Re: Add 64-bit XIDs into PostgreSQL 15

On Tue, Nov 22, 2022 at 7:44 PM Aleksander Alekseev
<aleksander(at)timescale(dot)com> wrote:
>
> Hi hackers,
>
> [ Excluding my personal e-mail from cc:, not sure how it got there.
> Please don't cc: to afiskon(at)gmail(dot)com, I'm not using it for reading
> pgsql-hackers(at)(dot) ]
>
> > I agree with Alexander, that notifications for DBA are a little bit
> > outside the scope of the activity in this thread unless we've just
> > dropped some existing notifications, considering they're not
> > significant anymore. If that was the point, please Chris mention what
> > existing notifications you want to return. I don't think it's a big
> > deal to have the patch with certain notifications inherited from
> > Master branch.
>
> To clarify a bit: currently we DO notify the user about the upcoming
> wraparound point [1]:
>
> """
> If for some reason autovacuum fails to clear old XIDs from a table,
> the system will begin to emit warning messages like this when the
> database's oldest XIDs reach forty million transactions from the
> wraparound point:
>
> WARNING: database "mydb" must be vacuumed within 39985967 transactions
> HINT: To avoid a database shutdown, execute a database-wide VACUUM in
> that database.
> """
>
> So I'm not sure how the notification Chris proposes should differ or
> why it is in scope of this patch. If the point was to make sure
> certain existing notifications will be preserved - sure, why not.

IMHO, after having 64-bit XID this WARNING doesn't really make sense.
Those warnings exist because those limits were problematic for 32-bit
xid but now it is not so I think we should not have such warnings.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com