Re: Skipping logical replication transactions on subscriber side

On Mon, Jul 12, 2021 at 8:52 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Mon, Jul 12, 2021 at 11:13 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > On Mon, Jul 12, 2021 at 1:15 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > >
> > > On Mon, Jul 12, 2021 at 9:37 AM Alexey Lesovsky <lesovsky(at)gmail(dot)com> wrote:
> > > >
> > > > On Mon, Jul 12, 2021 at 8:36 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> > > >>
> > > >> >
> > > >> > Ok, looks nice. But I am curious how this will work in the case when there are two (or more) errors in the same subscription, but different relations?
> > > >> >
> > > >>
> > > >> We can't proceed unless the first error is resolved, so there
> > > >> shouldn't be multiple unresolved errors.
> > > >
> > > >
> > > > Ok. I thought multiple errors are possible when many tables are initialized using parallel workers (with max_sync_workers_per_subscription > 1).
> > > >
> > >
> > > Yeah, that is possible but that covers under the second condition
> > > mentioned by me and in such cases I think we should have separate rows
> > > for each tablesync. Is that right, Sawada-san or do you have something
> > > else in mind?
> >
> > Yeah, I agree to have separate rows for each table sync. The table
> > should not be processed by both the table sync worker and the apply
> > worker at a time so the pair of subscription OID and relation OID will
> > be unique. I think that we have a boolean column in the view,
> > indicating whether the error entry is reported by the table sync
> > worker or the apply worker, or maybe we also can have the action
> > column show "TABLE SYNC" if the error is reported by the table sync
> > worker.
> >
>
> Or similar to backend_type (text) in pg_stat_activity, we can have
> something like error_source (text) which will display apply worker or
> tablesync worker? I think if we have this column then even if there is
> a chance that both apply and sync worker operates on the same
> relation, we can identify it via this column.

Sounds good. I'll incorporate this in the next version patch that I'm
planning to submit this week.

Regards,

--
Masahiko Sawada
EDB: https://www.enterprisedb.com/