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: 2023-01-30T06:23:17Z
Lists: pgsql-hackers

Attachments

On Monday, January 30, 2023 12:13 PM Peter Smith <smithpb2250@gmail.com> wrote:
> 
> Here are my review comments for v88-0002.

Thanks for your comments.

> 
> ======
> General
> 
> 1.
> The test cases are checking the log content but they are not checking for
> debug logs or untranslated elogs -- they are expecting a normal ereport LOG
> that might be translated. I’m not sure if that is OK, or if it is a potential problem.

We have tests that check the ereport ERROR and ereport WARNING message(by
search for the ERROR or WARNING keyword for all the tap tests), so I think
checking the LOG should be fine.

> ======
> doc/src/sgml/config.sgml
> 
> 2.
> On the publisher side, logical_replication_mode allows allows streaming or
> serializing changes immediately in logical decoding. 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, the decoding will stream or serialize changes when
> logical_decoding_work_mem is reached.
> 
> 2a.
> typo "allows allows"  (Kuroda-san reported same)
> 
> 2b.
> "if streaming option" --> "if the streaming option"

Changed.

> ~~~
> 
> 3.
> On the subscriber side, if streaming option is set to parallel,
> logical_replication_mode also allows the leader apply worker to send changes
> to the shared memory queue or to serialize changes.
> 
> SUGGESTION
> On the subscriber side, if the streaming option is set to parallel,
> logical_replication_mode can be used to direct the leader apply worker to
> send changes to the shared memory queue or to serialize changes.

Changed.

> ======
> src/backend/utils/misc/guc_tables.c
> 
> 4.
>   {
>   {"logical_replication_mode", PGC_USERSET, DEVELOPER_OPTIONS,
> - gettext_noop("Controls when to replicate each change."),
> - gettext_noop("On the publisher, it allows streaming or serializing each
> change in logical decoding."),
> + gettext_noop("Controls the internal behavior of logical replication
> publisher and subscriber"),
> + gettext_noop("On the publisher, it allows streaming or "
> + "serializing each change in logical decoding. On the "
> + "subscriber, in parallel streaming mode, it allows "
> + "the leader apply worker to serialize changes to "
> + "files and notifies the parallel apply workers to "
> + "read and apply them at the end of the transaction."),
>   GUC_NOT_IN_SAMPLE
>   },
> Suggest re-wording the long description (subscriber part) to be more like the
> documentation text.
> 
> BEFORE
> On the subscriber, in parallel streaming mode, it allows the leader apply worker
> to serialize changes to files and notifies the parallel apply workers to read and
> apply them at the end of the transaction.
> 
> SUGGESTION
> On the subscriber, if the streaming option is set to parallel, it directs the leader
> apply worker to send changes to the shared memory queue or to serialize
> changes and apply them at the end of the transaction.
> 

Changed.

Attach the new version patch which addressed all comments so far (the v88-0001
has been committed, so we only have one remaining patch this time).

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.