Horton

Re: BUG #17485: Records missing from Primary Key index when doing REINDEX INDEX CONCURRENTLY

x4mmm@yandex-team.ru

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From: Andrey Borodin <x4mmm@yandex-team.ru>
To: Andres Freund <andres@anarazel.de>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Peter Geoghegan <pg@bowt.ie>, Michael Paquier <michael@paquier.xyz>, Петър Славов <pet.slavov@gmail.com>, PostgreSQL mailing lists <pgsql-bugs@lists.postgresql.org>
Date: 2022-05-24T18:38:07Z
Lists: pgsql-bugs 

> On 24 May 2022, at 23:15, Andres Freund <andres@anarazel.de> wrote:
> 
> With fsync=on, it's much harder to reproduce.
That exaplains why it's easier to reproduce on MacOS: it seem it ignores fsync.



> On 24 May 2022, at 23:15, Andres Freund <andres@anarazel.de> wrote:
> 
> I suspect the problem might be related to pruning done during the validation
> scan. Once PROC_IN_SAFE_IC is set, the backend itself will not preserve tids
> its own snapshot might need. Which will wreak havoc during the validation
> scan.

I observe that removing PROC_IN_SAFE_IC for index_validate() fixes tests.
But why it's not a problem for index_build() scan?

And I do not understand why it's a problem that tuple is pruned during the scan... How does this "wreak havoc" happen?

Best regards, Andrey Borodin.

Commits

  1. Revert changes to CONCURRENTLY that "sped up" Xmin advance

  2. Fix possible HOT corruption when RECENTLY_DEAD changes to DEAD while pruning.