Feedback-ID: ia2694551:Fastmail
Date: Tue, 5 May 2026 17:02:39 +0200
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Antonin Houska <ah@cybertec.at>
Cc: Mihail Nikalayeu <mihailnikalayeu@gmail.com>,
	Amit Kapila <amit.kapila16@gmail.com>, Andres Freund <andres@anarazel.de>,
	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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On 2026-May-05, Antonin Houska wrote:

> However, I failed to notice that COMMIT record of
> a transaction listed in the xl_running_xacts WAL record is not guaranteed to
> follow the xl_running_xacts record in WAL. In other words, even if
> xl_running_xacts is created before a COMMIT record of the contained
> transaction, it may end up at higher LSN in WAL. So the cleanup I relied on
> might not take place.

That's pretty bad news.

> I've got no good idea how to fix that. Not sure I'm able to pursue the
> "database-specific snapshots" feature now.

It appears that the only reasonable course of action at this point is to
revert 0d3dba38c777.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/