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From: Amit Langote <amitlangote09@gmail.com>
Date: Fri, 27 Mar 2026 16:09:07 +0900
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 <CA+HiwqFT0fPPoYBr0iUFWNB-Og7bEXB9hB=6ogk_qD9=OM8Vbw@mail.gmail.com>
Subject: Re: pgsql: Doc: add information about partition locking
To: David Rowley <drowley@postgresql.org>
Cc: pgsql-committers@lists.postgresql.org
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Hi David,

On Wed, Apr 2, 2025 at 10:03=E2=80=AFAM David Rowley <drowley@postgresql.or=
g> wrote:
>
> Doc: add information about partition locking
>
> The documentation around locking of partitions for the executor startup
> phase of run-time partition pruning wasn't clear about which partitions
> were being locked.  Fix that.
>
> Reviewed-by: Tender Wang <tndrwang@gmail.com>
> Discussion: https://postgr.es/m/CAApHDvp738G75HfkKcfXaf3a8s%3D6mmtOLh46tM=
D0D2hAo1UCzA%40mail.gmail.com
> Backpatch-through: 13
>
> Branch
> ------
> master
>
> Details
> -------
> https://git.postgresql.org/pg/commitdiff/121d774caea4c93c8b36fb20a17ef774=
e60894d6

-       <command>EXPLAIN</command> output.
+       <command>EXPLAIN</command> output.  The query planner obtains locks=
 for
+       all partitions which are part of the plan.  However, when the execu=
tor
+       uses a cached plan, locks are only obtained on the partitions which
+       remain after partition pruning done during the initialization phase=
 of
+       execution, i.e., the ones shown in the <command>EXPLAIN</command>
+       output and not the ones referred to by the
+       <quote>Subplans Removed</quote> property.
       </para>
      </listitem>

This text was correct when committed, but became incorrect after I
reverted 525392d57 in May 2025. Sorry for not catching it sooner.

I think we should change the text in both master and REL_18_STABLE to
match what you added in the older branches.  I can change it back to
this when we get pruning-aware locking again.

--=20
Thanks, Amit Langote