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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: Masahiko Sawada <sawada.mshk@gmail.com>, Amit Kapila <amit.kapila16@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: 2022-11-10T15:15:11Z
Lists: pgsql-hackers 
On Monday, November 7, 2022 4:17 PM Peter Smith <smithpb2250@gmail.com>
> 
> Here are my review comments for v42-0001

Thanks for the comments.
> ======
> 
> 28. handle_streamed_transaction
> 
>  static bool
>  handle_streamed_transaction(LogicalRepMsgType action, StringInfo s)  {
> - TransactionId xid;
> + TransactionId current_xid;
> + ParallelApplyWorkerInfo *winfo;
> + TransApplyAction apply_action;
> + StringInfoData origin_msg;
> +
> + apply_action = get_transaction_apply_action(stream_xid, &winfo);
> 
>   /* not in streaming mode */
> - if (!in_streamed_transaction)
> + if (apply_action == TRANS_LEADER_APPLY)
>   return false;
> 
> - Assert(stream_fd != NULL);
>   Assert(TransactionIdIsValid(stream_xid));
> 
> + origin_msg = *s;
> 
> ~
> 
> 28b.
> Why not assign it at the declaration, the same as apply_handle_stream_prepare
> does?

The assignment is unnecessary for non-streaming transaction, so I delayed it.
> ~
> 
> 44b.
> If this is always written to a file, then wouldn't a better function name be
> something including the word "serialize" - e.g.
> serialize_message()?

I feel it would be better to be consistent with the existing style stream_xxx_xx().

I think I have addressed all the comments, but since quite a few logics are
changed in the new version so I might missed something. And dome code wrapping need to
be adjusted, I plan to run pg_indent for next version.

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.