update action, you must have the
   <literal>UPDATE</literal> privilege on the column(s)
   of the target table
   that are referred to in the <literal>SET</literal> clause.
   If you specify an insert action, you must have the <literal>INSERT</literal>
   privilege on the target table.
   If you specify a delete action, you must have the <literal>DELETE</literal>
   privilege on the target table.
   If you specify a <literal>DO NOTHING</literal> action, you must have
   the <literal>SELECT</literal> privilege on at least one column
   of the target table.
   You will also need <literal>SELECT</literal> privilege on any column(s)
   of the <replaceable class="parameter">data_source</replaceable> and
   of the target table referred to
   in any <literal>condition</literal> (including <literal>join_condition</literal>)
   or <literal>expression</literal>.
   Privileges are tested once at statement start and are checked
   whether or not particular <literal>WHEN</literal> clauses are executed.
  </para>

  <para>
   <command>MERGE</command> is not supported if the
   target table is a
   materialized view, foreign table, or if it has any
   rules defined on it.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><replaceable class="parameter">with_query</replaceable></term>
    <listitem>
     <para>
      The <literal>WITH</literal> clause allows you to specify one or more
      subqueries that can be referenced by name in the <command>MERGE</command>
      query. See <xref linkend="queries-with"/> and <xref linkend="sql-select"/>
      for details.  Note that <literal>WITH RECURSIVE</literal> is not supported
      by <command>MERGE</command>.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">target_table_name</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of the target table or view to
      merge into.  If <literal>ONLY</literal> is specified before a table
      name, matching rows are updated or deleted in the named table only.  If
      <literal>ONLY</literal> is not specified, matching rows are also updated
      or deleted in any tables inheriting from the named table.  Optionally,
      <literal>*</literal> can be specified after the table name to explicitly
      indicate that descendant tables are included.  The
      <literal>ONLY</literal> keyword and <literal>*</literal> option do not
      affect insert actions, which always insert into the named table only.
     </para>

     <para>
      If <replaceable class="parameter">target_table_name</replaceable> is a
      view, it must either be automatically updatable with no
      <literal>INSTEAD OF</literal> triggers, or it must have
      <literal>INSTEAD OF</literal> triggers for every type of action
      (<literal>INSERT</literal>, <literal>UPDATE</literal>, and
      <literal>DELETE</literal>) specified in the <literal>WHEN</literal>
      clauses.  Views with rules are not supported.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">target_alias</replaceable></term>
    <listitem>
     <para>
      A substitute name for the target table. When an alias is
      provided, it completely hides the actual name of the table.  For
      example, given <literal>MERGE INTO foo AS f</literal>, the remainder of the
      <command>MERGE</command> statement must refer to this table as
      <literal>f</literal> not <literal>foo</literal>.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">source_table_name</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of the source table, view, or
      transition table.  If <literal>ONLY</literal> is specified before the
      table name, matching rows are included from the named table only.  If
      <literal>ONLY</literal>