Horton
Menu

RE: Perform streaming logical transactions by background workers and parallel apply

Zhijie Hou (Fujitsu) <houzj.fnst@fujitsu.com>

View thread
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>, "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>, Masahiko Sawada <sawada.mshk@gmail.com>
Date: 2023-01-24T12:47:16Z
Lists: pgsql-hackers 
On Tuesday, January 24, 2023 11:43 AM Peter Smith <smithpb2250@gmail.com> wrote:

> 
> Here are my review comments for patch v86-0001.

Thanks for your comments.

> 
> 
> ======
> Commit message
> 
> 2.
> Since we may extend the developer option logical_decoding_mode to to test the
> parallel apply of large transaction on subscriber, rename this option to
> logical_replication_mode to make it easier to understand.
> 
> ~
> 
> 2a
> typo "to to"
> 
> typo "large transaction on subscriber" --> "large transactions on the subscriber"
> 
> ~
> 
> 2b.
> IMO better to rephrase the whole paragraph like shown below.
> 
> SUGGESTION
> 
> Rename the developer option 'logical_decoding_mode' to the more flexible
> name 'logical_replication_mode' because doing so will make it easier to extend
> this option in future to help test other areas of logical replication.

Changed.

> ======
> doc/src/sgml/config.sgml
> 
> 3.
> Allows streaming or serializing changes immediately in logical decoding. The
> allowed values of logical_replication_mode are buffered and immediate. When
> set to immediate, stream each change if streaming option (see optional
> parameters set by CREATE SUBSCRIPTION) is enabled, otherwise, serialize each
> change. When set to buffered, which is the default, decoding will stream or
> serialize changes when logical_decoding_work_mem is reached.
> 
> ~
> 
> IMO it's more clear to say the default when the options are first mentioned. So I
> suggested removing the "which is the default" part, and instead saying:
> 
> BEFORE
> The allowed values of logical_replication_mode are buffered and immediate.
> 
> AFTER
> The allowed values of logical_replication_mode are buffered and immediate. The
> default is buffered.

I included this change in the 0002 patch.

> ======
> src/backend/utils/misc/guc_tables.c
> 
> 4.
> @@ -396,8 +396,8 @@ static const struct config_enum_entry
> ssl_protocol_versions_info[] = {  };
> 
>  static const struct config_enum_entry logical_decoding_mode_options[] = {
> - {"buffered", LOGICAL_DECODING_MODE_BUFFERED, false},
> - {"immediate", LOGICAL_DECODING_MODE_IMMEDIATE, false},
> + {"buffered", LOGICAL_REP_MODE_BUFFERED, false}, {"immediate",
> + LOGICAL_REP_MODE_IMMEDIATE, false},
>   {NULL, 0, false}
>  };
> 
> I noticed this array is still called "logical_decoding_mode_options".
> Was that deliberate?

No, I didn't notice this one. Changed.

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.