Re: Bug in MultiXact replay compat logic for older minor version after crash-recovery - Mailing list pgsql-hackers

From Andrey Borodin
Subject Re: Bug in MultiXact replay compat logic for older minor version after crash-recovery
Date
Msg-id BD37E553-A017-4D2C-8203-702378BF5882@yandex-team.ru
Whole thread
In response to Re: Bug in MultiXact replay compat logic for older minor version after crash-recovery  (Heikki Linnakangas <hlinnaka@iki.fi>)
Responses Re: Bug in MultiXact replay compat logic for older minor version after crash-recovery
List pgsql-hackers

> On 20 Mar 2026, at 16:19, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
>
> Hmm, after startup, before we have zeroed any pages, it still works though. So I think my patch works, but it means
thattracking the latest page we have zeroed is not merely an optimization to avoid excessive
SimpleLruDoesPhysicalPageExist()calls, it's needed for correctness. Need to adjust the comments for that. 

If we are sure buffers have no this page we can detect it via FS.
Otherwise... nothing bad can happen, actually. We might get false positive and zero the page once more.

If we got init_needed==false, maybe cache it for this page and set last_initialized_offsets_page = pageno?
Or, perhaps, XLOG_MULTIXACT_ZERO_OFF_PAGE will do it for us anyway, but a bit later.

Best regards, Andrey Borodin.


pgsql-hackers by date:

Previous
From: Jianghua Yang
Date:
Subject: Re: [PATCH] initdb: Treat empty -U argument as unset username
Next
From: Ashutosh Bapat
Date:
Subject: Re: SQL Property Graph Queries (SQL/PGQ)