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 C44AF20B-7AA3-42A6-B30D-08DEFD2E3F8C@yandex-team.ru
Whole thread Raw
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 18:14, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
>
> Zeroing the page again is dangerous because the CREATE_ID records can be out of order. The page might already contain
somelater multixids, and zeroing will overwrite them. 

I see only cases when it's not a problem: we zeroed page, did not flush it, thus did not extend the file, crashed,
testedFS, zeroed page once more, overwrote again by replaying WAL, no big deal. 
We should never zero a page with offsets, that will not be replayed by WAL.

If the page was persisted, even partially, we will read it from disk without zeroing out.


Best regards, Andrey Borodin.


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