Function ExecGetTriggerOldSlot

src/backend/executor/execUtils.c:1223–1240

* Return a relInfo's tuple slot for a trigger's OLD tuples. */

 * Return a relInfo's tuple slot for a trigger's OLD tuples.
 */
TupleTableSlot *
ExecGetTriggerOldSlot(EState *estate, ResultRelInfo *relInfo)
{
	if (relInfo->ri_TrigOldSlot == NULL)
	{
		Relation	rel = relInfo->ri_RelationDesc;
		MemoryContext oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);

		relInfo->ri_TrigOldSlot =
			ExecInitExtraTupleSlot(estate,
								   RelationGetDescr(rel),
								   table_slot_callbacks(rel));

		MemoryContextSwitchTo(oldcontext);
	}

	return relInfo->ri_TrigOldSlot;
}

/*
 * Return a relInfo's tuple slot for a trigger's NEW tuples.