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From: Amit Kapila <amit.kapila16@gmail.com>
Date: Thu, 12 Jan 2023 16:37:30 +0530
Message-ID: <CAA4eK1KueUT_vr1cg43MpvRcaVvW03i6zDECQNAwFBK5PhXOVA@mail.gmail.com>
Subject: Re: Perform streaming logical transactions by background workers and
 parallel apply
To: shveta malik <shveta.malik@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>, 
	"houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Masahiko Sawada <sawada.mshk@gmail.com>, 
	"wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, 
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>
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Archived-At: <https://www.postgresql.org/message-id/CAA4eK1KueUT_vr1cg43MpvRcaVvW03i6zDECQNAwFBK5PhXOVA%40mail.gmail.com>
Precedence: bulk

On Thu, Jan 12, 2023 at 4:21 PM shveta malik <shveta.malik@gmail.com> wrote:
>
> On Thu, Jan 12, 2023 at 10:34 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Thu, Jan 12, 2023 at 9:54 AM Peter Smith <smithpb2250@gmail.com> wrote:
> > >
> > >
> > > doc/src/sgml/monitoring.sgml
> > >
> > > 5. pg_stat_subscription
> > >
> > > @@ -3198,11 +3198,22 @@ SELECT pid, wait_event_type, wait_event FROM
> > > pg_stat_activity WHERE wait_event i
> > >
> > >       <row>
> > >        <entry role="catalog_table_entry"><para role="column_definition">
> > > +       <structfield>apply_leader_pid</structfield> <type>integer</type>
> > > +      </para>
> > > +      <para>
> > > +       Process ID of the leader apply worker, if this process is a apply
> > > +       parallel worker. NULL if this process is a leader apply worker or a
> > > +       synchronization worker.
> > > +      </para></entry>
> > > +     </row>
> > > +
> > > +     <row>
> > > +      <entry role="catalog_table_entry"><para role="column_definition">
> > >         <structfield>relid</structfield> <type>oid</type>
> > >        </para>
> > >        <para>
> > >         OID of the relation that the worker is synchronizing; null for the
> > > -       main apply worker
> > > +       main apply worker and the parallel apply worker
> > >        </para></entry>
> > >       </row>
> > >
> > > 5a.
> > >
> > > (Same as general comment #1 about terminology)
> > >
> > > "apply_leader_pid" --> "leader_apply_pid"
> > >
> >
> > How about naming this as just leader_pid? I think it could be helpful
> > in the future if we decide to parallelize initial sync (aka parallel
> > copy) because then we could use this for the leader PID of parallel
> > sync workers as well.
> >
> > --
>
> I still prefer leader_apply_pid.
> leader_pid does not tell which 'operation' it belongs to. 'apply'
> gives the clarity that it is apply related process.
>

But then do you suggest that tomorrow if we allow parallel sync
workers then we have a separate column leader_sync_pid? I think that
doesn't sound like a good idea and moreover one can refer to docs for
clarification.

-- 
With Regards,
Amit Kapila.