Function ExecLimit

src/backend/executor/nodeLimit.c:351–370

}

static TupleTableSlot *
ExecLimit(PlanState *node)
{
	TupleTableSlot *result;

	result = ExecLimit_guts(node);

	if (TupIsNull(result) && ScanDirectionIsForward(node->state->es_direction) &&
		!((LimitState *) node)->expect_rescan)
	{
		/*
		 * CDB: We'll read no more from inner subtree. To keep our sibling
		 * QEs from being starved, tell source QEs not to clog up the
		 * pipeline with our never-to-be-consumed data.
		 */
		ExecSquelchNode(node, false);
	}

	return result;
}

/*
 * Evaluate the limit/offset expressions --- done at startup or rescan.