<literal>NULL</literal>, no additional plan-time actions are taken, and the
     <literal>fdw_private</literal> list delivered to
     <function>BeginForeignModify</function> will be NIL.
    </para>

    <para>
<programlisting>
void
BeginForeignModify(ModifyTableState *mtstate,
                   ResultRelInfo *rinfo,
                   List *fdw_private,
                   int subplan_index,
                   int eflags);
</programlisting>

     Begin executing a foreign table modification operation.  This routine is
     called during executor startup.  It should perform any initialization
     needed prior to the actual table modifications.  Subsequently,
     <function>ExecForeignInsert/ExecForeignBatchInsert</function>,
     <function>ExecForeignUpdate</function> or
     <function>ExecForeignDelete</function> will be called for tuple(s) to be
     inserted, updated, or deleted.
    </para>

    <para>
     <literal>mtstate</literal> is the overall state of the
     <structname>ModifyTable</structname> plan node being executed; global data about
     the plan and execution state is available via this structure.
     <literal>rinfo</literal> is the <structname>ResultRelInfo</structname> struct describing
     the target foreign table.  (The <structfield>ri_FdwState</structfield> field of
     <structname>ResultRelInfo</structname> is available for the FDW to store any
     private state it needs for this operation.)
     <literal>fdw_private</literal> contains the private data generated by
     <function>PlanForeignModify</function>, if any.
     <literal>subplan_index</literal> identifies which target of
     the <structname>ModifyTable</structname> plan node this is.
     <literal>eflags</literal> contains flag bits describing the executor's
     operating mode for this plan node.
    </para>

    <para>
     Note that when <literal>(eflags &amp; EXEC_FLAG_EXPLAIN_ONLY)</literal> is
     true, this function should not perform any externally-visible actions;
     it should only do the minimum required to make the node state valid
     for <function>ExplainForeignModify</function> and <function>EndForeignModify</function>.
    </para>

    <para>
     If the <function>BeginForeignModify</function> pointer is set to
     <literal>NULL</literal>, no action is taken during executor startup.
    </para>

    <para>
<programlisting>
TupleTableSlot *
ExecForeignInsert(EState *estate,
                  ResultRelInfo *rinfo,
                  TupleTableSlot *slot,
                  TupleTableSlot *planSlot);
</programlisting>

     Insert one tuple into the foreign table.
     <literal>estate</literal> is global execution state for the query.
     <literal>rinfo</literal> is the <structname>ResultRelInfo</structname> struct describing
     the target foreign table.
     <literal>slot</literal> contains the tuple to be inserted; it will match the
     row-type definition of the foreign table.
     <literal>planSlot</literal> contains the tuple that was generated by the
     <structname>ModifyTable</structname> plan node's subplan; it differs from
     <literal>slot</literal> in possibly containing additional <quote>junk</quote>
     columns.  (The <literal>planSlot</literal> is typically of little interest
     for <command>INSERT</command> cases, but is provided for completeness.)
    </para>

    <para>
     The return value is either a slot containing the data that was actually
     inserted (this might differ from the data supplied, for example as a
     result of trigger actions), or NULL if no row was actually inserted
     (again, typically as a result of triggers).  The passed-in
     <literal>slot</literal> can be re-used for this purpose.
    </para>

    <para>
     The data in the returned slot is used only if the <command>INSERT</command>
     statement has a <literal>RETURNING</literal> clause or involves a view
     <literal>WITH CHECK OPTION</literal>; or if the foreign table has
     an <literal>AFTER ROW</literal>