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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>, "wangw.fnst@fujitsu.com" <wangw.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: 2022-10-18T04:23:39Z
Lists: pgsql-hackers 
On Tuesday, October 18, 2022 10:36 AM Peter Smith <smithpb2250@gmail.com> wrote:
> 
> Hi, here are my review comments for patch v38-0001.

Thanks for the comments.

> ~~~
> 
> 12. get_transaction_apply_action
> 
> I still felt like there should be some tablesync checks/comments in
> this function, just for sanity, even if it works as-is now.
> 
> For example, are you saying ([3] #22b) that there might be rare cases
> where a Tablesync would call to parallel_apply_find_worker? That seems
> strange, given that "for streaming transactions that are being applied
> in the parallel ... we disallow applying changes on a table that is
> not in the READY state".
> 
> ------

I think because we won't try to start parallel apply worker in table sync
worker(see the check in parallel_apply_can_start()), so we won't find any
worker in parallel_apply_find_worker() which means get_transaction_apply_action
will return TRANS_LEADER_SERIALIZE. And get_transaction_apply_action is a
function which can be invoked for all kinds of workers(same is true for all
apply_handle_xxx functions), so not sure if table sync check/comment is
necessary.

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.