the <command>EXPLAIN ANALYZE</command>
     case.
    </para>

    <para>
     If the <function>IterateDirectModify</function> pointer is set to
     <literal>NULL</literal>, no attempts to execute a direct modification on the
     remote server are taken.
    </para>

    <para>
<programlisting>
void
EndDirectModify(ForeignScanState *node);
</programlisting>

     Clean up following a direct modification on the remote server.  It is
     normally not important to release palloc'd memory, but for example open
     files and connections to the remote server should be cleaned up.
    </para>

    <para>
     If the <function>EndDirectModify</function> pointer is set to
     <literal>NULL</literal>, no attempts to execute a direct modification on the
     remote server are taken.
    </para>

   </sect2>

   <sect2 id="fdw-callbacks-truncate">
    <title>FDW Routines for <command>TRUNCATE</command></title>

    <para>
<programlisting>
void
ExecForeignTruncate(List *rels,
                    DropBehavior behavior,
                    bool restart_seqs);
</programlisting>

     Truncate foreign tables.  This function is called when
     <xref linkend="sql-truncate"/> is executed on a foreign table.
     <literal>rels</literal> is a list of <structname>Relation</structname>
     data structures of foreign tables to truncate.
    </para>

    <para>
     <literal>behavior</literal> is either <literal>DROP_RESTRICT</literal>
     or <literal>DROP_CASCADE</literal> indicating that the
     <literal>RESTRICT</literal> or <literal>CASCADE</literal> option was
     requested in the original <command>TRUNCATE</command> command,
     respectively.
    </para>

    <para>
     If <literal>restart_seqs</literal> is <literal>true</literal>,
     the original <command>TRUNCATE</command> command requested the
     <literal>RESTART IDENTITY</literal> behavior, otherwise the
     <literal>CONTINUE IDENTITY</literal> behavior was requested.
    </para>

    <para>
     Note that the <literal>ONLY</literal> options specified
     in the original <command>TRUNCATE</command> command are not passed to
     <function>ExecForeignTruncate</function>.  This behavior is similar to
     the callback functions of <command>SELECT</command>,
     <command>UPDATE</command> and <command>DELETE</command> on
     a foreign table.
    </para>

    <para>
     <function>ExecForeignTruncate</function> is invoked once per
     foreign server for which foreign tables are to be truncated.
     This means that all foreign tables included in <literal>rels</literal>
     must belong to the same server.
    </para>

    <para>
     If the <function>ExecForeignTruncate</function> pointer is set to
     <literal>NULL</literal>, attempts to truncate foreign tables will
     fail with an error message.
    </para>
   </sect2>

   <sect2 id="fdw-callbacks-row-locking">
    <title>FDW Routines for Row Locking</title>

    <para>
     If an FDW wishes to support <firstterm>late row locking</firstterm> (as described
     in <xref linkend="fdw-row-locking"/>), it must provide the following
     callback functions:
    </para>

    <para>
<programlisting>
RowMarkType
GetForeignRowMarkType(RangeTblEntry *rte,
                      LockClauseStrength strength);
</programlisting>

     Report which row-marking option to use for a foreign table.
     <literal>rte</literal> is the <structname>RangeTblEntry</structname> node for the table
     and <literal>strength</literal> describes the lock strength requested by the
     relevant <literal>FOR UPDATE/SHARE</literal> clause, if any.  The result must be
     a member of the <literal>RowMarkType</literal> enum type.
    </para>

    <para>
     This function is called during query planning for each foreign table that
     appears in an <command>UPDATE</command>, <command>DELETE</command>, or <command>SELECT
     FOR UPDATE/SHARE</command> query and is not the target of <command>UPDATE</command>
     or <command>DELETE</command>.
    </para>