Subject: Re: Re: [COMMITTERS] pgsql: Make standby server
	continuously retry 	restoring the next WAL
From: Simon Riggs <simon@2ndQuadrant.com>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Fujii Masao <masao.fujii@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
In-Reply-To: <4B73FB99.4080403@enterprisedb.com>
References: <20100127152751.3B2047541B9@cvs.postgresql.org>
	<3f0b79eb1002092105r21e009d3v468496058ba04392@mail.gmail.com>
	<4B726120.80007@enterprisedb.com> <1265884657.7341.1192.camel@ebony>
	<4B73F678.8070109@enterprisedb.com> <1265891248.7341.1346.camel@ebony>
	<4B73FB99.4080403@enterprisedb.com>
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Date: Thu, 11 Feb 2010 13:06:39 +0000
Message-Id: <1265893599.7341.1454.camel@ebony>
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On Thu, 2010-02-11 at 14:44 +0200, Heikki Linnakangas wrote:
> Simon Riggs wrote:
> > On Thu, 2010-02-11 at 14:22 +0200, Heikki Linnakangas wrote:
> >> Simon Riggs wrote:
> >>> On Wed, 2010-02-10 at 09:32 +0200, Heikki Linnakangas wrote:
> >>>> Hmm, so after running restore_command, check the file size and if it's
> >>>> too short, treat it the same as if restore_command returned non-zero?
> >>>> And it will be retried on the next iteration. Works for me, though OTOH
> >>>> it will then fail to complain about a genuinely WAL file that's
> >>>> truncated for some reason. I guess there's no way around that, even if
> >>>> you have a script as restore_command that does the file size check, it
> >>>> will have the same problem.
> >>> Are we trying to re-invent pg_standby here?
> >> That's not the goal, but we seem to need some of the same functionality
> >> in the backend now.
> > 
> > I think you need to say why...
> 
> See the quoted paragraph above. We should check the file size, so that
> we will not fail if the WAL file is just being copied into the archive
> directory.

We can read, but that's not an explanation. By giving terse answers in
that way you are giving the impression that you don't want discussion on
these points.

If you were running pg_standby as the restore_command then this error
wouldn't happen. So you need to explain why running pg_standby cannot
solve your problem and why we must fix it by replicating code that has
previously existed elsewhere.

-- 
 Simon Riggs           www.2ndQuadrant.com