Horton

RE: wake up logical workers after ALTER SUBSCRIPTION

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: 'Nathan Bossart' <nathandbossart@gmail.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2022-11-30T04:48:03Z
Lists: pgsql-hackers 
Dear Nathan,

> I spent some more time on the prevent-unnecessary-wakeups patch for
> logical/worker.c that I've been alluding to in this thread, and I found a
> few more places where we depend on the worker periodically waking up.  This
> seems to be a common technique, so I'm beginning to wonder whether these
> changes are worthwhile.  I think there's a good chance it would become a
> game of whac-a-mole.

I think at least this feature is needed for waking up workers that are slept due to the min_apply_delay.
The author supposed this patch and pinned our thread[1].

[1]: https://www.postgresql.org/message-id/TYCPR01MB8373775ECC6972289AF8CB30ED0F9%40TYCPR01MB8373.jpnprd01.prod.outlook.com

Best Regards,
Hayato Kuroda
FUJITSU LIMITED

Commits

  1. Avoid type cheats for invalid dsa_handles and dshash_table_handles.

  2. Track logrep apply workers' last start times to avoid useless waits.

  3. Check for two_phase change at end of process_syncing_tables_for_apply.

  4. Wake up a subscription's replication worker processes after DDL.