From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
cc: Thomas Munro <thomas.munro@enterprisedb.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: subscriptionCheck failures on nightjar
In-reply-to: <20190213215147.cjbymfojf6xndr4t@alap3.anarazel.de>
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 <20190213174151.mfylkessxmapt4io@alap3.anarazel.de>
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 <20190213181225.fathyapig4sm4exa@alap3.anarazel.de>
 <31663.1550082243@sss.pgh.pa.us>
 <20190213183303.ns54frt7cmvo6pgg@alap3.anarazel.de>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
	message dated "Wed, 13 Feb 2019 13:51:47 -0800"
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Date: Wed, 26 Jun 2019 21:10:49 -0400
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Andres Freund <andres@anarazel.de> writes:
> On 2019-02-14 09:52:33 +1300, Thomas Munro wrote:
>> Just to make sure I understand: it's OK for the file not to be there
>> when we try to fsync it by name, because a concurrent checkpoint can
>> remove it, having determined that we don't need it anymore?  In other
>> words, we really needed either missing_ok=3Dtrue semantics, or to use
>> the fd we already had instead of the name?

> I'm not yet sure that that's actually something that's supposed to
> happen, I got to spend some time analysing how this actually
> happens. Normally the contents of the slot should actually prevent it
> from being removed (as they're newer than
> ReplicationSlotsComputeLogicalRestartLSN()). I kind of wonder if that's
> a bug in the drop logic in newer releases.

My animal dromedary just reproduced this failure, which we've previously
only seen on nightjar.

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=3Ddromedary&dt=3D2=
019-06-26%2023%3A57%3A45

			regards, tom lane