| From: | Richard Guo <guofenglinux(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Matheus Alcantara <matheusssilv97(at)gmail(dot)com>, leis(at)in(dot)tum(dot)de, pgsql-bugs(at)lists(dot)postgresql(dot)org |
| Subject: | Re: BUG #19553: Wrong results from nested LEFT JOINs over an empty subquery (regression since v16) |
| Date: | 2026-07-20 02:33:23 |
| Message-ID: | CAMbWs49H275KzgZr3Cd1Hy+6Lmwp35bZ+5PrVc62k3HDLj6hNQ@mail.gmail.com |
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| Lists: | pgsql-bugs |
On Sun, Jul 19, 2026 at 3:11 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Pushed.
It occurred to me that we can skip the new get_relids_in_jointree()
scan altogether when there are no PHVs anywhere in the query
(root->glob->lastPHId==0), since then the find_dependent_phvs() checks
are no-ops anyway. This is also consistent with how we check
root->glob->lastPHId in find_dependent_phvs() and
find_dependent_phvs_in_jointree(). Attached is a trivial patch doing
that.
- Richard
| Attachment | Content-Type | Size |
|---|---|---|
| v1-0001-Skip-unnecessary-get_relids_in_jointree-when-ther.patch | application/octet-stream | 2.9 KB |
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