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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: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, Peter Smith <smithpb2250@gmail.com>, "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Dilip Kumar <dilipbalaut@gmail.com>
Date: 2023-01-17T03:29:45Z
Lists: pgsql-hackers 
On Tue, Jan 17, 2023 at 8:35 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Mon, Jan 16, 2023 at 3:19 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > Okay, I have added the comments in get_transaction_apply_action() and
> > updated the comments to refer to the enum TransApplyAction where all
> > the actions are explained.
>
> Thank you for the patch.
>
> @@ -1710,6 +1712,7 @@ apply_handle_stream_stop(StringInfo s)
>         }
>
>         in_streamed_transaction = false;
> +       stream_xid = InvalidTransactionId;
>
> We reset stream_xid also in stream_close_file() but probably it's no
> longer necessary?
>

I think so.

> How about adding an assertion in apply_handle_stream_start() to make
> sure the stream_xid is invalid?
>

I think it would be better to add such an assert in
apply_handle_begin/apply_handle_begin_prepare because there won't be a
problem if we start_stream message even when stream_xid is valid.
However, maybe it is better to add in all three functions
(apply_handle_begin/apply_handle_begin_prepare/apply_handle_stream_start).
What do you think?

> ---
> It's not related to this issue but I realized that if the action
> returned by get_transaction_apply_action() is not handled in the
> switch statement, we do only Assert(false). Is it better to raise an
> error like "unexpected apply action %d" just in case in order to
> detect failure cases also in the production environment?
>

Yeah, that may be better. Shall we do that as part of this patch only
or as a separate patch?

-- 
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.