Re: Re: [COMMITTERS] pgsql: Basic Recovery Control functions for use in Hot Standby. Pause,

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Magnus Hagander <magnus(at)hagander(dot)net>, Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Re: [COMMITTERS] pgsql: Basic Recovery Control functions for use in Hot Standby. Pause,
Date: 2011-03-18 07:22:47
Message-ID: 4D830847.6040105@enterprisedb.com
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On 18.03.2011 07:13, Fujii Masao wrote:
> On Fri, Mar 18, 2011 at 1:17 AM, Robert Haas<robertmhaas(at)gmail(dot)com> wrote:
>> One thing I'm not quite clear on is what happens if we reach the
>> recovery target before we reach consistency. i.e. create restore
>> point, flush xlog, abnormal shutdown, try to recover to named restore
>> point. Is there any possibility that we can end up paused before Hot
>> Standby has actually started up. Because that would be fairly useless
>> and annoying.
>
> Good catch! In that case, the same situation as (3) would happen.
> I think that recovery should ignore pause_at_recovery_target until
> it reaches consistent point. If we do so, when recovery target is
> ahead of consistent point, recovery just ends in inconsistent point
> and throws FATAL error.

If recovery target is set to before its consistent, ie. before
minRecoveryPoint, we should throw an error before recovery even starts.
I'm not sure if we check that at the moment.

Not sure what to to do recovery target is beyond minRecoveryPoint and
pause_at_recovery_target=true, but the server hasn't been opened for hot
standby yet (because it hasn't seen a running-xacts record yet). I agree
it's pretty useless and annoying to stop there.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com

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