Re: Perform streaming logical transactions by background workers and parallel apply

On Thu, Jan 12, 2023 at 9:54 AM Peter Smith <smithpb2250(at)gmail(dot)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.

--
With Regards,
Amit Kapila.