Re: PITR potentially broken in 9.2

On 2012-12-05 17:24:42 +0000, Simon Riggs wrote:
> On 5 December 2012 17:17, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>
> > The recovery target and the consistency point are in some ways in
> > conflict. If the recovery target is before the consistency point there
> > is no point in stopping there, whether or not we pause. What we should
> > do is say "recovery target reached, yet recovery not yet consistent,
> > continuing".
> > So ISTM that we should make recoveryStopsHere() return false while we
> > are inconsistent. Problems solved.

I prefer the previous (fixed) behaviour where we error out if we reach a
recovery target before we are consistent:

/*
* Complain if we did not roll forward far enough to render the backup
* dump consistent. Note: it is indeed okay to look at the local variable
* minRecoveryPoint here, even though ControlFile->minRecoveryPoint might
* be further ahead --- ControlFile->minRecoveryPoint cannot have been
* advanced beyond the WAL we processed.
*/
if (InRecovery &&
(XLByteLT(EndOfLog, minRecoveryPoint) ||
!XLogRecPtrIsInvalid(ControlFile->backupStartPoint)))
{
if (reachedStopPoint)
{
/* stopped because of stop request */
ereport(FATAL,
(errmsg("requested recovery stop point is before consistent recovery point")));
}

/*
* Ran off end of WAL before reaching end-of-backup WAL record, or
* minRecoveryPoint. That's usually a bad sign, indicating that you
* tried to recover from an online backup but never called
* pg_stop_backup(), or you didn't archive all the WAL up to that
* point. However, this also happens in crash recovery, if the system
* crashes while an online backup is in progress. We must not treat
* that as an error, or the database will refuse to start up.
*/
if (InArchiveRecovery || ControlFile->backupEndRequired)
{
if (ControlFile->backupEndRequired)
ereport(FATAL,
(errmsg("WAL ends before end of online backup"),
errhint("All WAL generated while online backup was taken must be available at recovery.")));
else if (!XLogRecPtrIsInvalid(ControlFile->backupStartPoint))
ereport(FATAL,
(errmsg("WAL ends before end of online backup"),
errhint("Online backup started with pg_start_backup() must be ended with pg_stop_backup(), and all WAL up to that point must be available at recovery.")));
else
ereport(FATAL,
(errmsg("WAL ends before consistent recovery point")));
}
}

Seems to be good enough to me. Once the pause logic is fixed obviously.

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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