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Re: VM corruption on standby

Andrey Borodin <x4mmm@yandex-team.ru>

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From: Andrey Borodin <x4mmm@yandex-team.ru>
To: Aleksander Alekseev <aleksander@tigerdata.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Melanie Plageman <melanieplageman@gmail.com>
Date: 2025-08-09T15:53:54Z
Lists: pgsql-hackers 

> On 9 Aug 2025, at 18:28, Andrey Borodin <x4mmm@yandex-team.ru> wrote:
> 
> Also I investigated that in a moment of kill -9 checkpointer flushes heap page to disk despite content lock. I haven't found who released content lock though.

I've written this message and understood: its LWLockReleaseAll().

0. checkpointer is going to flush a heap buffer but waits on content lock
1. client is resetting PD_ALL_VISIBLE from page
2. postmaster is killed and command client to go down
3. client calls LWLockReleaseAll() at ProcKill() (?)
4. checkpointer flushes buffer with reset PG_ALL_VISIBLE that is not WAL-logged to standby
5. subsequent deletes do not log resetting this bit
6. deleted data is observable on standby with IndexOnlyScan

Any idea how to fix this?


Best regards, Andrey Borodin.

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Revert "Get rid of WALBufMappingLock"

  2. Get rid of WALBufMappingLock

  3. Split WaitEventSet functions to separate source file

  4. Add WL_EXIT_ON_PM_DEATH pseudo-event.