Re: [PATCH] Reuse Workers and Replication Slots during Logical Replication

On Wed, Jun 28, 2023 at 12:02 PM Hayato Kuroda (Fujitsu)
<kuroda(dot)hayato(at)fujitsu(dot)com> wrote:
>
> > > I have analyzed how we handle this. Please see attached the patch (0003) which
> > > allows reusing connection.
> > >
> >
> > Why did you change the application name during the connection?
>
> It was because the lifetime of tablesync worker is longer than slots's one and
> tablesync worker creates temporary replication slots many times, per the target
> relation. The name of each slots has relid, so I thought that it was not suitable.
>

Okay, but let's try to give a unique application name to each
tablesync worker for the purpose of pg_stat_activity and synchronous
replication (as mentioned in existing comments as well). One idea is
to generate a name like pg_<sub_id>_sync_<worker_slot> but feel free
to suggest if you have any better ideas.

> But in the later patch the tablesync worker tries to reuse the slot during the
> synchronization, so in this case the application_name should be same as slotname.
>

Fair enough. I am slightly afraid that if we can't show the benefits
with later patches then we may need to drop them but at this stage I
feel we need to investigate why those are not helping?

--
With Regards,
Amit Kapila.