Date: Tue, 30 Jun 2020 23:28:39 -0400
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Intermittent BRIN failures on hyrax and lousyjack
Message-ID: <20200701032839.GA16862@alvherre.pgsql>
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On 2020-Jun-30, Tom Lane wrote:

>  SELECT brin_desummarize_range('brinidx', 0);
> +WARNING:  leftover placeholder tuple detected in BRIN index "brinidx", deleting

> I think the "crash" actually was the forced autovac cancellation we see
> here.  Thus, the fact that both these animals use CLOBBER_CACHE_ALWAYS is
> not a direct cause of the failure, though it might contribute to getting
> the timing right for this to happen.

Oh, interesting.

> So (1) the comment needs to be adjusted to mention that vacuum
> cancellation is enough to create the situation, and (2) probably the
> message needs to be downgraded quite a lot, DEBUG2 or even less.
> Or maybe we could just delete the quoted stanza altogether.

Yeah, maybe deleting the whole thing is a decent answer.  When I wrote
that, I was thinking that it was a very unlikely event, but evidently
that's not true.

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