Date: Wed, 13 Sep 2017 19:39:31 +0200
From: Michael Banck <michael.banck@credativ.de>
To: Stephen Frost <sfrost@snowman.net>
Cc: Bruce Momjian <bruce@momjian.us>,
	Andreas Joseph Krogh <andreas@visena.com>,
	Michael Paquier <michael.paquier@gmail.com>,
	Robert Haas <robertmhaas@gmail.com>,
	"pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Subject: Re: Clarification in pg10's pgupgrade.html step 10
 (upgrading standby servers)
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References: <20170912215202.GA6766@momjian.us>
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 <20170912230020.GD6766@momjian.us>
 <20170912233840.GS4628@tamriel.snowman.net>
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On Tue, Sep 12, 2017 at 07:38:40PM -0400, Stephen Frost wrote:
> Further, really, I think we should provide a utility to do all of the
> above instead of using rsync- and that utility should do some additional
> things, such as:
> 
> - Check that the control file on the primary and replica show that they
>   reached the same point prior to the pg_upgrade.  If they didn't, then
>   things could go badly as there's unplayed WAL that the primary got
>   through and the replica didn't.
> 
> - Not copy over unlogged data, or any other information that shouldn't
>   be copied across.
> 
> - Allow the directory structures to be more different between the
>   primary and the replica than rsync allows (wouldn't have to have a
>   common subdirectory on the replica).
> 
> - Perhaps other validation checks or similar.
> 
> Unfortunately, this is a bit annoying as it necessairly involves running
> things on both the primary and the replica from the same tool, without
> access to PG, meaning we'd have to work through something else (such as
> SSH, like rsync does, but then what would we do for Windows...?).

Maybe pg_rewind's mechanism could be partially reused for this as it
seems to accomplish something vaguely similar AIUI?


Michael

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Michael Banck
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