From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Michael Paquier <michael@paquier.xyz>,
        Postgres hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: REINDEX INDEX results in a crash for an index of pg_class since
 9.6
In-reply-to: <20190430182741.s6o7mo5ebmgxxi5x@alap3.anarazel.de>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Tue, 30 Apr 2019 11:27:41 -0700"
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Date: Tue, 30 Apr 2019 14:41:00 -0400
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Andres Freund <andres@anarazel.de> writes:
> On 2019-04-30 14:05:50 -0400, Tom Lane wrote:
>> Possibly we could run them in a TAP test that configures a cluster
>> with autovac disabled?

> Hm. Would it be sufficient to instead move them to a non-concurrent
> test group, and stick a BEGIN; LOCK pg_class, ....; COMMIT; around it?

Doubt it.  Maybe you could get away with it given that autovacuum and
autoanalyze only do non-transactional updates to pg_class, but that
seems like a pretty shaky assumption.

> This is a pretty finnicky area of the code, with obviously not enough
> test coverage.  I'm inclined to remove them from the back branches, and
> try to get them working in master?

I think trying to get this "working" is a v13 task now.  We've obviously
never tried to stress the case before, so you're neither fixing a
regression nor fixing a new-in-v12 issue.

			regards, tom lane