From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Noah Misch <noah@leadboat.com>, Peter Geoghegan <pg@bowt.ie>,
        David Rowley <dgrowleyml@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Intermittent buildfarm failures on wrasse
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Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Fri, 15 Apr 2022 10:15:32 -0400"
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Date: Fri, 15 Apr 2022 11:14:13 -0400
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I wrote:
> the vacuum in test_setup sees
> ...
>         removable cutoff: 724, older by 26 xids when operation ended
> ...

BTW, before I forget: the wording of this log message is just awful.
On first sight, I thought that it meant that we'd computed OldestXmin
a second time and discovered that it advanced by 26 xids while the VACUUM
was running.  Looking at the code, I see that's not so:

            diff =3D (int32) (ReadNextTransactionId() - OldestXmin);
            appendStringInfo(&buf,
                             _("removable cutoff: %u, older by %d xids whe=
n operation ended\n"),
                             OldestXmin, diff);

but good luck understanding what it actually means from the message
text alone.  I think more appropriate wording would be something like

"removable cutoff: %u, which was %d xids old when operation ended\n"

Also, is it really our practice to spell XID in lower-case in
user-facing messages?

Thoughts, better ideas?

			regards, tom lane