Thread

Re: Try a presorted outer path when referenced by an ORDER BY prefix

Zsolt Parragi <zsolt.parragi@percona.com> — 2026-05-13T14:03:28Z

Hello!

+		NestLoopState  *nlstate = (NestLoopState *) child_node;
+		JoinType		jointype = nlstate->js.jointype;
+
+		if (jointype == JOIN_LEFT)

Isn't a `nlstate->js.ps.qual == NULL` missing from here?

CREATE TABLE outer_t (id int, k int, payload text);
CREATE TABLE inner_t (id int, fk int, val int);
INSERT INTO outer_t
SELECT g, g, 'row_' || g FROM generate_series(1, 200) g;
INSERT INTO inner_t
SELECT g, g, g FROM generate_series(1, 200) g;
SET enable_hashjoin = off;
SET enable_mergejoin = off;
SET enable_material = off;
SELECT o.id, i.val
FROM outer_t o
LEFT JOIN inner_t i ON o.k = i.fk
WHERE (i.val IS NULL OR i.val > 50)
ORDER BY o.id
LIMIT 10;

+		else if (jointype == JOIN_RIGHT)
+			ExecSetTupleBound(tuples_needed, innerPlanState(child_node));

Is this branch reachable? If I follow the code correctly, it can't
happen with create_nestloop_path.

pg_plan_advice also has test failures with the patch applied.