| From: | Maxim Orlov <orlovmg(at)gmail(dot)com> |
|---|---|
| To: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
| Cc: | wenhui qiu <qiuwenhuifx(at)gmail(dot)com>, Alexander Korotkov <aekorotkov(at)gmail(dot)com>, Postgres hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: POC: make mxidoff 64 bits |
| Date: | 2025-01-07 10:23:59 |
| Message-ID: | CACG=ezZwdvsijzuXE3hex3xHcoz75EQYBXRTsQJVwbo5J5sS3g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, 2 Jan 2025 at 01:12, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
>
> It might be best to just refuse the upgrade if oldestOffsetKnown==false.
> It's a very ancient corner case. It seems reasonable to require you to
> upgrade to a newer minor version and run VACUUM before upgrading. IIRC
> that sets oldestOffsetKnown.
>
I agree. After all, we do already have a ready-made solution in the form
of a vacuum, do we?
If I understand all this multixact_old.c machinery correctly, in case of
oldestOffsetKnown==false
we should fail with "could not open file" or offset will be 0 in
GetOldMultiXactIdSingleMember.
So, I suppose we can put an analogue of SimpleLruDoesPhysicalPageExist call
in the beginning
of GetOldMultiXactIdSingleMember. And if either
SimpleLruDoesPhysicalPageExist return false
or a corresponding offset will be 0 we have to bail out with "oldest offset
does not exist, consider
running vacuum before pg_upgrdade" or smth. Please, correct me if I'm wrong.
--
Best regards,
Maxim Orlov.
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