a> at server startup to enable it. </p> <p> Disabling the adaptive hash index empties the hash table immediately. Normal operations can continue while the hash table is emptied, and executing queries that were using the hash table access the index B-trees directly instead. When the adaptive hash index is re-enabled, the hash table is populated again during normal operation. </p> <p> Before MySQL 8.4, this option was enabled by default. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_hash_index_parts"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index_parts"> <code class="literal"> innodb_adaptive_hash_index_parts </code> </a> </p> <a class="indexterm" name="idm46045157256064"> </a> <a class="indexterm" name="idm46045157254960"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_hash_index_parts"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-hash-index-parts=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_hash_index_parts"> innodb_adaptive_hash_index_parts </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 8 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 512 </code> </td> </tr> </tbody> </table> </div> <p> Partitions the adaptive hash index search system. Each index is bound to a specific partition, with each partition protected by a separate latch. </p> <p> The adaptive hash index search system is partitioned into 8 parts by default. The maximum setting is 512. </p> <p> For related information, see <a class="xref" href="innodb-adaptive-hash.html" title="17.5.3 Adaptive Hash Index"> Section 17.5.3, “Adaptive Hash Index” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_adaptive_max_sleep_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> <code class="literal"> innodb_adaptive_max_sleep_delay </code> </a> </p> <a class="indexterm" name="idm46045157223728"> </a> <a class="indexterm" name="idm46045157222624"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_adaptive_max_sleep_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-adaptive-max-sleep-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> innodb_adaptive_max_sleep_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 150000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000000 </code> </td> </tr> <tr> <th> Unit </th> <td> microseconds </td> </tr> </tbody> </table> </div> <p> Permits <code class="literal"> InnoDB </code> to automatically adjust the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> up or down according to the current workload. Any nonzero value enables automated, dynamic adjustment of the <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> value, up to the maximum value specified in the <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> <code class="literal"> innodb_adaptive_max_sleep_delay </code> </a> option. The value represents the number of microseconds. This option can be useful in busy systems, with greater than 16 <code class="literal"> InnoDB </code> threads. (In practice, it is most valuable for MySQL systems with hundreds or thousands of simultaneous connections.) </p> <p> For more information, see <a class="xref" href="innodb-performance-thread_concurrency.html" title="17.8.4 Configuring Thread Concurrency for InnoDB"> Section 17.8.4, “Configuring Thread Concurrency for InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_autoextend_increment"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> <code class="literal"> innodb_autoextend_increment </code> </a> </p> <a class="indexterm" name="idm46045157184176"> </a> <a class="indexterm" name="idm46045157183072"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_autoextend_increment"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-autoextend-increment=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> innodb_autoextend_increment </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 64 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> <tr> <th> Unit </th> <td> megabytes </td> </tr> </tbody> </table> </div> <p> The increment size (in megabytes) for extending the size of an auto-extending <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> file when it becomes full. The default value is 64. For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-data-file-configuration" title="System Tablespace Data File Configuration"> System Tablespace Data File Configuration </a> , and <a class="xref" href="innodb-system-tablespace.html#innodb-resize-system-tablespace" title="Resizing the System Tablespace"> Resizing the System Tablespace </a> . </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> <code class="literal"> innodb_autoextend_increment </code> </a> setting does not affect <a class="link" href="glossary.html#glos_file_per_table" title="file-per-table"> file-per-table </a> tablespace files or <a class="link" href="glossary.html#glos_general_tablespace" title="general tablespace"> general tablespace </a> files. These files are auto-extending regardless of the <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> <code class="literal"> innodb_autoextend_increment </code> </a> setting. The initial extensions are by small amounts, after which extensions occur in increments of 4MB. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_autoinc_lock_mode"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode"> <code class="literal"> innodb_autoinc_lock_mode </code> </a> </p> <a class="indexterm" name="idm46045157143568"> </a> <a class="indexterm" name="idm46045157142464"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_autoinc_lock_mode"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-autoinc-lock-mode=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_autoinc_lock_mode"> innodb_autoinc_lock_mode </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 0 </code> </p> <p class="valid-value"> <code class="literal"> 1 </code> </p> <p class="valid-value"> <code class="literal"> 2 </code> </p> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="glossary.html#glos_lock_mode" title="lock mode"> lock mode </a> to use for generating <a class="link" href="glossary.html#glos_auto_increment" title="auto-increment"> auto-increment </a> values. Permissible values are 0, 1, or 2, for traditional, consecutive, or interleaved, respectively. </p> <p> The default setting is 2 (interleaved), for compatibility with row-based replication. </p> <p> For the characteristics of each lock mode, see <a class="xref" href="innodb-auto-increment-handling.html#innodb-auto-increment-lock-modes" title="InnoDB AUTO_INCREMENT Lock Modes"> InnoDB AUTO_INCREMENT Lock Modes </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_background_drop_list_empty"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> <code class="literal"> innodb_background_drop_list_empty </code> </a> </p> <a class="indexterm" name="idm46045157109440"> </a> <a class="indexterm" name="idm46045157108400"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_background_drop_list_empty"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-background-drop-list-empty[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> innodb_background_drop_list_empty </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enabling the <a class="link" href="innodb-parameters.html#sysvar_innodb_background_drop_list_empty"> <code class="literal"> innodb_background_drop_list_empty </code> </a> debug option helps avoid test case failures by delaying table creation until the background drop list is empty. For example, if test case A places table <code class="literal"> t1 </code> on the background drop list, test case B waits until the background drop list is empty before creating table <code class="literal"> t1 </code> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_chunk_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> </p> <a class="indexterm" name="idm46045157080768"> </a> <a class="indexterm" name="idm46045157079664"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_chunk_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-chunk-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> innodb_buffer_pool_chunk_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 134217728 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1048576 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> innodb_buffer_pool_size / innodb_buffer_pool_instances </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> defines the chunk size for <code class="literal"> InnoDB </code> buffer pool resizing operations. </p> <p> To avoid copying all buffer pool pages during resizing operations, the operation is performed in <span class="quote"> “ <span class="quote"> chunks </span> ” </span> . By default, <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> is 128MB (134217728 bytes). The number of pages contained in a chunk depends on the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> . <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> can be increased or decreased in units of 1MB (1048576 bytes). </p> <p> The following conditions apply when altering the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> value: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> is larger than the current buffer pool size when the buffer pool is initialized, <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> is truncated to <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> / <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . </p> </li> <li class="listitem"> <p> Buffer pool size must always be equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . If you alter <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> is automatically rounded to a value that is equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . The adjustment occurs when the buffer pool is initialized. </p> </li> </ul> </div> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> Care should be taken when changing <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> , as changing this value can automatically increase the size of the buffer pool. Before changing <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> , calculate its effect on <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> to ensure that the resulting buffer pool size is acceptable. </p> </div> <p> To avoid potential performance issues, the number of chunks ( <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> / <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> ) should not exceed 1000. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> variable is dynamic, which permits resizing the buffer pool while the server is online. However, the buffer pool size must be equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> , and changing either of those variable settings requires restarting the server. </p> <p> See <a class="xref" href="innodb-buffer-pool-resize.html" title="17.8.3.1 Configuring InnoDB Buffer Pool Size"> Section 17.8.3.1, “Configuring InnoDB Buffer Pool Size” </a> for more information. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_debug"> <code class="literal"> innodb_buffer_pool_debug </code> </a> </p> <a class="indexterm" name="idm46045157009264"> </a> <a class="indexterm" name="idm46045157008176"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-debug[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_debug"> innodb_buffer_pool_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enabling this option permits multiple buffer pool instances when the buffer pool is less than 1GB in size, ignoring the 1GB minimum buffer pool size constraint imposed on <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . The <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_debug"> <code class="literal"> innodb_buffer_pool_debug </code> </a> option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_dump_at_shutdown"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> </p> <a class="indexterm" name="idm46045156979072"> </a> <a class="indexterm" name="idm46045156978032"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_dump_at_shutdown"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-dump-at-shutdown[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> innodb_buffer_pool_dump_at_shutdown </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies whether to record the pages cached in the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> when the MySQL server is shut down, to shorten the <a class="link" href="glossary.html#glos_warm_up" title="warm up"> warmup </a> process at the next restart. Typically used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> . The <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> <code class="literal"> innodb_buffer_pool_dump_pct </code> </a> option defines the percentage of most recently used buffer pool pages to dump. </p> <p> Both <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> are enabled by default. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_dump_now"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> <code class="literal"> innodb_buffer_pool_dump_now </code> </a> </p> <a class="indexterm" name="idm46045156943904"> </a> <a class="indexterm" name="idm46045156942800"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_dump_now"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-dump-now[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> innodb_buffer_pool_dump_now </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Immediately makes a record of pages cached in the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> . Typically used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> <code class="literal"> innodb_buffer_pool_load_now </code> </a> . </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> <code class="literal"> innodb_buffer_pool_dump_now </code> </a> triggers the recording action but does not alter the variable setting, which always remains <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . To view buffer pool dump status after triggering a dump, query the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_dump_status"> <code class="literal"> Innodb_buffer_pool_dump_status </code> </a> variable. </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> <code class="literal"> innodb_buffer_pool_dump_now </code> </a> triggers the dump action but does not alter the variable setting, which always remains <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . To view buffer pool dump status after triggering a dump, query the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_dump_status"> <code class="literal"> Innodb_buffer_pool_dump_status </code> </a> variable. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_dump_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> <code class="literal"> innodb_buffer_pool_dump_pct </code> </a> </p> <a class="indexterm" name="idm46045156905040"> </a> <a class="indexterm" name="idm46045156903936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_dump_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-dump-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> innodb_buffer_pool_dump_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 25 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the percentage of the most recently used pages for each buffer pool to read out and dump. The range is 1 to 100. The default value is 25. For example, if there are 4 buffer pools with 100 pages each, and <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_pct"> <code class="literal"> innodb_buffer_pool_dump_pct </code> </a> is set to 25, the 25 most recently used pages from each buffer pool are dumped. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_filename"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_filename"> <code class="literal"> innodb_buffer_pool_filename </code> </a> </p> <a class="indexterm" name="idm46045156872896"> </a> <a class="indexterm" name="idm46045156871792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_filename"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-filename=file_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_filename"> innodb_buffer_pool_filename </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> File name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ib_buffer_pool </code> </td> </tr> </tbody> </table> </div> <p> Specifies the name of the file that holds the list of tablespace IDs and page IDs produced by <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> or <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_now"> <code class="literal"> innodb_buffer_pool_dump_now </code> </a> . Tablespace IDs and page IDs are saved in the following format: <code class="literal"> space, page_id </code> . By default, the file is named <code class="filename"> ib_buffer_pool </code> and is located in the <code class="literal"> InnoDB </code> data directory. A non-default location must be specified relative to the data directory. </p> <p> A file name can be specified at runtime, using a <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa45697009"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> innodb_buffer_pool_filename<span class="token operator">=</span><span class="token string"><em class="replaceable">'file_name'</em></span><span class="token punctuation">;</span></code></pre> </div> <p> You can also specify a file name at startup, in a startup string or MySQL configuration file. When specifying a file name at startup, the file must exist or <code class="literal"> InnoDB </code> returns a startup error indicating that there is no such file or directory. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_in_core_file"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> <code class="literal"> innodb_buffer_pool_in_core_file </code> </a> </p> <a class="indexterm" name="idm46045156836512"> </a> <a class="indexterm" name="idm46045156835408"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_in_core_file"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-in-core-file[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> innodb_buffer_pool_in_core_file </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Disabling (default) the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_in_core_file"> <code class="literal"> innodb_buffer_pool_in_core_file </code> </a> variable reduces the size of core files by excluding <code class="literal"> InnoDB </code> buffer pool pages. </p> <p> To use this variable, the <a class="link" href="server-system-variables.html#sysvar_core_file"> <code class="literal"> core_file </code> </a> variable must be enabled, and to disable this option the operating system must support the <code class="literal"> MADV_DONTDUMP </code> non-POSIX extension to <code class="literal"> madvise() </code> , which is supported in Linux 3.4 and later. For more information, see <a class="xref" href="innodb-buffer-pool-in-core-file.html" title="17.8.3.7 Excluding or Including Buffer Pool Pages from Core Files"> Section 17.8.3.7, “Excluding or Including Buffer Pool Pages from Core Files” </a> . </p> <p> This is disabled by default on systems that support <code class="literal"> MADV_DONTDUMP </code> , which is typically only Linux and not macOS or Windows. </p> <p> Before MySQL 8.4, this option was enabled by default. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_instances"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> </p> <a class="indexterm" name="idm46045156802944"> </a> <a class="indexterm" name="idm46045156801840"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_instances"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-instances=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> innodb_buffer_pool_instances </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> see description </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> The number of regions that the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> is divided into. For systems with buffer pools in the multi-gigabyte range, dividing the buffer pool into separate instances can improve concurrency, by reducing contention as different threads read and write to cached pages. Each page that is stored in or read from the buffer pool is assigned to one of the buffer pool instances randomly, using a hashing function. Each buffer pool manages its own free lists, <a class="link" href="glossary.html#glos_flush_list" title="flush list"> flush lists </a> , <a class="link" href="glossary.html#glos_lru" title="LRU"> LRUs </a> , and all other data structures connected to a buffer pool, and is protected by its own buffer pool <a class="link" href="glossary.html#glos_mutex" title="mutex"> mutex </a> . </p> <p> The total buffer pool size is divided among all the buffer pools. For best efficiency, specify a combination of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> so that each buffer pool instance is at least 1GB. </p> <p> If <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> <= 1 GiB, then the default <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> value is 1. </p> <p> If <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> > 1 GiB, then the default <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> value is the minimum value from the following two calculated hints, within a range of 1-64: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Buffer pool hint: calculated as 1/2 of ( <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> / <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> ) </p> </li> <li class="listitem"> <p> CPU hint: calculated as 1/4 of available logical processors </p> </li> </ul> </div> <p> For related information, see <a class="xref" href="innodb-buffer-pool-resize.html" title="17.8.3.1 Configuring InnoDB Buffer Pool Size"> Section 17.8.3.1, “Configuring InnoDB Buffer Pool Size” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_load_abort"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> <code class="literal"> innodb_buffer_pool_load_abort </code> </a> </p> <a class="indexterm" name="idm46045156752416"> </a> <a class="indexterm" name="idm46045156751312"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_load_abort"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-load-abort[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> innodb_buffer_pool_load_abort </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Interrupts the process of restoring <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> contents triggered by <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> or <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> <code class="literal"> innodb_buffer_pool_load_now </code> </a> . </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_abort"> <code class="literal"> innodb_buffer_pool_load_abort </code> </a> triggers the abort action but does not alter the variable setting, which always remains <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . To view buffer pool load status after triggering an abort action, query the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_load_status"> <code class="literal"> Innodb_buffer_pool_load_status </code> </a> variable. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_load_at_startup"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> </p> <a class="indexterm" name="idm46045156716688"> </a> <a class="indexterm" name="idm46045156715648"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_load_at_startup"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-load-at-startup[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> innodb_buffer_pool_load_at_startup </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies that, on MySQL server startup, the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> is automatically <a class="link" href="glossary.html#glos_warm_up" title="warm up"> warmed up </a> by loading the same pages it held at an earlier time. Typically used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> . </p> <p> Both <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_dump_at_shutdown"> <code class="literal"> innodb_buffer_pool_dump_at_shutdown </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_at_startup"> <code class="literal"> innodb_buffer_pool_load_at_startup </code> </a> are enabled by default. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_load_now"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> <code class="literal"> innodb_buffer_pool_load_now </code> </a> </p> <a class="indexterm" name="idm46045156682928"> </a> <a class="indexterm" name="idm46045156681824"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_load_now"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-load-now[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> innodb_buffer_pool_load_now </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Immediately <a class="link" href="glossary.html#glos_warm_up" title="warm up"> warms up </a> the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> by loading data pages without waiting for a server restart. Can be useful to bring cache memory back to a known state during benchmarking or to ready the MySQL server to resume its normal workload after running queries for reports or maintenance. </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_load_now"> <code class="literal"> innodb_buffer_pool_load_now </code> </a> triggers the load action but does not alter the variable setting, which always remains <code class="literal"> OFF </code> or <code class="literal"> 0 </code> . To view buffer pool load progress after triggering a load, query the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_load_status"> <code class="literal"> Innodb_buffer_pool_load_status </code> </a> variable. </p> <p> For more information, see <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_buffer_pool_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> </p> <a class="indexterm" name="idm46045156648848"> </a> <a class="indexterm" name="idm46045156647808"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_buffer_pool_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-buffer-pool-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> innodb_buffer_pool_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 134217728 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 5242880 </code> </td> </tr> <tr> <th> Maximum Value (64-bit platforms) </th> <td> <code class="literal"> 2**64-1 </code> </td> </tr> <tr> <th> Maximum Value (32-bit platforms) </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> The size in bytes of the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> , the memory area where <code class="literal"> InnoDB </code> caches table and index data. The default value is 134217728 bytes (128MB). The maximum value depends on the CPU architecture; the maximum is 4294967295 (2 <sup> 32 </sup> -1) on 32-bit systems and 18446744073709551615 (2 <sup> 64 </sup> -1) on 64-bit systems. On 32-bit systems, the CPU architecture and operating system may impose a lower practical maximum size than the stated maximum. When the size of the buffer pool is greater than 1GB, setting <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> to a value greater than 1 can improve the scalability on a busy server. </p> <p> A larger buffer pool requires less disk I/O to access the same table data more than once. On a dedicated database server, you might set the buffer pool size to 80% of the machine's physical memory size. Be aware of the following potential issues when configuring buffer pool size, and be prepared to scale back the size of the buffer pool if necessary. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Competition for physical memory can cause paging in the operating system. </p> </li> <li class="listitem"> <p> <code class="literal"> InnoDB </code> reserves additional memory for buffers and control structures, so that the total allocated space is approximately 10% greater than the specified buffer pool size. </p> </li> <li class="listitem"> <p> Address space for the buffer pool must be contiguous, which can be an issue on Windows systems with DLLs that load at specific addresses. </p> </li> <li class="listitem"> <p> The time to initialize the buffer pool is roughly proportional to its size. On instances with large buffer pools, initialization time might be significant. To reduce the initialization period, you can save the buffer pool state at server shutdown and restore it at server startup. See <a class="xref" href="innodb-preload-buffer-pool.html" title="17.8.3.6 Saving and Restoring the Buffer Pool State"> Section 17.8.3.6, “Saving and Restoring the Buffer Pool State” </a> . </p> </li> </ul> </div> <p> When you increase or decrease buffer pool size, the operation is performed in chunks. Chunk size is defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> variable, which has a default of 128 MB. </p> <p> Buffer pool size must always be equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . If you alter the buffer pool size to a value that is not equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> , buffer pool size is automatically adjusted to a value that is equal to or a multiple of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_chunk_size"> <code class="literal"> innodb_buffer_pool_chunk_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> can be set dynamically, which allows you to resize the buffer pool without restarting the server. The <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_resize_status"> <code class="literal"> Innodb_buffer_pool_resize_status </code> </a> status variable reports the status of online buffer pool resizing operations. See <a class="xref" href="innodb-buffer-pool-resize.html" title="17.8.3.1 Configuring InnoDB Buffer Pool Size"> Section 17.8.3.1, “Configuring InnoDB Buffer Pool Size” </a> for more information. </p> <p> If the server is started with <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> , the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_size"> <code class="literal"> innodb_buffer_pool_size </code> </a> is set automatically if it is not explicitly defined. For more information, see <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_change_buffer_max_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffer_max_size"> <code class="literal"> innodb_change_buffer_max_size </code> </a> </p> <a class="indexterm" name="idm46045156585376"> </a> <a class="indexterm" name="idm46045156584272"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_change_buffer_max_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-change-buffer-max-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffer_max_size"> innodb_change_buffer_max_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 25 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 50 </code> </td> </tr> </tbody> </table> </div> <p> Maximum size for the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_change_buffer" title="change buffer"> change buffer </a> , as a percentage of the total size of the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> . You might increase this value for a MySQL server with heavy insert, update, and delete activity, or decrease it for a MySQL server with unchanging data used for reporting. For more information, see <a class="xref" href="innodb-change-buffer.html" title="17.5.2 Change Buffer"> Section 17.5.2, “Change Buffer” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_change_buffering"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering"> <code class="literal"> innodb_change_buffering </code> </a> </p> <a class="indexterm" name="idm46045156550784"> </a> <a class="indexterm" name="idm46045156549744"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_change_buffering"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-change-buffering=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering"> innodb_change_buffering </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> none </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> none </code> </p> <p class="valid-value"> <code class="literal"> inserts </code> </p> <p class="valid-value"> <code class="literal"> deletes </code> </p> <p class="valid-value"> <code class="literal"> changes </code> </p> <p class="valid-value"> <code class="literal"> purges </code> </p> <p class="valid-value"> <code class="literal"> all </code> </p> </td> </tr> </tbody> </table> </div> <p> Whether <code class="literal"> InnoDB </code> performs <a class="link" href="glossary.html#glos_change_buffering" title="change buffering"> change buffering </a> , an optimization that delays write operations to secondary indexes so that the I/O operations can be performed sequentially. Permitted values are described in the following table. Values may also be specified numerically. </p> <div class="table"> <a name="innodb-change-buffer-permitted-values"> </a> <p class="title"> <b> Table 17.24 Permitted Values for innodb_change_buffering </b> </p> <div class="table-contents"> <table summary="Permitted values for the innodb_chansge_buffering variable. The first column defines the value. The second column describes the option effect."> <colgroup> <col style="width: 20%"/> <col style="width: 20%"/> <col style="width: 60%"/> </colgroup> <thead> <tr> <th scope="col"> Value </th> <th scope="col"> Numeric Value </th> <th scope="col"> Description </th> </tr> </thead> <tbody> <tr> <th scope="row"> <code class="literal"> none </code> </th> <td> <code class="literal"> 0 </code> </td> <td> Default. Do not buffer any operations. </td> </tr> <tr> <th scope="row"> <code class="literal"> inserts </code> </th> <td> <code class="literal"> 1 </code> </td> <td> Buffer insert operations. </td> </tr> <tr> <th scope="row"> <code class="literal"> deletes </code> </th> <td> <code class="literal"> 2 </code> </td> <td> Buffer delete marking operations; strictly speaking, the writes that mark index records for later deletion during a purge operation. </td> </tr> <tr> <th scope="row"> <code class="literal"> changes </code> </th> <td> <code class="literal"> 3 </code> </td> <td> Buffer inserts and delete-marking operations. </td> </tr> <tr> <th scope="row"> <code class="literal"> purges </code> </th> <td> <code class="literal"> 4 </code> </td> <td> Buffer the physical deletion operations that happen in the background. </td> </tr> <tr> <th scope="row"> <code class="literal"> all </code> </th> <td> <code class="literal"> 5 </code> </td> <td> Buffer inserts, delete-marking operations, and purges. </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> <p> Before MySQL 8.4, the default value was <code class="literal"> all </code> . </p> <p> For more information, see <a class="xref" href="innodb-change-buffer.html" title="17.5.2 Change Buffer"> Section 17.5.2, “Change Buffer” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_change_buffering_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering_debug"> <code class="literal"> innodb_change_buffering_debug </code> </a> </p> <a class="indexterm" name="idm46045156479408"> </a> <a class="indexterm" name="idm46045156478320"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_change_buffering_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-change-buffering-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_change_buffering_debug"> innodb_change_buffering_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2 </code> </td> </tr> </tbody> </table> </div> <p> Sets a debug flag for <code class="literal"> InnoDB </code> change buffering. A value of 1 forces all changes to the change buffer. A value of 2 causes an unexpected exit at merge. A default value of 0 indicates that the change buffering debug flag is not set. This option is only available when debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_checkpoint_disabled"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_checkpoint_disabled"> <code class="literal"> innodb_checkpoint_disabled </code> </a> </p> <a class="indexterm" name="idm46045156446208"> </a> <a class="indexterm" name="idm46045156445104"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_checkpoint_disabled"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-checkpoint-disabled[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checkpoint_disabled"> innodb_checkpoint_disabled </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> This is a debug option that is only intended for expert debugging use. It disables checkpoints so that a deliberate server exit always initiates <code class="literal"> InnoDB </code> recovery. It should only be enabled for a short interval, typically before running DML operations that write redo log entries that would require recovery following a server exit. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_checksum_algorithm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> <code class="literal"> innodb_checksum_algorithm </code> </a> </p> <a class="indexterm" name="idm46045156417712"> </a> <a class="indexterm" name="idm46045156416608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_checksum_algorithm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-checksum-algorithm=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> innodb_checksum_algorithm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> crc32 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> crc32 </code> </p> <p class="valid-value"> <code class="literal"> strict_crc32 </code> </p> <p class="valid-value"> <code class="literal"> innodb </code> </p> <p class="valid-value"> <code class="literal"> strict_innodb </code> </p> <p class="valid-value"> <code class="literal"> none </code> </p> <p class="valid-value"> <code class="literal"> strict_none </code> </p> </td> </tr> </tbody> </table> </div> <p> Specifies how to generate and verify the <a class="link" href="glossary.html#glos_checksum" title="checksum"> checksum </a> stored in the disk blocks of <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_tablespace" title="tablespace"> tablespaces </a> . The default value for <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> <code class="literal"> innodb_checksum_algorithm </code> </a> is <code class="literal"> crc32 </code> . </p> <p> The value <code class="literal"> innodb </code> is backward-compatible with earlier versions of MySQL. The value <code class="literal"> crc32 </code> uses an algorithm that is faster to compute the checksum for every modified block, and to check the checksums for each disk read. It scans blocks 64 bits at a time, which is faster than the <code class="literal"> innodb </code> checksum algorithm, which scans blocks 8 bits at a time. The value <code class="literal"> none </code> writes a constant value in the checksum field rather than computing a value based on the block data. The blocks in a tablespace can use a mix of old, new, and no checksum values, being updated gradually as the data is modified; once blocks in a tablespace are modified to use the <code class="literal"> crc32 </code> algorithm, the associated tables cannot be read by earlier versions of MySQL. </p> <p> The strict form of a checksum algorithm reports an error if it encounters a valid but non-matching checksum value in a tablespace. It is recommended that you only use strict settings in a new instance, to set up tablespaces for the first time. Strict settings are somewhat faster, because they do not need to compute all checksum values during disk reads. </p> <p> The following table shows the difference between the <code class="literal"> none </code> , <code class="literal"> innodb </code> , and <code class="literal"> crc32 </code> option values, and their strict counterparts. <code class="literal"> none </code> , <code class="literal"> innodb </code> , and <code class="literal"> crc32 </code> write the specified type of checksum value into each data block, but for compatibility accept other checksum values when verifying a block during a read operation. Strict settings also accept valid checksum values but print an error message when a valid non-matching checksum value is encountered. Using the strict form can make verification faster if all <code class="literal"> InnoDB </code> data files in an instance are created under an identical <a class="link" href="innodb-parameters.html#sysvar_innodb_checksum_algorithm"> <code class="literal"> innodb_checksum_algorithm </code> </a> value. </p> <div class="table"> <a name="innodb-checksum-algorithm-values"> </a> <p class="title"> <b> Table 17.25 Permitted innodb_checksum_algorithm Values </b> </p> <div class="table-contents"> <table summary="Permitted values for the innodb_checksum_algorithm variable. The first column defines the checksum value. The second column describes the generated checksum. The third column describes compatible checksums."> <colgroup> <col style="width: 20%"/> <col style="width: 40%"/> <col style="width: 40%"/> </colgroup> <thead> <tr> <th scope="col"> Value </th> <th scope="col"> Generated checksum (when writing) </th> <th scope="col"> Permitted checksums (when reading) </th> </tr> </thead> <tbody> <tr> <th scope="row"> none </th> <td> A constant number. </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . </td> </tr> <tr> <th scope="row"> innodb </th> <td> A checksum calculated in software, using the original algorithm from <code class="literal"> InnoDB </code> . </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . </td> </tr> <tr> <th scope="row"> crc32 </th> <td> A checksum calculated using the <code class="literal"> crc32 </code> algorithm, possibly done with a hardware assist. </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . </td> </tr> <tr> <th scope="row"> strict_none </th> <td> A constant number </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . <code class="literal"> InnoDB </code> prints an error message if a valid but non-matching checksum is encountered. </td> </tr> <tr> <th scope="row"> strict_innodb </th> <td> A checksum calculated in software, using the original algorithm from <code class="literal"> InnoDB </code> . </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . <code class="literal"> InnoDB </code> prints an error message if a valid but non-matching checksum is encountered. </td> </tr> <tr> <th scope="row"> strict_crc32 </th> <td> A checksum calculated using the <code class="literal"> crc32 </code> algorithm, possibly done with a hardware assist. </td> <td> Any of the checksums generated by <code class="literal"> none </code> , <code class="literal"> innodb </code> , or <code class="literal"> crc32 </code> . <code class="literal"> InnoDB </code> prints an error message if a valid but non-matching checksum is encountered. </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> </li> <li class="listitem"> <p> <a name="sysvar_innodb_cmp_per_index_enabled"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_cmp_per_index_enabled"> <code class="literal"> innodb_cmp_per_index_enabled </code> </a> </p> <a class="indexterm" name="idm46045156319904"> </a> <a class="indexterm" name="idm46045156318800"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_cmp_per_index_enabled"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-cmp-per-index-enabled[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_cmp_per_index_enabled"> innodb_cmp_per_index_enabled </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables per-index compression-related statistics in the Information Schema <a class="link" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> <code class="literal"> INNODB_CMP_PER_INDEX </code> </a> table. Because these statistics can be expensive to gather, only enable this option on development, test, or replica instances during performance tuning related to <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_compression" title="compression"> compressed </a> tables. </p> <p> For more information, see <a class="xref" href="information-schema-innodb-cmp-per-index-table.html" title="28.4.8 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables"> Section 28.4.8, “The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables” </a> , and <a class="xref" href="innodb-compression-tuning-monitoring.html" title="17.9.1.4 Monitoring InnoDB Table Compression at Runtime"> Section 17.9.1.4, “Monitoring InnoDB Table Compression at Runtime” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_commit_concurrency"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> <code class="literal"> innodb_commit_concurrency </code> </a> </p> <a class="indexterm" name="idm46045156289232"> </a> <a class="indexterm" name="idm46045156288128"> </a> <a class="indexterm" name="idm46045156286624"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_commit_concurrency"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-commit-concurrency=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> innodb_commit_concurrency </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> </tbody> </table> </div> <p> The number of <a class="link" href="glossary.html#glos_thread" title="thread"> threads </a> that can <a class="link" href="glossary.html#glos_commit" title="commit"> commit </a> at the same time. A value of 0 (the default) permits any number of <a class="link" href="glossary.html#glos_transaction" title="transaction"> transactions </a> to commit simultaneously. </p> <p> The value of <a class="link" href="innodb-parameters.html#sysvar_innodb_commit_concurrency"> <code class="literal"> innodb_commit_concurrency </code> </a> cannot be changed at runtime from zero to nonzero or vice versa. The value can be changed from one nonzero value to another. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_compress_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_compress_debug"> <code class="literal"> innodb_compress_debug </code> </a> </p> <a class="indexterm" name="idm46045156252688"> </a> <a class="indexterm" name="idm46045156251616"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_compress_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-compress-debug=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compress_debug"> innodb_compress_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> none </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> none </code> </p> <p class="valid-value"> <code class="literal"> zlib </code> </p> <p class="valid-value"> <code class="literal"> lz4 </code> </p> <p class="valid-value"> <code class="literal"> lz4hc </code> </p> </td> </tr> </tbody> </table> </div> <p> Compresses all tables using a specified compression algorithm without having to define a <code class="literal"> COMPRESSION </code> attribute for each table. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> <p> For related information, see <a class="xref" href="innodb-page-compression.html" title="17.9.2 InnoDB Page Compression"> Section 17.9.2, “InnoDB Page Compression” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_compression_failure_threshold_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> <code class="literal"> innodb_compression_failure_threshold_pct </code> </a> </p> <a class="indexterm" name="idm46045156217632"> </a> <a class="indexterm" name="idm46045156216512"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_compression_failure_threshold_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-compression-failure-threshold-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> innodb_compression_failure_threshold_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Defines the compression failure rate threshold for a table, as a percentage, at which point MySQL begins adding padding within <a class="link" href="glossary.html#glos_compression" title="compression"> compressed </a> pages to avoid expensive <a class="link" href="glossary.html#glos_compression_failure" title="compression failure"> compression failures </a> . When this threshold is passed, MySQL begins to leave additional free space within each new compressed page, dynamically adjusting the amount of free space up to the percentage of page size specified by <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> <code class="literal"> innodb_compression_pad_pct_max </code> </a> . A value of zero disables the mechanism that monitors compression efficiency and dynamically adjusts the padding amount. </p> <p> For more information, see <a class="xref" href="innodb-performance-compression-oltp.html" title="17.9.1.6 Compression for OLTP Workloads"> Section 17.9.1.6, “Compression for OLTP Workloads” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_compression_level"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_level"> <code class="literal"> innodb_compression_level </code> </a> </p> <a class="indexterm" name="idm46045156182336"> </a> <a class="indexterm" name="idm46045156181232"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_compression_level"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-compression-level=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_level"> innodb_compression_level </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 6 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 9 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the level of zlib compression to use for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_compression" title="compression"> compressed </a> tables and indexes. A higher value lets you fit more data onto a storage device, at the expense of more CPU overhead during compression. A lower value lets you reduce CPU overhead when storage space is not critical, or you expect the data is not especially compressible. </p> <p> For more information, see <a class="xref" href="innodb-performance-compression-oltp.html" title="17.9.1.6 Compression for OLTP Workloads"> Section 17.9.1.6, “Compression for OLTP Workloads” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_compression_pad_pct_max"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> <code class="literal"> innodb_compression_pad_pct_max </code> </a> </p> <a class="indexterm" name="idm46045156148784"> </a> <a class="indexterm" name="idm46045156147680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_compression_pad_pct_max"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-compression-pad-pct-max=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_pad_pct_max"> innodb_compression_pad_pct_max </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 75 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the maximum percentage that can be reserved as free space within each compressed <a class="link" href="glossary.html#glos_page" title="page"> page </a> , allowing room to reorganize the data and modification log within the page when a <a class="link" href="glossary.html#glos_compression" title="compression"> compressed </a> table or index is updated and the data might be recompressed. Only applies when <a class="link" href="innodb-parameters.html#sysvar_innodb_compression_failure_threshold_pct"> <code class="literal"> innodb_compression_failure_threshold_pct </code> </a> is set to a nonzero value, and the rate of <a class="link" href="glossary.html#glos_compression_failure" title="compression failure"> compression failures </a> passes the cutoff point. </p> <p> For more information, see <a class="xref" href="innodb-performance-compression-oltp.html" title="17.9.1.6 Compression for OLTP Workloads"> Section 17.9.1.6, “Compression for OLTP Workloads” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_concurrency_tickets"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> </p> <a class="indexterm" name="idm46045156112896"> </a> <a class="indexterm" name="idm46045156111792"> </a> <a class="indexterm" name="idm46045156110288"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_concurrency_tickets"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-concurrency-tickets=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> innodb_concurrency_tickets </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 5000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Determines the number of <a class="link" href="glossary.html#glos_thread" title="thread"> threads </a> that can enter <code class="literal"> InnoDB </code> concurrently. A thread is placed in a queue when it tries to enter <code class="literal"> InnoDB </code> if the number of threads has already reached the concurrency limit. When a thread is permitted to enter <code class="literal"> InnoDB </code> , it is given a number of <span class="quote"> “ <span class="quote"> tickets </span> ” </span> equal to the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> , and the thread can enter and leave <code class="literal"> InnoDB </code> freely until it has used up its tickets. After that point, the thread again becomes subject to the concurrency check (and possible queuing) the next time it tries to enter <code class="literal"> InnoDB </code> . The default value is 5000. </p> <p> With a small <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value, small transactions that only need to process a few rows compete fairly with larger transactions that process many rows. The disadvantage of a small <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value is that large transactions must loop through the queue many times before they can complete, which extends the amount of time required to complete their task. </p> <p> With a large <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value, large transactions spend less time waiting for a position at the end of the queue (controlled by <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> ) and more time retrieving rows. Large transactions also require fewer trips through the queue to complete their task. The disadvantage of a large <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value is that too many large transactions running at the same time can starve smaller transactions by making them wait a longer time before executing. </p> <p> With a nonzero <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> value, you may need to adjust the <a class="link" href="innodb-parameters.html#sysvar_innodb_concurrency_tickets"> <code class="literal"> innodb_concurrency_tickets </code> </a> value up or down to find the optimal balance between larger and smaller transactions. The <code class="literal"> SHOW ENGINE INNODB STATUS </code> report shows the number of tickets remaining for an executing transaction in its current pass through the queue. This data may also be obtained from the <code class="literal"> TRX_CONCURRENCY_TICKETS </code> column of the Information Schema <a class="link" href="information-schema-innodb-trx-table.html" title="28.4.28 The INFORMATION_SCHEMA INNODB_TRX Table"> <code class="literal"> INNODB_TRX </code> </a> table. </p> <p> For more information, see <a class="xref" href="innodb-performance-thread_concurrency.html" title="17.8.4 Configuring Thread Concurrency for InnoDB"> Section 17.8.4, “Configuring Thread Concurrency for InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_data_file_path"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> </p> <a class="indexterm" name="idm46045156058832"> </a> <a class="indexterm" name="idm46045156057792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_data_file_path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-data-file-path=file_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> innodb_data_file_path </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ibdata1:12M:autoextend </code> </td> </tr> </tbody> </table> </div> <p> Defines the name, size, and attributes of <code class="literal"> InnoDB </code> system tablespace data files. If you do not specify a value for <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> , the default behavior is to create a single auto-extending data file, slightly larger than 12MB, named <code class="filename"> ibdata1 </code> . </p> <p> The full syntax for a data file specification includes the file name, file size, <code class="literal"> autoextend </code> attribute, and <code class="literal"> max </code> attribute: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa64702669"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none"><em class="replaceable">file_name</em>:<em class="replaceable">file_size</em>[:autoextend[:max:<em class="replaceable">max_file_size</em>]]</code></pre> </div> <p> File sizes are specified in kilobytes, megabytes, or gigabytes by appending <code class="literal"> K </code> , <code class="literal"> M </code> or <code class="literal"> G </code> to the size value. If specifying the data file size in kilobytes, do so in multiples of 1024. Otherwise, KB values are rounded to nearest megabyte (MB) boundary. The sum of file sizes must be, at a minimum, slightly larger than 12MB. </p> <p> For additional configuration information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-data-file-configuration" title="System Tablespace Data File Configuration"> System Tablespace Data File Configuration </a> . For resizing instructions, see <a class="xref" href="innodb-system-tablespace.html#innodb-resize-system-tablespace" title="Resizing the System Tablespace"> Resizing the System Tablespace </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_data_home_dir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> </p> <a class="indexterm" name="idm46045156021632"> </a> <a class="indexterm" name="idm46045156020592"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_data_home_dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-data-home-dir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> innodb_data_home_dir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> </tbody> </table> </div> <p> The common part of the directory path for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> data files. The default value is the MySQL <code class="filename"> data </code> directory. The setting is concatenated with the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> setting, unless that setting is defined with an absolute path. </p> <p> A trailing slash is required when specifying a value for <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> . For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa58117203"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">innodb_data_home_dir</span> <span class="token attr-value"><span class="token punctuation">=</span> /path/to/myibdata/</span></code></pre> </div> <p> This setting does not affect the location of <a class="link" href="glossary.html#glos_file_per_table" title="file-per-table"> file-per-table </a> tablespaces. </p> <p> For related information, see <a class="xref" href="innodb-init-startup-configuration.html" title="17.8.1 InnoDB Startup Configuration"> Section 17.8.1, “InnoDB Startup Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ddl_buffer_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> <code class="literal"> innodb_ddl_buffer_size </code> </a> </p> <a class="indexterm" name="idm46045155989552"> </a> <a class="indexterm" name="idm46045155988512"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ddl_buffer_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ddl-buffer-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> innodb_ddl_buffer_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1048576 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 65536 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Defines the maximum buffer size for DDL operations. The default setting is 1048576 bytes (approximately 1 MB). Applies to online DDL operations that create or rebuild secondary indexes. See <a class="xref" href="online-ddl-memory-management.html" title="17.12.4 Online DDL Memory Management"> Section 17.12.4, “Online DDL Memory Management” </a> . The maximum buffer size per DDL thread is the maximum buffer size divided by the number of DDL threads ( <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_buffer_size"> <code class="literal"> innodb_ddl_buffer_size </code> </a> / <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> <code class="literal"> innodb_ddl_threads </code> </a> ). </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ddl_log_crash_reset_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_log_crash_reset_debug"> <code class="literal"> innodb_ddl_log_crash_reset_debug </code> </a> </p> <a class="indexterm" name="idm46045155953408"> </a> <a class="indexterm" name="idm46045155952304"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ddl_log_crash_reset_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ddl-log-crash-reset-debug[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_log_crash_reset_debug"> innodb_ddl_log_crash_reset_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enable this debug option to reset DDL log crash injection counters to 1. This option is only available when debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ddl_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> <code class="literal"> innodb_ddl_threads </code> </a> </p> <a class="indexterm" name="idm46045155925920"> </a> <a class="indexterm" name="idm46045155924880"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ddl_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ddl-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ddl_threads"> innodb_ddl_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> Defines the maximum number of parallel threads for the sort and build phases of index creation. Applies to online DDL operations that create or rebuild secondary indexes. For related information, see <a class="xref" href="online-ddl-parallel-thread-configuration.html" title="17.12.5 Configuring Parallel Threads for Online DDL Operations"> Section 17.12.5, “Configuring Parallel Threads for Online DDL Operations” </a> , and <a class="xref" href="online-ddl-memory-management.html" title="17.12.4 Online DDL Memory Management"> Section 17.12.4, “Online DDL Memory Management” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_deadlock_detect"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> <code class="literal"> innodb_deadlock_detect </code> </a> </p> <a class="indexterm" name="idm46045155893696"> </a> <a class="indexterm" name="idm46045155892656"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_deadlock_detect"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-deadlock-detect[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> innodb_deadlock_detect </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> This option is used to disable deadlock detection. On high concurrency systems, deadlock detection can cause a slowdown when numerous threads wait for the same lock. At times, it may be more efficient to disable deadlock detection and rely on the <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> setting for transaction rollback when a deadlock occurs. </p> <p> For related information, see <a class="xref" href="innodb-deadlock-detection.html" title="17.7.5.2 Deadlock Detection"> Section 17.7.5.2, “Deadlock Detection” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_default_row_format"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> </p> <a class="indexterm" name="idm46045155865408"> </a> <a class="indexterm" name="idm46045155864304"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_default_row_format"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-default-row-format=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> innodb_default_row_format </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> DYNAMIC </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> REDUNDANT </code> </p> <p class="valid-value"> <code class="literal"> COMPACT </code> </p> <p class="valid-value"> <code class="literal"> DYNAMIC </code> </p> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> option defines the default row format for <code class="literal"> InnoDB </code> tables and user-created temporary tables. The default setting is <code class="literal"> DYNAMIC </code> . Other permitted values are <code class="literal"> COMPACT </code> and <code class="literal"> REDUNDANT </code> . The <code class="literal"> COMPRESSED </code> row format, which is not supported for use in the <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> , cannot be defined as the default. </p> <p> Newly created tables use the row format defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> when a <code class="literal"> ROW_FORMAT </code> option is not specified explicitly or when <code class="literal"> ROW_FORMAT=DEFAULT </code> is used. </p> <p> When a <code class="literal"> ROW_FORMAT </code> option is not specified explicitly or when <code class="literal"> ROW_FORMAT=DEFAULT </code> is used, any operation that rebuilds a table also silently changes the row format of the table to the format defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> . For more information, see <a class="xref" href="innodb-row-format.html#innodb-row-format-defining" title="Defining the Row Format of a Table"> Defining the Row Format of a Table </a> . </p> <p> Internal <code class="literal"> InnoDB </code> temporary tables created by the server to process queries use the <code class="literal"> DYNAMIC </code> row format, regardless of the <a class="link" href="innodb-parameters.html#sysvar_innodb_default_row_format"> <code class="literal"> innodb_default_row_format </code> </a> setting. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_directories"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> </p> <a class="indexterm" name="idm46045155818432"> </a> <a class="indexterm" name="idm46045155817392"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_directories"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-directories=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> innodb_directories </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> Defines directories to scan at startup for tablespace files. This option is used when moving or restoring tablespace files to a new location while the server is offline. It is also used to specify directories of tablespace files created using an absolute path or that reside outside of the data directory. </p> <p> Tablespace discovery during crash recovery relies on the <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> setting to identify tablespaces referenced in the redo logs. For more information, see <a class="xref" href="innodb-recovery.html#innodb-recovery-tablespace-discovery" title="Tablespace Discovery During Crash Recovery"> Tablespace Discovery During Crash Recovery </a> . </p> <p> The default value is NULL, but directories defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> , and <a class="link" href="server-system-variables.html#sysvar_datadir"> <code class="literal"> datadir </code> </a> are always appended to the <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> argument value when <code class="literal"> InnoDB </code> builds a list of directories to scan at startup. These directories are appended regardless of whether an <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> setting is specified explicitly. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> may be specified as an option in a startup command or in a MySQL option file. Quotes surround the argument value because otherwise some command interpreters interpret semicolon ( <code class="literal"> ; </code> ) as a special character. (For example, Unix shells treat it as a command terminator.) </p> <p> Startup command: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa21029187"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">mysqld <span class="token constant">--innodb-directories</span>=<span class="token atrule">"<em class="replaceable">directory_path_1</em>;<em class="replaceable">directory_path_2</em>"</span></code></pre> </div> <p> MySQL option file: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa50695958"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">innodb_directories</span><span class="token attr-value"><span class="token punctuation">=</span>"<em class="replaceable">directory_path_1</em>;<em class="replaceable">directory_path_2</em>"</span></code></pre> </div> <p> Wildcard expressions cannot be used to specify directories. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_directories"> <code class="literal"> innodb_directories </code> </a> scan also traverses the subdirectories of specified directories. Duplicate directories and subdirectories are discarded from the list of directories to be scanned. </p> <p> For more information, see <a class="xref" href="innodb-moving-data-files-offline.html" title="17.6.3.6 Moving Tablespace Files While the Server is Offline"> Section 17.6.3.6, “Moving Tablespace Files While the Server is Offline” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_disable_sort_file_cache"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_disable_sort_file_cache"> <code class="literal"> innodb_disable_sort_file_cache </code> </a> </p> <a class="indexterm" name="idm46045155771600"> </a> <a class="indexterm" name="idm46045155770496"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_disable_sort_file_cache"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-disable-sort-file-cache[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_disable_sort_file_cache"> innodb_disable_sort_file_cache </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Disables the operating system file system cache for merge-sort temporary files. The effect is to open such files with the equivalent of <code class="literal"> O_DIRECT </code> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> </p> <a class="indexterm" name="idm46045155745008"> </a> <a class="indexterm" name="idm46045155743968"> </a> <a class="indexterm" name="idm46045155742480"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> innodb_doublewrite </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> ON </code> </p> <p class="valid-value"> <code class="literal"> OFF </code> </p> <p class="valid-value"> <code class="literal"> DETECT_AND_RECOVER </code> </p> <p class="valid-value"> <code class="literal"> DETECT_ONLY </code> </p> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> variable controls doublewrite buffering. Doublewrite buffering is enabled by default in most cases. </p> <p> You can set <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> to <code class="literal"> ON </code> or <code class="literal"> OFF </code> when starting the server to enable or disable doublewrite buffering, respectively. <code class="literal"> DETECT_AND_RECOVER </code> is the same as <code class="literal"> ON </code> . With this setting, except that the doublewrite buffer is fully enabled, with database page content written to the doublewrite buffer where it is accessed during recovery to fix incomplete page writes. With <code class="literal"> DETECT_ONLY </code> , only metadata is written to the doublewrite buffer. Database page content is not written to the doublewrite buffer, and recovery does not use the doublewrite buffer to fix incomplete page writes. This lightweight setting is intended for detecting incomplete page writes only. </p> <p> MySQL supports dynamic changes to the <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> setting that enables the doublewrite buffer, between <code class="literal"> ON </code> , <code class="literal"> DETECT_AND_RECOVER </code> , and <code class="literal"> DETECT_ONLY </code> . MySQL does not support dynamic changes between a setting that enables the doublewrite buffer and <code class="literal"> OFF </code> or vice versa. </p> <p> If the doublewrite buffer is located on a Fusion-io device that supports atomic writes, the doublewrite buffer is automatically disabled and data file writes are performed using Fusion-io atomic writes instead. However, be aware that the <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite"> <code class="literal"> innodb_doublewrite </code> </a> setting is global. When the doublewrite buffer is disabled, it is disabled for all data files including those that do not reside on Fusion-io hardware. This feature is only supported on Fusion-io hardware and is only enabled for Fusion-io NVMFS on Linux. To take full advantage of this feature, an <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> setting of <code class="literal"> O_DIRECT </code> is recommended. </p> <p> For related information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite_batch_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_batch_size"> <code class="literal"> innodb_doublewrite_batch_size </code> </a> </p> <a class="indexterm" name="idm46045155695328"> </a> <a class="indexterm" name="idm46045155694240"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite_batch_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite-batch-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_batch_size"> innodb_doublewrite_batch_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 256 </code> </td> </tr> </tbody> </table> </div> <p> This variable was intended to represent the number of doublewrite pages to write in a batch. This functionality was replaced by <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> <code class="literal"> innodb_doublewrite_pages </code> </a> . </p> <p> For more information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite_dir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_dir"> <code class="literal"> innodb_doublewrite_dir </code> </a> </p> <a class="indexterm" name="idm46045155662208"> </a> <a class="indexterm" name="idm46045155661136"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite_dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite-dir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_dir"> innodb_doublewrite_dir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> </tbody> </table> </div> <p> Defines the directory for doublewrite files. If no directory is specified, doublewrite files are created in the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> directory, which defaults to the data directory if unspecified. </p> <p> For more information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite_files"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_files"> <code class="literal"> innodb_doublewrite_files </code> </a> </p> <a class="indexterm" name="idm46045155636448"> </a> <a class="indexterm" name="idm46045155635360"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite_files"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite-files=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_files"> innodb_doublewrite_files </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 256 </code> </td> </tr> </tbody> </table> </div> <p> Defines the number of doublewrite files. By default, two doublewrite files are created for each buffer pool instance. </p> <p> At a minimum, there are two doublewrite files. The maximum number of doublewrite files is two times the number of buffer pool instances. (The number of buffer pool instances is controlled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> variable.) </p> <p> For more information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_doublewrite_pages"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> <code class="literal"> innodb_doublewrite_pages </code> </a> </p> <a class="indexterm" name="idm46045155602752"> </a> <a class="indexterm" name="idm46045155601664"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_doublewrite_pages"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-doublewrite-pages=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> innodb_doublewrite_pages </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 128 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 512 </code> </td> </tr> </tbody> </table> </div> <p> Defines the maximum number of doublewrite pages per thread for a batch write. If no value is specified, <a class="link" href="innodb-parameters.html#sysvar_innodb_doublewrite_pages"> <code class="literal"> innodb_doublewrite_pages </code> </a> defaults to 128. </p> <p> Before MySQL 8.4, the default value was the <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> value, which is 4 by default. </p> <p> For more information, see <a class="xref" href="innodb-doublewrite-buffer.html" title="17.6.4 Doublewrite Buffer"> Section 17.6.4, “Doublewrite Buffer” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_extend_and_initialize"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_extend_and_initialize"> <code class="literal"> innodb_extend_and_initialize </code> </a> </p> <a class="indexterm" name="idm46045155567952"> </a> <a class="indexterm" name="idm46045155566848"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_extend_and_initialize"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb=extend-and-initialize[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_extend_and_initialize"> innodb_extend_and_initialize </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Controls how space is allocated to file-per-table and general tablespaces on Linux systems. </p> <p> When enabled, <code class="literal"> InnoDB </code> writes NULLs to newly allocated pages. When disabled, space is allocated using <code class="literal"> posix_fallocate() </code> calls, which reserve space without physically writing NULLs. </p> <p> For more information, see <a class="xref" href="innodb-optimize-tablespace-page-allocation.html" title="17.6.3.8 Optimizing Tablespace Space Allocation on Linux"> Section 17.6.3.8, “Optimizing Tablespace Space Allocation on Linux” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_fast_shutdown"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> <code class="literal"> innodb_fast_shutdown </code> </a> </p> <a class="indexterm" name="idm46045155538784"> </a> <a class="indexterm" name="idm46045155537744"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_fast_shutdown"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-fast-shutdown=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> innodb_fast_shutdown </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 0 </code> </p> <p class="valid-value"> <code class="literal"> 1 </code> </p> <p class="valid-value"> <code class="literal"> 2 </code> </p> </td> </tr> </tbody> </table> </div> <p> The <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_shutdown" title="shutdown"> shutdown </a> mode. If the value is 0, <code class="literal"> InnoDB </code> does a <a class="link" href="glossary.html#glos_slow_shutdown" title="slow shutdown"> slow shutdown </a> , a full <a class="link" href="glossary.html#glos_purge" title="purge"> purge </a> and a change buffer merge before shutting down. If the value is 1 (the default), <code class="literal"> InnoDB </code> skips these operations at shutdown, a process known as a <a class="link" href="glossary.html#glos_fast_shutdown" title="fast shutdown"> fast shutdown </a> . If the value is 2, <code class="literal"> InnoDB </code> flushes its logs and shuts down cold, as if MySQL had crashed; no committed transactions are lost, but the <a class="link" href="glossary.html#glos_crash_recovery" title="crash recovery"> crash recovery </a> operation makes the next startup take longer. </p> <p> The slow shutdown can take minutes, or even hours in extreme cases where substantial amounts of data are still buffered. Use the slow shutdown technique before upgrading or downgrading between MySQL major releases, so that all data files are fully prepared in case the upgrade process updates the file format. </p> <p> Use <a class="link" href="innodb-parameters.html#sysvar_innodb_fast_shutdown"> <code class="literal"> innodb_fast_shutdown=2 </code> </a> in emergency or troubleshooting situations, to get the absolute fastest shutdown if data is at risk of corruption. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_fil_make_page_dirty_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> </p> <a class="indexterm" name="idm46045155498544"> </a> <a class="indexterm" name="idm46045155497456"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_fil_make_page_dirty_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-fil-make-page-dirty-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> innodb_fil_make_page_dirty_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> </tbody> </table> </div> <p> By default, setting <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> to the ID of a tablespace immediately dirties the first page of the tablespace. If <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> <code class="literal"> innodb_saved_page_number_debug </code> </a> is set to a non-default value, setting <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> dirties the specified page. The <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_file_per_table"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> </p> <a class="indexterm" name="idm46045155460928"> </a> <a class="indexterm" name="idm46045155459888"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_file_per_table"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-file-per-table[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> innodb_file_per_table </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> When <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> is enabled, tables are created in file-per-table tablespaces by default. When disabled, tables are created in the system tablespace by default. For information about file-per-table tablespaces, see <a class="xref" href="innodb-file-per-table-tablespaces.html" title="17.6.3.2 File-Per-Table Tablespaces"> Section 17.6.3.2, “File-Per-Table Tablespaces” </a> . For information about the <code class="literal"> InnoDB </code> system tablespace, see <a class="xref" href="innodb-system-tablespace.html" title="17.6.3.1 The System Tablespace"> Section 17.6.3.1, “The System Tablespace” </a> . </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> variable can be configured at runtime using a <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET GLOBAL </code> </a> statement, specified on the command line at startup, or specified in an option file. Configuration at runtime requires privileges sufficient to set global system variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ) and immediately affects the operation of all connections. </p> <p> When a table that resides in a file-per-table tablespace is truncated or dropped, the freed space is returned to the operating system. Truncating or dropping a table that resides in the system tablespace only frees space in the system tablespace. Freed space in the system tablespace can be used again for <code class="literal"> InnoDB </code> data but is not returned to the operating system, as system tablespace data files never shrink. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per-table </code> </a> setting does not affect the creation of temporary tables; temporary tables are created in session temporary tablespaces. See <a class="xref" href="innodb-temporary-tablespace.html" title="17.6.3.5 Temporary Tablespaces"> Section 17.6.3.5, “Temporary Tablespaces” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_fill_factor"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> </p> <a class="indexterm" name="idm46045155423488"> </a> <a class="indexterm" name="idm46045155422448"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_fill_factor"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-fill-factor=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> innodb_fill_factor </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> <code class="literal"> InnoDB </code> performs a bulk load when creating or rebuilding indexes. This method of index creation is known as a <span class="quote"> “ <span class="quote"> sorted index build </span> ” </span> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> defines the percentage of space on each B-tree page that is filled during a sorted index build, with the remaining space reserved for future index growth. For example, setting <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> to 80 reserves 20 percent of the space on each B-tree page for future index growth. Actual percentages may vary. The <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> setting is interpreted as a hint rather than a hard limit. </p> <p> An <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> setting of 100 leaves 1/16 of the space in clustered index pages free for future index growth. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_fill_factor"> <code class="literal"> innodb_fill_factor </code> </a> applies to both B-tree leaf and non-leaf pages. It does not apply to external pages used for <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> TEXT </code> </a> or <a class="link" href="blob.html" title="13.3.4 The BLOB and TEXT Types"> <code class="literal"> BLOB </code> </a> entries. </p> <p> For more information, see <a class="xref" href="sorted-index-builds.html" title="17.6.2.3 Sorted Index Builds"> Section 17.6.2.3, “Sorted Index Builds” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_log_at_timeout"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> <code class="literal"> innodb_flush_log_at_timeout </code> </a> </p> <a class="indexterm" name="idm46045155379456"> </a> <a class="indexterm" name="idm46045155378352"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_log_at_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-log-at-timeout=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> innodb_flush_log_at_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2700 </code> </td> </tr> <tr> <th> Unit </th> <td> seconds </td> </tr> </tbody> </table> </div> <p> Write and flush the logs every <em class="replaceable"> <code> N </code> </em> seconds. <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> <code class="literal"> innodb_flush_log_at_timeout </code> </a> allows the timeout period between flushes to be increased in order to reduce flushing and avoid impacting performance of binary log group commit. The default setting for <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> <code class="literal"> innodb_flush_log_at_timeout </code> </a> is once per second. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_log_at_trx_commit"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit </code> </a> </p> <a class="indexterm" name="idm46045155343632"> </a> <a class="indexterm" name="idm46045155342528"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_log_at_trx_commit"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-log-at-trx-commit=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> innodb_flush_log_at_trx_commit </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 0 </code> </p> <p class="valid-value"> <code class="literal"> 1 </code> </p> <p class="valid-value"> <code class="literal"> 2 </code> </p> </td> </tr> </tbody> </table> </div> <p> Controls the balance between strict <a class="link" href="glossary.html#glos_acid" title="ACID"> ACID </a> compliance for <a class="link" href="glossary.html#glos_commit" title="commit"> commit </a> operations and higher performance that is possible when commit-related I/O operations are rearranged and done in batches. You can achieve better performance by changing the default value but then you can lose transactions in a crash. </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> The default setting of 1 is required for full ACID compliance. Logs are written and flushed to disk at each transaction commit. </p> </li> <li class="listitem"> <p> With a setting of 0, logs are written and flushed to disk once per second. Transactions for which logs have not been flushed can be lost in a crash. </p> </li> <li class="listitem"> <p> With a setting of 2, logs are written after each transaction commit and flushed to disk once per second. Transactions for which logs have not been flushed can be lost in a crash. </p> </li> <li class="listitem"> <p> For settings 0 and 2, once-per-second flushing is not 100% guaranteed. Flushing may occur more frequently due to DDL changes and other internal <code class="literal"> InnoDB </code> activities that cause logs to be flushed independently of the <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit </code> </a> setting, and sometimes less frequently due to scheduling issues. If logs are flushed once per second, up to one second of transactions can be lost in a crash. If logs are flushed more or less frequently than once per second, the amount of transactions that can be lost varies accordingly. </p> </li> <li class="listitem"> <p> Log flushing frequency is controlled by <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_timeout"> <code class="literal"> innodb_flush_log_at_timeout </code> </a> , which allows you to set log flushing frequency to <em class="replaceable"> <code> N </code> </em> seconds (where <em class="replaceable"> <code> N </code> </em> is <code class="literal"> 1 ... 2700 </code> , with a default value of 1). However, any unexpected <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process exit can erase up to <em class="replaceable"> <code> N </code> </em> seconds of transactions. </p> </li> <li class="listitem"> <p> DDL changes and other internal <code class="literal"> InnoDB </code> activities flush the log independently of the <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit </code> </a> setting. </p> </li> <li class="listitem"> <p> <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_crash_recovery" title="crash recovery"> crash recovery </a> works regardless of the <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit </code> </a> setting. Transactions are either applied entirely or erased entirely. </p> </li> </ul> </div> <p> For durability and consistency in a replication setup that uses <code class="literal"> InnoDB </code> with transactions: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If binary logging is enabled, set <code class="literal"> sync_binlog=1 </code> . </p> </li> <li class="listitem"> <p> Always set <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_log_at_trx_commit"> <code class="literal"> innodb_flush_log_at_trx_commit=1 </code> </a> . </p> </li> </ul> </div> <p> For information on the combination of settings on a replica that is most resilient to unexpected halts, see <a class="xref" href="replication-solutions-unexpected-replica-halt.html" title="19.4.2 Handling an Unexpected Halt of a Replica"> Section 19.4.2, “Handling an Unexpected Halt of a Replica” </a> . </p> <div class="caution" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Caution </div> <p> Many operating systems and some disk hardware fool the flush-to-disk operation. They may tell <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> that the flush has taken place, even though it has not. In this case, the durability of transactions is not guaranteed even with the recommended settings, and in the worst case, a power outage can corrupt <code class="literal"> InnoDB </code> data. Using a battery-backed disk cache in the SCSI disk controller or in the disk itself speeds up file flushes, and makes the operation safer. You can also try to disable the caching of disk writes in hardware caches. </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_method"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> </p> <a class="indexterm" name="idm46045155282368"> </a> <a class="indexterm" name="idm46045155281328"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_method"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-method=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> innodb_flush_method </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value (Unix) </th> <td> <code class="literal"> O_DIRECT if supported, otherwise fsync </code> </td> </tr> <tr> <th> Default Value (Windows) </th> <td> <code class="literal"> unbuffered </code> </td> </tr> <tr> <th> Valid Values (Unix) </th> <td> <p class="valid-value"> <code class="literal"> fsync </code> </p> <p class="valid-value"> <code class="literal"> O_DSYNC </code> </p> <p class="valid-value"> <code class="literal"> littlesync </code> </p> <p class="valid-value"> <code class="literal"> nosync </code> </p> <p class="valid-value"> <code class="literal"> O_DIRECT </code> </p> <p class="valid-value"> <code class="literal"> O_DIRECT_NO_FSYNC </code> </p> </td> </tr> <tr> <th> Valid Values (Windows) </th> <td> <p class="valid-value"> <code class="literal"> unbuffered </code> </p> <p class="valid-value"> <code class="literal"> normal </code> </p> </td> </tr> </tbody> </table> </div> <p> Defines the method used to <a class="link" href="glossary.html#glos_flush" title="flush"> flush </a> data to <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_data_files" title="data files"> data files </a> and <a class="link" href="glossary.html#glos_log_file" title="log file"> log files </a> , which can affect I/O throughput. </p> <p> On Unix-like systems, the default value is <code class="literal"> O_DIRECT </code> if supported otherwise defaults to <code class="literal"> fsync </code> . On Windows, the default value is <code class="literal"> unbuffered </code> . </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> options for Unix-like systems include: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> fsync </code> or <code class="literal"> 0 </code> : <code class="literal"> InnoDB </code> uses the <code class="literal"> fsync() </code> system call to flush both the data and log files. </p> </li> <li class="listitem"> <p> <code class="literal"> O_DSYNC </code> or <code class="literal"> 1 </code> : <code class="literal"> InnoDB </code> uses <code class="literal"> O_SYNC </code> to open and flush the log files, and <code class="literal"> fsync() </code> to flush the data files. <code class="literal"> InnoDB </code> does not use <code class="literal"> O_DSYNC </code> directly because there have been problems with it on many varieties of Unix. </p> </li> <li class="listitem"> <p> <code class="literal"> littlesync </code> or <code class="literal"> 2 </code> : This option is used for internal performance testing and is currently unsupported. Use at your own risk. </p> </li> <li class="listitem"> <p> <code class="literal"> nosync </code> or <code class="literal"> 3 </code> : This option is used for internal performance testing and is currently unsupported. Use at your own risk. </p> </li> <li class="listitem"> <p> <code class="literal"> O_DIRECT </code> or <code class="literal"> 4 </code> : <code class="literal"> InnoDB </code> uses <code class="literal"> O_DIRECT </code> (or <code class="literal"> directio() </code> on Solaris) to open the data files, and uses <code class="literal"> fsync() </code> to flush both the data and log files. This option is available on some GNU/Linux versions, FreeBSD, and Solaris. </p> </li> <li class="listitem"> <p> <code class="literal"> O_DIRECT_NO_FSYNC </code> : <code class="literal"> InnoDB </code> uses <code class="literal"> O_DIRECT </code> during flushing I/O, but skips the <code class="literal"> fsync() </code> system call after each write operation. </p> <p> MySQL calls <code class="literal"> fsync() </code> after creating a new file, after increasing file size, and after closing a file, to ensure that file system metadata changes are synchronized. The <code class="literal"> fsync() </code> system call is still skipped after each write operation. </p> <p> Data loss is possible if redo log files and data files reside on different storage devices, and an unexpected exit occurs before data file writes are flushed from a device cache that is not battery-backed. If you use or intend to use different storage devices for redo log files and data files, and your data files reside on a device with a cache that is not battery-backed, use <code class="literal"> O_DIRECT </code> instead. </p> </li> </ul> </div> <p> On platforms that support <code class="literal"> fdatasync() </code> system calls, the <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> variable permits <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> options that use <code class="literal"> fsync() </code> to use <code class="literal"> fdatasync() </code> instead. An <code class="literal"> fdatasync() </code> system call does not flush changes to file metadata unless required for subsequent data retrieval, providing a potential performance benefit. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> options for Windows systems include: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> <code class="literal"> unbuffered </code> or <code class="literal"> 0 </code> : <code class="literal"> InnoDB </code> uses non-buffered I/O. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Running MySQL server on a 4K sector hard drive on Windows is not supported with <code class="literal"> unbuffered </code> . The workaround is to use <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method=normal </code> </a> . </p> </div> </li> <li class="listitem"> <p> <code class="literal"> normal </code> or <code class="literal"> 1 </code> : <code class="literal"> InnoDB </code> uses buffered I/O. </p> </li> </ul> </div> <p> How each setting affects performance depends on hardware configuration and workload. Benchmark your particular configuration to decide which setting to use, or whether to keep the default setting. Examine the <a class="link" href="server-status-variables.html#statvar_Innodb_data_fsyncs"> <code class="literal"> Innodb_data_fsyncs </code> </a> status variable to see the overall number of <code class="literal"> fsync() </code> calls (or <code class="literal"> fdatasync() </code> calls if <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> is enabled) for each setting. The mix of read and write operations in your workload can affect how a setting performs. For example, on a system with a hardware RAID controller and battery-backed write cache, <code class="literal"> O_DIRECT </code> can help to avoid double buffering between the <code class="literal"> InnoDB </code> buffer pool and the operating system file system cache. On some systems where <code class="literal"> InnoDB </code> data and log files are located on a SAN, the default value or <code class="literal"> O_DSYNC </code> might be faster for a read-heavy workload with mostly <code class="literal"> SELECT </code> statements. Always test this parameter with hardware and workload that reflect your production environment. For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_neighbors"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> </p> <a class="indexterm" name="idm46045155180336"> </a> <a class="indexterm" name="idm46045155179296"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_neighbors"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-neighbors=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> innodb_flush_neighbors </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 0 </code> </p> <p class="valid-value"> <code class="literal"> 1 </code> </p> <p class="valid-value"> <code class="literal"> 2 </code> </p> </td> </tr> </tbody> </table> </div> <p> Specifies whether <a class="link" href="glossary.html#glos_flush" title="flush"> flushing </a> a page from the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> also flushes other <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> in the same <a class="link" href="glossary.html#glos_extent" title="extent"> extent </a> . </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> A setting of 0 disables <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_neighbors"> <code class="literal"> innodb_flush_neighbors </code> </a> . Dirty pages in the same extent are not flushed. </p> </li> <li class="listitem"> <p> A setting of 1 flushes contiguous dirty pages in the same extent. </p> </li> <li class="listitem"> <p> A setting of 2 flushes dirty pages in the same extent. </p> </li> </ul> </div> <p> When the table data is stored on a traditional <a class="link" href="glossary.html#glos_hdd" title="HDD"> HDD </a> storage device, flushing such <a class="link" href="glossary.html#glos_neighbor_page" title="neighbor page"> neighbor pages </a> in one operation reduces I/O overhead (primarily for disk seek operations) compared to flushing individual pages at different times. For table data stored on <a class="link" href="glossary.html#glos_ssd" title="SSD"> SSD </a> , seek time is not a significant factor and you can set this option to 0 to spread out write operations. For related information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flush_sync"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> </p> <a class="indexterm" name="idm46045155137568"> </a> <a class="indexterm" name="idm46045155136528"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flush_sync"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flush-sync[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> innodb_flush_sync </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> variable, which is enabled by default, causes the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> settings to be ignored during bursts of I/O activity that occur at <a class="link" href="glossary.html#glos_checkpoint" title="checkpoint"> checkpoints </a> . To adhere to the I/O rate defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> , disable <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> . </p> <p> For information about configuring the <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> variable, see <a class="xref" href="innodb-configuring-io-capacity.html" title="17.8.7 Configuring InnoDB I/O Capacity"> Section 17.8.7, “Configuring InnoDB I/O Capacity” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_flushing_avg_loops"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> <code class="literal"> innodb_flushing_avg_loops </code> </a> </p> <a class="indexterm" name="idm46045155100960"> </a> <a class="indexterm" name="idm46045155099856"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_flushing_avg_loops"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-flushing-avg-loops=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_flushing_avg_loops"> innodb_flushing_avg_loops </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 30 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> </tbody> </table> </div> <p> Number of iterations for which <code class="literal"> InnoDB </code> keeps the previously calculated snapshot of the flushing state, controlling how quickly <a class="link" href="glossary.html#glos_adaptive_flushing" title="adaptive flushing"> adaptive flushing </a> responds to changing <a class="link" href="glossary.html#glos_workload" title="workload"> workloads </a> . Increasing the value makes the rate of <a class="link" href="glossary.html#glos_flush" title="flush"> flush </a> operations change smoothly and gradually as the workload changes. Decreasing the value makes adaptive flushing adjust quickly to workload changes, which can cause spikes in flushing activity if the workload increases and decreases suddenly. </p> <p> For related information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_force_load_corrupted"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_load_corrupted"> <code class="literal"> innodb_force_load_corrupted </code> </a> </p> <a class="indexterm" name="idm46045155065568"> </a> <a class="indexterm" name="idm46045155064464"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_force_load_corrupted"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-force-load-corrupted[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_load_corrupted"> innodb_force_load_corrupted </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Permits <code class="literal"> InnoDB </code> to load tables at startup that are marked as corrupted. Use only during troubleshooting, to recover data that is otherwise inaccessible. When troubleshooting is complete, disable this setting and restart the server. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_force_recovery"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> <code class="literal"> innodb_force_recovery </code> </a> </p> <a class="indexterm" name="idm46045155038864"> </a> <a class="indexterm" name="idm46045155037824"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_force_recovery"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-force-recovery=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> innodb_force_recovery </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 6 </code> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="glossary.html#glos_crash_recovery" title="crash recovery"> crash recovery </a> mode, typically only changed in serious troubleshooting situations. Possible values are from 0 to 6. For the meanings of these values and important information about <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> <code class="literal"> innodb_force_recovery </code> </a> , see <a class="xref" href="forcing-innodb-recovery.html" title="17.20.3 Forcing InnoDB Recovery"> Section 17.20.3, “Forcing InnoDB Recovery” </a> . </p> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> Only set this variable to a value greater than 0 in an emergency situation so that you can start <code class="literal"> InnoDB </code> and dump your tables. As a safety measure, <code class="literal"> InnoDB </code> prevents <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , or <a class="link" href="delete.html" title="15.2.2 DELETE Statement"> <code class="literal"> DELETE </code> </a> operations when <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> <code class="literal"> innodb_force_recovery </code> </a> is greater than 0. An <a class="link" href="innodb-parameters.html#sysvar_innodb_force_recovery"> <code class="literal"> innodb_force_recovery </code> </a> setting of 4 or greater places <code class="literal"> InnoDB </code> into read-only mode. </p> <p> These restrictions may cause replication administration commands to fail with an error, as replication stores the replica status logs in <code class="literal"> InnoDB </code> tables. </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_fsync_threshold"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> <code class="literal"> innodb_fsync_threshold </code> </a> </p> <a class="indexterm" name="idm46045154994720"> </a> <a class="indexterm" name="idm46045154993680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_fsync_threshold"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-fsync-threshold=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> innodb_fsync_threshold </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**64-1 </code> </td> </tr> </tbody> </table> </div> <p> By default, when <code class="literal"> InnoDB </code> creates a new data file, such as a new log file or tablespace file, the file is fully written to the operating system cache before it is flushed to disk, which can cause a large amount of disk write activity to occur at once. To force smaller, periodic flushes of data from the operating system cache, you can use the <a class="link" href="innodb-parameters.html#sysvar_innodb_fsync_threshold"> <code class="literal"> innodb_fsync_threshold </code> </a> variable to define a threshold value, in bytes. When the byte threshold is reached, the contents of the operating system cache are flushed to disk. The default value of 0 forces the default behavior, which is to flush data to disk only after a file is fully written to the cache. </p> <p> Specifying a threshold to force smaller, periodic flushes may be beneficial in cases where multiple MySQL instances use the same storage devices. For example, creating a new MySQL instance and its associated data files could cause large surges of disk write activity, impeding the performance of other MySQL instances that use the same storage devices. Configuring a threshold helps avoid such surges in write activity. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_aux_table"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_aux_table"> <code class="literal"> innodb_ft_aux_table </code> </a> </p> <a class="indexterm" name="idm46045154960656"> </a> <a class="indexterm" name="idm46045154959616"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_aux_table"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_aux_table"> innodb_ft_aux_table </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> </tbody> </table> </div> <p> Specifies the qualified name of an <code class="literal"> InnoDB </code> table containing a <code class="literal"> FULLTEXT </code> index. This variable is intended for diagnostic purposes and can only be set at runtime. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa51050869"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SET</span> <span class="token keyword">GLOBAL</span> innodb_ft_aux_table <span class="token operator">=</span> <span class="token string">'test/t1'</span><span class="token punctuation">;</span></code></pre> </div> <p> After you set this variable to a name in the format <code class="literal"> <em class="replaceable"> <code> db_name </code> </em> / <em class="replaceable"> <code> table_name </code> </em> </code> , the <code class="literal"> INFORMATION_SCHEMA </code> tables <a class="link" href="information-schema-innodb-ft-index-table-table.html" title="28.4.19 The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table"> <code class="literal"> INNODB_FT_INDEX_TABLE </code> </a> , <a class="link" href="information-schema-innodb-ft-index-cache-table.html" title="28.4.18 The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table"> <code class="literal"> INNODB_FT_INDEX_CACHE </code> </a> , <a class="link" href="information-schema-innodb-ft-config-table.html" title="28.4.15 The INFORMATION_SCHEMA INNODB_FT_CONFIG Table"> <code class="literal"> INNODB_FT_CONFIG </code> </a> , <a class="link" href="information-schema-innodb-ft-deleted-table.html" title="28.4.17 The INFORMATION_SCHEMA INNODB_FT_DELETED Table"> <code class="literal"> INNODB_FT_DELETED </code> </a> , and <a class="link" href="information-schema-innodb-ft-being-deleted-table.html" title="28.4.14 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table"> <code class="literal"> INNODB_FT_BEING_DELETED </code> </a> show information about the search index for the specified table. </p> <p> For more information, see <a class="xref" href="innodb-information-schema-fulltext_index-tables.html" title="17.15.4 InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables"> Section 17.15.4, “InnoDB INFORMATION_SCHEMA FULLTEXT Index Tables” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_cache_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> <code class="literal"> innodb_ft_cache_size </code> </a> </p> <a class="indexterm" name="idm46045154927184"> </a> <a class="indexterm" name="idm46045154926144"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_cache_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-cache-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> innodb_ft_cache_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 8000000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1600000 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 80000000 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> The memory allocated, in bytes, for the <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> search index cache, which holds a parsed document in memory while creating an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index. Index inserts and updates are only committed to disk when the <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> <code class="literal"> innodb_ft_cache_size </code> </a> size limit is reached. <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_cache_size"> <code class="literal"> innodb_ft_cache_size </code> </a> defines the cache size on a per table basis. To set a global limit for all tables, see <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> <code class="literal"> innodb_ft_total_cache_size </code> </a> . </p> <p> For more information, see <a class="xref" href="innodb-fulltext-index.html#innodb-fulltext-index-cache" title="InnoDB Full-Text Index Cache"> InnoDB Full-Text Index Cache </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_enable_diag_print"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_diag_print"> <code class="literal"> innodb_ft_enable_diag_print </code> </a> </p> <a class="indexterm" name="idm46045154886528"> </a> <a class="indexterm" name="idm46045154885424"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_enable_diag_print"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-enable-diag-print[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_diag_print"> innodb_ft_enable_diag_print </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Whether to enable additional full-text search (FTS) diagnostic output. This option is primarily intended for advanced FTS debugging and is not of interest to most users. Output is printed to the error log and includes information such as: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> FTS index sync progress (when the FTS cache limit is reached). For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa84819959"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">FTS SYNC for table test<span class="token punctuation">,</span> deleted count<span class="token punctuation">:</span> 100 size<span class="token punctuation">:</span> 10000 bytes SYNC words<span class="token punctuation">:</span> 100</code></pre> </div> </li> <li class="listitem"> <p> FTS optimize progress. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa19082731"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">FTS start optimize test FTS_OPTIMIZE<span class="token punctuation">:</span> optimize <span class="token atrule">"mysql"</span> FTS_OPTIMIZE<span class="token punctuation">:</span> processed <span class="token atrule">"mysql"</span></code></pre> </div> </li> <li class="listitem"> <p> FTS index build progress. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa92060829"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">Number of doc processed<span class="token punctuation">:</span> 1000</code></pre> </div> </li> <li class="listitem"> <p> For FTS queries, the query parsing tree, word weight, query processing time, and memory usage are printed. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa44572851"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">FTS Search Processing time<span class="token punctuation">:</span> 1 secs<span class="token punctuation">:</span> 100 millisec<span class="token punctuation">:</span> row<span class="token punctuation">(</span>s<span class="token punctuation">)</span> 10000 Full Search Memory<span class="token punctuation">:</span> 245666 <span class="token punctuation">(</span>bytes<span class="token punctuation">)</span><span class="token punctuation">,</span> Row<span class="token punctuation">:</span> 10000</code></pre> </div> </li> </ul> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_enable_stopword"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> <code class="literal"> innodb_ft_enable_stopword </code> </a> </p> <a class="indexterm" name="idm46045154852544"> </a> <a class="indexterm" name="idm46045154851440"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_enable_stopword"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-enable-stopword[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> innodb_ft_enable_stopword </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies that a set of <a class="link" href="glossary.html#glos_stopword" title="stopword"> stopwords </a> is associated with an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index at the time the index is created. If the <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> option is set, the stopwords are taken from that table. Else, if the <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> option is set, the stopwords are taken from that table. Otherwise, a built-in set of default stopwords is used. </p> <p> For more information, see <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_max_token_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_max_token_size"> <code class="literal"> innodb_ft_max_token_size </code> </a> </p> <a class="indexterm" name="idm46045154820528"> </a> <a class="indexterm" name="idm46045154819424"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_max_token_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-max-token-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_max_token_size"> innodb_ft_max_token_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 84 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 84 </code> </td> </tr> </tbody> </table> </div> <p> Maximum character length of words that are stored in an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index. Setting a limit on this value reduces the size of the index, thus speeding up queries, by omitting long keywords or arbitrary collections of letters that are not real words and are not likely to be search terms. </p> <p> For more information, see <a class="xref" href="fulltext-fine-tuning.html" title="14.9.6 Fine-Tuning MySQL Full-Text Search"> Section 14.9.6, “Fine-Tuning MySQL Full-Text Search” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_min_token_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_min_token_size"> <code class="literal"> innodb_ft_min_token_size </code> </a> </p> <a class="indexterm" name="idm46045154787184"> </a> <a class="indexterm" name="idm46045154786080"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_min_token_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-min-token-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_min_token_size"> innodb_ft_min_token_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 3 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 16 </code> </td> </tr> </tbody> </table> </div> <p> Minimum length of words that are stored in an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index. Increasing this value reduces the size of the index, thus speeding up queries, by omitting common words that are unlikely to be significant in a search context, such as the English words <span class="quote"> “ <span class="quote"> a </span> ” </span> and <span class="quote"> “ <span class="quote"> to </span> ” </span> . For content using a CJK (Chinese, Japanese, Korean) character set, specify a value of 1. </p> <p> For more information, see <a class="xref" href="fulltext-fine-tuning.html" title="14.9.6 Fine-Tuning MySQL Full-Text Search"> Section 14.9.6, “Fine-Tuning MySQL Full-Text Search” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_num_word_optimize"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_num_word_optimize"> <code class="literal"> innodb_ft_num_word_optimize </code> </a> </p> <a class="indexterm" name="idm46045154752960"> </a> <a class="indexterm" name="idm46045154751856"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_num_word_optimize"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-num-word-optimize=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_num_word_optimize"> innodb_ft_num_word_optimize </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> </tbody> </table> </div> <p> Number of words to process during each <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> operation on an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index. Because a bulk insert or update operation to a table containing a full-text search index could require substantial index maintenance to incorporate all changes, you might do a series of <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> statements, each picking up where the last left off. </p> <p> For more information, see <a class="xref" href="fulltext-fine-tuning.html" title="14.9.6 Fine-Tuning MySQL Full-Text Search"> Section 14.9.6, “Fine-Tuning MySQL Full-Text Search” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_result_cache_limit"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> <code class="literal"> innodb_ft_result_cache_limit </code> </a> </p> <a class="indexterm" name="idm46045154717008"> </a> <a class="indexterm" name="idm46045154715904"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_result_cache_limit"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-result-cache-limit=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> innodb_ft_result_cache_limit </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2000000000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1000000 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> The <code class="literal"> InnoDB </code> full-text search query result cache limit (defined in bytes) per full-text search query or per thread. Intermediate and final <code class="literal"> InnoDB </code> full-text search query results are handled in memory. Use <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> <code class="literal"> innodb_ft_result_cache_limit </code> </a> to place a size limit on the full-text search query result cache to avoid excessive memory consumption in case of very large <code class="literal"> InnoDB </code> full-text search query results (millions or hundreds of millions of rows, for example). Memory is allocated as required when a full-text search query is processed. If the result cache size limit is reached, an error is returned indicating that the query exceeds the maximum allowed memory. </p> <p> The maximum value of <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_result_cache_limit"> <code class="literal"> innodb_ft_result_cache_limit </code> </a> for all platform types and bit sizes is 2**32-1. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_server_stopword_table"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> </p> <a class="indexterm" name="idm46045154678464"> </a> <a class="indexterm" name="idm46045154677360"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_server_stopword_table"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-server-stopword-table=db_name/table_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> innodb_ft_server_stopword_table </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> This option is used to specify your own <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index stopword list for all <code class="literal"> InnoDB </code> tables. To configure your own stopword list for a specific <code class="literal"> InnoDB </code> table, use <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> . </p> <p> Set <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> to the name of the table containing a list of stopwords, in the format <code class="literal"> <em class="replaceable"> <code> db_name </code> </em> / <em class="replaceable"> <code> table_name </code> </em> </code> . </p> <p> The stopword table must exist before you configure <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> . <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> <code class="literal"> innodb_ft_enable_stopword </code> </a> must be enabled and <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> option must be configured before you create the <code class="literal"> FULLTEXT </code> index. </p> <p> The stopword table must be an <code class="literal"> InnoDB </code> table, containing a single <code class="literal"> VARCHAR </code> column named <code class="literal"> value </code> . </p> <p> For more information, see <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_sort_pll_degree"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_sort_pll_degree"> <code class="literal"> innodb_ft_sort_pll_degree </code> </a> </p> <a class="indexterm" name="idm46045154636544"> </a> <a class="indexterm" name="idm46045154635440"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_sort_pll_degree"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-sort-pll-degree=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_sort_pll_degree"> innodb_ft_sort_pll_degree </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 16 </code> </td> </tr> </tbody> </table> </div> <p> Number of threads used in parallel to index and tokenize text in an <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index when building a <a class="link" href="glossary.html#glos_search_index" title="search index"> search index </a> . </p> <p> For related information, see <a class="xref" href="innodb-fulltext-index.html" title="17.6.2.4 InnoDB Full-Text Indexes"> Section 17.6.2.4, “InnoDB Full-Text Indexes” </a> , and <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> <code class="literal"> innodb_sort_buffer_size </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_total_cache_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> <code class="literal"> innodb_ft_total_cache_size </code> </a> </p> <a class="indexterm" name="idm46045154601200"> </a> <a class="indexterm" name="idm46045154600096"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_total_cache_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-total-cache-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> innodb_ft_total_cache_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 640000000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 32000000 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1600000000 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> The total memory allocated, in bytes, for the <code class="literal"> InnoDB </code> full-text search index cache for all tables. Creating numerous tables, each with a <code class="literal"> FULLTEXT </code> search index, could consume a significant portion of available memory. <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_total_cache_size"> <code class="literal"> innodb_ft_total_cache_size </code> </a> defines a global memory limit for all full-text search indexes to help avoid excessive memory consumption. If the global limit is reached by an index operation, a forced sync is triggered. </p> <p> For more information, see <a class="xref" href="innodb-fulltext-index.html#innodb-fulltext-index-cache" title="InnoDB Full-Text Index Cache"> InnoDB Full-Text Index Cache </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_ft_user_stopword_table"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> </p> <a class="indexterm" name="idm46045154564224"> </a> <a class="indexterm" name="idm46045154563120"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_ft_user_stopword_table"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-ft-user-stopword-table=db_name/table_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> innodb_ft_user_stopword_table </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> This option is used to specify your own <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> index stopword list on a specific table. To configure your own stopword list for all <code class="literal"> InnoDB </code> tables, use <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_server_stopword_table"> <code class="literal"> innodb_ft_server_stopword_table </code> </a> . </p> <p> Set <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> to the name of the table containing a list of stopwords, in the format <code class="literal"> <em class="replaceable"> <code> db_name </code> </em> / <em class="replaceable"> <code> table_name </code> </em> </code> . </p> <p> The stopword table must exist before you configure <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> . <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_enable_stopword"> <code class="literal"> innodb_ft_enable_stopword </code> </a> must be enabled and <a class="link" href="innodb-parameters.html#sysvar_innodb_ft_user_stopword_table"> <code class="literal"> innodb_ft_user_stopword_table </code> </a> must be configured before you create the <code class="literal"> FULLTEXT </code> index. </p> <p> The stopword table must be an <code class="literal"> InnoDB </code> table, containing a single <code class="literal"> VARCHAR </code> column named <code class="literal"> value </code> . </p> <p> For more information, see <a class="xref" href="fulltext-stopwords.html" title="14.9.4 Full-Text Stopwords"> Section 14.9.4, “Full-Text Stopwords” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_idle_flush_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> <code class="literal"> innodb_idle_flush_pct </code> </a> </p> <a class="indexterm" name="idm46045154522976"> </a> <a class="indexterm" name="idm46045154521936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_idle_flush_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-idle-flush-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> innodb_idle_flush_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Limits page flushing when <code class="literal"> InnoDB </code> is idle. The <a class="link" href="innodb-parameters.html#sysvar_innodb_idle_flush_pct"> <code class="literal"> innodb_idle_flush_pct </code> </a> value is a percentage of the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> setting, which defines the number of I/O operations per second available to <code class="literal"> InnoDB </code> . For more information, see <a class="xref" href="innodb-buffer-pool-flushing.html#innodb-limit-flushing-rate" title="Limiting Buffer Flushing During Idle Periods"> Limiting Buffer Flushing During Idle Periods </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_io_capacity"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> </p> <a class="indexterm" name="idm46045154487648"> </a> <a class="indexterm" name="idm46045154486608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_io_capacity"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-io-capacity=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> innodb_io_capacity </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Maximum Value (64-bit platforms, 8.4.0) </th> <td> <code class="literal"> 2**64-1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> </tbody> </table> </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> variable defines the number of I/O operations per second (IOPS) available to <code class="literal"> InnoDB </code> background tasks, such as <a class="link" href="glossary.html#glos_flush" title="flush"> flushing </a> pages from the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> and merging data from the <a class="link" href="glossary.html#glos_change_buffer" title="change buffer"> change buffer </a> . </p> <p> For information about configuring the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> variable, see <a class="xref" href="innodb-configuring-io-capacity.html" title="17.8.7 Configuring InnoDB I/O Capacity"> Section 17.8.7, “Configuring InnoDB I/O Capacity” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_io_capacity_max"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> </p> <a class="indexterm" name="idm46045154447648"> </a> <a class="indexterm" name="idm46045154446608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_io_capacity_max"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-io-capacity-max=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> innodb_io_capacity_max </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 * innodb_io_capacity </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> </tbody> </table> </div> <p> If flushing activity falls behind, <code class="literal"> InnoDB </code> can flush more aggressively, at a higher rate of I/O operations per second (IOPS) than defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> variable. The <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> variable defines a maximum number of IOPS performed by <code class="literal"> InnoDB </code> background tasks in such situations. This option does not control <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_sync"> <code class="literal"> innodb_flush_sync </code> </a> behavior. </p> <p> The default value is twice the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity"> <code class="literal"> innodb_io_capacity </code> </a> . </p> <p> For information about configuring the <a class="link" href="innodb-parameters.html#sysvar_innodb_io_capacity_max"> <code class="literal"> innodb_io_capacity_max </code> </a> variable, see <a class="xref" href="innodb-configuring-io-capacity.html" title="17.8.7 Configuring InnoDB I/O Capacity"> Section 17.8.7, “Configuring InnoDB I/O Capacity” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_limit_optimistic_insert_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_limit_optimistic_insert_debug"> <code class="literal"> innodb_limit_optimistic_insert_debug </code> </a> </p> <a class="indexterm" name="idm46045154407360"> </a> <a class="indexterm" name="idm46045154406272"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_limit_optimistic_insert_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-limit-optimistic-insert-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_limit_optimistic_insert_debug"> innodb_limit_optimistic_insert_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> </tbody> </table> </div> <p> Limits the number of records per <a class="link" href="glossary.html#glos_b_tree" title="B-tree"> B-tree </a> page. A default value of 0 means that no limit is imposed. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_lock_wait_timeout"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> </p> <a class="indexterm" name="idm46045154374192"> </a> <a class="indexterm" name="idm46045154373088"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_lock_wait_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-lock-wait-timeout=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> innodb_lock_wait_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1073741824 </code> </td> </tr> <tr> <th> Unit </th> <td> seconds </td> </tr> </tbody> </table> </div> <p> The length of time in seconds an <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_transaction" title="transaction"> transaction </a> waits for a <a class="link" href="glossary.html#glos_row_lock" title="row lock"> row lock </a> before giving up. The default value is 50 seconds. A transaction that tries to access a row that is locked by another <code class="literal"> InnoDB </code> transaction waits at most this many seconds for write access to the row before issuing the following error: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa55581655"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token output">ERROR 1205 (HY000)<span class="token punctuation">:</span> Lock wait timeout exceeded; try restarting transaction</span></code></pre> </div> <p> When a lock wait timeout occurs, the current statement is <a class="link" href="glossary.html#glos_rollback" title="rollback"> rolled back </a> (not the entire transaction). To have the entire transaction roll back, start the server with the <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> <code class="option"> --innodb-rollback-on-timeout </code> </a> option. See also <a class="xref" href="innodb-error-handling.html" title="17.20.5 InnoDB Error Handling"> Section 17.20.5, “InnoDB Error Handling” </a> . </p> <p> You might decrease this value for highly interactive applications or <a class="link" href="glossary.html#glos_oltp" title="OLTP"> OLTP </a> systems, to display user feedback quickly or put the update into a queue for processing later. You might increase this value for long-running back-end operations, such as a transform step in a data warehouse that waits for other large insert or update operations to finish. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> applies to <code class="literal"> InnoDB </code> row locks. A MySQL <a class="link" href="glossary.html#glos_table_lock" title="table lock"> table lock </a> does not happen inside <code class="literal"> InnoDB </code> and this timeout does not apply to waits for table locks. </p> <p> The lock wait timeout value does not apply to <a class="link" href="glossary.html#glos_deadlock" title="deadlock"> deadlocks </a> when <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> <code class="literal"> innodb_deadlock_detect </code> </a> is enabled (the default) because <code class="literal"> InnoDB </code> detects deadlocks immediately and rolls back one of the deadlocked transactions. When <a class="link" href="innodb-parameters.html#sysvar_innodb_deadlock_detect"> <code class="literal"> innodb_deadlock_detect </code> </a> is disabled, <code class="literal"> InnoDB </code> relies on <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> for transaction rollback when a deadlock occurs. See <a class="xref" href="innodb-deadlock-detection.html" title="17.7.5.2 Deadlock Detection"> Section 17.7.5.2, “Deadlock Detection” </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> can be set at runtime with the <code class="literal"> SET GLOBAL </code> or <code class="literal"> SET SESSION </code> statement. Changing the <code class="literal"> GLOBAL </code> setting requires privileges sufficient to set global system variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ) and affects the operation of all clients that subsequently connect. Any client can change the <code class="literal"> SESSION </code> setting for <a class="link" href="innodb-parameters.html#sysvar_innodb_lock_wait_timeout"> <code class="literal"> innodb_lock_wait_timeout </code> </a> , which affects only that client. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_buffer_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> <code class="literal"> innodb_log_buffer_size </code> </a> </p> <a class="indexterm" name="idm46045154314160"> </a> <a class="indexterm" name="idm46045154313120"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_buffer_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-buffer-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> innodb_log_buffer_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 67108864 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1048576 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> The size in bytes of the buffer that <code class="literal"> InnoDB </code> uses to write to the <a class="link" href="glossary.html#glos_log_file" title="log file"> log files </a> on disk. The default is 64MB. A large <a class="link" href="glossary.html#glos_log_buffer" title="log buffer"> log buffer </a> enables large <a class="link" href="glossary.html#glos_transaction" title="transaction"> transactions </a> to run without the need to write the log to disk before the transactions <a class="link" href="glossary.html#glos_commit" title="commit"> commit </a> . Thus, if you have transactions that update, insert, or delete many rows, making the log buffer larger saves disk I/O. For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-memory-configuration" title="Memory Configuration"> Memory Configuration </a> , and <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_checkpoint_fuzzy_now"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_fuzzy_now"> <code class="literal"> innodb_log_checkpoint_fuzzy_now </code> </a> </p> <a class="indexterm" name="idm46045154277120"> </a> <a class="indexterm" name="idm46045154276016"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_checkpoint_fuzzy_now"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-checkpoint-fuzzy-now[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_fuzzy_now"> innodb_log_checkpoint_fuzzy_now </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enable this debug option to force <code class="literal"> InnoDB </code> to write a fuzzy checkpoint. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_checkpoint_now"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_now"> <code class="literal"> innodb_log_checkpoint_now </code> </a> </p> <a class="indexterm" name="idm46045154248896"> </a> <a class="indexterm" name="idm46045154247792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_checkpoint_now"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-checkpoint-now[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checkpoint_now"> innodb_log_checkpoint_now </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enable this debug option to force <code class="literal"> InnoDB </code> to write a checkpoint. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_checksums"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> <code class="literal"> innodb_log_checksums </code> </a> </p> <a class="indexterm" name="idm46045154220672"> </a> <a class="indexterm" name="idm46045154219632"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_checksums"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-checksums[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> innodb_log_checksums </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Enables or disables checksums for redo log pages. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> <code class="literal"> innodb_log_checksums=ON </code> </a> enables the <code class="literal"> CRC-32C </code> checksum algorithm for redo log pages. When <a class="link" href="innodb-parameters.html#sysvar_innodb_log_checksums"> <code class="literal"> innodb_log_checksums </code> </a> is disabled, the contents of the redo log page checksum field are ignored. </p> <p> Checksums on the redo log header page and redo log checkpoint pages are never disabled. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_compressed_pages"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> <code class="literal"> innodb_log_compressed_pages </code> </a> </p> <a class="indexterm" name="idm46045154190768"> </a> <a class="indexterm" name="idm46045154189664"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_compressed_pages"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-compressed-pages[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> innodb_log_compressed_pages </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies whether images of <a class="link" href="glossary.html#glos_compression" title="compression"> re-compressed </a> <a class="link" href="glossary.html#glos_page" title="page"> pages </a> are written to the <a class="link" href="glossary.html#glos_redo_log" title="redo log"> redo log </a> . Re-compression may occur when changes are made to compressed data. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> <code class="literal"> innodb_log_compressed_pages </code> </a> is enabled by default to prevent corruption that could occur if a different version of the <code class="literal"> zlib </code> compression algorithm is used during recovery. If you are certain that the <code class="literal"> zlib </code> version is not subject to change, you can disable <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> <code class="literal"> innodb_log_compressed_pages </code> </a> to reduce redo log generation for workloads that modify compressed data. </p> <p> To measure the effect of enabling or disabling <a class="link" href="innodb-parameters.html#sysvar_innodb_log_compressed_pages"> <code class="literal"> innodb_log_compressed_pages </code> </a> , compare redo log generation for both settings under the same workload. Options for measuring redo log generation include observing the <code class="literal"> Log sequence number </code> (LSN) in the <code class="literal"> LOG </code> section of <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output, or monitoring <a class="link" href="server-status-variables.html#statvar_Innodb_os_log_written"> <code class="literal"> Innodb_os_log_written </code> </a> status for the number of bytes written to the redo log files. </p> <p> For related information, see <a class="xref" href="innodb-performance-compression-oltp.html" title="17.9.1.6 Compression for OLTP Workloads"> Section 17.9.1.6, “Compression for OLTP Workloads” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_file_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> </p> <a class="indexterm" name="idm46045154150720"> </a> <a class="indexterm" name="idm46045154149680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_file_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-file-size=# </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> innodb_log_file_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50331648 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 4194304 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 512GB / innodb_log_files_in_group </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> have been superseded by <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> ; see <a class="xref" href="innodb-redo-log.html" title="17.6.5 Redo Log"> Section 17.6.5, “Redo Log” </a> . </p> </div> <p> The size in bytes of each <a class="link" href="glossary.html#glos_log_file" title="log file"> log file </a> in a <a class="link" href="glossary.html#glos_log_group" title="log group"> log group </a> . The combined size of log files ( <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> ) cannot exceed a maximum value that is slightly less than 512GB. A pair of 255 GB log files, for example, approaches the limit but does not exceed it. The default value is 48MB. </p> <p> Generally, the combined size of the log files should be large enough that the server can smooth out peaks and troughs in workload activity, which often means that there is enough redo log space to handle more than an hour of write activity. The larger the value, the less checkpoint flush activity is required in the buffer pool, saving disk I/O. Larger log files also make <a class="link" href="glossary.html#glos_crash_recovery" title="crash recovery"> crash recovery </a> slower. </p> <p> The minimum <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> is 4MB. </p> <p> For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-log-file-configuration" title="Redo Log Configuration"> Redo Log Configuration </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> <p> If the server is started with <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> , the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> is set automatically if it is not explicitly defined. For more information, see <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_files_in_group"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> </p> <a class="indexterm" name="idm46045154097488"> </a> <a class="indexterm" name="idm46045154096384"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_files_in_group"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-files-in-group=# </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> innodb_log_files_in_group </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> have been superseded by <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> ; see <a class="xref" href="innodb-redo-log.html" title="17.6.5 Redo Log"> Section 17.6.5, “Redo Log” </a> . </p> </div> <p> The number of <a class="link" href="glossary.html#glos_log_file" title="log file"> log files </a> in the <a class="link" href="glossary.html#glos_log_group" title="log group"> log group </a> . <code class="literal"> InnoDB </code> writes to the files in a circular fashion. The default (and recommended) value is 2. The location of the files is specified by <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> <code class="literal"> innodb_log_group_home_dir </code> </a> . The combined size of log files ( <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> ) can be up to 512GB. </p> <p> For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-log-file-configuration" title="Redo Log Configuration"> Redo Log Configuration </a> . </p> <p> If the server is started with <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> , the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> is set automatically if it is not explicitly defined. For more information, see <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_group_home_dir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> <code class="literal"> innodb_log_group_home_dir </code> </a> </p> <a class="indexterm" name="idm46045154048576"> </a> <a class="indexterm" name="idm46045154047472"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_group_home_dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-group-home-dir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_group_home_dir"> innodb_log_group_home_dir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> </tbody> </table> </div> <p> The directory path to the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_redo_log" title="redo log"> redo log </a> files. </p> <p> For related information, see <a class="xref" href="innodb-init-startup-configuration.html#innodb-startup-log-file-configuration" title="Redo Log Configuration"> Redo Log Configuration </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_spin_cpu_abs_lwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_abs_lwm"> <code class="literal"> innodb_log_spin_cpu_abs_lwm </code> </a> </p> <a class="indexterm" name="idm46045154022624"> </a> <a class="indexterm" name="idm46045154021520"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_spin_cpu_abs_lwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-spin-cpu-abs-lwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_abs_lwm"> innodb_log_spin_cpu_abs_lwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 80 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Defines the minimum amount of CPU usage below which user threads no longer spin while waiting for flushed redo. The value is expressed as a sum of CPU core usage. For example, The default value of 80 is 80% of a single CPU core. On a system with a multi-core processor, a value of 150 represents 100% usage of one CPU core plus 50% usage of a second CPU core. </p> <p> For related information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_spin_cpu_pct_hwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> <code class="literal"> innodb_log_spin_cpu_pct_hwm </code> </a> </p> <a class="indexterm" name="idm46045153990512"> </a> <a class="indexterm" name="idm46045153989408"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_spin_cpu_pct_hwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-spin-cpu-pct-hwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> innodb_log_spin_cpu_pct_hwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Defines the maximum amount of CPU usage above which user threads no longer spin while waiting for flushed redo. The value is expressed as a percentage of the combined total processing power of all CPU cores. The default value is 50%. For example, 100% usage of two CPU cores is 50% of the combined CPU processing power on a server with four CPU cores. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_log_spin_cpu_pct_hwm"> <code class="literal"> innodb_log_spin_cpu_pct_hwm </code> </a> variable respects processor affinity. For example, if a server has 48 cores but the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process is pinned to only four CPU cores, the other 44 CPU cores are ignored. </p> <p> For related information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_wait_for_flush_spin_hwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_wait_for_flush_spin_hwm"> <code class="literal"> innodb_log_wait_for_flush_spin_hwm </code> </a> </p> <a class="indexterm" name="idm46045153955184"> </a> <a class="indexterm" name="idm46045153954144"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_wait_for_flush_spin_hwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-wait-for-flush-spin-hwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_wait_for_flush_spin_hwm"> innodb_log_wait_for_flush_spin_hwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 400 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value (64-bit platforms, 8.4.0) </th> <td> <code class="literal"> 2**64-1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> <tr> <th> Unit </th> <td> microseconds </td> </tr> </tbody> </table> </div> <p> Defines the maximum average log flush time beyond which user threads no longer spin while waiting for flushed redo. The default value is 400 microseconds. </p> <p> For related information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_write_ahead_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> </p> <a class="indexterm" name="idm46045153918832"> </a> <a class="indexterm" name="idm46045153917728"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_write_ahead_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-write-ahead-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> innodb_log_write_ahead_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 8192 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 512 (log file block size) </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> Equal to innodb_page_size </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Defines the write-ahead block size for the redo log, in bytes. To avoid <span class="quote"> “ <span class="quote"> read-on-write </span> ” </span> , set <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> to match the operating system or file system cache block size. The default setting is 8192 bytes. Read-on-write occurs when redo log blocks are not entirely cached to the operating system or file system due to a mismatch between write-ahead block size for the redo log and operating system or file system cache block size. </p> <p> Valid values for <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> are multiples of the <code class="literal"> InnoDB </code> log file block size (2 <sup> n </sup> ). The minimum value is the <code class="literal"> InnoDB </code> log file block size (512). Write-ahead does not occur when the minimum value is specified. The maximum value is equal to the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value. If you specify a value for <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> that is larger than the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value, the <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> setting is truncated to the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value. </p> <p> Setting the <a class="link" href="innodb-parameters.html#sysvar_innodb_log_write_ahead_size"> <code class="literal"> innodb_log_write_ahead_size </code> </a> value too low in relation to the operating system or file system cache block size results in <span class="quote"> “ <span class="quote"> read-on-write </span> ” </span> . Setting the value too high may have a slight impact on <code class="literal"> fsync </code> performance for log file writes due to several blocks being written at once. </p> <p> For related information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_log_writer_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_writer_threads"> <code class="literal"> innodb_log_writer_threads </code> </a> </p> <a class="indexterm" name="idm46045153869616"> </a> <a class="indexterm" name="idm46045153868512"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_log_writer_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-log-writer-threads[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_log_writer_threads"> innodb_log_writer_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Enables dedicated log writer threads for writing redo log records from the log buffer to the system buffers and flushing the system buffers to the redo log files. Dedicated log writer threads can improve performance on high-concurrency systems, but for low-concurrency systems, disabling dedicated log writer threads provides better performance. </p> <p> For more information, see <a class="xref" href="optimizing-innodb-logging.html" title="10.5.4 Optimizing InnoDB Redo Logging"> Section 10.5.4, “Optimizing InnoDB Redo Logging” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_lru_scan_depth"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> </p> <a class="indexterm" name="idm46045153842352"> </a> <a class="indexterm" name="idm46045153841312"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_lru_scan_depth"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-lru-scan-depth=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> innodb_lru_scan_depth </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1024 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> <tr> <th> Maximum Value (64-bit platforms, 8.4.0) </th> <td> <code class="literal"> 2**64-1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> </tbody> </table> </div> <p> A parameter that influences the algorithms and heuristics for the <a class="link" href="glossary.html#glos_flush" title="flush"> flush </a> operation for the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> . Primarily of interest to performance experts tuning I/O-intensive workloads. It specifies, per buffer pool instance, how far down the buffer pool LRU page list the page cleaner thread scans looking for <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> to flush. This is a background operation performed once per second. </p> <p> A setting smaller than the default is generally suitable for most workloads. A value that is much higher than necessary may impact performance. Only consider increasing the value if you have spare I/O capacity under a typical workload. Conversely, if a write-intensive workload saturates your I/O capacity, decrease the value, especially in the case of a large buffer pool. </p> <p> When tuning <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> , start with a low value and configure the setting upward with the goal of rarely seeing zero free pages. Also, consider adjusting <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> when changing the number of buffer pool instances, since <a class="link" href="innodb-parameters.html#sysvar_innodb_lru_scan_depth"> <code class="literal"> innodb_lru_scan_depth </code> </a> * <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> defines the amount of work performed by the page cleaner thread each second. </p> <p> For related information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_dirty_pages_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> </p> <a class="indexterm" name="idm46045153797312"> </a> <a class="indexterm" name="idm46045153796208"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_dirty_pages_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-dirty-pages-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> innodb_max_dirty_pages_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 90 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 99.999 </code> </td> </tr> </tbody> </table> </div> <p> <code class="literal"> InnoDB </code> tries to <a class="link" href="glossary.html#glos_flush" title="flush"> flush </a> data from the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> so that the percentage of <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> does not exceed this value. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> setting establishes a target for flushing activity. It does not affect the rate of flushing. For information about managing the rate of flushing, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> <p> For related information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_dirty_pages_pct_lwm"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> <code class="literal"> innodb_max_dirty_pages_pct_lwm </code> </a> </p> <a class="indexterm" name="idm46045153758256"> </a> <a class="indexterm" name="idm46045153757152"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_dirty_pages_pct_lwm"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-dirty-pages-pct-lwm=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct_lwm"> innodb_max_dirty_pages_pct_lwm </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 99.999 </code> </td> </tr> </tbody> </table> </div> <p> Defines a low water mark representing the percentage of <a class="link" href="glossary.html#glos_dirty_page" title="dirty page"> dirty pages </a> at which preflushing is enabled to control the dirty page ratio. A value of 0 disables the pre-flushing behavior entirely. The configured value should always be lower than the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_dirty_pages_pct"> <code class="literal"> innodb_max_dirty_pages_pct </code> </a> value. For more information, see <a class="xref" href="innodb-buffer-pool-flushing.html" title="17.8.3.5 Configuring Buffer Pool Flushing"> Section 17.8.3.5, “Configuring Buffer Pool Flushing” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_purge_lag"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> <code class="literal"> innodb_max_purge_lag </code> </a> </p> <a class="indexterm" name="idm46045153724560"> </a> <a class="indexterm" name="idm46045153723520"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_purge_lag"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-purge-lag=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> innodb_max_purge_lag </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> Defines the desired maximum purge lag. If this value is exceeded, a delay is imposed on <a class="link" href="insert.html" title="15.2.7 INSERT Statement"> <code class="literal"> INSERT </code> </a> , <a class="link" href="update.html" title="15.2.17 UPDATE Statement"> <code class="literal"> UPDATE </code> </a> , and <a class="link" href="delete.html" title="15.2.2 DELETE Statement"> <code class="literal"> DELETE </code> </a> operations to allow time for purge to catch up. The default value is 0, which means there is no maximum purge lag and no delay. </p> <p> For more information, see <a class="xref" href="innodb-purge-configuration.html" title="17.8.9 Purge Configuration"> Section 17.8.9, “Purge Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_purge_lag_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> <code class="literal"> innodb_max_purge_lag_delay </code> </a> </p> <a class="indexterm" name="idm46045153689040"> </a> <a class="indexterm" name="idm46045153687936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_purge_lag_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-purge-lag-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> innodb_max_purge_lag_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 10000000 </code> </td> </tr> <tr> <th> Unit </th> <td> microseconds </td> </tr> </tbody> </table> </div> <p> Specifies the maximum delay in microseconds for the delay imposed when the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> <code class="literal"> innodb_max_purge_lag </code> </a> threshold is exceeded. The specified <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag_delay"> <code class="literal"> innodb_max_purge_lag_delay </code> </a> value is an upper limit on the delay period calculated by the <a class="link" href="innodb-parameters.html#sysvar_innodb_max_purge_lag"> <code class="literal"> innodb_max_purge_lag </code> </a> formula. </p> <p> For more information, see <a class="xref" href="innodb-purge-configuration.html" title="17.8.9 Purge Configuration"> Section 17.8.9, “Purge Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_max_undo_log_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> <code class="literal"> innodb_max_undo_log_size </code> </a> </p> <a class="indexterm" name="idm46045153651280"> </a> <a class="indexterm" name="idm46045153650176"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_max_undo_log_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-max-undo-log-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> innodb_max_undo_log_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1073741824 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 10485760 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**64-1 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Defines a threshold size for undo tablespaces. If an undo tablespace exceeds the threshold, it can be marked for truncation when <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> <code class="literal"> innodb_undo_log_truncate </code> </a> is enabled. The default value is 1073741824 bytes (1024 MiB). </p> <p> For more information, see <a class="xref" href="innodb-undo-tablespaces.html#truncate-undo-tablespace" title="Truncating Undo Tablespaces"> Truncating Undo Tablespaces </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_merge_threshold_set_all_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_merge_threshold_set_all_debug"> <code class="literal"> innodb_merge_threshold_set_all_debug </code> </a> </p> <a class="indexterm" name="idm46045153615856"> </a> <a class="indexterm" name="idm46045153614768"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_merge_threshold_set_all_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-merge-threshold-set-all-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_merge_threshold_set_all_debug"> innodb_merge_threshold_set_all_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 50 </code> </td> </tr> </tbody> </table> </div> <p> Defines a page-full percentage value for index pages that overrides the current <code class="literal"> MERGE_THRESHOLD </code> setting for all indexes that are currently in the dictionary cache. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. For related information, see <a class="xref" href="index-page-merge-threshold.html" title="17.8.11 Configuring the Merge Threshold for Index Pages"> Section 17.8.11, “Configuring the Merge Threshold for Index Pages” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_monitor_disable"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> <code class="literal"> innodb_monitor_disable </code> </a> </p> <a class="indexterm" name="idm46045153582000"> </a> <a class="indexterm" name="idm46045153580960"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_monitor_disable"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-monitor-disable={counter|module|pattern|all} </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> innodb_monitor_disable </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> </tbody> </table> </div> <p> This variable acts as a switch, disabling <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_metrics_counter" title="metrics counter"> metrics counters </a> . Counter data may be queried using the Information Schema <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> <code class="literal"> INNODB_METRICS </code> </a> table. For usage information, see <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_disable"> <code class="literal"> innodb_monitor_disable='latch' </code> </a> disables statistics collection for <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB MUTEX </code> </a> . For more information, see <a class="xref" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> Section 15.7.7.16, “SHOW ENGINE Statement” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_monitor_enable"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> <code class="literal"> innodb_monitor_enable </code> </a> </p> <a class="indexterm" name="idm46045153551408"> </a> <a class="indexterm" name="idm46045153550368"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_monitor_enable"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-monitor-enable={counter|module|pattern|all} </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> innodb_monitor_enable </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> </tbody> </table> </div> <p> This variable acts as a switch, enabling <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_metrics_counter" title="metrics counter"> metrics counters </a> . Counter data may be queried using the Information Schema <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> <code class="literal"> INNODB_METRICS </code> </a> table. For usage information, see <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> . </p> <p> </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_enable"> <code class="literal"> innodb_monitor_enable='latch' </code> </a> enables statistics collection for <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB MUTEX </code> </a> . For more information, see <a class="xref" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> Section 15.7.7.16, “SHOW ENGINE Statement” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_monitor_reset"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> <code class="literal"> innodb_monitor_reset </code> </a> </p> <a class="indexterm" name="idm46045153520688"> </a> <a class="indexterm" name="idm46045153519648"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_monitor_reset"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-monitor-reset={counter|module|pattern|all} </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> innodb_monitor_reset </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> counter </code> </p> <p class="valid-value"> <code class="literal"> module </code> </p> <p class="valid-value"> <code class="literal"> pattern </code> </p> <p class="valid-value"> <code class="literal"> all </code> </p> </td> </tr> </tbody> </table> </div> <p> This variable acts as a switch, resetting the count value for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_metrics_counter" title="metrics counter"> metrics counters </a> to zero. Counter data may be queried using the Information Schema <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> <code class="literal"> INNODB_METRICS </code> </a> table. For usage information, see <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset"> <code class="literal"> innodb_monitor_reset='latch' </code> </a> resets statistics reported by <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB MUTEX </code> </a> . For more information, see <a class="xref" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> Section 15.7.7.16, “SHOW ENGINE Statement” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_monitor_reset_all"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset_all"> <code class="literal"> innodb_monitor_reset_all </code> </a> </p> <a class="indexterm" name="idm46045153482096"> </a> <a class="indexterm" name="idm46045153480992"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_monitor_reset_all"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-monitor-reset-all={counter|module|pattern|all} </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_monitor_reset_all"> innodb_monitor_reset_all </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> counter </code> </p> <p class="valid-value"> <code class="literal"> module </code> </p> <p class="valid-value"> <code class="literal"> pattern </code> </p> <p class="valid-value"> <code class="literal"> all </code> </p> </td> </tr> </tbody> </table> </div> <p> This variable acts as a switch, resetting all values (minimum, maximum, and so on) for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_metrics_counter" title="metrics counter"> metrics counters </a> . Counter data may be queried using the Information Schema <a class="link" href="information-schema-innodb-metrics-table.html" title="28.4.21 The INFORMATION_SCHEMA INNODB_METRICS Table"> <code class="literal"> INNODB_METRICS </code> </a> table. For usage information, see <a class="xref" href="innodb-information-schema-metrics-table.html" title="17.15.6 InnoDB INFORMATION_SCHEMA Metrics Table"> Section 17.15.6, “InnoDB INFORMATION_SCHEMA Metrics Table” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_numa_interleave"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> <code class="literal"> innodb_numa_interleave </code> </a> </p> <a class="indexterm" name="idm46045153446976"> </a> <a class="indexterm" name="idm46045153445936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_numa_interleave"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-numa-interleave[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> innodb_numa_interleave </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Enables the NUMA interleave memory policy for allocation of the <code class="literal"> InnoDB </code> buffer pool. When <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> <code class="literal"> innodb_numa_interleave </code> </a> is enabled, the NUMA memory policy is set to <code class="literal"> MPOL_INTERLEAVE </code> for the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process. After the <code class="literal"> InnoDB </code> buffer pool is allocated, the NUMA memory policy is set back to <code class="literal"> MPOL_DEFAULT </code> . For the <a class="link" href="innodb-parameters.html#sysvar_innodb_numa_interleave"> <code class="literal"> innodb_numa_interleave </code> </a> option to be available, MySQL must be compiled on a NUMA-enabled Linux system. The default value is <code class="literal"> ON </code> if the system supports it, otherwise it defaults to <code class="literal"> OFF </code> . </p> <p> <span class="command"> <strong> CMake </strong> </span> sets the default <a class="link" href="source-configuration-options.html#option_cmake_with_numa"> <code class="option"> WITH_NUMA </code> </a> value based on whether the current platform has <code class="literal"> NUMA </code> support. For more information, see <a class="xref" href="source-configuration-options.html" title="2.8.7 MySQL Source-Configuration Options"> Section 2.8.7, “MySQL Source-Configuration Options” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_old_blocks_pct"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> <code class="literal"> innodb_old_blocks_pct </code> </a> </p> <a class="indexterm" name="idm46045153409360"> </a> <a class="indexterm" name="idm46045153408320"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_old_blocks_pct"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-old-blocks-pct=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> innodb_old_blocks_pct </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 37 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 5 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 95 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the approximate percentage of the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> used for the old block <a class="link" href="glossary.html#glos_sublist" title="sublist"> sublist </a> . The range of values is 5 to 95. The default value is 37 (that is, 3/8 of the pool). Often used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> <code class="literal"> innodb_old_blocks_time </code> </a> . </p> <p> For more information, see <a class="xref" href="innodb-performance-midpoint_insertion.html" title="17.8.3.3 Making the Buffer Pool Scan Resistant"> Section 17.8.3.3, “Making the Buffer Pool Scan Resistant” </a> . For information about buffer pool management, the <a class="link" href="glossary.html#glos_lru" title="LRU"> LRU </a> algorithm, and <a class="link" href="glossary.html#glos_eviction" title="eviction"> eviction </a> policies, see <a class="xref" href="innodb-buffer-pool.html" title="17.5.1 Buffer Pool"> Section 17.5.1, “Buffer Pool” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_old_blocks_time"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> <code class="literal"> innodb_old_blocks_time </code> </a> </p> <a class="indexterm" name="idm46045153371456"> </a> <a class="indexterm" name="idm46045153370416"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_old_blocks_time"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-old-blocks-time=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_time"> innodb_old_blocks_time </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> <tr> <th> Unit </th> <td> milliseconds </td> </tr> </tbody> </table> </div> <p> Non-zero values protect against the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> being filled by data that is referenced only for a brief period, such as during a <a class="link" href="glossary.html#glos_full_table_scan" title="full table scan"> full table scan </a> . Increasing this value offers more protection against full table scans interfering with data cached in the buffer pool. </p> <p> Specifies how long in milliseconds a block inserted into the old <a class="link" href="glossary.html#glos_sublist" title="sublist"> sublist </a> must stay there after its first access before it can be moved to the new sublist. If the value is 0, a block inserted into the old sublist moves immediately to the new sublist the first time it is accessed, no matter how soon after insertion the access occurs. If the value is greater than 0, blocks remain in the old sublist until an access occurs at least that many milliseconds after the first access. For example, a value of 1000 causes blocks to stay in the old sublist for 1 second after the first access before they become eligible to move to the new sublist. </p> <p> The default value is 1000. </p> <p> This variable is often used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_old_blocks_pct"> <code class="literal"> innodb_old_blocks_pct </code> </a> . For more information, see <a class="xref" href="innodb-performance-midpoint_insertion.html" title="17.8.3.3 Making the Buffer Pool Scan Resistant"> Section 17.8.3.3, “Making the Buffer Pool Scan Resistant” </a> . For information about buffer pool management, the <a class="link" href="glossary.html#glos_lru" title="LRU"> LRU </a> algorithm, and <a class="link" href="glossary.html#glos_eviction" title="eviction"> eviction </a> policies, see <a class="xref" href="innodb-buffer-pool.html" title="17.5.1 Buffer Pool"> Section 17.5.1, “Buffer Pool” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_online_alter_log_max_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> <code class="literal"> innodb_online_alter_log_max_size </code> </a> </p> <a class="indexterm" name="idm46045153329728"> </a> <a class="indexterm" name="idm46045153328624"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_online_alter_log_max_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-online-alter-log-max-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> innodb_online_alter_log_max_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 134217728 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 65536 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**64-1 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Specifies an upper limit in bytes on the size of the temporary log files used during <a class="link" href="glossary.html#glos_online_ddl" title="online DDL"> online DDL </a> operations for <code class="literal"> InnoDB </code> tables. There is one such log file for each index being created or table being altered. This log file stores data inserted, updated, or deleted in the table during the DDL operation. The temporary log file is extended when needed by the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> <code class="literal"> innodb_sort_buffer_size </code> </a> , up to the maximum specified by <a class="link" href="innodb-parameters.html#sysvar_innodb_online_alter_log_max_size"> <code class="literal"> innodb_online_alter_log_max_size </code> </a> . If a temporary log file exceeds the upper size limit, the <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operation fails and all uncommitted concurrent DML operations are rolled back. Thus, a large value for this option allows more DML to happen during an online DDL operation, but also extends the period of time at the end of the DDL operation when the table is locked to apply the data from the log. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_open_files"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> </p> <a class="indexterm" name="idm46045153290896"> </a> <a class="indexterm" name="idm46045153289856"> </a> <a class="indexterm" name="idm46045153288368"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_open_files"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-open-files=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> innodb_open_files </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> -1 </code> (signifies autosizing; do not assign this literal value) </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 10 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2147483647 </code> </td> </tr> </tbody> </table> </div> <p> Specifies the maximum number of files that <code class="literal"> InnoDB </code> can have open at one time. The minimum value is 10. If <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> is disabled, the default value is 300; otherwise, the default value is 300 or the <a class="link" href="server-system-variables.html#sysvar_table_open_cache"> <code class="literal"> table_open_cache </code> </a> setting, whichever is higher. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> limit can be set at runtime using a <code class="literal"> SELECT innodb_set_open_files_limit( <em class="replaceable"> <code> N </code> </em> ) </code> statement, where <em class="replaceable"> <code> N </code> </em> is the desired <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> limit; for example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-sql"><div class="docs-select-all right" id="sa50026232"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token prompt">mysql></span> <span class="token keyword">SELECT</span> innodb_set_open_files_limit<span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span></code></pre> </div> <p> The statement executes a stored procedure that sets the new limit. If the procedure is successful, it returns the value of the newly set limit; otherwise, a failure message is returned. </p> <p> It is not permitted to set <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> using a <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement. To set <code class="literal"> innodb_open_files </code> at runtime, use the <code class="literal"> SELECT innodb_set_open_files_limit( <em class="replaceable"> <code> N </code> </em> ) </code> statement described above. </p> <p> Setting <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files=default </code> </a> is not supported. Only integer values are permitted. </p> <p> To prevent non-LRU managed files from consuming the entire <a class="link" href="innodb-parameters.html#sysvar_innodb_open_files"> <code class="literal"> innodb_open_files </code> </a> limit, non-LRU managed files are limited to 90 percent of this limit, which reserves 10 percent of it for LRU managed files. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_optimize_fulltext_only"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_optimize_fulltext_only"> <code class="literal"> innodb_optimize_fulltext_only </code> </a> </p> <a class="indexterm" name="idm46045153239056"> </a> <a class="indexterm" name="idm46045153237952"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_optimize_fulltext_only"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-optimize-fulltext-only[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_optimize_fulltext_only"> innodb_optimize_fulltext_only </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Changes the way <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> operates on <code class="literal"> InnoDB </code> tables. Intended to be enabled temporarily, during maintenance operations for <code class="literal"> InnoDB </code> tables with <code class="literal"> FULLTEXT </code> indexes. </p> <p> By default, <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> reorganizes data in the <a class="link" href="glossary.html#glos_clustered_index" title="clustered index"> clustered index </a> of the table. When this option is enabled, <a class="link" href="optimize-table.html" title="15.7.3.4 OPTIMIZE TABLE Statement"> <code class="literal"> OPTIMIZE TABLE </code> </a> skips the reorganization of table data, and instead processes newly added, deleted, and updated token data for <code class="literal"> InnoDB </code> <code class="literal"> FULLTEXT </code> indexes. For more information, see <a class="xref" href="fulltext-fine-tuning.html#fulltext-optimize" title="Optimizing InnoDB Full-Text Indexes"> Optimizing InnoDB Full-Text Indexes </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_page_cleaners"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> <code class="literal"> innodb_page_cleaners </code> </a> </p> <a class="indexterm" name="idm46045153203808"> </a> <a class="indexterm" name="idm46045153202768"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_page_cleaners"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-page-cleaners=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> innodb_page_cleaners </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> innodb_buffer_pool_instances </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> The number of page cleaner threads that flush dirty pages from buffer pool instances. Page cleaner threads perform flush list and LRU flushing. When there are multiple page cleaner threads, buffer pool flushing tasks for each buffer pool instance are dispatched to idle page cleaner threads. The <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> <code class="literal"> innodb_page_cleaners </code> </a> default value is set to the same value as <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . If the specified number of page cleaner threads exceeds the number of buffer pool instances, then <a class="link" href="innodb-parameters.html#sysvar_innodb_page_cleaners"> <code class="literal"> innodb_page_cleaners </code> </a> is automatically set to the same value as <a class="link" href="innodb-parameters.html#sysvar_innodb_buffer_pool_instances"> <code class="literal"> innodb_buffer_pool_instances </code> </a> . </p> <p> If your workload is write-IO bound when flushing dirty pages from buffer pool instances to data files, and if your system hardware has available capacity, increasing the number of page cleaner threads may help improve write-IO throughput. </p> <p> Multithreaded page cleaner support extends to shutdown and recovery phases. </p> <p> The <code class="literal"> setpriority() </code> system call is used on Linux platforms where it is supported, and where the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> execution user is authorized to give <code class="literal"> page_cleaner </code> threads priority over other MySQL and <code class="literal"> InnoDB </code> threads to help page flushing keep pace with the current workload. <code class="literal"> setpriority() </code> support is indicated by this <code class="literal"> InnoDB </code> startup message: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa59335561"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token punctuation">[</span>Note<span class="token punctuation">]</span> InnoDB<span class="token punctuation">:</span> If the mysqld execution user is authorized<span class="token punctuation">,</span> page cleaner thread priority can be changed<span class="token punctuation">.</span> See the man page of setpriority<span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span></code></pre> </div> <p> For systems where server startup and shutdown is not managed by systemd, <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> execution user authorization can be configured in <code class="filename"> /etc/security/limits.conf </code> . For example, if <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> is run under the <code class="literal"> mysql </code> user, you can authorize the <code class="literal"> mysql </code> user by adding these lines to <code class="filename"> /etc/security/limits.conf </code> : </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa42253882"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini">mysql hard nice -20 mysql soft nice -20</code></pre> </div> <p> For systemd managed systems, the same can be achieved by specifying <code class="literal"> LimitNICE=-20 </code> in a localized systemd configuration file. For example, create a file named <code class="filename"> override.conf </code> in <code class="filename"> /etc/systemd/system/mysqld.service.d/override.conf </code> and add this entry: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa78683224"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[Service]</span> <span class="token constant">LimitNICE</span><span class="token attr-value"><span class="token punctuation">=</span>-20</span></code></pre> </div> <p> After creating or changing <code class="filename"> override.conf </code> , reload the systemd configuration, then tell systemd to restart the MySQL service: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa91362659"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini">systemctl daemon-reload systemctl restart mysqld <span class="token comment" spellcheck="true"># RPM platforms</span> systemctl restart mysql <span class="token comment" spellcheck="true"># Debian platforms</span></code></pre> </div> <p> For more information about using a localized systemd configuration file, see <a class="xref" href="using-systemd.html#systemd-mysql-configuration" title="Configuring systemd for MySQL"> Configuring systemd for MySQL </a> . </p> <p> After authorizing the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> execution user, use the <span class="command"> <strong> cat </strong> </span> command to verify the configured <code class="literal"> Nice </code> limits for the <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> process: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-terminal"><div class="docs-select-all right" id="sa80479455"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token prompt">$> </span><span class="token command">cat</span> /proc/<em class="replaceable">mysqld_pid</em>/limits | grep nice Max nice priority 18446744073709551596 18446744073709551596</code></pre> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_page_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> </p> <a class="indexterm" name="idm46045153139920"> </a> <a class="indexterm" name="idm46045153138832"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_page_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-page-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> innodb_page_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 16384 </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> 4096 </code> </p> <p class="valid-value"> <code class="literal"> 8192 </code> </p> <p class="valid-value"> <code class="literal"> 16384 </code> </p> <p class="valid-value"> <code class="literal"> 32768 </code> </p> <p class="valid-value"> <code class="literal"> 65536 </code> </p> </td> </tr> </tbody> </table> </div> <p> Specifies the <a class="link" href="glossary.html#glos_page_size" title="page size"> page size </a> for <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_tablespace" title="tablespace"> tablespaces </a> . Values can be specified in bytes or kilobytes. For example, a 16 kilobyte page size value can be specified as 16384, 16KB, or 16k. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> can only be configured prior to initializing the MySQL instance and cannot be changed afterward. If no value is specified, the instance is initialized using the default page size. See <a class="xref" href="innodb-init-startup-configuration.html" title="17.8.1 InnoDB Startup Configuration"> Section 17.8.1, “InnoDB Startup Configuration” </a> . </p> <p> For both 32KB and 64KB page sizes, the maximum row length is approximately 16000 bytes. <code class="literal"> ROW_FORMAT=COMPRESSED </code> is not supported when <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> is set to 32KB or 64KB. For <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size=32KB </code> </a> , extent size is 2MB. For <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size=64KB </code> </a> , extent size is 4MB. <a class="link" href="innodb-parameters.html#sysvar_innodb_log_buffer_size"> <code class="literal"> innodb_log_buffer_size </code> </a> should be set to at least 16MB (the default is 64MB) when using 32KB or 64KB page sizes. </p> <p> The default 16KB page size or larger is appropriate for a wide range of <a class="link" href="glossary.html#glos_workload" title="workload"> workloads </a> , particularly for queries involving table scans and DML operations involving bulk updates. Smaller page sizes might be more efficient for <a class="link" href="glossary.html#glos_oltp" title="OLTP"> OLTP </a> workloads involving many small writes, where contention can be an issue when single pages contain many rows. Smaller pages might also be efficient with <a class="link" href="glossary.html#glos_ssd" title="SSD"> SSD </a> storage devices, which typically use small block sizes. Keeping the <code class="literal"> InnoDB </code> page size close to the storage device block size minimizes the amount of unchanged data that is rewritten to disk. </p> <p> The minimum file size for the first system tablespace data file ( <code class="literal"> ibdata1 </code> ) differs depending on the <a class="link" href="innodb-parameters.html#sysvar_innodb_page_size"> <code class="literal"> innodb_page_size </code> </a> value. See the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_file_path"> <code class="literal"> innodb_data_file_path </code> </a> option description for more information. </p> <p> A MySQL instance using a particular <code class="literal"> InnoDB </code> page size cannot use data files or log files from an instance that uses a different page size. </p> <p> For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_parallel_read_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> <code class="literal"> innodb_parallel_read_threads </code> </a> </p> <a class="indexterm" name="idm46045153085744"> </a> <a class="indexterm" name="idm46045153084640"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_parallel_read_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-parallel-read-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> innodb_parallel_read_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> (available logical processors / 8), min of 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 256 </code> </td> </tr> </tbody> </table> </div> <p> Defines the number of threads that can be used for parallel clustered index reads. Parallel scanning of partitions is also supported. Parallel read threads can improve <a class="link" href="check-table.html" title="15.7.3.2 CHECK TABLE Statement"> <code class="literal"> CHECK TABLE </code> </a> performance. <code class="literal"> InnoDB </code> reads the clustered index twice during a <a class="link" href="check-table.html" title="15.7.3.2 CHECK TABLE Statement"> <code class="literal"> CHECK TABLE </code> </a> operation. The second read can be performed in parallel. This feature does not apply to secondary index scans. The <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> <code class="literal"> innodb_parallel_read_threads </code> </a> session variable must be set to a value greater than 1 for parallel clustered index reads to occur. The actual number of threads used to perform a parallel clustered index read is determined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_parallel_read_threads"> <code class="literal"> innodb_parallel_read_threads </code> </a> setting or the number of index subtrees to scan, whichever is smaller. The pages read into the buffer pool during the scan are kept at the tail of the buffer pool LRU list so that they can be discarded quickly when free buffer pool pages are required. </p> <p> The maximum number of parallel read threads (256) is the total number of threads for all client connections. If the thread limit is reached, connections fall back to using a single thread. The default value is calculated by the number of available logical processors on the system divided by 8, with a minimum default value of 4. </p> <p> Before MySQL 8.4, the default value was always 4. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_print_all_deadlocks"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_all_deadlocks"> <code class="literal"> innodb_print_all_deadlocks </code> </a> </p> <a class="indexterm" name="idm46045153047264"> </a> <a class="indexterm" name="idm46045153046160"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_print_all_deadlocks"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-print-all-deadlocks[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_all_deadlocks"> innodb_print_all_deadlocks </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <a class="indexterm" name="idm46045153024448"> </a> <p> When this option is enabled, information about all <a class="link" href="glossary.html#glos_deadlock" title="deadlock"> deadlocks </a> in <code class="literal"> InnoDB </code> user transactions is recorded in the <code class="literal"> mysqld </code> <a class="link" href="error-log.html" title="7.4.2 The Error Log"> error log </a> . Otherwise, you see information about only the last deadlock, using the <code class="literal"> SHOW ENGINE INNODB STATUS </code> statement. An occasional <code class="literal"> InnoDB </code> deadlock is not necessarily an issue, because <code class="literal"> InnoDB </code> detects the condition immediately and rolls back one of the transactions automatically. You might use this option to troubleshoot why deadlocks are occurring if an application does not have appropriate error-handling logic to detect the rollback and retry its operation. A large number of deadlocks might indicate the need to restructure transactions that issue <a class="link" href="glossary.html#glos_dml" title="DML"> DML </a> or <code class="literal"> SELECT ... FOR UPDATE </code> statements for multiple tables, so that each transaction accesses the tables in the same order, thus avoiding the deadlock condition. </p> <p> For related information, see <a class="xref" href="innodb-deadlocks.html" title="17.7.5 Deadlocks in InnoDB"> Section 17.7.5, “Deadlocks in InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_print_ddl_logs"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_ddl_logs"> <code class="literal"> innodb_print_ddl_logs </code> </a> </p> <a class="indexterm" name="idm46045153011760"> </a> <a class="indexterm" name="idm46045153010720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_print_ddl_logs"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-print-ddl-logs[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_print_ddl_logs"> innodb_print_ddl_logs </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enabling this option causes MySQL to write DDL logs to <code class="literal"> stderr </code> . For more information, see <a class="xref" href="atomic-ddl.html#atomic-ddl-view-logs" title="Viewing DDL Logs"> Viewing DDL Logs </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_purge_batch_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> </p> <a class="indexterm" name="idm46045152984688"> </a> <a class="indexterm" name="idm46045152983648"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_purge_batch_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-purge-batch-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> innodb_purge_batch_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 300 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 5000 </code> </td> </tr> </tbody> </table> </div> <p> Defines the number of undo log pages that purge parses and processes in one batch from the <a class="link" href="glossary.html#glos_history_list" title="history list"> history list </a> . In a multithreaded purge configuration, the coordinator purge thread divides <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> by <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> <code class="literal"> innodb_purge_threads </code> </a> and assigns that number of pages to each purge thread. The <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> variable also defines the number of undo log pages that purge frees after every 128 iterations through the undo logs. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> option is intended for advanced performance tuning in combination with the <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> <code class="literal"> innodb_purge_threads </code> </a> setting. Most users need not change <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_batch_size"> <code class="literal"> innodb_purge_batch_size </code> </a> from its default value. </p> <p> For related information, see <a class="xref" href="innodb-purge-configuration.html" title="17.8.9 Purge Configuration"> Section 17.8.9, “Purge Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_purge_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> <code class="literal"> innodb_purge_threads </code> </a> </p> <a class="indexterm" name="idm46045152943488"> </a> <a class="indexterm" name="idm46045152942448"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_purge_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-purge-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_threads"> innodb_purge_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 if # of available logical processors is <= 16; otherwise 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 32 </code> </td> </tr> </tbody> </table> </div> <p> The number of background threads devoted to the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_purge" title="purge"> purge </a> operation. Increasing the value creates additional purge threads, which can improve efficiency on systems where <a class="link" href="glossary.html#glos_dml" title="DML"> DML </a> operations are performed on multiple tables. </p> <p> For related information, see <a class="xref" href="innodb-purge-configuration.html" title="17.8.9 Purge Configuration"> Section 17.8.9, “Purge Configuration” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_purge_rseg_truncate_frequency"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> <code class="literal"> innodb_purge_rseg_truncate_frequency </code> </a> </p> <a class="indexterm" name="idm46045152909168"> </a> <a class="indexterm" name="idm46045152908128"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_purge_rseg_truncate_frequency"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-purge-rseg-truncate-frequency=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> innodb_purge_rseg_truncate_frequency </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 128 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 128 </code> </td> </tr> </tbody> </table> </div> <p> Defines the frequency with which the purge system frees rollback segments in terms of the number of times that purge is invoked. An undo tablespace cannot be truncated until its rollback segments are freed. Normally, the purge system frees rollback segments once every 128 times that purge is invoked. The default value is 128. Reducing this value increases the frequency with which the purge thread frees rollback segments. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> <code class="literal"> innodb_purge_rseg_truncate_frequency </code> </a> is intended for use with <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> <code class="literal"> innodb_undo_log_truncate </code> </a> . For more information, see <a class="xref" href="innodb-undo-tablespaces.html#truncate-undo-tablespace" title="Truncating Undo Tablespaces"> Truncating Undo Tablespaces </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_random_read_ahead"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_random_read_ahead"> <code class="literal"> innodb_random_read_ahead </code> </a> </p> <a class="indexterm" name="idm46045152874432"> </a> <a class="indexterm" name="idm46045152873328"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_random_read_ahead"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-random-read-ahead[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_random_read_ahead"> innodb_random_read_ahead </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables the random <a class="link" href="glossary.html#glos_read_ahead" title="read-ahead"> read-ahead </a> technique for optimizing <code class="literal"> InnoDB </code> I/O. </p> <p> For details about performance considerations for different types of read-ahead requests, see <a class="xref" href="innodb-performance-read_ahead.html" title="17.8.3.4 Configuring InnoDB Buffer Pool Prefetching (Read-Ahead)"> Section 17.8.3.4, “Configuring InnoDB Buffer Pool Prefetching (Read-Ahead)” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_read_ahead_threshold"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> <code class="literal"> innodb_read_ahead_threshold </code> </a> </p> <a class="indexterm" name="idm46045309042080"> </a> <a class="indexterm" name="idm46045309041040"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_read_ahead_threshold"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-read-ahead-threshold=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> innodb_read_ahead_threshold </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 56 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> Controls the sensitivity of linear <a class="link" href="glossary.html#glos_read_ahead" title="read-ahead"> read-ahead </a> that <code class="literal"> InnoDB </code> uses to prefetch pages into the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> . If <code class="literal"> InnoDB </code> reads at least <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> <code class="literal"> innodb_read_ahead_threshold </code> </a> pages sequentially from an <a class="link" href="glossary.html#glos_extent" title="extent"> extent </a> (64 pages), it initiates an asynchronous read for the entire following extent. The permissible range of values is 0 to 64. A value of 0 disables read-ahead. For the default of 56, <code class="literal"> InnoDB </code> must read at least 56 pages sequentially from an extent to initiate an asynchronous read for the following extent. </p> <p> Knowing how many pages are read through the read-ahead mechanism, and how many of these pages are evicted from the buffer pool without ever being accessed, can be useful when fine-tuning the <a class="link" href="innodb-parameters.html#sysvar_innodb_read_ahead_threshold"> <code class="literal"> innodb_read_ahead_threshold </code> </a> setting. <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output displays counter information from the <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead"> <code class="literal"> Innodb_buffer_pool_read_ahead </code> </a> and <a class="link" href="server-status-variables.html#statvar_Innodb_buffer_pool_read_ahead_evicted"> <code class="literal"> Innodb_buffer_pool_read_ahead_evicted </code> </a> global status variables, which report the number of pages brought into the <a class="link" href="glossary.html#glos_buffer_pool" title="buffer pool"> buffer pool </a> by read-ahead requests, and the number of such pages <a class="link" href="glossary.html#glos_eviction" title="eviction"> evicted </a> from the buffer pool without ever being accessed, respectively. The status variables report global values since the last server restart. </p> <p> <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> also shows the rate at which the read-ahead pages are read and the rate at which such pages are evicted without being accessed. The per-second averages are based on the statistics collected since the last invocation of <code class="literal"> SHOW ENGINE INNODB STATUS </code> and are displayed in the <code class="literal"> BUFFER POOL AND MEMORY </code> section of the <a class="link" href="show-engine.html" title="15.7.7.16 SHOW ENGINE Statement"> <code class="literal"> SHOW ENGINE INNODB STATUS </code> </a> output. </p> <p> For more information, see <a class="xref" href="innodb-performance-read_ahead.html" title="17.8.3.4 Configuring InnoDB Buffer Pool Prefetching (Read-Ahead)"> Section 17.8.3.4, “Configuring InnoDB Buffer Pool Prefetching (Read-Ahead)” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_read_io_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> <code class="literal"> innodb_read_io_threads </code> </a> </p> <a class="indexterm" name="idm46045308991376"> </a> <a class="indexterm" name="idm46045308990336"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_read_io_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-read-io-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> innodb_read_io_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> (available logical processors / 2), min of 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> The number of I/O threads for read operations in <code class="literal"> InnoDB </code> . Its counterpart for write threads is <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> . For more information, see <a class="xref" href="innodb-performance-multiple_io_threads.html" title="17.8.5 Configuring the Number of Background InnoDB I/O Threads"> Section 17.8.5, “Configuring the Number of Background InnoDB I/O Threads” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . The default value is the number of available logical processors on the system divided by 2, with a minimum default value of 4. </p> <p> Before MySQL 8.4, the default value was always 4. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> On Linux systems, running multiple MySQL servers (typically more than 12) with default settings for <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> <code class="literal"> innodb_read_io_threads </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> , and the Linux <code class="literal"> aio-max-nr </code> setting can exceed system limits. Ideally, increase the <code class="literal"> aio-max-nr </code> setting; as a workaround, you might reduce the settings for one or both of the MySQL variables. </p> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_read_only"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> <code class="literal"> innodb_read_only </code> </a> </p> <a class="indexterm" name="idm46045308952064"> </a> <a class="indexterm" name="idm46045308950976"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_read_only"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-read-only[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> innodb_read_only </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Starts <code class="literal"> InnoDB </code> in read-only mode. For distributing database applications or data sets on read-only media. Can also be used in data warehouses to share the same data directory between multiple instances. For more information, see <a class="xref" href="innodb-read-only-instance.html" title="17.8.2 Configuring InnoDB for Read-Only Operation"> Section 17.8.2, “Configuring InnoDB for Read-Only Operation” </a> . </p> <p> Enabling <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> <code class="literal"> innodb_read_only </code> </a> prevents creating and dropping tables for all storage engines, and not only <code class="literal"> InnoDB </code> . Table creation and drop operations for any storage engine modify data dictionary tables in the <code class="literal"> mysql </code> system database, but those tables use the <code class="literal"> InnoDB </code> storage engine and cannot be modified when <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> <code class="literal"> innodb_read_only </code> </a> is enabled. The same principle applies to other table operations that require modifying data dictionary tables. Examples: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If the <a class="link" href="innodb-parameters.html#sysvar_innodb_read_only"> <code class="literal"> innodb_read_only </code> </a> system variable is enabled, <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> may fail because it cannot update statistics tables in the data dictionary, which use <code class="literal"> InnoDB </code> . For <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> operations that update the key distribution, failure may occur even if the operation updates the table itself (for example, if it is a <code class="literal"> MyISAM </code> table). To obtain the updated distribution statistics, set <a class="link" href="server-system-variables.html#sysvar_information_schema_stats_expiry"> <code class="literal"> information_schema_stats_expiry=0 </code> </a> . </p> </li> <li class="listitem"> <p> <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE <em class="replaceable"> <code> tbl_name </code> </em> ENGINE= <em class="replaceable"> <code> engine_name </code> </em> </code> </a> fails because it updates the storage engine designation, which is stored in the data dictionary. </p> </li> </ul> </div> <p> In addition, other tables in the <code class="literal"> mysql </code> system database use the <code class="literal"> InnoDB </code> storage engine. Making those tables read-only results in restrictions on operations that modify them. Examples: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> Account-management statements such as <a class="link" href="create-user.html" title="15.7.1.3 CREATE USER Statement"> <code class="literal"> CREATE USER </code> </a> and <a class="link" href="grant.html" title="15.7.1.6 GRANT Statement"> <code class="literal"> GRANT </code> </a> fail because the grant tables use <code class="literal"> InnoDB </code> . </p> </li> <li class="listitem"> <p> The <a class="link" href="install-plugin.html" title="15.7.4.4 INSTALL PLUGIN Statement"> <code class="literal"> INSTALL PLUGIN </code> </a> and <a class="link" href="uninstall-plugin.html" title="15.7.4.6 UNINSTALL PLUGIN Statement"> <code class="literal"> UNINSTALL PLUGIN </code> </a> plugin-management statements fail because the <code class="literal"> mysql.plugin </code> system table uses <code class="literal"> InnoDB </code> . </p> </li> <li class="listitem"> <p> The <a class="link" href="create-function-loadable.html" title="15.7.4.1 CREATE FUNCTION Statement for Loadable Functions"> <code class="literal"> CREATE FUNCTION </code> </a> and <a class="link" href="drop-function-loadable.html" title="15.7.4.2 DROP FUNCTION Statement for Loadable Functions"> <code class="literal"> DROP FUNCTION </code> </a> loadable function-management statements fail because the <code class="literal"> mysql.func </code> system table uses <code class="literal"> InnoDB </code> . </p> </li> </ul> </div> </li> <li class="listitem"> <p> <a name="sysvar_innodb_redo_log_archive_dirs"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_archive_dirs"> <code class="literal"> innodb_redo_log_archive_dirs </code> </a> </p> <a class="indexterm" name="idm46045152799920"> </a> <a class="indexterm" name="idm46045152798912"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_redo_log_archive_dirs"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-redo-log-archive-dirs </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_archive_dirs"> innodb_redo_log_archive_dirs </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> Defines labeled directories where redo log archive files can be created. You can define multiple labeled directories in a semicolon-separated list. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-ini"><div class="docs-select-all right" id="sa2846136"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token constant">innodb_redo_log_archive_dirs</span><span class="token attr-value"><span class="token punctuation">=</span>'label1:/backups1;label2:/backups2'</span></code></pre> </div> <p> A label can be any string of characters, with the exception of colons (:), which are not permitted. An empty label is also permitted, but the colon (:) is still required in this case. </p> <p> A path must be specified, and the directory must exist. The path can contain colons (':'), but semicolons (;) are not permitted. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_redo_log_capacity"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> </p> <a class="indexterm" name="idm46045152773584"> </a> <a class="indexterm" name="idm46045152772576"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_redo_log_capacity"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-redo-log-capacity=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> innodb_redo_log_capacity </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 104857600 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 8388608 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 549755813888 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> Defines the amount of disk space occupied by redo log files. </p> <p> <code class="literal"> innodb_redo_log_capacity </code> supercedes the <a class="link" href="innodb-parameters.html#sysvar_innodb_log_files_in_group"> <code class="literal"> innodb_log_files_in_group </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_log_file_size"> <code class="literal"> innodb_log_file_size </code> </a> variables, which are both ignored if <code class="literal"> innodb_redo_log_capacity </code> is defined. </p> <p> If <code class="literal"> innodb_redo_log_capacity </code> is not defined, and if neither <code class="literal"> innodb_log_file_size </code> or <code class="literal"> innodb_log_files_in_group </code> are defined, then the default <code class="literal"> innodb_redo_log_capacity </code> value is used. </p> <p> If <code class="literal"> innodb_redo_log_capacity </code> is not defined, and if <code class="literal"> innodb_log_file_size </code> and/or <code class="literal"> innodb_log_files_in_group </code> is defined, then the InnoDB redo log capacity is calculated as <span class="emphasis"> <em> (innodb_log_files_in_group * innodb_log_file_size) </em> </span> . This calculation does not modify the unused <code class="literal"> innodb_redo_log_capacity </code> setting's value. </p> <p> The <a class="link" href="server-status-variables.html#statvar_Innodb_redo_log_capacity_resized"> <code class="literal"> Innodb_redo_log_capacity_resized </code> </a> server status variable indicates the total redo log capacity for all redo log files. </p> <p> If the server is started with <a class="link" href="innodb-parameters.html#option_mysqld_innodb-dedicated-server"> <code class="option"> --innodb-dedicated-server </code> </a> , the value of <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_capacity"> <code class="literal"> innodb_redo_log_capacity </code> </a> is set automatically if it is not explicitly defined. For more information, see <a class="xref" href="innodb-dedicated-server.html" title="17.8.12 Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server"> Section 17.8.12, “Enabling Automatic InnoDB Configuration for a Dedicated MySQL Server” </a> . </p> <p> For more information, see <a class="xref" href="innodb-redo-log.html" title="17.6.5 Redo Log"> Section 17.6.5, “Redo Log” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_redo_log_encrypt"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_encrypt"> <code class="literal"> innodb_redo_log_encrypt </code> </a> </p> <a class="indexterm" name="idm46045152727616"> </a> <a class="indexterm" name="idm46045152726608"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_redo_log_encrypt"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-redo-log-encrypt[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_redo_log_encrypt"> innodb_redo_log_encrypt </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Controls encryption of redo log data for tables encrypted using the <code class="literal"> InnoDB </code> <a class="link" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> data-at-rest encryption feature </a> . Encryption of redo log data is disabled by default. For more information, see <a class="xref" href="innodb-data-encryption.html#innodb-data-encryption-redo-log" title="Redo Log Encryption"> Redo Log Encryption </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_replication_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_replication_delay"> <code class="literal"> innodb_replication_delay </code> </a> </p> <a class="indexterm" name="idm46045152701680"> </a> <a class="indexterm" name="idm46045152700672"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_replication_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-replication-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_replication_delay"> innodb_replication_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> <tr> <th> Unit </th> <td> milliseconds </td> </tr> </tbody> </table> </div> <p> The replication thread delay in milliseconds on a replica server if <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> is reached. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_rollback_on_timeout"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> <code class="literal"> innodb_rollback_on_timeout </code> </a> </p> <a class="indexterm" name="idm46045152669920"> </a> <a class="indexterm" name="idm46045152668912"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_rollback_on_timeout"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-rollback-on-timeout[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> innodb_rollback_on_timeout </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_rollback" title="rollback"> rolls back </a> only the last statement on a transaction timeout by default. If <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_on_timeout"> <code class="option"> --innodb-rollback-on-timeout </code> </a> is specified, a transaction timeout causes <code class="literal"> InnoDB </code> to abort and roll back the entire transaction. </p> <p> For more information, see <a class="xref" href="innodb-error-handling.html" title="17.20.5 InnoDB Error Handling"> Section 17.20.5, “InnoDB Error Handling” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_rollback_segments"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> <code class="literal"> innodb_rollback_segments </code> </a> </p> <a class="indexterm" name="idm46045152642192"> </a> <a class="indexterm" name="idm46045152641184"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_rollback_segments"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-rollback-segments=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> innodb_rollback_segments </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 128 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 128 </code> </td> </tr> </tbody> </table> </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_rollback_segments"> <code class="literal"> innodb_rollback_segments </code> </a> defines the number of <a class="link" href="glossary.html#glos_rollback_segment" title="rollback segment"> rollback segments </a> allocated to each undo tablespace and the global temporary tablespace for transactions that generate undo records. The number of transactions that each rollback segment supports depends on the <code class="literal"> InnoDB </code> page size and the number of undo logs assigned to each transaction. For more information, see <a class="xref" href="innodb-undo-logs.html" title="17.6.6 Undo Logs"> Section 17.6.6, “Undo Logs” </a> . </p> <p> For related information, see <a class="xref" href="innodb-multi-versioning.html" title="17.3 InnoDB Multi-Versioning"> Section 17.3, “InnoDB Multi-Versioning” </a> . For information about undo tablespaces, see <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_saved_page_number_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> <code class="literal"> innodb_saved_page_number_debug </code> </a> </p> <a class="indexterm" name="idm46045152608944"> </a> <a class="indexterm" name="idm46045152607936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_saved_page_number_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-saved-page-number-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> innodb_saved_page_number_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 2**32-1 </code> </td> </tr> </tbody> </table> </div> <p> Saves a page number. Setting the <a class="link" href="innodb-parameters.html#sysvar_innodb_fil_make_page_dirty_debug"> <code class="literal"> innodb_fil_make_page_dirty_debug </code> </a> option dirties the page defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> <code class="literal"> innodb_saved_page_number_debug </code> </a> . The <a class="link" href="innodb-parameters.html#sysvar_innodb_saved_page_number_debug"> <code class="literal"> innodb_saved_page_number_debug </code> </a> option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_segment_reserve_factor"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> <code class="literal"> innodb_segment_reserve_factor </code> </a> </p> <a class="indexterm" name="idm46045152575728"> </a> <a class="indexterm" name="idm46045152574720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_segment_reserve_factor"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-segment-reserve-factor=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> innodb_segment_reserve_factor </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Numeric </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 12.5 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0.03 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 40 </code> </td> </tr> </tbody> </table> </div> <p> Defines the percentage of tablespace file segment pages reserved as empty pages. The setting is applicable to file-per-table and general tablespaces. The <a class="link" href="innodb-parameters.html#sysvar_innodb_segment_reserve_factor"> <code class="literal"> innodb_segment_reserve_factor </code> </a> default setting is 12.5 percent, which is the same percentage of pages reserved in previous MySQL releases. </p> <p> For more information, see <a class="xref" href="innodb-file-space.html#innodb-config-reserved-file-segment-pages" title="Configuring the Percentage of Reserved File Segment Pages"> Configuring the Percentage of Reserved File Segment Pages </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_sort_buffer_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> <code class="literal"> innodb_sort_buffer_size </code> </a> </p> <a class="indexterm" name="idm46045152544816"> </a> <a class="indexterm" name="idm46045152543808"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_sort_buffer_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-sort-buffer-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sort_buffer_size"> innodb_sort_buffer_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1048576 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 65536 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 67108864 </code> </td> </tr> <tr> <th> Unit </th> <td> bytes </td> </tr> </tbody> </table> </div> <p> This variable defines the amount by which the temporary log file is extended when recording concurrent DML during an <a class="link" href="glossary.html#glos_online_ddl" title="online DDL"> online DDL </a> operation, and the size of the temporary log file read buffer and write buffer. </p> <p> For more information, see <a class="xref" href="innodb-online-ddl-space-requirements.html" title="17.12.3 Online DDL Space Requirements"> Section 17.12.3, “Online DDL Space Requirements” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_spin_wait_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_delay"> <code class="literal"> innodb_spin_wait_delay </code> </a> </p> <a class="indexterm" name="idm46045152512368"> </a> <a class="indexterm" name="idm46045152511360"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_spin_wait_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-spin-wait-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_delay"> innodb_spin_wait_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 6 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> </tbody> </table> </div> <p> The maximum delay between polls for a <a class="link" href="glossary.html#glos_spin" title="spin"> spin </a> lock. The low-level implementation of this mechanism varies depending on the combination of hardware and operating system, so the delay does not correspond to a fixed time interval. </p> <p> Can be used in combination with the <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> <code class="literal"> innodb_spin_wait_pause_multiplier </code> </a> variable for greater control over the duration of spin-lock polling delays. </p> <p> For more information, see <a class="xref" href="innodb-performance-spin_lock_polling.html" title="17.8.8 Configuring Spin Lock Polling"> Section 17.8.8, “Configuring Spin Lock Polling” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_spin_wait_pause_multiplier"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> <code class="literal"> innodb_spin_wait_pause_multiplier </code> </a> </p> <a class="indexterm" name="idm46045152480288"> </a> <a class="indexterm" name="idm46045152479280"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_spin_wait_pause_multiplier"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-spin-wait-pause-multiplier=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_spin_wait_pause_multiplier"> innodb_spin_wait_pause_multiplier </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 50 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 100 </code> </td> </tr> </tbody> </table> </div> <p> Defines a multiplier value used to determine the number of PAUSE instructions in spin-wait loops that occur when a thread waits to acquire a mutex or rw-lock. </p> <p> For more information, see <a class="xref" href="innodb-performance-spin_lock_polling.html" title="17.8.8 Configuring Spin Lock Polling"> Section 17.8.8, “Configuring Spin Lock Polling” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_auto_recalc"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_auto_recalc"> <code class="literal"> innodb_stats_auto_recalc </code> </a> </p> <a class="indexterm" name="idm46045152450528"> </a> <a class="indexterm" name="idm46045152449520"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_auto_recalc"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-auto-recalc[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_auto_recalc"> innodb_stats_auto_recalc </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Causes <code class="literal"> InnoDB </code> to automatically recalculate <a class="link" href="glossary.html#glos_persistent_statistics" title="persistent statistics"> persistent statistics </a> after the data in a table is changed substantially. The threshold value is 10% of the rows in the table. This setting applies to tables created when the <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> option is enabled. Automatic statistics recalculation may also be configured by specifying <code class="literal"> STATS_AUTO_RECALC=1 </code> in a <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> or <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statement. The amount of data sampled to produce the statistics is controlled by the <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> variable. </p> <p> For more information, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_include_delete_marked"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> <code class="literal"> innodb_stats_include_delete_marked </code> </a> </p> <a class="indexterm" name="idm46045152419360"> </a> <a class="indexterm" name="idm46045152418352"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_include_delete_marked"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-include-delete-marked[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> innodb_stats_include_delete_marked </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> By default, <code class="literal"> InnoDB </code> reads uncommitted data when calculating statistics. In the case of an uncommitted transaction that deletes rows from a table, <code class="literal"> InnoDB </code> excludes records that are delete-marked when calculating row estimates and index statistics, which can lead to non-optimal execution plans for other transactions that are operating on the table concurrently using a transaction isolation level other than <a class="link" href="innodb-transaction-isolation-levels.html#isolevel_read-uncommitted"> <code class="literal"> READ UNCOMMITTED </code> </a> . To avoid this scenario, <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> <code class="literal"> innodb_stats_include_delete_marked </code> </a> can be enabled to ensure that <code class="literal"> InnoDB </code> includes delete-marked records when calculating persistent optimizer statistics. </p> <p> When <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> <code class="literal"> innodb_stats_include_delete_marked </code> </a> is enabled, <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> considers delete-marked records when recalculating statistics. </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_include_delete_marked"> <code class="literal"> innodb_stats_include_delete_marked </code> </a> is a global setting that affects all <code class="literal"> InnoDB </code> tables. It is only applicable to persistent optimizer statistics. </p> <p> For related information, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_method"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> <code class="literal"> innodb_stats_method </code> </a> </p> <a class="indexterm" name="idm46045152385456"> </a> <a class="indexterm" name="idm46045152384448"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_method"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-method=value </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_method"> innodb_stats_method </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Enumeration </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> nulls_equal </code> </td> </tr> <tr> <th> Valid Values </th> <td> <p class="valid-value"> <code class="literal"> nulls_equal </code> </p> <p class="valid-value"> <code class="literal"> nulls_unequal </code> </p> <p class="valid-value"> <code class="literal"> nulls_ignored </code> </p> </td> </tr> </tbody> </table> </div> <p> How the server treats <code class="literal"> NULL </code> values when collecting <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> about the distribution of index values for <code class="literal"> InnoDB </code> tables. Permitted values are <code class="literal"> nulls_equal </code> , <code class="literal"> nulls_unequal </code> , and <code class="literal"> nulls_ignored </code> . For <code class="literal"> nulls_equal </code> , all <code class="literal"> NULL </code> index values are considered equal and form a single value group with a size equal to the number of <code class="literal"> NULL </code> values. For <code class="literal"> nulls_unequal </code> , <code class="literal"> NULL </code> values are considered unequal, and each <code class="literal"> NULL </code> forms a distinct value group of size 1. For <code class="literal"> nulls_ignored </code> , <code class="literal"> NULL </code> values are ignored. </p> <p> The method used to generate table statistics influences how the optimizer chooses indexes for query execution, as described in <a class="xref" href="index-statistics.html" title="10.3.8 InnoDB and MyISAM Index Statistics Collection"> Section 10.3.8, “InnoDB and MyISAM Index Statistics Collection” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_on_metadata"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> <code class="literal"> innodb_stats_on_metadata </code> </a> </p> <a class="indexterm" name="idm46045152346944"> </a> <a class="indexterm" name="idm46045152345936"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_on_metadata"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-on-metadata[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> innodb_stats_on_metadata </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> This option only applies when optimizer <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> are configured to be non-persistent. Optimizer statistics are not persisted to disk when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is disabled or when individual tables are created or altered with <code class="literal"> STATS_PERSISTENT=0 </code> . For more information, see <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> . </p> <p> When <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_on_metadata"> <code class="literal"> innodb_stats_on_metadata </code> </a> is enabled, <code class="literal"> InnoDB </code> updates non-persistent <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> when metadata statements such as <a class="link" href="show-table-status.html" title="15.7.7.38 SHOW TABLE STATUS Statement"> <code class="literal"> SHOW TABLE STATUS </code> </a> or when accessing the Information Schema <a class="link" href="information-schema-tables-table.html" title="28.3.38 The INFORMATION_SCHEMA TABLES Table"> <code class="literal"> TABLES </code> </a> or <a class="link" href="information-schema-statistics-table.html" title="28.3.34 The INFORMATION_SCHEMA STATISTICS Table"> <code class="literal"> STATISTICS </code> </a> tables. (These updates are similar to what happens for <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> .) When disabled, <code class="literal"> InnoDB </code> does not update statistics during these operations. Leaving the setting disabled can improve access speed for schemas that have a large number of tables or indexes. It can also improve the stability of <a class="link" href="glossary.html#glos_query_execution_plan" title="query execution plan"> execution plans </a> for queries that involve <code class="literal"> InnoDB </code> tables. </p> <p> To change the setting, issue the statement <code class="literal"> SET GLOBAL innodb_stats_on_metadata= <em class="replaceable"> <code> mode </code> </em> </code> , where <code class="literal"> <em class="replaceable"> <code> mode </code> </em> </code> is either <code class="literal"> ON </code> or <code class="literal"> OFF </code> (or <code class="literal"> 1 </code> or <code class="literal"> 0 </code> ). Changing the setting requires privileges sufficient to set global system variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ) and immediately affects the operation of all connections. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_persistent"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> </p> <a class="indexterm" name="idm46045152305872"> </a> <a class="indexterm" name="idm46045152304864"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_persistent"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-persistent[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> innodb_stats_persistent </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies whether <code class="literal"> InnoDB </code> index statistics are persisted to disk. Otherwise, statistics may be recalculated frequently which can lead to variations in <a class="link" href="glossary.html#glos_query_execution_plan" title="query execution plan"> query execution plans </a> . This setting is stored with each table when the table is created. You can set <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> at the global level before creating a table, or use the <code class="literal"> STATS_PERSISTENT </code> clause of the <a class="link" href="create-table.html" title="15.1.20 CREATE TABLE Statement"> <code class="literal"> CREATE TABLE </code> </a> and <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> statements to override the system-wide setting and configure persistent statistics for individual tables. </p> <p> For more information, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_persistent_sample_pages"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> </p> <a class="indexterm" name="idm46045152275648"> </a> <a class="indexterm" name="idm46045152274640"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_persistent_sample_pages"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-persistent-sample-pages=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> innodb_stats_persistent_sample_pages </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 20 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 18446744073709551615 </code> </td> </tr> </tbody> </table> </div> <p> The number of index <a class="link" href="glossary.html#glos_page" title="page"> pages </a> to sample when estimating <a class="link" href="glossary.html#glos_cardinality" title="cardinality"> cardinality </a> and other <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> for an indexed column, such as those calculated by <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> . Increasing the value improves the accuracy of index statistics, which can improve the <a class="link" href="glossary.html#glos_query_execution_plan" title="query execution plan"> query execution plan </a> , at the expense of increased I/O during the execution of <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> for an <code class="literal"> InnoDB </code> table. For more information, see <a class="xref" href="innodb-persistent-stats.html" title="17.8.10.1 Configuring Persistent Optimizer Statistics Parameters"> Section 17.8.10.1, “Configuring Persistent Optimizer Statistics Parameters” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Setting a high value for <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> could result in lengthy <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> execution time. To estimate the number of database pages accessed by <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> , see <a class="xref" href="innodb-analyze-table-complexity.html" title="17.8.10.3 Estimating ANALYZE TABLE Complexity for InnoDB Tables"> Section 17.8.10.3, “Estimating ANALYZE TABLE Complexity for InnoDB Tables” </a> . </p> </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> only applies when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is enabled for a table; when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is disabled, <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> <code class="literal"> innodb_stats_transient_sample_pages </code> </a> applies instead. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_stats_transient_sample_pages"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> <code class="literal"> innodb_stats_transient_sample_pages </code> </a> </p> <a class="indexterm" name="idm46045152232384"> </a> <a class="indexterm" name="idm46045152231376"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_stats_transient_sample_pages"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-stats-transient-sample-pages=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> innodb_stats_transient_sample_pages </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 8 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 18446744073709551615 </code> </td> </tr> </tbody> </table> </div> <p> The number of index <a class="link" href="glossary.html#glos_page" title="page"> pages </a> to sample when estimating <a class="link" href="glossary.html#glos_cardinality" title="cardinality"> cardinality </a> and other <a class="link" href="glossary.html#glos_statistics" title="statistics"> statistics </a> for an indexed column, such as those calculated by <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> . The default value is 8. Increasing the value improves the accuracy of index statistics, which can improve the <a class="link" href="glossary.html#glos_query_execution_plan" title="query execution plan"> query execution plan </a> , at the expense of increased I/O when opening an <code class="literal"> InnoDB </code> table or recalculating statistics. For more information, see <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> Setting a high value for <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> <code class="literal"> innodb_stats_transient_sample_pages </code> </a> could result in lengthy <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> execution time. To estimate the number of database pages accessed by <a class="link" href="analyze-table.html" title="15.7.3.1 ANALYZE TABLE Statement"> <code class="literal"> ANALYZE TABLE </code> </a> , see <a class="xref" href="innodb-analyze-table-complexity.html" title="17.8.10.3 Estimating ANALYZE TABLE Complexity for InnoDB Tables"> Section 17.8.10.3, “Estimating ANALYZE TABLE Complexity for InnoDB Tables” </a> . </p> </div> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_transient_sample_pages"> <code class="literal"> innodb_stats_transient_sample_pages </code> </a> only applies when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is disabled for a table; when <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent"> <code class="literal"> innodb_stats_persistent </code> </a> is enabled, <a class="link" href="innodb-parameters.html#sysvar_innodb_stats_persistent_sample_pages"> <code class="literal"> innodb_stats_persistent_sample_pages </code> </a> applies instead. Takes the place of <code class="literal"> innodb_stats_sample_pages </code> that was removed in MySQL 8.0. For more information, see <a class="xref" href="innodb-statistics-estimation.html" title="17.8.10.2 Configuring Non-Persistent Optimizer Statistics Parameters"> Section 17.8.10.2, “Configuring Non-Persistent Optimizer Statistics Parameters” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_status_output"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output"> <code class="literal"> innodb_status_output </code> </a> </p> <a class="indexterm" name="idm46045152188688"> </a> <a class="indexterm" name="idm46045152187680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_status_output"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-status-output[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output"> innodb_status_output </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables or disables periodic output for the standard <code class="literal"> InnoDB </code> Monitor. Also used in combination with <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> <code class="literal"> innodb_status_output_locks </code> </a> to enable or disable periodic output for the <code class="literal"> InnoDB </code> Lock Monitor. For more information, see <a class="xref" href="innodb-enabling-monitors.html" title="17.17.2 Enabling InnoDB Monitors"> Section 17.17.2, “Enabling InnoDB Monitors” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_status_output_locks"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> <code class="literal"> innodb_status_output_locks </code> </a> </p> <a class="indexterm" name="idm46045152161728"> </a> <a class="indexterm" name="idm46045152160720"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_status_output_locks"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-status-output-locks[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_status_output_locks"> innodb_status_output_locks </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables or disables the <code class="literal"> InnoDB </code> Lock Monitor. When enabled, the <code class="literal"> InnoDB </code> Lock Monitor prints additional information about locks in <code class="literal"> SHOW ENGINE INNODB STATUS </code> output and in periodic output printed to the MySQL error log. Periodic output for the <code class="literal"> InnoDB </code> Lock Monitor is printed as part of the standard <code class="literal"> InnoDB </code> Monitor output. The standard <code class="literal"> InnoDB </code> Monitor must therefore be enabled for the <code class="literal"> InnoDB </code> Lock Monitor to print data to the MySQL error log periodically. For more information, see <a class="xref" href="innodb-enabling-monitors.html" title="17.17.2 Enabling InnoDB Monitors"> Section 17.17.2, “Enabling InnoDB Monitors” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_strict_mode"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> </p> <a class="indexterm" name="idm46045152132448"> </a> <a class="indexterm" name="idm46045152131440"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_strict_mode"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-strict-mode[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> innodb_strict_mode </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> When <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> is enabled, <code class="literal"> InnoDB </code> returns errors rather than warnings when checking for invalid or incompatible table options. </p> <p> It checks that <code class="literal"> KEY_BLOCK_SIZE </code> , <code class="literal"> ROW_FORMAT </code> , <code class="literal"> DATA DIRECTORY </code> , <code class="literal"> TEMPORARY </code> , and <code class="literal"> TABLESPACE </code> options are compatible with each other and other settings. </p> <p> <code class="literal"> innodb_strict_mode=ON </code> also enables a row size check when creating or altering a table, to prevent <code class="literal"> INSERT </code> or <code class="literal"> UPDATE </code> from failing due to the record being too large for the selected page size. <code class="literal"> </code> </p> <p> You can enable or disable <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> on the command line when starting <code class="literal"> mysqld </code> , or in a MySQL <a class="link" href="glossary.html#glos_configuration_file" title="configuration file"> configuration file </a> . You can also enable or disable <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> at runtime with the statement <code class="literal"> SET [GLOBAL|SESSION] innodb_strict_mode= <em class="replaceable"> <code> mode </code> </em> </code> , where <code class="literal"> <em class="replaceable"> <code> mode </code> </em> </code> is either <code class="literal"> ON </code> or <code class="literal"> OFF </code> . Changing the <code class="literal"> GLOBAL </code> setting requires privileges sufficient to set global system variables (see <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> ) and affects the operation of all clients that subsequently connect. Any client can change the <code class="literal"> SESSION </code> setting for <a class="link" href="innodb-parameters.html#sysvar_innodb_strict_mode"> <code class="literal"> innodb_strict_mode </code> </a> , and the setting affects only that client. </p> <p> Setting the session value of this system variable is a restricted operation. The session user must have privileges sufficient to set restricted session variables. See <a class="xref" href="system-variable-privileges.html" title="7.1.9.1 System Variable Privileges"> Section 7.1.9.1, “System Variable Privileges” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_sync_array_size"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_array_size"> <code class="literal"> innodb_sync_array_size </code> </a> </p> <a class="indexterm" name="idm46045152089488"> </a> <a class="indexterm" name="idm46045152088480"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_sync_array_size"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-sync-array-size=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_array_size"> innodb_sync_array_size </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1024 </code> </td> </tr> </tbody> </table> </div> <p> Defines the size of the mutex/lock wait array. Increasing the value splits the internal data structure used to coordinate threads, for higher concurrency in workloads with large numbers of waiting threads. This setting must be configured when the MySQL instance is starting up, and cannot be changed afterward. Increasing the value is recommended for workloads that frequently produce a large number of waiting threads, typically greater than 768. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_sync_spin_loops"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_spin_loops"> <code class="literal"> innodb_sync_spin_loops </code> </a> </p> <a class="indexterm" name="idm46045152060256"> </a> <a class="indexterm" name="idm46045152059248"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_sync_spin_loops"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-sync-spin-loops=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_spin_loops"> innodb_sync_spin_loops </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 30 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 4294967295 </code> </td> </tr> </tbody> </table> </div> <p> The number of times a thread waits for an <code class="literal"> InnoDB </code> mutex to be freed before the thread is suspended. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_sync_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_debug"> <code class="literal"> innodb_sync_debug </code> </a> </p> <a class="indexterm" name="idm46045152030800"> </a> <a class="indexterm" name="idm46045152029792"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_sync_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-sync-debug[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_sync_debug"> innodb_sync_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Enables sync debug checking for the <code class="literal"> InnoDB </code> storage engine. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_table_locks"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> <code class="literal"> innodb_table_locks </code> </a> </p> <a class="indexterm" name="idm46045152004688"> </a> <a class="indexterm" name="idm46045152003680"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_table_locks"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-table-locks[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> innodb_table_locks </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> If <a class="link" href="server-system-variables.html#sysvar_autocommit"> <code class="literal"> autocommit = 0 </code> </a> , <code class="literal"> InnoDB </code> honors <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES </code> </a> ; MySQL does not return from <code class="literal"> LOCK TABLES ... WRITE </code> until all other threads have released all their locks to the table. The default value of <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> <code class="literal"> innodb_table_locks </code> </a> is 1, which means that <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES </code> </a> causes InnoDB to lock a table internally if <a class="link" href="server-system-variables.html#sysvar_autocommit"> <code class="literal"> autocommit = 0 </code> </a> . </p> <p> <a class="link" href="innodb-parameters.html#sysvar_innodb_table_locks"> <code class="literal"> innodb_table_locks = 0 </code> </a> has no effect for tables locked explicitly with <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES ... WRITE </code> </a> . It does have an effect for tables locked for read or write by <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES ... WRITE </code> </a> implicitly (for example, through triggers) or by <a class="link" href="lock-tables.html" title="15.3.6 LOCK TABLES and UNLOCK TABLES Statements"> <code class="literal"> LOCK TABLES ... READ </code> </a> . </p> <p> For related information, see <a class="xref" href="innodb-locking-transaction-model.html" title="17.7 InnoDB Locking and Transaction Model"> Section 17.7, “InnoDB Locking and Transaction Model” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_temp_data_file_path"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> </p> <a class="indexterm" name="idm46045151968816"> </a> <a class="indexterm" name="idm46045151967808"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_temp_data_file_path"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-temp-data-file-path=file_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> innodb_temp_data_file_path </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> String </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ibtmp1:12M:autoextend </code> </td> </tr> </tbody> </table> </div> <p> Defines the relative path, name, size, and attributes of global temporary tablespace data files. The global temporary tablespace stores rollback segments for changes made to user-created temporary tables. </p> <p> If no value is specified for <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> , the default behavior is to create a single auto-extending data file named <code class="filename"> ibtmp1 </code> in the <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> directory. The initial file size is slightly larger than 12MB. </p> <p> The syntax for a global temporary tablespace data file specification includes the file name, file size, and <code class="literal"> autoextend </code> and <code class="literal"> max </code> attributes: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-none"><div class="docs-select-all right" id="sa16657423"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-none"><em class="replaceable">file_name</em>:<em class="replaceable">file_size</em>[:autoextend[:max:<em class="replaceable">max_file_size</em>]]</code></pre> </div> <p> The global temporary tablespace data file cannot have the same name as another <code class="literal"> InnoDB </code> data file. Any inability or error creating the global temporary tablespace data file is treated as fatal and server startup is refused. </p> <p> File sizes are specified in KB, MB, or GB by appending <code class="literal"> K </code> , <code class="literal"> M </code> or <code class="literal"> G </code> to the size value. The sum of file sizes must be slightly larger than 12MB. </p> <p> The size limit of individual files is determined by the operating system. File size can be more than 4GB on operating systems that support large files. Use of raw disk partitions for global temporary tablespace data files is not supported. </p> <p> The <code class="literal"> autoextend </code> and <code class="literal"> max </code> attributes can be used only for the data file specified last in the <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> setting. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa43730906"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token selector">[mysqld]</span> <span class="token constant">innodb_temp_data_file_path</span><span class="token attr-value"><span class="token punctuation">=</span>ibtmp1:50M;ibtmp2:12M:autoextend:max:500M</span></code></pre> </div> <p> The <code class="literal"> autoextend </code> option causes the data file to automatically increase in size when it runs out of free space. The <code class="literal"> autoextend </code> increment is 64MB by default. To modify the increment, change the <a class="link" href="innodb-parameters.html#sysvar_innodb_autoextend_increment"> <code class="literal"> innodb_autoextend_increment </code> </a> variable setting. </p> <p> The directory path for global temporary tablespace data files is formed by concatenating the paths defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_data_home_dir"> <code class="literal"> innodb_data_home_dir </code> </a> and <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> . </p> <p> Before running <code class="literal"> InnoDB </code> in read-only mode, set <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_data_file_path"> <code class="literal"> innodb_temp_data_file_path </code> </a> to a location outside of the data directory. The path must be relative to the data directory. For example: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa54676602"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal"><span class="token constant">--innodb-temp-data-file-path</span><span class="token attr-value"><span class="token punctuation">=</span>../../../tmp/ibtmp1:12M:autoextend</span></code></pre> </div> <p> For more information, see <a class="xref" href="innodb-temporary-tablespace.html#innodb-global-temporary-tablespace" title="Global Temporary Tablespace"> Global Temporary Tablespace </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_temp_tablespaces_dir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_tablespaces_dir"> <code class="literal"> innodb_temp_tablespaces_dir </code> </a> </p> <a class="indexterm" name="idm46045151920192"> </a> <a class="indexterm" name="idm46045151919184"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_temp_tablespaces_dir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-temp-tablespaces-dir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_temp_tablespaces_dir"> innodb_temp_tablespaces_dir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> #innodb_temp </code> </td> </tr> </tbody> </table> </div> <p> Defines the location where <code class="literal"> InnoDB </code> creates a pool of session temporary tablespaces at startup. The default location is the <code class="filename"> #innodb_temp </code> directory in the data directory. A fully qualified path or path relative to the data directory is permitted. </p> <p> Session temporary tablespaces always store user-created temporary tables and internal temporary tables created by the optimizer using <code class="literal"> InnoDB </code> . (Previously, the on-disk storage engine for internal temporary tables was determined by the <a class="ulink" href="/doc/refman/8.0/en/server-system-variables.html#sysvar_internal_tmp_disk_storage_engine" target="_top"> <code class="literal"> internal_tmp_disk_storage_engine </code> </a> system variable, which is no longer supported. See <a class="xref" href="internal-temporary-tables.html#internal-temporary-tables-engines-disk" title="Storage Engine for On-Disk Internal Temporary Tables"> Storage Engine for On-Disk Internal Temporary Tables </a> .) </p> <p> For more information, see <a class="xref" href="innodb-temporary-tablespace.html#innodb-session-temporary-tablespaces" title="Session Temporary Tablespaces"> Session Temporary Tablespaces </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_thread_concurrency"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> </p> <a class="indexterm" name="idm46045151890768"> </a> <a class="indexterm" name="idm46045151889760"> </a> <a class="indexterm" name="idm46045151888368"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_thread_concurrency"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-thread-concurrency=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> innodb_thread_concurrency </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000 </code> </td> </tr> </tbody> </table> </div> <p> Defines the maximum number of threads permitted inside of <code class="literal"> InnoDB </code> . A value of 0 (the default) is interpreted as infinite concurrency (no limit). This variable is intended for performance tuning on high concurrency systems. </p> <p> <code class="literal"> InnoDB </code> tries to keep the number of threads inside <code class="literal"> InnoDB </code> less than or equal to the <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> limit. Threads waiting for locks are not counted in the number of concurrently executing threads. </p> <p> The correct setting depends on workload and computing environment. Consider setting this variable if your MySQL instance shares CPU resources with other applications or if your workload or number of concurrent users is growing. Test a range of values to determine the setting that provides the best performance. <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> is a dynamic variable, which permits experimenting with different settings on a live test system. If a particular setting performs poorly, you can quickly set <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> back to 0. </p> <p> Use the following guidelines to help find and maintain an appropriate setting: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: circle; "> <li class="listitem"> <p> If the number of concurrent user threads for a workload is consistently small and does not affect performance, set <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency=0 </code> </a> (no limit). </p> </li> <li class="listitem"> <p> If your workload is consistently heavy or occasionally spikes, set an <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> value and adjust it until you find the number of threads that provides the best performance. For example, suppose that your system typically has 40 to 50 users, but periodically the number increases to 60, 70, or more. Through testing, you find that performance remains largely stable with a limit of 80 concurrent users. In this case, set <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> to 80. </p> </li> <li class="listitem"> <p> If you do not want <code class="literal"> InnoDB </code> to use more than a certain number of virtual CPUs for user threads (20 virtual CPUs, for example), set <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> to this number (or possibly lower, depending on performance testing). If your goal is to isolate MySQL from other applications, consider binding the <code class="literal"> mysqld </code> process exclusively to the virtual CPUs. Be aware, however, that exclusive binding can result in non-optimal hardware usage if the <code class="literal"> mysqld </code> process is not consistently busy. In this case, you can bind the <code class="literal"> mysqld </code> process to the virtual CPUs but allow other applications to use some or all of the virtual CPUs. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> From an operating system perspective, using a resource management solution to manage how CPU time is shared among applications may be preferable to binding the <code class="literal"> mysqld </code> process. For example, you could assign 90% of virtual CPU time to a given application while other critical processes <span class="emphasis"> <em> are not </em> </span> running, and scale that value back to 40% when other critical processes <span class="emphasis"> <em> are </em> </span> running. </p> </div> </li> <li class="listitem"> <p> In some cases, the optimal <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> setting can be smaller than the number of virtual CPUs. </p> </li> <li class="listitem"> <p> An <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> value that is too high can cause performance regression due to increased contention on system internals and resources. </p> </li> <li class="listitem"> <p> Monitor and analyze your system regularly. Changes to workload, number of users, or computing environment may require that you adjust the <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_concurrency"> <code class="literal"> innodb_thread_concurrency </code> </a> setting. </p> </li> </ul> </div> <p> A value of 0 disables the <code class="literal"> queries inside InnoDB </code> and <code class="literal"> queries in queue </code> counters in the <code class="literal"> ROW OPERATIONS </code> section of <code class="literal"> SHOW ENGINE INNODB STATUS </code> output. </p> <p> For related information, see <a class="xref" href="innodb-performance-thread_concurrency.html" title="17.8.4 Configuring Thread Concurrency for InnoDB"> Section 17.8.4, “Configuring Thread Concurrency for InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_thread_sleep_delay"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> </p> <a class="indexterm" name="idm46045151830448"> </a> <a class="indexterm" name="idm46045151829440"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_thread_sleep_delay"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-thread-sleep-delay=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> innodb_thread_sleep_delay </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 10000 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1000000 </code> </td> </tr> <tr> <th> Unit </th> <td> microseconds </td> </tr> </tbody> </table> </div> <p> How long <code class="literal"> InnoDB </code> threads sleep before joining the <code class="literal"> InnoDB </code> queue, in microseconds. The default value is 10000. A value of 0 disables sleep. You can set <a class="link" href="innodb-parameters.html#sysvar_innodb_adaptive_max_sleep_delay"> <code class="literal"> innodb_adaptive_max_sleep_delay </code> </a> to the highest value you would allow for <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> , and <code class="literal"> InnoDB </code> automatically adjusts <a class="link" href="innodb-parameters.html#sysvar_innodb_thread_sleep_delay"> <code class="literal"> innodb_thread_sleep_delay </code> </a> up or down depending on current thread-scheduling activity. This dynamic adjustment helps the thread scheduling mechanism to work smoothly during times when the system is lightly loaded or when it is operating near full capacity. </p> <p> For more information, see <a class="xref" href="innodb-performance-thread_concurrency.html" title="17.8.4 Configuring Thread Concurrency for InnoDB"> Section 17.8.4, “Configuring Thread Concurrency for InnoDB” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_tmpdir"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> </p> <a class="indexterm" name="idm46045151793552"> </a> <a class="indexterm" name="idm46045151792544"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_tmpdir"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-tmpdir=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> innodb_tmpdir </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global, Session </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> NULL </code> </td> </tr> </tbody> </table> </div> <p> Used to define an alternate directory for temporary sort files created during online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations that rebuild the table. </p> <p> Online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations that rebuild the table also create an <span class="emphasis"> <em> intermediate </em> </span> table file in the same directory as the original table. The <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> option is not applicable to intermediate table files. </p> <p> A valid value is any directory path other than the MySQL data directory path. If the value is NULL (the default), temporary files are created MySQL temporary directory ( <code class="literal"> $TMPDIR </code> on Unix, <code class="literal"> %TEMP% </code> on Windows, or the directory specified by the <a class="link" href="server-system-variables.html#sysvar_tmpdir"> <code class="literal"> --tmpdir </code> </a> configuration option). If a directory is specified, existence of the directory and permissions are only checked when <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> is configured using a <a class="link" href="set-variable.html" title="15.7.6.1 SET Syntax for Variable Assignment"> <code class="literal"> SET </code> </a> statement. If a symlink is provided in a directory string, the symlink is resolved and stored as an absolute path. The path should not exceed 512 bytes. An online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operation reports an error if <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> is set to an invalid directory. <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> overrides the MySQL <a class="link" href="server-system-variables.html#sysvar_tmpdir"> <code class="literal"> tmpdir </code> </a> setting but only for online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations. </p> <p> The <code class="literal"> FILE </code> privilege is required to configure <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> . </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> option was introduced to help avoid overflowing a temporary file directory located on a <code class="literal"> tmpfs </code> file system. Such overflows could occur as a result of large temporary sort files created during online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations that rebuild the table. </p> <p> In replication environments, only consider replicating the <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> setting if all servers have the same operating system environment. Otherwise, replicating the <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> setting could result in a replication failure when running online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations that rebuild the table. If server operating environments differ, it is recommended that you configure <a class="link" href="innodb-parameters.html#sysvar_innodb_tmpdir"> <code class="literal"> innodb_tmpdir </code> </a> on each server individually. </p> <p> For more information, see <a class="xref" href="innodb-online-ddl-space-requirements.html" title="17.12.3 Online DDL Space Requirements"> Section 17.12.3, “Online DDL Space Requirements” </a> . For information about online <a class="link" href="alter-table.html" title="15.1.9 ALTER TABLE Statement"> <code class="literal"> ALTER TABLE </code> </a> operations, see <a class="xref" href="innodb-online-ddl.html" title="17.12 InnoDB and Online DDL"> Section 17.12, “InnoDB and Online DDL” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_trx_purge_view_update_only_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_purge_view_update_only_debug"> <code class="literal"> innodb_trx_purge_view_update_only_debug </code> </a> </p> <a class="indexterm" name="idm46045151742720"> </a> <a class="indexterm" name="idm46045151741712"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_trx_purge_view_update_only_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-trx-purge-view-update-only-debug[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_purge_view_update_only_debug"> innodb_trx_purge_view_update_only_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Pauses purging of delete-marked records while allowing the purge view to be updated. This option artificially creates a situation in which the purge view is updated but purges have not yet been performed. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_trx_rseg_n_slots_debug"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_rseg_n_slots_debug"> <code class="literal"> innodb_trx_rseg_n_slots_debug </code> </a> </p> <a class="indexterm" name="idm46045151717024"> </a> <a class="indexterm" name="idm46045151716016"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_trx_rseg_n_slots_debug"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-trx-rseg-n-slots-debug=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_trx_rseg_n_slots_debug"> innodb_trx_rseg_n_slots_debug </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 0 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 1024 </code> </td> </tr> </tbody> </table> </div> <p> Sets a debug flag that limits <code class="literal"> TRX_RSEG_N_SLOTS </code> to a given value for the <code class="literal"> trx_rsegf_undo_find_free </code> function that looks for free slots for undo log segments. This option is only available if debugging support is compiled in using the <a class="link" href="source-configuration-options.html#option_cmake_with_debug"> <code class="option"> WITH_DEBUG </code> </a> <span class="command"> <strong> CMake </strong> </span> option. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_undo_directory"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> </p> <a class="indexterm" name="idm46045151685552"> </a> <a class="indexterm" name="idm46045151684544"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_undo_directory"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-undo-directory=dir_name </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> innodb_undo_directory </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Directory name </td> </tr> </tbody> </table> </div> <p> The path where <code class="literal"> InnoDB </code> creates undo tablespaces. Typically used to place undo tablespaces on a different storage device. </p> <p> There is no default value (it is NULL). If the <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> variable is undefined, undo tablespaces are created in the data directory. </p> <p> The default undo tablespaces ( <code class="filename"> innodb_undo_001 </code> and <code class="filename"> innodb_undo_002 </code> ) created when the MySQL instance is initialized always reside in the directory defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> variable. </p> <p> Undo tablespaces created using <a class="link" href="create-tablespace.html" title="15.1.21 CREATE TABLESPACE Statement"> <code class="literal"> CREATE UNDO TABLESPACE </code> </a> syntax are created in the directory defined by the <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_directory"> <code class="literal"> innodb_undo_directory </code> </a> variable if a different path is not specified. </p> <p> For more information, see <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_undo_log_encrypt"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_encrypt"> <code class="literal"> innodb_undo_log_encrypt </code> </a> </p> <a class="indexterm" name="idm46045151655408"> </a> <a class="indexterm" name="idm46045151654400"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_undo_log_encrypt"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-undo-log-encrypt[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_encrypt"> innodb_undo_log_encrypt </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> OFF </code> </td> </tr> </tbody> </table> </div> <p> Controls encryption of undo log data for tables encrypted using the <code class="literal"> InnoDB </code> <a class="link" href="innodb-data-encryption.html" title="17.13 InnoDB Data-at-Rest Encryption"> data-at-rest encryption feature </a> . Only applies to undo logs that reside in separate <a class="link" href="glossary.html#glos_undo_tablespace" title="undo tablespace"> undo tablespaces </a> . See <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> . Encryption is not supported for undo log data that resides in the system tablespace. For more information, see <a class="xref" href="innodb-data-encryption.html#innodb-data-encryption-undo-log" title="Undo Log Encryption"> Undo Log Encryption </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_undo_log_truncate"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> <code class="literal"> innodb_undo_log_truncate </code> </a> </p> <a class="indexterm" name="idm46045151628224"> </a> <a class="indexterm" name="idm46045151627216"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_undo_log_truncate"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-undo-log-truncate[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_log_truncate"> innodb_undo_log_truncate </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> When enabled, undo tablespaces that exceed the threshold value defined by <a class="link" href="innodb-parameters.html#sysvar_innodb_max_undo_log_size"> <code class="literal"> innodb_max_undo_log_size </code> </a> are marked for truncation. Only undo tablespaces can be truncated. Truncating undo logs that reside in the system tablespace is not supported. For truncation to occur, there must be at least two undo tablespaces. </p> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_purge_rseg_truncate_frequency"> <code class="literal"> innodb_purge_rseg_truncate_frequency </code> </a> variable can be used to expedite truncation of undo tablespaces. </p> <p> For more information, see <a class="xref" href="innodb-undo-tablespaces.html#truncate-undo-tablespace" title="Truncating Undo Tablespaces"> Truncating Undo Tablespaces </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_undo_tablespaces"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> <code class="literal"> innodb_undo_tablespaces </code> </a> </p> <a class="indexterm" name="idm46045151600496"> </a> <a class="indexterm" name="idm46045151599488"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_undo_tablespaces"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-undo-tablespaces=# </code> </td> </tr> <tr> <th> Deprecated </th> <td> Yes </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> innodb_undo_tablespaces </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 2 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 127 </code> </td> </tr> </tbody> </table> </div> <p> Defines the number of <a class="link" href="glossary.html#glos_undo_tablespace" title="undo tablespace"> undo tablespaces </a> used by <code class="literal"> InnoDB </code> . The default and minimum value is 2. </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> The <a class="link" href="innodb-parameters.html#sysvar_innodb_undo_tablespaces"> <code class="literal"> innodb_undo_tablespaces </code> </a> variable is deprecated; setting it has no effect. You should expect it to be removed in a future MySQL release. </p> </div> <p> For more information, see <a class="xref" href="innodb-undo-tablespaces.html" title="17.6.3.4 Undo Tablespaces"> Section 17.6.3.4, “Undo Tablespaces” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_use_fdatasync"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> </p> <a class="indexterm" name="idm46045151565712"> </a> <a class="indexterm" name="idm46045151564704"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_use_fdatasync"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-use-fdatasync[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> innodb_use_fdatasync </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> Yes </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> On platforms that support <code class="literal"> fdatasync() </code> system calls, having <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> enabled permits using <code class="literal"> fdatasync() </code> instead of <code class="literal"> fsync() </code> system calls for operating system flushes. An <code class="literal"> fdatasync() </code> call does not flush changes to file metadata unless required for subsequent data retrieval, providing a potential performance benefit. </p> <p> A subset of <a class="link" href="innodb-parameters.html#sysvar_innodb_flush_method"> <code class="literal"> innodb_flush_method </code> </a> settings such as <code class="literal"> fsync </code> , <code class="literal"> O_DSYNC </code> , and <code class="literal"> O_DIRECT </code> use <code class="literal"> fsync() </code> system calls. The <a class="link" href="innodb-parameters.html#sysvar_innodb_use_fdatasync"> <code class="literal"> innodb_use_fdatasync </code> </a> variable is applicable when using those settings. </p> <p> Before MySQL 8.4, this option was disabled by default. </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_use_native_aio"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_native_aio"> <code class="literal"> innodb_use_native_aio </code> </a> </p> <a class="indexterm" name="idm46045151532576"> </a> <a class="indexterm" name="idm46045151531568"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_use_native_aio"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-use-native-aio[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_use_native_aio"> innodb_use_native_aio </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Specifies whether to use the <a class="link" href="glossary.html#glos_asynchronous_io" title="asynchronous I/O"> asynchronous I/O </a> subsystem. This variable cannot be changed while the server is running. Normally, you do not need to configure this option, because it is enabled by default. </p> <p> This feature improves the scalability of heavily I/O-bound systems, which typically show many pending reads/writes in <code class="literal"> SHOW ENGINE INNODB STATUS </code> output. </p> <p> Running with a large number of <code class="literal"> InnoDB </code> I/O threads, and especially running multiple such instances on the same server machine, can exceed capacity limits on Linux systems. In this case, you may receive the following error: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting one-line language-terminal"><div class="docs-select-all right" id="sa14581038"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-terminal">EAGAIN<span class="token punctuation">:</span> The specified maxevents exceeds the user's limit of available events<span class="token punctuation">.</span></code></pre> </div> <p> You can typically address this error by writing a higher limit to <code class="literal"> /proc/sys/fs/aio-max-nr </code> . </p> <p> However, if a problem with the asynchronous I/O subsystem in the OS prevents <code class="literal"> InnoDB </code> from starting, you can start the server with <a class="link" href="innodb-parameters.html#sysvar_innodb_use_native_aio"> <code class="literal"> innodb_use_native_aio=0 </code> </a> . This option may also be disabled automatically during startup if <code class="literal"> InnoDB </code> detects a potential problem such as a combination of <code class="literal"> tmpdir </code> location, <code class="literal"> tmpfs </code> file system, and Linux kernel that does not support AIO on <code class="literal"> tmpfs </code> . </p> <p> For more information, see <a class="xref" href="innodb-linux-native-aio.html" title="17.8.6 Using Asynchronous I/O on Linux"> Section 17.8.6, “Using Asynchronous I/O on Linux” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_validate_tablespace_paths"> </a> <code class="literal"> innodb_validate_tablespace_paths </code> </p> <a class="indexterm" name="idm46045151497840"> </a> <a class="indexterm" name="idm46045151496832"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_validate_tablespace_paths"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-validate-tablespace-paths[={OFF|ON}] </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_validate_tablespace_paths"> innodb_validate_tablespace_paths </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Boolean </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> ON </code> </td> </tr> </tbody> </table> </div> <p> Controls tablespace file path validation. At startup, <code class="literal"> InnoDB </code> validates the paths of known tablespace files against tablespace file paths stored in the data dictionary in case tablespace files have been moved to a different location. The <a class="link" href="innodb-parameters.html#sysvar_innodb_validate_tablespace_paths"> <code class="literal"> innodb_validate_tablespace_paths </code> </a> variable permits disabling tablespace path validation. This feature is intended for environments where tablespaces files are not moved. Disabling path validation improves startup time on systems with a large number of tablespace files. </p> <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Warning </div> <p> Starting the server with tablespace path validation disabled after moving tablespace files can lead to undefined behavior. </p> </div> <p> For more information, see <a class="xref" href="innodb-disabling-tablespace-path-validation.html" title="17.6.3.7 Disabling Tablespace Path Validation"> Section 17.6.3.7, “Disabling Tablespace Path Validation” </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_version"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_version"> <code class="literal"> innodb_version </code> </a> </p> <a class="indexterm" name="idm46045151469776"> </a> <a class="indexterm" name="idm46045151468768"> </a> <p> The <code class="literal"> InnoDB </code> version number. This is a legacy variable, the value is the same as the MySQL server <a class="link" href="server-system-variables.html#sysvar_version"> <code class="literal"> version </code> </a> . </p> </li> <li class="listitem"> <p> <a name="sysvar_innodb_write_io_threads"> </a> <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> </p> <a class="indexterm" name="idm46045151463248"> </a> <a class="indexterm" name="idm46045151462240"> </a> <div class="informaltable"> <table frame="box" rules="all" summary="Properties for innodb_write_io_threads"> <colgroup> <col style="width: 30%"/> <col style="width: 70%"/> </colgroup> <tbody> <tr> <th> Command-Line Format </th> <td> <code class="literal"> --innodb-write-io-threads=# </code> </td> </tr> <tr> <th> System Variable </th> <td> <code class="literal"> <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> innodb_write_io_threads </a> </code> </td> </tr> <tr> <th> Scope </th> <td> Global </td> </tr> <tr> <th> Dynamic </th> <td> No </td> </tr> <tr> <th> <a class="link" href="optimizer-hints.html#optimizer-hints-set-var" title="Variable-Setting Hint Syntax"> <code class="literal"> SET_VAR </code> </a> Hint Applies </th> <td> No </td> </tr> <tr> <th> Type </th> <td> Integer </td> </tr> <tr> <th> Default Value </th> <td> <code class="literal"> 4 </code> </td> </tr> <tr> <th> Minimum Value </th> <td> <code class="literal"> 1 </code> </td> </tr> <tr> <th> Maximum Value </th> <td> <code class="literal"> 64 </code> </td> </tr> </tbody> </table> </div> <p> The number of I/O threads for write operations in <code class="literal"> InnoDB </code> . The default value is 4. Its counterpart for read threads is <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> <code class="literal"> innodb_read_io_threads </code> </a> . For more information, see <a class="xref" href="innodb-performance-multiple_io_threads.html" title="17.8.5 Configuring the Number of Background InnoDB I/O Threads"> Section 17.8.5, “Configuring the Number of Background InnoDB I/O Threads” </a> . For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Note </div> <p> On Linux systems, running multiple MySQL servers (typically more than 12) with default settings for <a class="link" href="innodb-parameters.html#sysvar_innodb_read_io_threads"> <code class="literal"> innodb_read_io_threads </code> </a> , <a class="link" href="innodb-parameters.html#sysvar_innodb_write_io_threads"> <code class="literal"> innodb_write_io_threads </code> </a> , and the Linux <code class="literal"> aio-max-nr </code> setting can exceed system limits. Ideally, increase the <code class="literal"> aio-max-nr </code> setting; as a workaround, you might reduce the settings for one or both of the MySQL variables. </p> </div> <p> Also take into consideration the value of <a class="link" href="replication-options-binary-log.html#sysvar_sync_binlog"> <code class="literal"> sync_binlog </code> </a> , which controls synchronization of the binary log to disk. </p> <p> For general I/O tuning advice, see <a class="xref" href="optimizing-innodb-diskio.html" title="10.5.8 Optimizing InnoDB Disk I/O"> Section 10.5.8, “Optimizing InnoDB Disk I/O” </a> . </p> </li> </ul> </div> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-installation.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h2 class="title"> <a name="mysql-cluster-installation"> </a> 25.3 NDB Cluster Installation </h2> </div> </div> </div> <div class="toc"> <dl class="toc"> <dt> <span class="section"> <a href="mysql-cluster-install-linux.html"> 25.3.1 Installation of NDB Cluster on Linux </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-windows.html"> 25.3.2 Installing NDB Cluster on Windows </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-configuration.html"> 25.3.3 Initial Configuration of NDB Cluster </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-first-start.html"> 25.3.4 Initial Startup of NDB Cluster </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-example-data.html"> 25.3.5 NDB Cluster Example with Tables and Data </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-install-shutdown-restart.html"> 25.3.6 Safe Shutdown and Restart of NDB Cluster </a> </span> </dt> <dt> <span class="section"> <a href="mysql-cluster-upgrade-downgrade.html"> 25.3.7 Upgrading and Downgrading NDB Cluster </a> </span> </dt> </dl> </div> <a class="indexterm" name="idm46045123109936"> </a> <a class="indexterm" name="idm46045123108864"> </a> <a class="indexterm" name="idm46045123107792"> </a> <a class="indexterm" name="idm46045123106304"> </a> <a class="indexterm" name="idm46045123105232"> </a> <p> This section describes the basics for planning, installing, configuring, and running an NDB Cluster. Whereas the examples in <a class="xref" href="mysql-cluster-configuration.html" title="25.4 Configuration of NDB Cluster"> Section 25.4, “Configuration of NDB Cluster” </a> provide more in-depth information on a variety of clustering options and configuration, the result of following the guidelines and procedures outlined here should be a usable NDB Cluster which meets the <span class="emphasis"> <em> minimum </em> </span> requirements for availability and safeguarding of data. </p> <p> For information about upgrading or downgrading an NDB Cluster between release versions, see <a class="xref" href="mysql-cluster-upgrade-downgrade.html" title="25.3.7 Upgrading and Downgrading NDB Cluster"> Section 25.3.7, “Upgrading and Downgrading NDB Cluster” </a> . </p> <p> This section covers hardware and software requirements; networking issues; installation of NDB Cluster; basic configuration issues; starting, stopping, and restarting the cluster; loading of a sample database; and performing queries. </p> <p> <b> Assumptions. </b> The following sections make a number of assumptions regarding the cluster's physical and network configuration. These assumptions are discussed in the next few paragraphs. </p> <p> <a name="mysql-cluster-install-nodes-hosts"> </a> <b> Cluster nodes and host computers. </b> The cluster consists of four nodes, each on a separate host computer, and each with a fixed network address on a typical Ethernet network as shown here: </p> <div class="table"> <a name="idm46045123096512"> </a> <p class="title"> <b> Table 25.4 Network addresses of nodes in example cluster </b> </p> <div class="table-contents"> <table> <colgroup> <col style="width: 50%"/> <col style="width: 50%"/> </colgroup> <thead> <tr> <th> Node </th> <th> IP Address </th> </tr> </thead> <tbody> <tr> <td> Management node ( <span class="command"> <strong> mgmd </strong> </span> ) </td> <td> 198.51.100.10 </td> </tr> <tr> <td> SQL node ( <a class="link" href="mysqld.html" title="6.3.1 mysqld — The MySQL Server"> <span class="command"> <strong> mysqld </strong> </span> </a> ) </td> <td> 198.51.100.20 </td> </tr> <tr> <td> Data node "A" ( <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> ) </td> <td> 198.51.100.30 </td> </tr> <tr> <td> Data node "B" ( <a class="link" href="mysql-cluster-programs-ndbd.html" title="25.5.1 ndbd — The NDB Cluster Data Node Daemon"> <span class="command"> <strong> ndbd </strong> </span> </a> ) </td> <td> 198.51.100.40 </td> </tr> </tbody> </table> </div> </div> <br class="table-break"/> <p> This setup is also shown in the following diagram: </p> <div class="figure"> <a name="fig-mysql-cluster-multi-computer"> </a> <p class="title"> <b> Figure 25.4 NDB Cluster Multi-Computer Setup </b> </p> <div class="figure-contents"> <div class="mediaobject"> <img alt="Most content is described in the surrounding text. The four nodes each connect to a central switch that connects to a network." src="images/multi-comp-1.png" style="width: 100%; max-width: 550px;"/> </div> </div> </div> <br class="figure-break"/> <p> <b> Network addressing. </b> <a class="indexterm" name="idm46045123069952"> </a> <a class="indexterm" name="idm46045123068464"> </a> In the interest of simplicity (and reliability), this <em class="citetitle"> How-To </em> uses only numeric IP addresses. However, if DNS resolution is available on your network, it is possible to use host names in lieu of IP addresses in configuring Cluster. Alternatively, you can use the <code class="filename"> hosts </code> file (typically <code class="filename"> /etc/hosts </code> for Linux and other Unix-like operating systems, <code class="filename"> C:\WINDOWS\system32\drivers\etc\hosts </code> on Windows, or your operating system's equivalent) for providing a means to do host lookup if such is available. </p> <p> <code class="literal"> NDB </code> 8.4 supports IPv6 for connections between all NDB Cluster nodes. </p> <p> <b> Potential hosts file issues. </b> A common problem when trying to use host names for Cluster nodes arises because of the way in which some operating systems (including some Linux distributions) set up the system's own host name in the <code class="filename"> /etc/hosts </code> during installation. Consider two machines with the host names <code class="literal"> ndb1 </code> and <code class="literal"> ndb2 </code> , both in the <code class="literal"> cluster </code> network domain. Red Hat Linux (including some derivatives such as CentOS and Fedora) places the following entries in these machines' <code class="filename"> /etc/hosts </code> files: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa81670398"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># ndb1 /etc/hosts:</span> 127.0.0.1 ndb1.cluster ndb1 localhost.localdomain localhost</code></pre> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa68312983"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># ndb2 /etc/hosts:</span> 127.0.0.1 ndb2.cluster ndb2 localhost.localdomain localhost</code></pre> </div> <p> SUSE Linux (including OpenSUSE) places these entries in the machines' <code class="filename"> /etc/hosts </code> files: </p> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa51699949"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># ndb1 /etc/hosts:</span> 127.0.0.1 localhost 127.0.0.2 ndb1.cluster ndb1</code></pre> </div> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-ini"><div class="docs-select-all right" id="sa88610707"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-ini"><span class="token comment" spellcheck="true"># ndb2 /etc/hosts:</span> 127.0.0.1 localhost 127.0.0.2 ndb2.cluster ndb2</code></pre> </div> <p> In both instances, <code class="literal"> ndb1 </code> routes <code class="literal"> ndb1.cluster </code> to a loopback IP address, but gets a public IP address from DNS for <code class="literal"> ndb2.cluster </code> , while <code class="literal"> ndb2 </code> routes <code class="literal"> ndb2.cluster </code> to a loopback address and obtains a public address for <code class="literal"> ndb1.cluster </code> . The result is that each data node connects to the management server, but cannot tell when any other data nodes have connected, and so the data nodes appear to hang while starting. </p> <div class="caution" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Caution </div> <p> You cannot mix <code class="literal"> localhost </code> and other host names or IP addresses in <code class="filename"> config.ini </code> . For these reasons, the solution in such cases (other than to use IP addresses for <span class="emphasis"> <em> all </em> </span> <code class="filename"> config.ini </code> <code class="literal"> HostName </code> entries) is to remove the fully qualified host names from <code class="filename"> /etc/hosts </code> and use these in <code class="filename"> config.ini </code> for all cluster hosts. </p> </div> <p> <b> Host computer type. </b> Each host computer in our installation scenario is an Intel-based desktop PC running a supported operating system installed to disk in a standard configuration, and running no unnecessary services. The core operating system with standard TCP/IP networking capabilities should be sufficient. Also for the sake of simplicity, we also assume that the file systems on all hosts are set up identically. In the event that they are not, you should adapt these instructions accordingly. </p> <p> <b> Network hardware. </b> Standard 100 Mbps or 1 gigabit Ethernet cards are installed on each machine, along with the proper drivers for the cards, and that all four hosts are connected through a standard-issue Ethernet networking appliance such as a switch. (All machines should use network cards with the same throughput. That is, all four machines in the cluster should have 100 Mbps cards <span class="emphasis"> <em> or </em> </span> all four machines should have 1 Gbps cards.) NDB Cluster works in a 100 Mbps network; however, gigabit Ethernet provides better performance. </p> <div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"> <div class="admon-title"> Important </div> <p> NDB Cluster is <span class="emphasis"> <em> not </em> </span> intended for use in a network for which throughput is less than 100 Mbps or which experiences a high degree of latency. For this reason (among others), attempting to run an NDB Cluster over a wide area network such as the Internet is not likely to be successful, and is not supported in production. </p> </div> <p> <b> Sample data. </b> We use the <code class="literal"> world </code> database which is available for download from the MySQL website (see <a class="ulink" href="/doc/index-other.html" target="_top"> https://dev.mysql.com/doc/index-other.html </a> ). We assume that each machine has sufficient memory for running the operating system, required NDB Cluster processes, and (on the data nodes) storing the database. </p> <p> For general information about installing MySQL, see <a class="xref" href="installing.html" title="Chapter 2 Installing MySQL"> Chapter 2, <i> Installing MySQL </i> </a> . For information about installation of NDB Cluster on Linux and other Unix-like operating systems, see <a class="xref" href="mysql-cluster-install-linux.html" title="25.3.1 Installation of NDB Cluster on Linux"> Section 25.3.1, “Installation of NDB Cluster on Linux” </a> . For information about installation of NDB Cluster on Windows operating systems, see <a class="xref" href="mysql-cluster-install-windows.html" title="25.3.2 Installing NDB Cluster on Windows"> Section 25.3.2, “Installing NDB Cluster on Windows” </a> . </p> <p> For general information about NDB Cluster hardware, software, and networking requirements, see <a class="xref" href="mysql-cluster-overview-requirements.html" title="25.2.3 NDB Cluster Hardware, Software, and Networking Requirements"> Section 25.2.3, “NDB Cluster Hardware, Software, and Networking Requirements” </a> . </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/innodb-truncate-table-reclaim-space.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h3 class="title"> <a name="innodb-truncate-table-reclaim-space"> </a> 17.11.5 Reclaiming Disk Space with TRUNCATE TABLE </h3> </div> </div> </div> <p> To reclaim operating system disk space when <a class="link" href="glossary.html#glos_truncate" title="truncate"> truncating </a> an <code class="literal"> InnoDB </code> table, the table must be stored in its own <a class="link" href="glossary.html#glos_ibd_file" title=".ibd file"> .ibd </a> file. For a table to be stored in its own <a class="link" href="glossary.html#glos_ibd_file" title=".ibd file"> .ibd </a> file, <a class="link" href="innodb-parameters.html#sysvar_innodb_file_per_table"> <code class="literal"> innodb_file_per_table </code> </a> must enabled when the table is created. Additionally, there cannot be a <a class="link" href="glossary.html#glos_foreign_key" title="foreign key"> foreign key </a> constraint between the table being truncated and other tables, otherwise the <code class="literal"> TRUNCATE TABLE </code> operation fails. A foreign key constraint between two columns in the same table, however, is permitted. </p> <p> When a table is truncated, it is dropped and re-created in a new <code class="filename"> .ibd </code> file, and the freed space is returned to the operating system. This is in contrast to truncating <code class="literal"> InnoDB </code> tables that are stored within the <code class="literal"> InnoDB </code> <a class="link" href="glossary.html#glos_system_tablespace" title="system tablespace"> system tablespace </a> (tables created when <code class="literal"> innodb_file_per_table=OFF </code> ) and tables stored in shared <a class="link" href="glossary.html#glos_general_tablespace" title="general tablespace"> general tablespaces </a> , where only <code class="literal"> InnoDB </code> can use the freed space after the table is truncated. </p> <p> The ability to truncate tables and return disk space to the operating system also means that <a class="link" href="glossary.html#glos_physical_backup" title="physical backup"> physical backups </a> can be smaller. Truncating tables that are stored in the system tablespace (tables created when <code class="literal"> innodb_file_per_table=OFF </code> ) or in a general tablespace leaves blocks of unused space in the tablespace. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/mysqlbinlog-server-id.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="mysqlbinlog-server-id"> </a> 6.6.9.4 Specifying the mysqlbinlog Server ID </h4> </div> </div> </div> <p> When invoked with the <code class="option"> --read-from-remote-server </code> option, <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects to a MySQL server, specifies a server ID to identify itself, and requests binary log files from the server. You can use <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> to request log files from a server in several ways: </p> <div class="itemizedlist"> <ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> <p> Specify an explicitly named set of files: For each file, <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects and issues a <code class="literal"> Binlog dump </code> command. The server sends the file and disconnects. There is one connection per file. </p> </li> <li class="listitem"> <p> Specify the beginning file and <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_to-last-log"> <code class="option"> --to-last-log </code> </a> : <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects and issues a <code class="literal"> Binlog dump </code> command for all files. The server sends all files and disconnects. </p> </li> <li class="listitem"> <p> Specify the beginning file and <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_stop-never"> <code class="option"> --stop-never </code> </a> (which implies <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_to-last-log"> <code class="option"> --to-last-log </code> </a> ): <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects and issues a <code class="literal"> Binlog dump </code> command for all files. The server sends all files, but does not disconnect after sending the last one. </p> </li> </ul> </div> <p> With <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_read-from-remote-server"> <code class="option"> --read-from-remote-server </code> </a> only, <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects using a server ID of 0, which tells the server to disconnect after sending the last requested log file. </p> <p> With <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_read-from-remote-server"> <code class="option"> --read-from-remote-server </code> </a> and <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_stop-never"> <code class="option"> --stop-never </code> </a> , <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> connects using a nonzero server ID, so the server does not disconnect after sending the last log file. The server ID is 1 by default, but this can be changed with <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_connection-server-id"> <code class="option"> --connection-server-id </code> </a> . </p> <p> Thus, for the first two ways of requesting files, the server disconnects because <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> specifies a server ID of 0. It does not disconnect if <a class="link" href="mysqlbinlog.html#option_mysqlbinlog_stop-never"> <code class="option"> --stop-never </code> </a> is given because <a class="link" href="mysqlbinlog.html" title="6.6.9 mysqlbinlog — Utility for Processing Binary Log Files"> <span class="command"> <strong> mysqlbinlog </strong> </span> </a> specifies a nonzero server ID. </p> </div> <br/> </div>

https://dev.mysql.com/doc/refman/8.4/en/show-function-status.html

<div id="docs-body"> <div class="section"> <div class="titlepage"> <div> <div> <h4 class="title"> <a name="show-function-status"> </a> 15.7.7.21 SHOW FUNCTION STATUS Statement </h4> </div> </div> </div> <a class="indexterm" name="idm46045170329424"> </a> <div class="copytoclipboard-wrapper"> <pre class="programlisting language-sql"><div class="docs-select-all right" id="sa257780"><div class="copy-help left">Press ⌘+C to copy</div> <div class="right"><button class="clipboard-btn" title="Copy to Clipboard"><span class="icon-clipboard"></span></button></div></div><code class="language-sql"><span class="token keyword">SHOW</span> <span class="token keyword">FUNCTION</span> <span class="token keyword">STATUS</span> <span class="token punctuation">[</span><span class="token operator">LIKE</span> <span class="token string">'<em class="replaceable">pattern</em>'</span> <span class="token operator">|</span> <span class="token keyword">WHERE</span> <em class="replaceable">expr</em><span class="token punctuation">]</span></code></pre> </div> <p> This statement is similar to <a class="link" href="show-procedure-status.html" title="15.7.7.30 SHOW PROCEDURE STATUS Statement"> <code class="literal"> SHOW PROCEDURE STATUS </code> </a> but for stored functions. See <a class="xref" href="show-procedure-status.html" title="15.7.7.30 SHOW PROCEDURE STATUS Statement"> Section 15.7.7.30, “SHOW PROCEDURE STATUS Statement” </a> . </p> </div> <br/> </div>