Re: Updated backup APIs for non-exclusive backups

On Tue, Mar 22, 2016 at 5:27 PM, David Steele <david(at)pgmasters(dot)net> wrote:

> On 3/22/16 12:14 PM, Magnus Hagander wrote:
> > On Tue, Mar 22, 2016 at 5:08 PM, David Steele <david(at)pgmasters(dot)net
> > <mailto:david(at)pgmasters(dot)net>> wrote:
> >
> > On 3/19/16 8:15 AM, Magnus Hagander wrote:
> >
> > > I've attached an updated patch, which is rebased on current master
> and
> > > includes the oid fix.
> >
> > Before doing a thorough review of this patch there are a few points I
> > would like to consider:
> >
> > * I think it's really important to provide the stop time in some
> fashion
> > when using this new technique. I would prefer a new column to be
> > returned from pg_stop_backup() but I could live with STOP TIME being
> > recorded in the label file. STOP TIME should probably be included in
> > the label file anyway.
> >
> > Adding the stop time column should be a simple addition and I don't see
> > a problem with that. I think I misunderstood your original request on
> > that. Because you are just talking about returning a timestamptz with
> > the "right now" value for when you called pg_stop_backup()? Or to be
> > specific, just before pg_Stop_backup *finished*. Or do you mean when
> > pg_stop_backup() started?
>
> What would be ideal is the minimum time that could be used for PITR. In
> an exclusive backup that's the time the end-of-backup record is written
> to WAL. In a non-exlusive backup I'm not quite sure how that works.
>

Having an actual definition of that is kind of required before adding it :P

> > Doing it in the backup label file is obviously a different target, where
> > we might need to consider backwards compatibility, Should we?
>
> Physical backups can only be restored in the same version so I'm not
> sure why it would be a problem? Do you mean for programs outside of
> Postgres that are parsing this file?
>

Yes, I meant programs outside postgres.

--
Magnus Hagander
Me: http://www.hagander.net/
Work: http://www.redpill-linpro.com/