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module Shell
  module Commands
    class Alter < Command
      def help
        return <<-EOF
Alter column family schema;  pass table name and a dictionary
specifying new column family schema. Dictionaries are described
on the main help command output. Dictionary must include name
of column family to alter. For example,

To change or add the 'f1' column family in table 't1' from defaults
to instead keep a maximum of 5 cell VERSIONS, do:

  hbase> alter 't1', NAME => 'f1', VERSIONS => 5

To delete the 'f1' column family in table 't1', do:

  hbase> alter 't1', NAME => 'f1', METHOD => 'delete'

or a shorter version:

  hbase> alter 't1', 'delete' => 'f1'

You can also change table-scope attributes like MAX_FILESIZE
MEMSTORE_FLUSHSIZE, READONLY, and DEFERRED_LOG_FLUSH.

For example, to change the max size of a family to 128MB, do:

  hbase> alter 't1', METHOD => 'table_att', MAX_FILESIZE => '134217728'

You can add a table coprocessor by setting a table coprocessor attribute:

  hbase> alter 't1', METHOD => 'table_att',
    'coprocessor'=>'hdfs:///foo.jar|com.foo.FooRegionObserver|1001|arg1=1,arg2=2'

Since you can have multiple coprocessors configured for a table, a
sequence number will be automatically appended to the attribute name
to uniquely identify it.

The coprocessor attribute must match the pattern below in order for
the framework to understand how to load the coprocessor classes:

  [coprocessor jar file location] | class name | [priority] | [arguments]

You can also remove a table-scope attribute:

  hbase> alter 't1', METHOD => 'table_att_unset', NAME => 'MAX_FILESIZE'

  hbase> alter 't1', METHOD => 'table_att_unset', NAME => 'coprocessor$1'

There could be more than one alteration in one command:

  hbase> alter 't1', {NAME => 'f1'}, {NAME => 'f2', METHOD => 'delete'}
EOF
      end

      def command(table, *args)
        format_simple_command do
          admin.alter(table, true, *args)
        end
      end
    end
  end
end
