| From: | Chengpeng Yan <chengpeng_yan(at)Outlook(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, David Rowley <dgrowleyml(at)gmail(dot)com> |
| Subject: | Re: Unfortunate pushing down of expressions below sort |
| Date: | 2026-02-11 14:17:01 |
| Message-ID: | 13636E54-C27A-4A49-926D-B9E3EBAA8A10@Outlook.com |
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| Thread: | |
| Lists: | pgsql-hackers |
Hi,
I've attached v2 of the patch.
Changes since v1:
- No planner logic changes.
- Fixed one regression-test fallout in contrib/postgres_fdw by updating
expected EXPLAIN output. With the planner change, the deparsed remote
SQL can omit a redundant constant there, so GROUP BY positional
references shift accordingly; query results are unchanged.
Behavior is unchanged from v1:
- Postpone additional non-sort target expressions only when doing so
does not require carrying any extra Vars/PlaceHolderVars through Sort.
- Existing volatile/SRF/expensive-expression behavior is unchanged.
Validation:
- make check-world passes.
Would especially appreciate feedback on whether the “no extra Vars/PHVs
through sort” rule is the right safety boundary.
Thanks!
--
Best regards,
Chengpeng Yan
| Attachment | Content-Type | Size |
|---|---|---|
| v2-0001-planner-postpone-some-non-sort-output-expressions.patch | application/octet-stream | 21.2 KB |
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