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

Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>

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From: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
To: Amit Kapila <amit.kapila16@gmail.com>, "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>
Cc: Peter Smith <smithpb2250@gmail.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: 2022-10-14T09:08:13Z
Lists: pgsql-hackers

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On Friday, October 14, 2022 12:30 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> 
> On Wed, Oct 12, 2022 at 7:41 AM wangw.fnst@fujitsu.com
> <wangw.fnst@fujitsu.com> wrote:
> >
> > On Fri, Oct 7, 2022 at 14:18 PM Hou, Zhijie/侯 志杰
> <houzj.fnst@cn.fujitsu.com> wrote:
> > > Attach the new version patch set which addressed most of the comments.
> >
> > Rebased the patch set because the new change in HEAD (776e1c8).
> >
> > Attach the new patch set.
> >
> 
> +static void
> +HandleParallelApplyMessage(ParallelApplyWorkerInfo *winfo, StringInfo
> +msg)
> {
> ...
> + case 'X': /* Terminate, indicating clean exit */ {
> + shm_mq_detach(winfo->error_mq_handle);
> + winfo->error_mq_handle = NULL;
> + break;
> + }
> ...
> }
> 
> I don't see the use of this message in the patch. If this is not required by the
> latest version then we can remove it and its corresponding handling in
> parallel_apply_start_worker(). I am referring to the below code in
> parallel_apply_start_worker():

Thanks for the comments, I removed these codes in the new version patch set.

I also did the following changes in the new version patch:

[0001] 
* Teach the parallel apply worker to catch the subscription parameter change in
the main loop so that user can change the streaming option to "on" to stop
the parallel apply workers in case the leader apply workers get stuck because of
some deadlock problems discussed in [1].

* Some cosmetic changes.

* Address comments from Peter[2].

[0004]
* Disallow replicating from or to a partitioned table in parallel streaming
mode. This is to avoid the deadlock cases when the partitioned table's
inheritance structure is different between publisher and subscriber as
discussed [1].


[1] https://www.postgresql.org/message-id/CAA4eK1JYFXEoFhJAvg1qU%3DnZrZLw_87X%3D2YWQGFBbcBGirAUwA%40mail.gmail.com
[2] https://www.postgresql.org/message-id/CAHut%2BPvxL8tJ2ZUpEjkbRFe6qKSH%2Br54BQ7wM8p%3D335tUbuXbg%40mail.gmail.com

Best regards,
Hou zj

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.