Hi, On Tue, Apr 16, 2024 at 08:21:04AM +0530, Amit Kapila wrote: > On Mon, Apr 15, 2024 at 7:47 PM Bertrand Drouvot > <bertranddrouvot...@gmail.com> wrote: > > > > On Mon, Apr 15, 2024 at 06:29:49PM +0530, Amit Kapila wrote: > > > On Mon, Apr 15, 2024 at 6:21 PM Bertrand Drouvot > > > <bertranddrouvot...@gmail.com> wrote: > > > > > > > > On Mon, Apr 15, 2024 at 03:38:53PM +0530, shveta malik wrote: > > > > > Now both worker and SQL > > > > > function set 'syncing' when they start and reset it when they exit. > > > > > > > > It means that it's not possible anymore to trigger a manual sync if > > > > sync_replication_slots is on. Indeed that would trigger: > > > > > > > > postgres=# select pg_sync_replication_slots(); > > > > ERROR: cannot synchronize replication slots concurrently > > > > > > > > That looks like an issue to me, thoughts? > > > > > > > > > > This is intentional as of now for the sake of keeping > > > implementation/code simple. It is not difficult to allow them but I am > > > not sure whether we want to add another set of conditions allowing > > > them in parallel. > > > > I think that the ability to launch a manual sync before a switchover would > > be > > missed. Except for this case I don't think that's an issue to prevent them > > to > > run in parallel. > > > > I think if the slotsync worker is available, it can do that as well.
Right, but one has no control as to when the sync is triggered. > There is no clear use case for allowing them in parallel and I feel it > would add more confusion when it can work sometimes but not other > times. However, if we receive some report from the field where there > is a real demand for such a thing, it should be easy to achieve. For > example, I can imagine that we can have sync_state that has values > 'started', 'in_progress' , and 'finished'. This should allow us to > achieve what the current proposed patch is doing along with allowing > the API to work in parallel when the sync_state is not 'in_progress'. > > I think for now let's restrict their usage in parallel and make the > promotion behavior consistent both for worker and API. Okay, let's do it that way. Is it worth to add a few words in the doc related to pg_sync_replication_slots() though? (to mention it can not be used if the sync slot worker is running). Regards, -- Bertrand Drouvot PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
