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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Abhijit Menon-Sen <ams@2ndquadrant.com>
Cc: Simon Riggs <simon@2ndquadrant.com>
Cc: Craig Ringer <craig@2ndquadrant.com>
Cc: Petr Jelinek <petr@2ndquadrant.com>
Cc: Magnus Hagander <magnus@hagander.net>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: 9.6 and fsync=off
Date: Mon, 02 May 2016 12:04:29 -0400
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Andres Freund <andres@anarazel.de> writes:
> On 2016-05-02 10:07:50 -0400, Robert Haas wrote:
>> - If that flag is set on a subsequent startup, say:
>> WARNING: Recovery was previously performed with fsync=off; this
>> cluster may be irretrievably corrupted.

> Well, the problem with that is that postgres crashes are actually
> harmless with regard to fsync=on/off. It's just OS crashes that are a
> problem. So it seems quite likely that the false-positive rate here
> would be high enough, to make people ignore it.

That's a pretty good point.  Also, as sketched, I believe this would
start bleating after a crash recovery performed because a backend
died --- which is a case where we know for certain there was no OS
crash.  So this idea needs some more thought.

			regards, tom lane


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