On Sat, Jun 20, 2020 at 9:04 AM Paul Förster <paul.foerster@xxxxxxxxx> wrote:
Hi Stephen,
> On 19. Jun, 2020, at 18:02, Stephen Frost <sfrost@xxxxxxxxxxx> wrote:
> When it comes to 'backup mode', it's actually the case that there can be
> multiple backups running concurrently because there isn't actually a
> single 'cluster wide backup mode', really.
this is what I don't understand. Why would there be a reason to run multiple backups concurrently? I mean, using pg_start_backup() means I then have to backup (using whatever method) of the while PGDATA and not just some random file ${PGDATA}/base/13297/2685. And since I have to backup the whole of PGDATA anyway, why would I want to do that multiple times, even more so, concurrently?
I read the backup doc but I just can't grasp the idea of why multiple concurrent backup capabilities should yield any benefit at all.
One not uncommon case is for example being able to provision a new replica while a backup is running. Since replicas are provisioned starting off a base backup, being able to run that concurrently is very useful. Especially if base backups take a long time to run.
