Horton

Re: Skipping logical replication transactions on subscriber side

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Greg Nancarrow <gregn4422@gmail.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, "osumi.takamichi@fujitsu.com" <osumi.takamichi@fujitsu.com>, Alexey Lesovsky <lesovsky@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2021-11-02T10:07:18Z
Lists: pgsql-hackers 
On Tue, Nov 2, 2021 at 2:17 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Tue, Nov 2, 2021 at 2:35 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> >
> > > >
> > > > I have another question in this regard. Currently, the reset function
> > > > seems to be resetting only the first stat entry for a subscription.
> > > > But can't we have multiple stat entries for a subscription considering
> > > > the view's cumulative nature?
> > >
> > > I might be missing your points but I think that with the current
> > > patch, the view has multiple entries for a subscription. That is,
> > > there is one apply worker stats and multiple table sync worker stats
> > > per subscription.
> > >
> >
> > Can't we have multiple entries for one apply worker?
>
> Umm, I think we have one stats entry per one logical replication
> worker (apply worker or table sync worker). Am I missing something?
>

No, you are right. I got confused.

> >
> > > And pg_stat_reset_subscription() function can reset
> > > any stats by specifying subscription OID and relation OID.
> > >
> >
> > Say, if the user has supplied just subscription OID then isn't it
> > better to reset all the error entries for that subscription?
>
> Agreed. So pg_stat_reset_subscription_worker(oid) removes all errors
> for the subscription whereas pg_stat_reset_subscription_worker(oid,
> null) reset only the apply worker error for the subscription?
>

Yes.

-- 
With Regards,
Amit Kapila.

Commits

  1. Test ALIGNOF_DOUBLE==4 compatibility under ALIGNOF_DOUBLE==8.

  2. Reorder subskiplsn in pg_subscription to avoid alignment issues.

  3. Add ALTER SUBSCRIPTION ... SKIP.

  4. Optionally disable subscriptions on error.

  5. Update docs of logical replication for commit 8d74fc96db.

  6. Respect permissions within logical replication.

  7. Fix regression test failure caused by commit 8d74fc96db.

  8. Add a view to show the stats of subscription workers.

  9. Add logical change details to logical replication worker errcontext.

  10. Rename LOGICAL_REP_MSG_STREAM_END to LOGICAL_REP_MSG_STREAM_STOP.

  11. Fix typo in protocol.sgml.

  12. Remove unused argument in apply_handle_commit_internal().

  13. Fix replication of in-progress transactions in tablesync worker.

  14. Reorder pg_sequence columns to avoid alignment issue