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

Peter Smith <smithpb2250@gmail.com>

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From: Peter Smith <smithpb2250@gmail.com>
To: "kuroda.hayato@fujitsu.com" <kuroda.hayato@fujitsu.com>
Cc: "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Dilip Kumar <dilipbalaut@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-08-23T04:20:08Z
Lists: pgsql-hackers 
On Mon, Aug 22, 2022 at 10:49 PM kuroda.hayato@fujitsu.com
<kuroda.hayato@fujitsu.com> wrote:
>

> 04. launcher.c
>
> 04.a
>
> +       worker->main_worker_pid = is_subworker ? MyProcPid : 0;
>
> You can use InvalidPid instead of 0.
> （I thought pid should be represented by the datatype pid_t, but in some codes it is defined as int...)
>
> 04.b
>
> +       worker->main_worker_pid = 0;
>
> You can use InvalidPid instead of 0, same as above.
>
> 05. origin.c
>
>  void
> -replorigin_session_setup(RepOriginId node)
> +replorigin_session_setup(RepOriginId node, int acquired_by)
>
> IIUC the same slot can be used only when the apply main worker has already acquired the slot
> and the subworker for the same subscription tries to acquire, but it cannot understand from comments.
> How about adding comments, or an assertion that acquired_by is same as session_replication_state->acquired_by ?
> Moreover acquired_by should be compared with InvalidPid, based on above comments.
>

In general I agree, and I also suggested to use pid_t and InvalidPid
(at least for all the new code)

In practice, please be aware that InvalidPid is -1 (not 0), so
replacing any existing code (e.g. in replorigin_session_setup) that
was already checking for 0 has to be done with lots of care.

------
Kind Regards,
Peter Smith.
Fujitsu Australia.

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.