Horton

Re: lastOverflowedXid does not handle transaction ID wraparound

Stan Hu <stanhu@gmail.com>

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From: Stan Hu <stanhu@gmail.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Simon Riggs <simon.riggs@enterprisedb.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Andrey Borodin <x4mmm@yandex-team.ru>, Dmitry Dolgov <9erthalion6@gmail.com>, PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Date: 2021-11-03T23:27:35Z
Lists: pgsql-hackers 
Good catch on doing this in ExpireAllKnownAssignedTransactionIds() as well.
Thanks. Looks good to me!

As Nikolay mentioned, I think this is an important bug that we are seeing
in production and would appreciate a backport to v12 if possible.

On Wed, Nov 3, 2021 at 3:07 PM Alexander Korotkov <aekorotkov@gmail.com>
wrote:

> Hi!
>
> On Wed, Nov 3, 2021 at 8:51 PM Simon Riggs <simon.riggs@enterprisedb.com>
> wrote:
> > It is however, an undocumented modularity violation. I think that is
> > acceptable because of the ProcArrayLock traffic, but needs to have a
> > comment to explain this at the call to
> > ExpireOldKnownAssignedTransactionIds() i.e. " and potentially reset
> > lastOverflowedXid", as well as a comment on the
> > ExpireOldKnownAssignedTransactionIds() function.
>
> Thank you for your feedback.  Please find the revised patch attached.
> It incorporates this function comment changes altogether with minor
> editings and commit message. Let me know if you have further
> suggestions.
>
> I'm going to push this if no objections.
>
> ------
> Regards,
> Alexander Korotkov
>

Commits

  1. Reset lastOverflowedXid on standby when needed

  2. Fix variable shadowing in procarray.c.

  3. Move InRecovery and standbyState global vars to xlogutils.c.