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help / color / mirror / Atom feedFrom: Antonin Houska <ah@cybertec.at>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Justin Pryzby <pryzby@telsasoft.com>
Cc: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
Cc: Andres Freund <andres@anarazel.de>
Cc: Amit Kapila <amit.kapila16@gmail.com>
Cc: Srinath Reddy Sadipiralla <srinath2133@gmail.com>
Cc: Matthias van de Meent <boekewurm+postgres@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org, Robert Treat <rob@xzilla.net>
Subject: Re: Adding REPACK [concurrently]
Date: Mon, 20 Apr 2026 15:46:13 +0200
Message-ID: <62070.1776692773@localhost> (raw)
In-Reply-To: <aeYQwx9WwD-g-Fc9@alvherre.pgsql>
References: <aeYQwx9WwD-g-Fc9@alvherre.pgsql>
Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
> On 2026-Apr-20, Antonin Houska wrote:
>
> > Antonin Houska <ah@cybertec.at> wrote:
> >
> > > It was discussed earlier [1] and the concerns about possibly excessive
> > > resource consumptions were addressed by [2]. So I think it the fix was just
> > > forgotten. Attached here.
> >
> > Sorry, I attached wrong patch. This is what I meant.
>
> Yeah, I had also written the same patch a couple of days ago.
>
> BTW I ran into a small problem after adding some tests in cluster.sql
> that would exercise this -- that test would die more or less randomly
> but frequently in CI (which it never did in my laptop) because of the
> size of the snapshot,
>
> ALTER TABLE ptnowner1 REPLICA IDENTITY USING INDEX ptnowner1_i_key;
> REPACK (CONCURRENTLY) ptnowner1;
> +ERROR: initial slot snapshot too large
> +CONTEXT: REPACK decoding worker
> RESET SESSION AUTHORIZATION;
>
> I think the solution for this is to move cluster to a separate parallel
> test. The one where it is now is a bit too crowded. Maybe the one for
> compression is okay? I'll test and push if I see it passing CI.
That shouldn't break anything, but I have no idea why this problem was not
triggered (as far as I remember) by the stress tests we ran during
development.
I thought that it might be due to less frequent calls of
SnapBuildPurgeOlderTxn(), which might in turn be due to less frequent
checkpoints (because xl_running_xacts is typically written during checkpoint),
and that checkpoints may be deliberately less frequent to make regression
tests run faster. However I don't immediately see related configuration in the
regression test setup.
> Another obvious thing after adding tests is that the LOGIN privilege is
> required, which is also quite bogus IMO. 0002 here should solve that.
ok
> >From b3d4158356f4914d2b0cba86eef6994c0ee50ab9 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?=C3=81lvaro=20Herrera?= <alvherre@kurilemu.de>
> Date: Mon, 20 Apr 2026 11:38:48 +0200
> Subject: [PATCH 1/2] REPACK: do not require the user to have REPLICATION
> Because there are now successful concurrent repack runs in the
> regression tests, we're forced to run test_plan_advice under
> wal_level=replica.
Is this an attempt to disable REPACK (CONCURRENTLY)? That would require
wal_level=minimal (due to commit 67c20979ce). In which way does REPACK seem to
break test_plan_advice?
--
Antonin Houska
Web: https://www.cybertec-postgresql.com
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To: pgsql-hackers@postgresql.org
Cc: ah@cybertec.at, alvherre@alvh.no-ip.org, pryzby@telsasoft.com, mihailnikalayeu@gmail.com, andres@anarazel.de, amit.kapila16@gmail.com, srinath2133@gmail.com, boekewurm+postgres@gmail.com, rob@xzilla.net
Subject: Re: Adding REPACK [concurrently]
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