<!--
doc/src/sgml/ref/alter_aggregate.sgml
PostgreSQL documentation
-->

<refentry id="sql-alteraggregate">
 <indexterm zone="sql-alteraggregate">
  <primary>ALTER AGGREGATE</primary>
 </indexterm>

 <refmeta>
  <refentrytitle>ALTER AGGREGATE</refentrytitle>
  <manvolnum>7</manvolnum>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>ALTER AGGREGATE</refname>
  <refpurpose>change the definition of an aggregate function</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
ALTER AGGREGATE <replaceable>name</replaceable> ( <replaceable>aggregate_signature</replaceable> ) RENAME TO <replaceable>new_name</replaceable>
ALTER AGGREGATE <replaceable>name</replaceable> ( <replaceable>aggregate_signature</replaceable> )
                OWNER TO { <replaceable>new_owner</replaceable> | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
ALTER AGGREGATE <replaceable>name</replaceable> ( <replaceable>aggregate_signature</replaceable> ) SET SCHEMA <replaceable>new_schema</replaceable>

<phrase>where <replaceable>aggregate_signature</replaceable> is:</phrase>

* |
[ <replaceable>argmode</replaceable> ] [ <replaceable>argname</replaceable> ] <replaceable>argtype</replaceable> [ , ... ] |
[ [ <replaceable>argmode</replaceable> ] [ <replaceable>argname</replaceable> ] <replaceable>argtype</replaceable> [ , ... ] ] ORDER BY [ <replaceable>argmode</replaceable> ] [ <replaceable>argname</replaceable> ] <replaceable>argtype</replaceable> [ , ... ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>ALTER AGGREGATE</command> changes the definition of an
   aggregate function.
  </para>

  <para>
   You must own the aggregate function to use <command>ALTER AGGREGATE</command>.
   To change the schema of an aggregate function, you must also have
   <literal>CREATE</literal> privilege on the new schema.
   To alter the owner, you must be able to <literal>SET ROLE</literal> to the
   new owning role, and that role must have <literal>CREATE</literal>
   privilege on the aggregate function's schema.
   (These restrictions enforce that altering
   the owner doesn't do anything you couldn't do by dropping and recreating
   the aggregate function.  However, a superuser can alter ownership of any
   aggregate function anyway.)
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><replaceable class="parameter">name</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of an existing aggregate function.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">argmode</replaceable></term>

    <listitem>
     <para>
      The mode of an argument: <literal>IN</literal> or <literal>VARIADIC</literal>.
      If omitted, the default is <literal>IN</literal>.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">argname</replaceable></term>

    <listitem>
     <para>
      The name of an argument.
      Note that <command>ALTER AGGREGATE</command> does not actually pay
      any attention to argument names, since only the argument data
      types are needed to determine the aggregate function's identity.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">argtype</replaceable></term>
    <listitem>
     <para>
      An input data type on which the aggregate function operates.
      To reference a zero-argument aggregate function, write <literal>*</literal>
      in place of the list of argument specifications.
      To reference an ordered-set aggregate function, write
      <literal>ORDER BY</literal> between the direct and aggregated argument
      specifications.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">new_name</replaceable></term>
    <listitem>
     <para>
      The new name of the aggregate function.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">new_owner</replaceable></term>
    <listitem>
     <para>
      The new owner of the aggregate function.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">new_schema</replaceable></term>
    <listitem>
     <para>
      The new schema for the aggregate function.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Notes</title>

   <para>
    The recommended syntax for referencing an ordered-set aggregate
    is to write <literal>ORDER BY</literal> between the direct and aggregated
    argument specifications, in the same style as in
    <link linkend="sql-createaggregate"><command>CREATE AGGREGATE</command></link>.  However, it will also work to
    omit <literal>ORDER BY</literal> and just run the direct and aggregated
    argument specifications into a single list.  In this abbreviated form,
    if <literal>VARIADIC "any"</literal> was used in both the direct and
    aggregated argument lists, write <literal>VARIADIC "any"</literal> only once.
   </para>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   To rename the aggregate function <literal>myavg</literal> for type
   <type>integer</type> to <literal>my_average</literal>:
<programlisting>
ALTER AGGREGATE myavg(integer) RENAME TO my_average;
</programlisting>
  </para>

  <para>
   To change the owner of the aggregate function <literal>myavg</literal> for type
   <type>integer</type> to <literal>joe</literal>:
<programlisting>
ALTER AGGREGATE myavg(integer) OWNER TO joe;
</programlisting>
  </para>

  <para>
   To move the ordered-set aggregate <literal>mypercentile</literal> with
   direct argument of type <type>float8</type> and aggregated argument
   of type <type>integer</type> into schema <literal>myschema</literal>:
<programlisting>
ALTER AGGREGATE mypercentile(float8 ORDER BY integer) SET SCHEMA myschema;
</programlisting>
   This will work too:
<programlisting>
ALTER AGGREGATE mypercentile(float8, integer) SET SCHEMA myschema;
</programlisting></para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   There is no <command>ALTER AGGREGATE</command> statement in the SQL
   standard.
  </para>
 </refsect1>

 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="sql-createaggregate"/></member>
   <member><xref linkend="sql-dropaggregate"/></member>
  </simplelist>
 </refsect1>
</refentry>