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pgsql: Propagate disabled_nodes to single-child Append paths 3+ messages / 1 participants [nested] [flat]
* pgsql: Propagate disabled_nodes to single-child Append paths @ 2026-08-28 06:06 Richard Guo <rguo@postgresql.org> 0 siblings, 0 replies; 3+ messages in thread From: Richard Guo @ 2026-08-28 06:06 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org 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 <zengman@halodbtech.com> Author: Tender Wang <tndrwang@gmail.com> Reviewed-by: Richard Guo <guofenglinux@gmail.com> Reviewed-by: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/CAHewXNm_Zx5EDoaD7wo7bq6cfRroNznS+RBCzT_p2-CWQXpgSw@mail.gmail.com Backpatch-through: 18 Branch ------ REL_19_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/15ccc2041ee864cccc8b72de4a1f21e9b51ccc47 Modified Files -------------- src/backend/optimizer/util/pathnode.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) ^ permalink raw reply [nested|flat] 3+ messages in thread
* pgsql: Propagate disabled_nodes to single-child Append paths @ 2026-08-28 06:06 Richard Guo <rguo@postgresql.org> 0 siblings, 0 replies; 3+ messages in thread From: Richard Guo @ 2026-08-28 06:06 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org 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 <zengman@halodbtech.com> Author: Tender Wang <tndrwang@gmail.com> Reviewed-by: Richard Guo <guofenglinux@gmail.com> Reviewed-by: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/CAHewXNm_Zx5EDoaD7wo7bq6cfRroNznS+RBCzT_p2-CWQXpgSw@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(-) ^ permalink raw reply [nested|flat] 3+ messages in thread
* pgsql: Propagate disabled_nodes to single-child Append paths @ 2026-08-28 06:06 Richard Guo <rguo@postgresql.org> 0 siblings, 0 replies; 3+ messages in thread From: Richard Guo @ 2026-08-28 06:06 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org 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 <zengman@halodbtech.com> Author: Tender Wang <tndrwang@gmail.com> Reviewed-by: Richard Guo <guofenglinux@gmail.com> Reviewed-by: David Rowley <dgrowleyml@gmail.com> Discussion: https://postgr.es/m/CAHewXNm_Zx5EDoaD7wo7bq6cfRroNznS+RBCzT_p2-CWQXpgSw@mail.gmail.com Backpatch-through: 18 Branch ------ REL_18_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/718f281672a91856f0d241aa5602d4d14f055a93 Modified Files -------------- src/backend/optimizer/util/pathnode.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) ^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2026-08-28 06:06 UTC | newest] Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2026-08-28 06:06 pgsql: Propagate disabled_nodes to single-child Append paths Richard Guo <rguo@postgresql.org> 2026-08-28 06:06 pgsql: Propagate disabled_nodes to single-child Append paths Richard Guo <rguo@postgresql.org> 2026-08-28 06:06 pgsql: Propagate disabled_nodes to single-child Append paths Richard Guo <rguo@postgresql.org>
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