Date: Thu, 18 Jul 2013 15:40:24 -0400
From: Stephen Frost <sfrost@snowman.net>
To: Greg Smith <greg@2ndQuadrant.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>,
 Robert Haas <robertmhaas@gmail.com>,
 Heikki Linnakangas <hlinnakangas@vmware.com>,
 KONDO Mitsumasa <kondo.mitsumasa@lab.ntt.co.jp>,
 PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Improvement of checkpoint IO scheduler for stable
 transaction responses
Message-ID: <20130718194024.GR15510@tamriel.snowman.net>
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* Greg Smith (greg@2ndQuadrant.com) wrote:
> The first word that comes to mind for for just disregarding the end
> time is that it's a sloppy checkpoint.  There is all sorts of sloppy
> behavior you might do here, but I've worked under the assumption
> that ignoring the contract with the administrator was frowned on by
> this project.  If people want this sort of behavior in the server,
> I'm satisfied my distaste for the idea and the reasoning behind it
> is clear now.

For my part, I agree with Greg on this.  While we might want to provide
an option of "go ahead and go past checkpoint timeout if the server gets
too busy to keep up", I don't think it should be the default.

To be honest, I'm also not convinced that this approach is better than
the existing mechanism where the user can adjust checkpoint_timeout to
be higher if they're ok with recovery taking longer and I share Greg's
concern about this backoff potentially running away and causing
checkpoints which never complete or do so far outside the configured
time.

	Thanks,

		Stephen

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