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help / color / mirror / Atom feedFrom: Antonin Houska <ah@cybertec.at>
To: Andres Freund <andres@anarazel.de>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Amit Kapila <amit.kapila16@gmail.com>
Cc: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Cc: Srinath Reddy Sadipiralla <srinath2133@gmail.com>
Cc: Matthias van de Meent <boekewurm+postgres@gmail.com>
Cc: Pg Hackers <pgsql-hackers@lists.postgresql.org>
Cc: Robert Treat <rob@xzilla.net>
Subject: Re: Adding REPACK [concurrently]
Date: Tue, 07 Apr 2026 18:01:16 +0200
Message-ID: <230042.1775577676@localhost> (raw)
In-Reply-To: <pveffyxhnuurhb44uzqlwo3rkyzorkfh2rot7uwzlf2axhfvbp@7nrs2omysxkc>
References: <CAA4eK1Jg21ODQ7fS2fvN5W_S5kDRhAP5inj3XMRQaa=s-GbYhw@mail.gmail.com>
<202604071230.b5axxf3qna3m@alvherre.pgsql>
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<227677.1775576304@localhost>
<pveffyxhnuurhb44uzqlwo3rkyzorkfh2rot7uwzlf2axhfvbp@7nrs2omysxkc>
Andres Freund <andres@anarazel.de> wrote:
> On 2026-04-07 17:38:24 +0200, Antonin Houska wrote:
> > The REPACK plugin only deforms tuples and writes them to a file, so I think
> > that things like this should not happen.
>
> You don't need to do it yourself. It just requires a shared_preload_library
> extension to register a relcache invalidation callback that accesses shared
> catalog.
>
> It's only kind of an accident that we don't have a case today that accesses
> shared catcaches during a relcache build in core (I'm not even sure there's
> nothing). You'd just need somebody to add e.g. relcache caching for
> publications for that to change. Or look up information about a reloption in
> pg_parameter_acl. Or lookup tablespace configuration.
>
>
> > However, I admit that an option that allows the plugin developer to declare
> > "I don't need shared catalogs" may be considered deceptive.
>
> At the very least it would need to be a runtime check rather than just an
> assert. This would much more likely to be hit in production because otherwise
> it's probably hard to hit the case where shared invalidations happen in the
> wrong moment. And the consequences are corrupted caches, which could cause
> all kinds of havoc.
>
>
> But I think this may need more infrastructure / deeper analysis than what we
> can do right now.
ok, thanks a lot for having looked at it.
--
Antonin Houska
Web: https://www.cybertec-postgresql.com
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To: pgsql-hackers@postgresql.org
Cc: ah@cybertec.at, andres@anarazel.de, alvherre@alvh.no-ip.org, amit.kapila16@gmail.com, mihailnikalayeu@gmail.com, srinath2133@gmail.com, boekewurm+postgres@gmail.com, pgsql-hackers@lists.postgresql.org, rob@xzilla.net
Subject: Re: Adding REPACK [concurrently]
In-Reply-To: <230042.1775577676@localhost>
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