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Date: Thu, 14 Mar 2019 15:28:15 +0100
From: Christoph Berg <myon@debian.org>
To: Magnus Hagander <magnus@hagander.net>
Cc: Michael Paquier <michael@paquier.xyz>, Sergei Kornilov <sk@zsrv.org>,
	Fabien COELHO <coelho@cri.ensmp.fr>,
	Michael Banck <michael.banck@credativ.de>,
	PostgreSQL Developers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Offline enabling/disabling of data checksums
Message-ID: <20190314142815.GD32045@msg.df7cb.de>
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Re: Magnus Hagander 2019-03-14 <CABUevEx7QZLOjWDvwTdm1VM+mjsDm7=ZmB8qck7nDmcHEY5O5g@mail.gmail.com>
> Are you suggesting we should support running with a master with checksums
> on and a standby with checksums off in the same cluster? That seems.. Very
> fragile.

The case "shut down master and standby, run pg_checksums on both, and
start them again" should be supported. That seems safe to do, and a
real-world use case.

Changing the system id to a random number would complicate this.

(Horrible idea: maybe just adding 1 (= checksum version) to the system
id would work?)

Christoph