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

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
Cc: "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, Peter Smith <smithpb2250@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-09-08T11:24:38Z
Lists: pgsql-hackers

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On Thu, Sep 8, 2022 at 12:21 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Mon, Sep 5, 2022 at 6:34 PM houzj.fnst@fujitsu.com
> <houzj.fnst@fujitsu.com> wrote:
> >
> > Attach the correct patch set this time.
> >
>
> Few comments on v28-0001*:
> =======================
>

Some suggestions for comments in v28-0001*
1.
+/*
+ * Entry for a hash table we use to map from xid to the parallel apply worker
+ * state.
+ */
+typedef struct ParallelApplyWorkerEntry

Let's change this comment to: "Hash table entry to map xid to the
parallel apply worker state."

2.
+/*
+ * List that stores the information of parallel apply workers that were
+ * started. Newly added worker information will be removed from the list at the
+ * end of the transaction when there are enough workers in the pool. Besides,
+ * exited workers will be removed from the list after being detected.
+ */
+static List *ParallelApplyWorkersList = NIL;

Can we change this to: "A list to maintain the active parallel apply
workers. The information for the new worker is added to the list after
successfully launching it. The list entry is removed at the end of the
transaction if there are already enough workers in the worker pool.
For more information about the worker pool, see comments atop
worker.c. We also remove the entry from the list if the worker is
exited due to some error."

Apart from this, I have added/changed a few other comments in
v28-0001*. Kindly check the attached, if you are fine with it then
please include it in the next version.

-- 
With Regards,
Amit Kapila.

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.