Re: BUG #4796: Recovery followed by backup creates unrecoverable WAL-file

Simon Riggs wrote:
> On Thu, 2009-05-07 at 12:15 +0300, Heikki Linnakangas wrote:
>
>> Yeah, I think you're right. If you omit pg_xlog from the base backup,
>> as we recommend in the manual, and clear the old files from the
>> archive too, then you won't have the old history file around.
>
> ...
> A more useful thing might be to do an xlog switch before we do the
> shutdown checkpoint at end of recovery. That gives the same sequence of
> actions without modifying the existing sequence of activities for
> backups, which is delicate enough for me to not want to touch it.

Hmm, yeah should work as well. I find the recovery sequence to be even
more delicate, though, than pg_start_backup(). I think you'd need to
write the XLOG switch record using the old timeline ID, as we currently
require that the timeline changes only at a shutdown checkpoint record.
That's not hard, but does make me a bit nervous.

The advantage of that over switching xlog segment in pg_start_backup()
would be that you would go through fewer XLOG segments if you took
backups often.

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