From: Antonin Houska <ah@cybertec.at>
To: Mihail Nikalayeu <mihailnikalayeu@gmail.com>
cc: Andres Freund <andres@anarazel.de>,
    Amit Kapila <amit.kapila16@gmail.com>,
    Alvaro Herrera <alvherre@alvh.no-ip.org>,
    Srinath Reddy Sadipiralla <srinath2133@gmail.com>,
    Matthias van de Meent <boekewurm+postgres@gmail.com>,
    Pg Hackers <pgsql-hackers@lists.postgresql.org>,
    Robert Treat <rob@xzilla.net>
Subject: Re: Adding REPACK [concurrently]
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Comments: In-reply-to Mihail Nikalayeu <mihailnikalayeu@gmail.com>
   message dated "Sun, 19 Apr 2026 00:46:00 +0200."
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Date: Mon, 20 Apr 2026 19:44:52 +0200
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Mihail Nikalayeu <mihailnikalayeu@gmail.com> wrote:

> I've briefly looked at your patch. As I understand it, it cancels the other
> process only when REPACK actually tries to upgrade the lock. ...
>
> AFAIU, Andres's concern is that the "victim" should be cancelled
> sooner, rather than waiting until REPACK actually attempts the
> upgrade.

I thought the point is that the deadlock should be resolved in a controlled
way, i.e. w/o relying on deadlock timeout. Once both processes sleep, the
decision which one should be kicked off is effectively random. In other words,
the actual deadlock IMO starts exactly at the moment both processes end up
sleeping. But I may be wrong.

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