Re: BUG #19530: Crash (SIGSEGV/SIGBUS) in parallel B-tree index vacuum during plain VACUUM

On Mon, Jun 22, 2026 at 3:19 PM PG Bug reporting form
<noreply(at)postgresql(dot)org> wrote:
> PostgreSQL 17.7 intermittently crashes a parallel maintenance worker during
> 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 memory
> 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/VI0PR07MB10718A4DC292E068C51404AB2974EA@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