Re: PITR potentially broken in 9.2

From: Andres Freund <andres(at)2ndquadrant(dot)com>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, Pg Bugs <pgsql-bugs(at)postgresql(dot)org>
Subject: Re: PITR potentially broken in 9.2
Date: 2012-12-05 02:15:38
Message-ID: 20121205021537.GB9811@awork2.anarazel.de
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On 2012-12-04 18:05:15 -0800, Jeff Janes wrote:
> On Tue, Dec 4, 2012 at 4:20 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
> >> I've reproduced it again using the just-tagged 9.2.2, and uploaded a
> >> 135MB tarball of the /tmp/data_slave2 and /tmp/archivedir to google
> >> drive. The data directory contains the recovery.conf which is set to
> >> end recovery between the two critical time points.
> >
> > Hmmm ... I can reproduce this with current 9.2 branch tip. However,
> > more or less by accident I first tried it with a 9.2-branch postmaster
> > from a couple weeks ago, and it works as expected with that: the log
> > output looks like
> >
> > LOG: restored log file "00000001000000000000001B" from archive
> > LOG: restored log file "00000001000000000000001C" from archive
> > LOG: restored log file "00000001000000000000001D" from archive
> > LOG: database system is ready to accept read only connections
> > LOG: recovery stopping before commit of transaction 305610, time 2012-12-02 15:08:54.000131-08
> > LOG: recovery has paused
> > HINT: Execute pg_xlog_replay_resume() to continue.
> >
> > and I can connect and do the pg_xlog_replay_resume() thing.
>
> But the key is, the database was not actually consistent at that
> point, and so opening hot standby was a dangerous thing to do.
>
> The bug that allowed the database to open early (the original topic if
> this email chain) was masking this secondary issue.
>
> > So apparently this is something we broke since Nov 18. Don't know what
> > yet --- any thoughts? Also, I am still not seeing what the connection
> > is to the original report against 9.1.6.
>
> The behavior that we both see in 9.2.2, where it waits for a
> pg_xlog_replay_resume() that cannot be delivered because the database
> is not yet open, is the same thing I'm seeing in 9.1.6. I'll see if I
> can repeat it in 9.1.7 and post the tarball of the data directory.

Could you check whether the attached patch fixes the behaviour?

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

Attachment Content-Type Size
fix-recovery-pause.path text/plain 565 bytes

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