Re: LISTEN/NOTIFY bug: VACUUM sets frozenxid past a xid in async queue

29.08.2025 01:31, Matheus Alcantara пишет:
> On Thu Aug 21, 2025 at 8:14 PM -03, Matheus Alcantara wrote:
>> I'll work on this considering the initial Daniil comments at [1]
>>
>> [1] https://www.postgresql.org/message-id/CAJDiXgg1ArRB1-6wLtXfVVnQ38P9Y%2BCDfEc9M2TXiOf_4kfBMg%40mail.gmail.com
>>
> I've been working on this on the last few days, please see the attached
> patch version.
>
> In this new version I tried to follow the suggestion from Daniil of
> scanning all pages from tail to head of the async queue.

Since we still need to scan those pages, couldn't we mark finished
transactions as committed/aborted?
This way we may to not hold datfrozenxid for a long time and will allow
both safe clog truncation and safe async queue notification.
More over, most notifications could be marked as completed in
AtCommit_Notify already. So there is a need to recheck a few notifications
that were written but not marked in AtCommit_Notify.

Since AsyncQueueEntry field is used only to check visibility, looks like it
is safe to set it to FrozenTransactionId.

--
regards
Yura Sokolov aka funny-falcon