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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>, Masahiko Sawada <sawada.mshk@gmail.com>, "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, Dilip Kumar <dilipbalaut@gmail.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-12-13T13:07:09Z
Lists: pgsql-hackers 
On Tue, Dec 13, 2022 7:06 AM Peter Smith <smithpb2250@gmail.com> wrote:
> Some minor review comments for v58-0001

Thanks for your comments.

> ======
> 
> .../replication/logical/applyparallelworker.c
> 
> 1. pa_can_start
> 
> + /*
> + * Don't start a new parallel worker if user has set skiplsn as it's
> + * possible that user want to skip the streaming transaction. For 
> + streaming
> + * transaction, we need to serialize the transaction to a file so 
> + that we
> + * can get the last LSN of the transaction to judge whether to skip 
> + before
> + * starting to apply the change.
> + */
> + if (!XLogRecPtrIsInvalid(MySubscription->skiplsn))
> + return false;
> 
> 
> "that user want" -> "that they want"
> 
> "For streaming transaction," -> "For streaming transactions,"

Changed.

> ~~~
> 
> 2. pa_free_worker_info
> 
> + /* Remove from the worker pool. */
> + ParallelApplyWorkerPool = list_delete_ptr(ParallelApplyWorkerPool,
> +    winfo);
> 
> Unnecessary wrapping

Changed.

> ~~~
> 
> 3. pa_set_stream_apply_worker
> 
> +/*
> + * Set the worker that required to apply the current streaming transaction.
> + */
> +void
> +pa_set_stream_apply_worker(ParallelApplyWorkerInfo *winfo) {  
> +stream_apply_worker = winfo; }
> 
> Comment wording seems wrong.

Tried to improve this comment.

> ======
> 
> src/include/replication/worker_internal.h
> 
> 4. ParallelApplyWorkerShared
> 
> + * XactLastCommitEnd from the parallel apply worker. This is required 
> +to
> + * update the lsn_mappings by leader worker.
> + */
> + XLogRecPtr last_commit_end;
> +} ParallelApplyWorkerShared;
> 
> 
> "This is required to update the lsn_mappings by leader worker." --> 
> did you mean "This is required by the leader worker so it can update 
> the lsn_mappings." ??

Changed.

Also thanks for the kind reminder in [1], rebased the patch set.
Attach the new patch set.

[1] - https://www.postgresql.org/message-id/CAHut%2BPt4qv7xfJUmwdn6Vy47L5mqzKtkPr31%3DDmEayJWXetvYg%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.