On Wed, Mar 30, 2016 at 10:09 AM, Amit Kapila <amit.kapil...@gmail.com> wrote:
> On Tue, Mar 29, 2016 at 11:39 PM, Magnus Hagander <mag...@hagander.net> > wrote: > >> On Tue, Mar 29, 2016 at 6:40 PM, Magnus Hagander <mag...@hagander.net> >> wrote: >> >>> So - I can definitely see the argument for returning the stop wal >>> *location*. But I'm still not sure what the definition of the time would >>> be? We can't return it before we know what it means... >>> >> >> >> I had a chat with Heikki, and here's another suggestion: >> >> 1. We don't touch the current exclusive backups at all, as previously >> discussed, other than deprecating their use. For backwards compat. >> >> 2. For new backups, we return the contents of pg_control as a bytea from >> pg_stop_backup(). We tell backup programs they are supposed to write this >> out as pg_control.backup, *not* as pg_control. >> >> 3a. On recovery, if it's an exlcusive backup, we do as we did before. >> >> 3b. on recovery, in non-exclusive backups (determined from backup_label), >> we check that pg_control.backup exists *and* that pg_control does *not* >> exist. >> > > Currently pg_control has been read before backup_label file, so as per > this proposal do you want to change that? If yes, I think that will make > this patch more invasive with respect to handling of failure modes. Also > as David points out, I also feel that it will raise the bar for usage of > this API. > Yes, we'd have to change that. I don't think it's going to be much more invasive than reading part of it from pg_control and part of it from backup_label, as suggested by David. It would be a bit more complicated than what we have today - but it would move complication from user scripts (that are likely to get it wrong) to a central place in the backend (where we can be more certain that it's at least less wrong). -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/
