Function ExecSetOp

src/backend/executor/nodeSetOp.c:189–221

---------------------------------------------------------------- * ExecSetOp * ---------------------------------------------------------------- */

 * ----------------------------------------------------------------
 */
static TupleTableSlot *			/* return: a tuple or NULL */
ExecSetOp(PlanState *pstate)
{
	SetOpState *node = castNode(SetOpState, pstate);
	SetOp	   *plannode = (SetOp *) node->ps.plan;
	TupleTableSlot *resultTupleSlot = node->ps.ps_ResultTupleSlot;

	CHECK_FOR_INTERRUPTS();

	/*
	 * If the previously-returned tuple needs to be returned more than once,
	 * keep returning it.
	 */
	if (node->numOutput > 0)
	{
		node->numOutput--;
		return resultTupleSlot;
	}

	/* Otherwise, we're done if we are out of groups */
	if (node->setop_done)
		return NULL;

	/* Fetch the next tuple group according to the correct strategy */
	if (plannode->strategy == SETOP_HASHED)
	{
		if (!node->table_filled)
			setop_fill_hash_table(node);
		return setop_retrieve_hash_table(node);
	}
	else
		return setop_retrieve_direct(node);
}

/*
 * ExecSetOp for non-hashed case