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

<refentry id="SQL-ALTERPOLICY">
 <indexterm zone="sql-alterpolicy">
  <primary>ALTER POLICY</primary>
 </indexterm>

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

 <refnamediv>
  <refname>ALTER POLICY</refname>
  <refpurpose>change the definition of a policy</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
ALTER POLICY <replaceable class="parameter">name</replaceable> ON <replaceable class="parameter">table_name</replaceable>
    [ RENAME TO <replaceable class="PARAMETER">new_name</replaceable> ]
    [ TO { <replaceable class="parameter">role_name</replaceable> | PUBLIC | CURRENT_USER | SESSION_USER } [, ...] ]
    [ USING ( <replaceable class="parameter">using_expression</replaceable> ) ]
    [ WITH CHECK ( <replaceable class="parameter">check_expression</replaceable> ) ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>ALTER POLICY</command> changes the <replaceable class="parameter">
   definition</replaceable> of an existing policy.
  </para>

  <para>
   To use <command>ALTER POLICY</command>, you must own the table that
   the policy applies to.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><replaceable class="parameter">name</replaceable></term>
    <listitem>
     <para>
      The name of an existing policy to alter.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">table_name</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of the table that the
      policy is on.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">new_name</replaceable></term>
    <listitem>
     <para>
      The new name for the policy.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">role_name</replaceable></term>
    <listitem>
     <para>
      The role to which the policy applies.  Multiple roles can be specified at one time.
      To apply the policy to all roles, use <literal>PUBLIC</literal>, which is also
      the default.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">using_expression</replaceable></term>
    <listitem>
     <para>
      The USING expression for the policy.  This expression will be added as a
      security-barrier qualification to queries which use the table
      automatically.  If multiple policies are being applied for a given
      table then they are all combined and added using OR.  The USING
      expression applies to records which are being retrieved from the table.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">check_expression</replaceable></term>
    <listitem>
     <para>
      The with-check expression for the policy.  This expression will be
      added as a WITH CHECK OPTION qualification to queries which use the
      table automatically.  If multiple policies are being applied for a
      given table then they are all combined and added using OR.  The WITH
      CHECK expression applies to records which are being added to the table.
     </para>
    </listitem>
   </varlistentry>

  </variablelist>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   <command>ALTER POLICY</command> is a <productname>PostgreSQL</productname> extension.
  </para>
 </refsect1>

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

  <simplelist type="inline">
   <member><xref linkend="sql-createpolicy"></member>
   <member><xref linkend="sql-droppolicy"></member>
  </simplelist>
 </refsect1>

</refentry>
