Re: Offline enabling/disabling of data checksums

From: Michael Banck <michael(dot)banck(at)credativ(dot)de>
To: Magnus Hagander <magnus(at)hagander(dot)net>, Michael Paquier <michael(at)paquier(dot)xyz>
Cc: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>, Sergei Kornilov <sk(at)zsrv(dot)org>, PostgreSQL Developers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Offline enabling/disabling of data checksums
Date: 2019-03-14 15:26:20
Message-ID: 1552577180.9697.4.camel@credativ.de
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Hi,

Am Donnerstag, den 14.03.2019, 15:26 +0100 schrieb Magnus Hagander:
> Given that the failure is data corruption, I don't think big fat
> warning is enough. We should really make it impossible to start up the
> postmaster by mistake during the checksum generation. People don't
> read the documentation until it's too late. And it might not even be
> under their control - some automated tool might go in and try to start
> postgres, and boom, corruption.

I guess you're right.

> One big-hammer method could be similar to what pg_upgrade does --
> temporarily rename away the controlfile so postgresql can't start, and
> when done, put it back.

That sounds like a good solution to me. I've made PoC patch for that,
see attached.

The only question is whether pg_checksums should try to move pg_control
back (i) on failure (ii) when interrupted?

Michael

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Attachment Content-Type Size
0001-Rename-away-pg_control-while-enabling-checksums.patch text/x-patch 3.4 KB

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