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

Masahiko Sawada <sawada.mshk@gmail.com>

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From: Masahiko Sawada <sawada.mshk@gmail.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-05-10T05:09:14Z
Lists: pgsql-hackers 
On Wed, May 4, 2022 at 8:44 AM Peter Smith <smithpb2250@gmail.com> wrote:
>
> On Tue, May 3, 2022 at 5:16 PM Peter Smith <smithpb2250@gmail.com> wrote:
> >
> ...
>
> > Avoiding unexpected differences like this is why I suggested the
> > option should have to be explicitly enabled instead of being on by
> > default as it is in the current patch. See my review comment #14 [1].
> > It means the user won't have to change their existing code as a
> > workaround.
> >
> > ------
> > [1] https://www.postgresql.org/message-id/CAHut%2BPuqYP5eD5wcSCtk%3Da6KuMjat2UCzqyGoE7sieCaBsVskQ%40mail.gmail.com
> >
>
> Sorry I was wrong above. It seems this behaviour was already changed
> in the latest patch v5 so now the option value 'on' means what it
> always did. Thanks!

Having it optional seems a good idea. BTW can the user configure how
many apply bgworkers can be used per subscription or in the whole
system? Like max_sync_workers_per_subscription, is it better to have a
configuration parameter or a subscription option for that? If so,
setting it to 0 probably means to disable the parallel apply feature.

Regards,

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

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Fix invalid memory access during the shutdown of the parallel apply worker.

  2. Fix assertion failure in apply worker.

  3. Use elog to report unexpected action in handle_streamed_transaction().

  4. Use appropriate wait event when sending data in the apply worker.

  5. Allow the logical_replication_mode to be used on the subscriber.

  6. Rename GUC logical_decoding_mode to logical_replication_mode.

  7. Display the leader apply worker's PID for parallel apply workers.

  8. Improve the code to decide and process the apply action.

  9. Document the newly added wait events added by commit 216a784829.

  10. Perform apply of large transactions by parallel workers.

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

  12. Add copyright notices to meson files

  13. Better document logical replication parameters

  14. Add a common function to generate the origin name.

  15. Harmonize parameter names in storage and AM code.

  16. Avoid using list_length() to test for empty list.

  17. Improve two comments related to a boolean DefElem's value

  18. Fix partition table's REPLICA IDENTITY checking on the subscriber.

  19. Fix data inconsistency between publisher and subscriber.

  20. Fix cache look-up failures while applying changes in logical replication.