From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jeff Davis <pgsql@j-davis.com>
cc: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>,
        Corey Huinker <corey.huinker@gmail.com>,
        Andres Freund <andres@anarazel.de>,
        Michael Paquier <michael@paquier.xyz>,
        Nathan Bossart <nathandbossart@gmail.com>,
        Bruce Momjian <bruce@momjian.us>,
        Matthias van de Meent <boekewurm+postgres@gmail.com>,
        Magnus Hagander <magnus@hagander.net>,
        Stephen Frost <sfrost@snowman.net>,
        Peter Smith <smithpb2250@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
        Alvaro Herrera <alvherre@alvh.no-ip.org>,
        jian he <jian.universality@gmail.com>
Subject: Re: Statistics Import and Export: difference in statistics dumped
In-reply-to: <c720ac7bf88721947faf87e174ed8e0d10c782eb.camel@j-davis.com>
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Comments: In-reply-to Jeff Davis <pgsql@j-davis.com>
	message dated "Wed, 05 Mar 2025 22:52:08 -0800"
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Date: Fri, 07 Mar 2025 14:14:08 -0500
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Jeff Davis <pgsql@j-davis.com> writes:
> Sounds good. I will commit something like the v2 patch then soon, and
> if we need a different condition we can change it later.

Sadly, this made things worse not better: crake is failing
cross-version-upgrade tests again [1], with dump diffs like

@@ -270836,8 +270836,8 @@
 --
 SELECT * FROM pg_catalog.pg_restore_relation_stats(	'version', '000000'::=
integer,
 	'relation', 'public.hash_f8_index'::regclass,
-	'relpages', '66'::integer,
-	'reltuples', '10000'::real,
+	'relpages', '0'::integer,
+	'reltuples', '-1'::real,
 	'relallvisible', '0'::integer
 );

I think what is happening is that the patch shut off CREATE
INDEX's update of not only the table's stats but also the
index's stats.  This seems unhelpful: the index's empty
stats can never be what's wanted.

We could band-aid over this by making AdjustUpgrade.pm
lobotomize the comparisons of all three stats fields,
but I think it's just wrong as-is.  Perhaps fix by
checking the relation's relkind before applying the
autovacuum heuristic?

			regards, tom lane

[1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Dcrake&dt=3D2=
025-03-07%2018%3A19%3A14