Propagate disabled_nodes to single-child Append paths create_append_path() skips cost_append() when an Append has exactly one child whose parallel awareness matches its own, since setrefs.c strips such an Append out entirely. In that case it copies the child's rowcount and costs directly, but it failed to copy disabled_nodes. An Append over a disabled child therefore claimed to contain no disabled nodes, letting a disabled path win over one that is not disabled.
This is a regression in v18; before e22253467, disable_cost was folded into a path's startup and total costs, so it rode along in the fields this shortcut already copies. Back-patch to v18. This can change plans in stable branches, but only for installations that have explicitly disabled a node type, and only to stop using the node they asked us to avoid. Reported-by: Man Zeng <[email protected]> Author: Tender Wang <[email protected]> Reviewed-by: Richard Guo <[email protected]> Reviewed-by: David Rowley <[email protected]> Discussion: https://postgr.es/m/cahewxnm_zx5edoad7wo7bq6cfrronzns+rbczt_p2-cwqxp...@mail.gmail.com Backpatch-through: 18 Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/de5659440dbcfe0ef61b474cec0e5ec50a9c3841 Modified Files -------------- src/backend/optimizer/util/pathnode.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
