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From: John Naylor <johncnaylorls@gmail.com>
Date: Mon, 22 Jun 2026 16:51:23 +0700
Message-ID: 
 <CANWCAZaQ8sxPy2w0zWExnJXsK9t0y4AAxhENz3mhaO1Z2wdFoA@mail.gmail.com>
Subject: Re: BUG #19530: Crash (SIGSEGV/SIGBUS) in parallel B-tree index
 vacuum during plain VACUUM
To: webmaster@algedi.pl, pgsql-bugs@lists.postgresql.org
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On Mon, Jun 22, 2026 at 3:19=E2=80=AFPM PG Bug reporting form
<noreply@postgresql.org> wrote:
> PostgreSQL 17.7 intermittently crashes a parallel maintenance worker duri=
ng
> routine VACUUM, taking the server through automatic crash recovery each
>   time.

>   What the crashing process was doing:
>   The crashing process is a parallel maintenance worker. A preserved core
> dump shows the process title "parallel worker for PID <leader>", with mem=
ory
>   contexts "BTree Vacuum State" and "AutoVacuum Data" present and no

This doesn't really give us any actionable info. Are you able to get a
backtrace from the core dump?

(Autovacuum in v17 cannot use parallel workers, so I'm not sure where
that came from)

>   Possibly related:
>   This appears to reach the same btbulkdelete / btvacuumscan code as the
> report "Segmentation fault in PostgreSQL 17.7 during REINDEX TABLE
>   CONCURRENTLY"
> (https://www.postgresql.org/message-id/VI0PR07MB10718A4DC292E068C51404AB2=
974EA@VI0PR07MB10718.eurprd07.prod.outlook.com),
> but reached
>   via the plain-VACUUM index-vacuum path rather than validate_index /
> ReindexRelationConcurrently. That suggests the fault is in the (parallel)
> B-tree
>   index-vacuum code, reachable from both paths.

That operation was writing TIDs to a file, which is not what vacuum
does, and it's not clear from that thread whether there's a bug in the
first place.

--
John Naylor
Amazon Web Services