Date: Thu, 25 Apr 2019 11:05:54 -0400
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Tom Lane <tgl@sss.pgh.pa.us>,
	Postgres hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: REINDEX INDEX results in a crash for an index of pg_class since
 9.6
Message-ID: <20190425150554.GA555@alvherre.pgsql>
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On 2019-Apr-25, Michael Paquier wrote:

> 2) Bisecting between the merge base points of REL9_4_STABLE/master and
> REL9_5_STABLE/master, I am being pointed to the introduction of
> replication origins:
> commit: 5aa2350426c4fdb3d04568b65aadac397012bbcb
> author: Andres Freund <andres@anarazel.de>
> date: Wed, 29 Apr 2015 19:30:53 +0200
> Introduce replication progress tracking infrastructure.
> 
> In order to see the problem, also one needs to patch initdb.c so as
> the final VACUUM FULL on pg_database is replaced by VACUUM as on
> 9.6~.  The root of the problem is actually surprising, but manually
> testing on 5aa2350 commit and 5aa2350~1 the difference shows up as the
> issue is easily reproducible here.

Hmm ... I suspect the problem is even older, and that this commit made
it possible to see as a side effect of changing the catalog contents
(since it creates one more view and does a REVOKE, which becomes an
update on pg_class.)

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services