On Wed, Jul 1, 2020 at 05:20:16PM -0400, David Steele wrote: > On 7/1/20 4:32 PM, Bruce Momjian wrote: > > On Wed, Jul 1, 2020 at 04:27:58PM -0400, David Steele wrote: > > > On 7/1/20 3:58 PM, Robert Haas wrote: > > > > If we could jigger things so that you don't need to stop the backup at > > > > all, you only start it, and whether you ever finish copying everything > > > > is something about which the system need not know or care, that would > > > > be a lot nicer. I'm not sure I see how to do that, though. > > > > > > Well, the only thing pg_stop_backup() *really* needs to know is the > > > starting > > > WAL position. pg_start_backup() gets that info so if it passes it back to > > > pg_stop_backup() that could be enough. Or as was proposed above, it just > > > > Doesn't pg_start_backup already return this? > > > > SELECT pg_start_backup('test'); > > pg_start_backup > > ----------------- > > --> 0/2000028 > > It does, though after looking at the code I think we need the entire > backup_label. For any of this to be useful, pg_start_backup() *must* return > backup_label anyway so it can be stored somewhere the backup software can > find it.
Sure, sounds good to me. > > > Here's a thought. What if we just stored the oldest starting LSN and a > > > count > > > of how many backups have been requested. When the backup ends it checks > > > that > > > backup count is > 0 and starting LSN is <= its starting LSN. If not, it > > > throws an error. When backups go to 0 FPWs are turned off if they were off > > > before the first backup. > > > > Can't we just error out of an exclusive-style backup is requested to > > start and a previous exclusive-style backup has not been stopped? > > That means only allowing one exclusive backup but it's not like we don't > already have that limitation. But -- I'd rather not even need to specify > exclusive/non-exclusive when the backup is started. Basically, all backups > would be non-exclusive but we'd allow pg_stop_backup() to be called in a new > session (or the same session). OK, however you want. -- Bruce Momjian <br...@momjian.us> https://momjian.us EnterpriseDB https://enterprisedb.com The usefulness of a cup is in its emptiness, Bruce Lee