From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alexander Korotkov <aekorotkov@gmail.com>
cc: Andrei Lepikhov <a.lepikhov@postgrespro.ru>,
        Richard Guo <guofenglinux@gmail.com>,
        Pavel Borisov <pashkin.elfe@gmail.com>,
        vignesh C <vignesh21@gmail.com>,
        PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>,
        Tomas Vondra <tomas.vondra@enterprisedb.com>,
        Teodor Sigaev <teodor@sigaev.ru>, David Rowley <dgrowleyml@gmail.com>,
        "a.rybakina" <a.rybakina@postgrespro.ru>
Subject: Re: POC: GROUP BY optimization
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Comments: In-reply-to Alexander Korotkov <aekorotkov@gmail.com>
	message dated "Fri, 19 Jan 2024 16:21:48 +0200"
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Date: Thu, 01 Feb 2024 21:02:35 -0500
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Alexander Korotkov <aekorotkov@gmail.com> writes:
> I'm going to push this if there are no objections.

One of the test cases added by this commit has not been very
stable in the buildfarm.  Latest example is here:

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dprion&dt=3D2024-=
02-01%2021%3A28%3A04

and I've seen similar failures intermittently on other machines.

I'd suggest building this test atop a table that is more stable
than pg_class.  You're just waving a red flag in front of a bull
if you expect stable statistics from that during a regression run.
Nor do I see any particular reason for pg_class to be especially
suited to the test.

			regards, tom lane