Subject: Re: Point in Time Recovery
From: Simon Riggs <simon@2ndquadrant.com>
To: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@postgresql.org
In-Reply-To: <200407132242.i6DMgg612564@candle.pha.pa.us>
References: <200407132242.i6DMgg612564@candle.pha.pa.us>
Content-Type: text/plain
Organization: 2nd Quadrant
Message-Id: <1089759153.17493.3270.camel@stromboli>
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Date: Tue, 13 Jul 2004 23:52:34 +0100
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On Tue, 2004-07-13 at 23:42, Bruce Momjian wrote:
> Simon Riggs wrote:
> > On Tue, 2004-07-13 at 22:19, Tom Lane wrote:
> > 
> > > To have a consistent recovery at all, you must replay the log starting
> > > from a checkpoint before the backup began and extending to the time that
> > > the backup finished.  You only get to decide where to stop after that
> > > point.
> > > 
> > 
> > So the situation is: 
> > - You must only stop recovery at a point in time (in the logs) after the
> > backup had completed.
> > 
> > No way to enforce that currently, apart from procedurally. Not exactly
> > frequent, so I think I just document that and move on, eh?
> 
> If it happens, could you use your previous full backup and the PITR logs
> from before stop stopped logging, and then after?  

Yes.

> Is there a period
> where they could not restore reliably?

Good question. No is the answer. 

The situation is that the backup isn't timestamped with respect to the
logs, so its possible to attempt to use the wrong backup for recovery.

The solution is procedural - make sure you timestamp your backup files,
so you know which ones to recover with...

Best Regards, Simon Riggs