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

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
Cc: Peter Smith <smithpb2250@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>, Amit Kapila <amit.kapila16@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>
Date: 2023-01-23T12:34:00Z
Lists: pgsql-hackers 
Dear Hou,

Thank you for updating the patch! Followings are my comments.

1. guc_tables.c

```
 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}
 };
```

This struct should be also modified.

2. guc_tables.c


```
-               {"logical_decoding_mode", PGC_USERSET, DEVELOPER_OPTIONS,
+               {"logical_replication_mode", PGC_USERSET, DEVELOPER_OPTIONS,
                        gettext_noop("Allows streaming or serializing each change in logical decoding."),
                        NULL,
```

I felt the description seems not to be suitable for current behavior.
A short description should be like "Sets a behavior of logical replication", and
further descriptions can be added in lond description.

3. config.sgml

```
       <para>
        This parameter is intended to be used to test logical decoding and
        replication of large transactions for which otherwise we need to
        generate the changes till <varname>logical_decoding_work_mem</varname>
        is reached.
       </para>
```

I understood that this part described the usage of the parameter. How about adding
a statement like:

" Moreover, this can be also used to test the message passing between the leader
and parallel apply workers."

4. 015_stream.pl

```
+# Ensure that the messages are serialized.
```

In other parts "changes" are used instead of "messages". Can you change the word?

Best Regards,
Hayato Kuroda
FUJITSU LIMITED

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.