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From: Antonin Houska <ah@cybertec.at>
To: Alvaro Herrera <alvherre@kurilemu.de>
Cc: Ewan Young <kdbase.hack@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Cc: mihailnikalayeu@gmail.com
Subject: Re: REPACK CONCURRENTLY fails on tables with generated columns
Date: Fri, 03 Jul 2026 19:26:17 +0200
Message-ID: <135099.1783099577@localhost> (raw)
In-Reply-To: <akeN0fZ_Dc4SSjN0@alvherre.pgsql>
References: <akeN0fZ_Dc4SSjN0@alvherre.pgsql>

Alvaro Herrera <alvherre@kurilemu.de> wrote:

> On 2026-Jun-22, Ewan Young wrote:
> 
> > I applied the patch and ran it through an injection-point reproducer
> > (cassert). Without the fix the bug reproduces (ERROR: no generation
> > expression found for column number 3 ...); with it, REPACK CONCURRENTLY
> > succeeds under a concurrent non-HOT UPDATE for a STORED generated column, an
> > index directly on the generated column, and a VIRTUAL column, with correct
> > values afterwards. Your repack.spec change passes.
> > 
> > The approach is right and I've confirmed it fixes the bug, so +1 from me in
> > this direction.
> 
> Cool, thanks for reviewing -- I have pushed this fix, with some
> stylistic changes and one bigger change: these catalog rows are only
> needed in concurrent mode, so there was no reason to copy them in the
> other case.  So I restricted the copying to that case.

Good point, thanks.

> I've been looking at the other proposed change, and I agree with it.
> Here's it, again with some style changes, and only one other proposed
> change: for setting up updatedCols, ignore dropped columns.  I don't
> think this should change anything in practice, but it just feels wrong
> to claim that a dropped column is being changed by an update.

+1

-- 
Antonin Houska
Web: https://www.cybertec-postgresql.com

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