Re: Adding REPACK [concurrently] - Mailing list pgsql-hackers

Mihail Nikalayeu <mihailnikalayeu@gmail.com> wrote:

> On Thu, Apr 9, 2026 at 10:43 AM Antonin Houska <ah@cybertec.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