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$PostgreSQL: pgsql/doc/src/sgml/ref/alter_type.sgml,v 1.4 2006/09/16 00:30:16 momjian Exp $
PostgreSQL documentation
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<refentry id="SQL-ALTERTYPE">
 <refmeta>
  <refentrytitle id="sql-altertype-title">ALTER TYPE</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>
   ALTER TYPE
  </refname>
  <refpurpose>
   change the definition of a type
  </refpurpose>
 </refnamediv>

 <indexterm zone="sql-altertype">
  <primary>ALTER TYPE</primary>
 </indexterm>

 <refsynopsisdiv>
  <synopsis>
ALTER TYPE <replaceable class="PARAMETER">name</replaceable> 
   SET DEFAULT ENCODING ( storage_directive )
     SET SCHEMA <replaceable class="PARAMETER">new_schema</replaceable>
  </synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>ALTER TYPE</command> changes the definition of an existing type.
   The only currently available capabilities are changing the schema
   of a type.
  </para>

  <para>
   You must own the type to use <command>ALTER TYPE</>.
   To change the schema of a type, you must also have
   <literal>CREATE</literal> privilege on the new schema.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

   <para>
    <variablelist>
     <varlistentry>
      <term><replaceable class="PARAMETER">name</replaceable></term>
      <listitem>
       <para>
        The name (possibly schema-qualified) of an existing type to
        alter.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable class="PARAMETER">new_schema</replaceable></term>
      <listitem>
       <para>
        The new schema for the type.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable class="PARAMETER">storage_directive</replaceable></term>
      <listitem>
       <para>
        Sets any or all of the following: compression type, compression level, 
        and blocksize, using the following format:
        COMPRESSTYPE={ZLIB | QUICKLZ | RLE_TYPE | NONE} | 
        COMPRESSLEVEL={0-9} | BLOCKSIZE={8192-2097152}
       </para>
       <para>
       For more information on the compression and blocksize parameters, see the
       "Storage Directives for Column-level Compression" in the Greenplum
       Database Administrator Guide.
       </para>
      </listitem>
     </varlistentry>

    </variablelist>
   </para>
  </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   To change the schema of the user-defined type <literal>email</literal>
   to <literal>customers</literal>:
   <programlisting>
ALTER TYPE email SET SCHEMA customers;
   </programlisting>
  </para>

  <para>
   To change the type int to have ZLIB column compression:
   <programlisting>
ALTER TYPE int SET DEFAULT ENCODING (COMPRESSTYPE=ZLIB);
   </programlisting>
  </para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>
    
  <para>
   There is no <command>ALTER TYPE</command> statement in the SQL
   standard.
  </para>
 </refsect1>
</refentry>