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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: Peter Smith <smithpb2250@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, shveta malik <shveta.malik@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2023-01-13T10:13:39Z
Lists: pgsql-hackers 
On Friday, January 13, 2023 2:20 PM Peter Smith <smithpb2250@gmail.com> wrote:
> 
> Here are some review comments for patch v79-0002.

Thanks for your comments.

> ======
> 
> General
> 
> 1.
> 
> I saw that earlier in this thread Hou-san [1] and Amit [2] also seemed to say
> there is not much point for this patch.
> 
> So I wanted to +1 that same opinion.
> 
> I feel this patch just adds more complexity for almost no gain:
> - reducing the 'max_apply_workers_per_suibscription' seems not very
> common in the first place.
> - even when the GUC is reduced, at that point in time all the workers might be in
> use so there may be nothing that can be immediately done.
> - IIUC the excess workers (for a reduced GUC) are going to get freed naturally
> anyway over time as more transactions are completed so the pool size will
> reduce accordingly.

I need to think over it, and we can have detailed discussion after committing
the first patch. So I didn't address the comments for 0002 for now.

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.