Re: 9.2.3 crashes during archive recovery

From: Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
To: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
Cc: Ants Aasma <ants(at)cybertec(dot)at>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: 9.2.3 crashes during archive recovery
Date: 2013-02-22 00:13:53
Message-ID: CAB7nPqSRRXgT-CH=A+vh8WXwXEWP=fYTb0YZ9N6KYwY75yqbNQ@mail.gmail.com
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On Thu, Feb 21, 2013 at 11:09 PM, Heikki Linnakangas <
hlinnakangas(at)vmware(dot)com> wrote:

> On 15.02.2013 15:49, Heikki Linnakangas wrote:
>
>> Attached is a patch for git master. The basic idea is to split
>> InArchiveRecovery into two variables, InArchiveRecovery and
>> ArchiveRecoveryRequested. ArchiveRecoveryRequested is set when
>> recovery.conf exists. But if we don't know how far we need to recover,
>> we first perform crash recovery with InArchiveRecovery=false. When we
>> reach the end of WAL in pg_xlog, InArchiveRecovery is set, and we
>> continue with normal archive recovery.
>>
>
> New version of this attached, with a few bugs fixed.
>
> I'm thinking that this should be back-patched to 9.2, but not to earlier
> branches. Before 9.2, we don't PANIC at a reference to a non-existent page
> until end of recovery, even if we've already reached consistency. The same
> basic issue still exists in earlier versions, though: if you have
> hot_standby=on, the system will open for read-only queries too early,
> before the database is consistent. But this patch is invasive enough that
> I'm weary of back-patching it further, when the worst that can happen is
> that there's a small window right after startup when you can see an
> inconsistent database in hot standby mode. Maybe after we get some more
> testing of this in 9.2 and master. Opinions on that?
>
People have not yet complained about this problem with versions prior to
9.1. Is it worth backpatching in this case?
--
Michael

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