From 94ee13191828fb883da18471c070039faf1d3cfb Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Thu, 5 Feb 2026 15:23:36 -0500 Subject: [PATCH v55 1/2] Fix add_partial_path interaction with disabled_nodes Commit e22253467942fdb100087787c3e1e3a8620c54b2 adjusted the logic in add_path() to keep the path list sorted by disabled_nodes and then by total_cost, but failed to make the corresponding adjustment to add_partial_path. As a result, add_partial_path might sort the path list just by total cost, which could lead to later planner misbehavior. In principle, this should be back-patched to v18, but we are typically reluctant to back-patch planner fixes for fear of destabilizing working installations, and it is unclear to me that this has sufficiently serious consequences to justify an exception, so for now, no back-patch. --- src/backend/optimizer/util/pathnode.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c index 7b6c5d51e5d..aab2570f159 100644 --- a/src/backend/optimizer/util/pathnode.c +++ b/src/backend/optimizer/util/pathnode.c @@ -878,8 +878,13 @@ add_partial_path(RelOptInfo *parent_rel, Path *new_path) } else { - /* new belongs after this old path if it has cost >= old's */ - if (new_path->total_cost >= old_path->total_cost) + /* + * new belongs after this old path if it has more disabled nodes + * or if it has the same number of nodes but a greater total cost + */ + if (new_path->disabled_nodes > old_path->disabled_nodes || + (new_path->disabled_nodes == old_path->disabled_nodes && + new_path->total_cost >= old_path->total_cost)) insert_at = foreach_current_index(p1) + 1; } -- 2.51.0