From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Paquier <michael@paquier.xyz>
Cc: Postgres hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: REINDEX INDEX results in a crash for an index of pg_class since 9.6
Date: Tue, 23 Apr 2019 20:03:37 -0400
Message-ID: <14271.1556064217@sss.pgh.pa.us> (raw)
In-Reply-To: <13930.1556063692@sss.pgh.pa.us>
References: <20190418011430.GA19133@paquier.xyz>
<18233.1556052439@sss.pgh.pa.us>
<20190423233540.GB1878@paquier.xyz>
<13930.1556063692@sss.pgh.pa.us>
I wrote:
> It also seems quite odd that it doesn't fail every time; surely it's
> not conditional whether we'll try to insert a new pg_class tuple or not?
> We need to understand that, too.
Oh! One gets you ten it "works" as long as the pg_class update is a
HOT update, so that we don't actually end up touching the indexes.
This explains why the crash is less likely to happen in a database
where one's done some work (and, probably, created some dead space in
pg_class). On the other hand, it doesn't quite fit the observation
that a VACUUM FULL masked the problem ... wouldn't that have ended up
with densely packed pg_class? Maybe not, if it rebuilt everything
else after pg_class...
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, michael@paquier.xyz, 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: <14271.1556064217@sss.pgh.pa.us>
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