From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
cc: Andrew Dunstan <andrew@dunslane.net>,
        Mark Dilger <mark.dilger@enterprisedb.com>,
        Noah Misch <noah@leadboat.com>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Fixing WAL instability in various TAP tests
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Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Mon, 27 Sep 2021 22:20:12 -0400"
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Date: Tue, 28 Sep 2021 13:27:11 -0400
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Precedence: bulk

I wrote:
> So that's the same hardware, and identical PG source tree, and different
> results.  This seems to leave only two theories standing:

I forgot theory 3: it's intermittent.  Apparently the probability has
dropped a lot since 2018, but behold:

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dflaviventris&dt=3D=
2021-09-28%2014%3A20%3A41

(with successful runs just before and after this one, on the same
animal)

Note that the delta is not exactly like the previous result, either.
So there's more than one symptom, but in any case it seems like
we have an issue in WAL replay.  I wonder whether it's bloom's fault
or a core bug.

			regards, tom lane