Function EvalPlanQualSlot

src/backend/executor/execMain.c:3731–3751

* Return, and create if necessary, a slot for an EPQ test tuple. * * Note this only requires EvalPlanQualInit() to have been called, * EvalPlanQualBegin() is not necessary. */

 * EvalPlanQualBegin() is not necessary.
 */
TupleTableSlot *
EvalPlanQualSlot(EPQState *epqstate,
				 Relation relation, Index rti)
{
	TupleTableSlot **slot;

	Assert(relation);
	Assert(rti > 0 && rti <= epqstate->parentestate->es_range_table_size);
	slot = &epqstate->relsubs_slot[rti - 1];

	if (*slot == NULL)
	{
		MemoryContext oldcontext;

		oldcontext = MemoryContextSwitchTo(epqstate->parentestate->es_query_cxt);
		*slot = table_slot_create(relation, &epqstate->tuple_table);
		MemoryContextSwitchTo(oldcontext);
	}

	return *slot;
}

/*
 * Fetch the current row value for a non-locked relation, identified by rti,