<section>
 <h1 class="contains-headerlink leafygreen-ui-41fr9s" weight="medium">
  movePrimary
  <a class="headerlink leafygreen-ui-1kepx47" href="#moveprimary" title="Permalink to this heading">
   <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
    <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
    </path>
    <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
    </path>
   </svg>
   <div class="css-1btu0w3 evvkmar0" id="moveprimary">
   </div>
  </a>
 </h1>
 <div class="leafygreen-ui-a5yxub">
  <p class="css-1cmx2d4 ef7gu8j0">
   On this page
  </p>
  <ul class="css-1qb0mst ef7gu8j1">
   <li class="leafygreen-ui-1e7a0ei">
    <a class="lg-ui-0001 leafygreen-ui-e98ikf" href="#compatibility" target="_self">
     <span>
      Compatibility
     </span>
    </a>
   </li>
   <li class="leafygreen-ui-1jqtqlb">
    <a class="lg-ui-0001 leafygreen-ui-cpmeq5" href="#considerations" target="_self">
     <span>
      Considerations
     </span>
    </a>
   </li>
   <li class="leafygreen-ui-1jqtqlb">
    <a class="lg-ui-0001 leafygreen-ui-cpmeq5" href="#additional-information" target="_self">
     <span>
      Additional Information
     </span>
    </a>
   </li>
  </ul>
 </div>
 <dl class="dbcommand">
  <dt>
   <code class="leafygreen-ui-1l06pbn">
    movePrimary
   </code>
   <a class="headerlink leafygreen-ui-1kepx47" href="#mongodb-dbcommand-dbcmd.movePrimary" title="Permalink to this definition">
    <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
     <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
     </path>
     <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
     </path>
    </svg>
    <div class="css-1btu0w3 evvkmar0" id="mongodb-dbcommand-dbcmd.movePrimary">
    </div>
   </a>
  </dt>
  <dd>
   <p class="leafygreen-ui-1kp3ins">
    In a
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/glossary/#std-term-sharded-cluster">
     sharded cluster
    </a>
    ,
    <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="#mongodb-dbcommand-dbcmd.movePrimary" target="_self">
     <span>
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
     </span>
    </a>
    reassigns the
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/glossary/#std-term-primary-shard">
     primary shard
    </a>
    which holds all un-sharded collections in
the database.
    <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="#mongodb-dbcommand-dbcmd.movePrimary" target="_self">
     <span>
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
     </span>
    </a>
    first changes the primary shard in
the cluster metadata, and then migrates all un-sharded collections to the
specified
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/glossary/#std-term-shard">
     shard
    </a>
    . Use the command with the following form:
   </p>
   <script class="structured_data" type="application/ld+json">
    {"@context":"https://schema.org","@type":"SoftwareSourceCode","codeSampleType":"code snippet","text":"db.adminCommand( { movePrimary: &lt;databasename&gt;, to: &lt;newprimaryshard&gt; } )","programmingLanguage":"JavaScript"}
   </script>
   <div class="css-16lmvu9">
    <div class="leafygreen-ui-196mwvg">
     <div class="leafygreen-ui-1b1bvay">
      <pre class="leafygreen-ui-1q4bxgx" tabindex="0"><code class="lg-highlight-hljs-light javascript leafygreen-ui-9ybzas"><table class="leafygreen-ui-1tr4g10"><tbody><tr class=""><td class="leafygreen-ui-7razhx">db.<span class="lg-highlight-title lg-highlight-function">adminCommand</span>( <!-- -->{ <span class="lg-highlight-attr">movePrimary</span>: &lt;<!-- -->databaseName<!-- -->&gt;<!-- -->,<!-- --> <span class="lg-highlight-attr">to</span>: &lt;<!-- -->newPrimaryShard<!-- -->&gt; <!-- -->} )</td></tr></tbody></table></code></pre>
      <div class="leafygreen-ui-1bqcprk" data-testid="leafygreen-code-panel">
       <button aria-disabled="false" aria-label="Copy" class="leafygreen-ui-1c6zwke" data-testid="code_copy-button" tabindex="0">
        <div class="leafygreen-ui-xhlipt">
         <svg aria-label="Copy Icon" class="leafygreen-ui-1st74h4" height="16" role="img" viewbox="0 0 16 16" width="16">
          <path clip-rule="evenodd" d="M1 5.71428V10.2857C1 11.2325 1.76751 12 2.71429 12H5.75V7.10957C5.75 6.54414 5.97724 6.00244 6.38065 5.60623L8.67403 3.35381C8.77447 3.25516 8.88376 3.16757 9 3.09182V2.71429C9 1.76751 8.23249 1 7.28571 1H5.8V4.42857C5.8 5.13865 5.22437 5.71428 4.51429 5.71428H1ZM9 4.78571L7.25654 6.49804C7.24689 6.50752 7.23749 6.5172 7.22834 6.52708C7.22208 6.53383 7.21594 6.54068 7.20991 6.54762C7.07504 6.70295 7 6.90234 7 7.10957V7.79762H9H10.0095C10.4829 7.79762 10.8667 7.41386 10.8667 6.94047V4H10.1505C9.92587 4 9.7102 4.0882 9.54992 4.24562L9 4.78571ZM4.86667 1H4.15053C3.92587 1 3.7102 1.0882 3.54992 1.24562L1.25654 3.49804C1.09244 3.65921 1 3.87957 1 4.10957V4.79762H4.00952C4.48291 4.79762 4.86667 4.41386 4.86667 3.94047V1ZM7 12V8.71428H9H10.5143C11.2244 8.71428 11.8 8.13865 11.8 7.42857V4H13.2857C14.2325 4 15 4.76751 15 5.71429V13.2857C15 14.2325 14.2325 15 13.2857 15H8.71429C7.76751 15 7 14.2325 7 13.2857V12Z" fill="currentColor" fill-rule="evenodd">
          </path>
         </svg>
        </div>
       </button>
      </div>
     </div>
    </div>
   </div>
   <p class="leafygreen-ui-1kp3ins">
    For example, the following command moves the primary shard from
    <code class="leafygreen-ui-1l06pbn">
     test
    </code>
    to
    <code class="leafygreen-ui-1l06pbn">
     shard0001
    </code>
    :
   </p>
   <script class="structured_data" type="application/ld+json">
    {"@context":"https://schema.org","@type":"SoftwareSourceCode","codeSampleType":"code snippet","text":"db.adminCommand( { movePrimary : \"test\", to : \"shard0001\" } )","programmingLanguage":"JavaScript"}
   </script>
   <div class="css-16lmvu9">
    <div class="leafygreen-ui-196mwvg">
     <div class="leafygreen-ui-1b1bvay">
      <pre class="leafygreen-ui-1q4bxgx" tabindex="0"><code class="lg-highlight-hljs-light javascript leafygreen-ui-9ybzas"><table class="leafygreen-ui-1tr4g10"><tbody><tr class=""><td class="leafygreen-ui-7razhx">db.<span class="lg-highlight-title lg-highlight-function">adminCommand</span>( <!-- -->{ <!-- -->movePrimary <!-- -->: <span class="lg-highlight-string">"test"</span>, <!-- -->to <!-- -->: <span class="lg-highlight-string">"shard0001"</span> } )</td></tr></tbody></table></code></pre>
      <div class="leafygreen-ui-1bqcprk" data-testid="leafygreen-code-panel">
       <button aria-disabled="false" aria-label="Copy" class="leafygreen-ui-1c6zwke" data-testid="code_copy-button" tabindex="0">
        <div class="leafygreen-ui-xhlipt">
         <svg aria-label="Copy Icon" class="leafygreen-ui-1st74h4" height="16" role="img" viewbox="0 0 16 16" width="16">
          <path clip-rule="evenodd" d="M1 5.71428V10.2857C1 11.2325 1.76751 12 2.71429 12H5.75V7.10957C5.75 6.54414 5.97724 6.00244 6.38065 5.60623L8.67403 3.35381C8.77447 3.25516 8.88376 3.16757 9 3.09182V2.71429C9 1.76751 8.23249 1 7.28571 1H5.8V4.42857C5.8 5.13865 5.22437 5.71428 4.51429 5.71428H1ZM9 4.78571L7.25654 6.49804C7.24689 6.50752 7.23749 6.5172 7.22834 6.52708C7.22208 6.53383 7.21594 6.54068 7.20991 6.54762C7.07504 6.70295 7 6.90234 7 7.10957V7.79762H9H10.0095C10.4829 7.79762 10.8667 7.41386 10.8667 6.94047V4H10.1505C9.92587 4 9.7102 4.0882 9.54992 4.24562L9 4.78571ZM4.86667 1H4.15053C3.92587 1 3.7102 1.0882 3.54992 1.24562L1.25654 3.49804C1.09244 3.65921 1 3.87957 1 4.10957V4.79762H4.00952C4.48291 4.79762 4.86667 4.41386 4.86667 3.94047V1ZM7 12V8.71428H9H10.5143C11.2244 8.71428 11.8 8.13865 11.8 7.42857V4H13.2857C14.2325 4 15 4.76751 15 5.71429V13.2857C15 14.2325 14.2325 15 13.2857 15H8.71429C7.76751 15 7 14.2325 7 13.2857V12Z" fill="currentColor" fill-rule="evenodd">
          </path>
         </svg>
        </div>
       </button>
      </div>
     </div>
    </div>
   </div>
   <p class="leafygreen-ui-1kp3ins">
    When the command returns, the database's primary shard location
has switched to the specified shard. To fully decommission a
shard, use the
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/command/removeShard/#mongodb-dbcommand-dbcmd.removeShard">
     <code class="leafygreen-ui-1l06pbn">
      removeShard
     </code>
    </a>
    command.
   </p>
   <p class="leafygreen-ui-1kp3ins">
    <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="#mongodb-dbcommand-dbcmd.movePrimary" target="_self">
     <span>
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
     </span>
    </a>
    is an administrative command that is only
available for
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/program/mongos/#mongodb-binary-bin.mongos">
     <code class="leafygreen-ui-1l06pbn">
      mongos
     </code>
    </a>
    instances.
   </p>
   <div class="leafygreen-ui-1sjx7ru" role="note">
    <h2 class="leafygreen-ui-29m78u">
     Warning
    </h2>
    <div class="leafygreen-ui-9mycqc">
     <p class="leafygreen-ui-1kp3ins">
      After starting
      <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="#mongodb-dbcommand-dbcmd.movePrimary" target="_self">
       <span>
        <code class="leafygreen-ui-1l06pbn">
         movePrimary
        </code>
       </span>
      </a>
      , do
      <strong>
       not
      </strong>
      perform any
read or write operations against any unsharded collection in that
database until the command completes. Read or write operations
issued against those collections during the migration can result
in unexpected behavior, including potential failure of the
migration operation or loss of data.
     </p>
    </div>
   </div>
  </dd>
 </dl>
 <span class="leafygreen-ui-1qnjd6d" id="std-label-movePrimary-consideration">
 </span>
 <section>
  <h2 class="contains-headerlink leafygreen-ui-19f71ei" weight="medium">
   Compatibility
   <a class="headerlink leafygreen-ui-1kepx47" href="#compatibility" title="Permalink to this heading">
    <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
     <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
     </path>
     <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
     </path>
    </svg>
    <div class="css-1btu0w3 evvkmar0" id="compatibility">
    </div>
   </a>
  </h2>
  <p class="leafygreen-ui-1kp3ins">
   This command is available in deployments hosted in the following environments:
  </p>
  <ul class="leafygreen-ui-rioki0">
   <li class="leafygreen-ui-d7p7b6">
    <p class="leafygreen-ui-1kp3ins">
     <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="https://www.mongodb.com/docs/atlas?tck=docs_server" target="_self">
      <span>
       MongoDB Atlas
      </span>
     </a>
     : The fully
managed service for MongoDB deployments in the cloud
    </p>
   </li>
  </ul>
  <div class="leafygreen-ui-85da11" role="note">
   <h2 class="leafygreen-ui-1ac4g5h">
    Important
   </h2>
   <div class="leafygreen-ui-9mycqc">
    <p class="leafygreen-ui-1kp3ins">
     This command is not supported in serverless instances.
For more information, see
     <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="https://www.mongodb.com/docs/atlas/unsupported-commands/" target="_self">
      <span>
       Unsupported Commands
       <!-- -->
       .
      </span>
     </a>
    </p>
   </div>
  </div>
  <ul class="leafygreen-ui-rioki0">
   <li class="leafygreen-ui-d7p7b6">
    <p class="leafygreen-ui-1kp3ins">
     <a class="leafygreen-ui-tqgtui" href="/docs/manual/administration/install-enterprise/#std-label-install-mdb-enterprise">
      MongoDB Enterprise
     </a>
     : The
subscription-based, self-managed version of MongoDB
    </p>
   </li>
   <li class="leafygreen-ui-d7p7b6">
    <p class="leafygreen-ui-1kp3ins">
     <a class="leafygreen-ui-tqgtui" href="/docs/manual/administration/install-community/#std-label-install-mdb-community-edition">
      MongoDB Community
     </a>
     : The
source-available, free-to-use, and self-managed version of MongoDB
    </p>
   </li>
  </ul>
 </section>
 <section>
  <h2 class="contains-headerlink leafygreen-ui-19f71ei" weight="medium">
   Considerations
   <a class="headerlink leafygreen-ui-1kepx47" href="#considerations" title="Permalink to this heading">
    <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
     <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
     </path>
     <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
     </path>
    </svg>
    <div class="css-1btu0w3 evvkmar0" id="considerations">
    </div>
   </a>
  </h2>
  <p class="leafygreen-ui-1kp3ins">
   <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/program/mongos/#mongodb-binary-bin.mongos">
    <code class="leafygreen-ui-1l06pbn">
     mongos
    </code>
   </a>
   uses
   <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/write-concern/#mongodb-writeconcern-writeconcern.-majority-">
    <code class="leafygreen-ui-1l06pbn">
     "majority"
    </code>
   </a>
   write concern for
   <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="#mongodb-dbcommand-dbcmd.movePrimary" target="_self">
    <span>
     <code class="leafygreen-ui-1l06pbn">
      movePrimary
     </code>
     .
    </span>
   </a>
  </p>
  <span class="leafygreen-ui-1qnjd6d" id="std-label-movePrimary-maintenance-window">
  </span>
  <section>
   <h3 class="contains-headerlink leafygreen-ui-15ajumo" weight="medium">
    Issue
    <code class="leafygreen-ui-1l06pbn">
     movePrimary
    </code>
    During A Maintenance Window
    <a class="headerlink leafygreen-ui-1kepx47" href="#issue-moveprimary-during-a-maintenance-window" title="Permalink to this heading">
     <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
      <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
      </path>
      <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
      </path>
     </svg>
     <div class="css-1btu0w3 evvkmar0" id="issue-moveprimary-during-a-maintenance-window">
     </div>
    </a>
   </h3>
   <p class="leafygreen-ui-1kp3ins">
    <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="#mongodb-dbcommand-dbcmd.movePrimary" target="_self">
     <span>
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
     </span>
    </a>
    may require a significant time to complete
depending on the size of the database and factors such as network health
or machine resources. Read or write operations issued against the
database during the migration can result in unexpected behavior,
including potential failure of the migration operation or loss of data.
   </p>
   <p class="leafygreen-ui-1kp3ins">
    Consider scheduling a maintenance window during which applications stop
all reads and writes to the cluster. Issuing
    <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="#mongodb-dbcommand-dbcmd.movePrimary" target="_self">
     <span>
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
     </span>
    </a>
    during planned downtime mitigates the risk of encountering undefined
behavior due to interleaving reads or writes to the unsharded
collections in the database.
   </p>
  </section>
  <section>
   <h3 class="contains-headerlink leafygreen-ui-15ajumo" weight="medium">
    Namespace Conflicts Prevent Migration
    <a class="headerlink leafygreen-ui-1kepx47" href="#namespace-conflicts-prevent-migration" title="Permalink to this heading">
     <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
      <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
      </path>
      <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
      </path>
     </svg>
     <div class="css-1btu0w3 evvkmar0" id="namespace-conflicts-prevent-migration">
     </div>
    </a>
   </h3>
   <p class="leafygreen-ui-1kp3ins">
    <a class="lg-ui-0001 leafygreen-ui-fgcsv5" href="#mongodb-dbcommand-dbcmd.movePrimary" target="_self">
     <span>
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
     </span>
    </a>
    fails if the destination shard contains a
conflicting collection namespace. For example:
   </p>
   <ol class="leafygreen-ui-rioki0" type="1">
    <li class="leafygreen-ui-d7p7b6">
     <p class="leafygreen-ui-1kp3ins">
      An administrator issues
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
      to change the
primary shard for the
      <code class="leafygreen-ui-1l06pbn">
       hr
      </code>
      database.
     </p>
    </li>
    <li class="leafygreen-ui-d7p7b6">
     <p class="leafygreen-ui-1kp3ins">
      A user or application issues a write operation against an unsharded
collection in
      <code class="leafygreen-ui-1l06pbn">
       hr
      </code>
      while
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
      is moving that collection.
The write operation creates the collection in the original primary
shard.
     </p>
    </li>
    <li class="leafygreen-ui-d7p7b6">
     <p class="leafygreen-ui-1kp3ins">
      An administrator later issues
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
      to restore
the original primary shard for the
      <code class="leafygreen-ui-1l06pbn">
       hr
      </code>
      database.
     </p>
    </li>
    <li class="leafygreen-ui-d7p7b6">
     <p class="leafygreen-ui-1kp3ins">
      <code class="leafygreen-ui-1l06pbn">
       movePrimary
      </code>
      fails due to the conflicting namespace
left behind from the interleaving write operation.
     </p>
    </li>
   </ol>
  </section>
  <section>
   <h3 class="contains-headerlink leafygreen-ui-15ajumo" weight="medium">
    Destination Shard Must Rebuild Indexes
    <a class="headerlink leafygreen-ui-1kepx47" href="#destination-shard-must-rebuild-indexes" title="Permalink to this heading">
     <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
      <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
      </path>
      <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
      </path>
     </svg>
     <div class="css-1btu0w3 evvkmar0" id="destination-shard-must-rebuild-indexes">
     </div>
    </a>
   </h3>
   <p class="leafygreen-ui-1kp3ins">
    As part of the
    <code class="leafygreen-ui-1l06pbn">
     movePrimary
    </code>
    operation, the destination shard must
rebuild indexes on the migrated collections after becoming the primary
shard. This may require a significant amount of time depending on
the number of indexes per collection and the amount of data to index.
   </p>
   <p class="leafygreen-ui-1kp3ins">
    See
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/core/index-creation/">
     Index Builds on Populated Collections
    </a>
    for more information on the index
build process.
   </p>
   <span class="leafygreen-ui-1qnjd6d" id="std-label-movePrimary-change-streams">
   </span>
  </section>
  <section>
   <h3 class="contains-headerlink leafygreen-ui-15ajumo" weight="medium">
    Moving Collections that have Change Streams
    <a class="headerlink leafygreen-ui-1kepx47" href="#moving-collections-that-have-change-streams" title="Permalink to this heading">
     <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
      <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
      </path>
      <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
      </path>
     </svg>
     <div class="css-1btu0w3 evvkmar0" id="moving-collections-that-have-change-streams">
     </div>
    </a>
   </h3>
   <p class="leafygreen-ui-1kp3ins">
    Starting in MongoDB 8.0,
    <code class="leafygreen-ui-1l06pbn">
     movePrimary
    </code>
    doesn't
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/reference/change-events/invalidate/#std-label-change-event-invalidate">
     invalidate
    </a>
    collections that have
    <a class="leafygreen-ui-tqgtui" href="/docs/manual/changeStreams/#std-label-changeStreams">
     change
streams
    </a>
    . The change streams can continue to read events
from collections after the collections are moved to a new shard.
   </p>
   <p class="leafygreen-ui-1kp3ins">
    In earlier MongoDB versions,
    <code class="leafygreen-ui-1l06pbn">
     movePrimary
    </code>
    invalidates collection
change streams and the change streams cannot read events from the
collections.
   </p>
   <p class="leafygreen-ui-1kp3ins">
    In all MongoDB versions,
    <code class="leafygreen-ui-1l06pbn">
     movePrimary
    </code>
    updates the
    <span class="leafygreen-ui-vm4wms" tabindex="0">
     UUID
    </span>
    for moved unsharded collections.
   </p>
  </section>
 </section>
 <section>
  <h2 class="contains-headerlink leafygreen-ui-19f71ei" weight="medium">
   Additional Information
   <a class="headerlink leafygreen-ui-1kepx47" href="#additional-information" title="Permalink to this heading">
    <svg aria-label="Link Icon" class="leafygreen-ui-a30zj9" fill="none" height="12" role="img" viewbox="0 0 16 16" width="12" xmlns="http://www.w3.org/2000/svg">
     <path d="M6.039 9.953a3.596 3.596 0 0 1-.327-.38l1.45-1.445a1.553 1.553 0 0 0 2.496.423l2.885-2.87a1.57 1.57 0 0 0 .01-2.213 1.553 1.553 0 0 0-2.203-.01l-.379.377A.995.995 0 0 1 8.56 3.83a1.005 1.005 0 0 1 .006-1.418l.38-.377a3.542 3.542 0 0 1 5.024.023 3.58 3.58 0 0 1-.022 5.047l-2.884 2.871a3.542 3.542 0 0 1-5.025-.022Z" fill="currentColor">
     </path>
     <path d="M9.961 6.047c.12.12.228.248.327.38l-1.45 1.445a1.553 1.553 0 0 0-2.496-.423l-2.885 2.87a1.57 1.57 0 0 0-.01 2.213 1.553 1.553 0 0 0 2.203.01l.379-.377a.995.995 0 0 1 1.411.006 1.005 1.005 0 0 1-.006 1.418l-.38.377a3.542 3.542 0 0 1-5.024-.023 3.58 3.58 0 0 1 .022-5.047l2.884-2.871a3.542 3.542 0 0 1 5.025.022Z" fill="currentColor">
     </path>
    </svg>
    <div class="css-1btu0w3 evvkmar0" id="additional-information">
    </div>
   </a>
  </h2>
  <p class="leafygreen-ui-1kp3ins">
   See
   <a class="leafygreen-ui-tqgtui" href="/docs/manual/tutorial/remove-shards-from-cluster/">
    Remove Shards from a Sharded Cluster
   </a>
   for a complete
procedure.
  </p>
 </section>
</section>
