Re: BRIN autosummarization lacking a snapshot

Michael Paquier <michael@paquier.xyz>

From: Michael Paquier <michael@paquier.xyz>

To: Álvaro Herrera <alvherre@kurilemu.de>

Cc: Pg Hackers <pgsql-hackers@lists.postgresql.org>

Date: 2025-11-04T05:38:01Z

Lists: pgsql-hackers

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Fix snapshot handling bug in recent BRIN fix
- ef81697fee77 13.23 landed
- bcfbd3f747d7 15.15 landed
- 8733f0b54c05 18.1 landed
- 65b0d1f74098 14.20 landed
- 3b5007347b5d 17.7 landed
- 20442cf5075d 16.11 landed
- 0a3d27bfe0fb 19 (unreleased) landed
BRIN autosummarization may need a snapshot
- f4b68b0336bd 17.7 landed
- f0ad41716197 14.20 landed
- a95e3d84c0e0 19 (unreleased) landed
- 6ef33c8051dd 16.11 landed
- 419ffde23546 18.1 landed
- 3c7b47974ec7 13.23 landed
- 23ddadf6835e 15.15 landed

On Mon, Nov 03, 2025 at 12:21:50PM +0100, Alvaro Herrera wrote:
> This patch fixes it.  I haven't given much thought to adding a good way
> to test this yet ...

Spawning an autovacuum worker can feel artistic as we try to make the
tests run fast, but it's not that bad.  The trick is to use an
"autovacuum_naptime = 1".  Then you could either scan the server logs
for some 'autovacuum: processing database "blah"', or just a polling
query based on pg_stat_all_tables.autovacuum_count.  See for example
006_signal_autovacuum.pl.
--
Michael