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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>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, Peter Smith <smithpb2250@gmail.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2023-01-08T03:58:50Z
Lists: pgsql-hackers

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On Sunday, January 8, 2023 10:14 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> 
> On Sat, Jan 7, 2023 at 2:25 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> >
> 
> Today, I was analyzing this patch w.r.t recent commit c6e1f62e2c and found that
> pa_set_xact_state() should set the latch (wake up) for the leader worker as the
> leader could be waiting in pa_wait_for_xact_state(). What do you think? But
> otherwise, it should be okay w.r.t DDLs because this patch allows the leader
> worker to restart logical replication for subscription parameter change which will
> in turn stop/restart parallel workers if required.

Thanks for the analysis. I agree that it would be better to signal the leader
when setting the state to PARALLEL_TRANS_STARTED, otherwise it might slightly
delay the timing of catch the state change in pa_wait_for_xact_state(), so I
have updated the patch for the same. Besides, I also checked commit c6e1f62e2c,
I think DDL operation doesn't need to wake up the parallel apply worker
directly as the parallel apply worker doesn't start table sync and only
communicate with the leader, so I didn't find some other places that need to be
changed.

Attach the updated patch set.

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.