| From: | Antonin Houska <ah(at)cybertec(dot)at> |
|---|---|
| To: | Mihail Nikalayeu <mihailnikalayeu(at)gmail(dot)com> |
| Cc: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, Srinath Reddy Sadipiralla <srinath2133(at)gmail(dot)com>, Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Robert Treat <rob(at)xzilla(dot)net> |
| Subject: | Re: Adding REPACK [concurrently] |
| Date: | 2026-04-09 09:26:29 |
| Message-ID: | 10697.1775726789@localhost |
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| Lists: | pgsql-hackers |
Mihail Nikalayeu <mihailnikalayeu(at)gmail(dot)com> wrote:
> On Thu, Apr 9, 2026 at 10:43 AM Antonin Houska <ah(at)cybertec(dot)at> wrote:
> > This approach LGTM when it comes to concurrent DDLs. However, consider REPACK
> > holding ShareUpdateExclusiveLock (SUEL) and VACUUM (w/o VACOPT_SKIP_LOCKED)
> > waiting for the same lock. Once REPACK releases its SUEL, VACUUM gets it and
> > processes the table, then REPACK finally gets AccessExclusiveLock (AEL) and
> > finishes too.
>
> > One more thing we may prevent from sneaking into that hole is a
> > VACUUM. It will not break anything, but will be huge waste of time and
> > resources.
>
>
> I thought about that too, I think we may just add some kind of
> CheckTableNotInUse in VACUUM after getting the SUEL.
Sure, it's possible, but IMO the principal question is whether REPACK should
let VACUUM and DDLs error out, or just let them wait.
--
Antonin Houska
Web: https://www.cybertec-postgresql.com
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