From: Antonin Houska <ah@cybertec.at>
To: Alvaro Herrera <alvherre@kurilemu.de>
cc: Ewan Young <kdbase.hack@gmail.com>,
    PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
    mihailnikalayeu@gmail.com
Subject: Re: REPACK CONCURRENTLY fails on tables with generated columns
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Comments: In-reply-to Alvaro Herrera <alvherre@kurilemu.de>
   message dated "Fri, 03 Jul 2026 13:12:39 +0200."
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Date: Fri, 03 Jul 2026 19:26:17 +0200
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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 CONCURRENTL=
Y
> > succeeds under a concurrent non-HOT UPDATE for a STORED generated colu=
mn, an
> > index directly on the generated column, and a VIRTUAL column, with cor=
rect
> > 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