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From: Antonin Houska <[email protected]>
To: Andres Freund <[email protected]>
Cc: Alvaro Herrera <[email protected]>
Cc: Amit Kapila <[email protected]>
Cc: Mihail Nikalayeu <[email protected]>
Cc: Srinath Reddy Sadipiralla <[email protected]>
Cc: Matthias van de Meent <[email protected]>
Cc: Pg Hackers <[email protected]>
Cc: Robert Treat <[email protected]>
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>
	<[email protected]>
	<cdgw4sbbfcgk6du3iv54r2dgiy4tfywoklbotlmj4irxavdcr3@glxfw5jj277q>
	<227677.1775576304@localhost>
	<pveffyxhnuurhb44uzqlwo3rkyzorkfh2rot7uwzlf2axhfvbp@7nrs2omysxkc>

Andres Freund <[email protected]> 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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