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

Wei Wang (Fujitsu) <wangw.fnst@fujitsu.com>

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From: "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>
To: "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Peter Smith <smithpb2250@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-09-21T02:09:27Z
Lists: pgsql-hackers

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On Tues, Sep 20, 2022 at 11:41 AM Shi, Yu/侍 雨 <shiy.fnst@cn.fujitsu.com> wrote:
> On Mon, Sept 19, 2022 11:26 AM Wang, Wei/王 威 <wangw.fnst@fujitsu.com>
> wrote:
> >
> >
> > Improved as suggested.
> >
> 
> Thanks for updating the patch. Here are some comments on 0001 patch.

Thanks for your comments.

> 1.
> +		case TRANS_LEADER_SERIALIZE:
> 
> -		oldctx = MemoryContextSwitchTo(ApplyContext);
> +			/*
> +			 * Notify handle methods we're processing a remote in-
> progress
> +			 * transaction.
> +			 */
> +			in_streamed_transaction = true;
> 
> -		MyLogicalRepWorker->stream_fileset = palloc(sizeof(FileSet));
> -		FileSetInit(MyLogicalRepWorker->stream_fileset);
> +			/*
> +			 * Since no parallel apply worker is used for the first
> stream
> +			 * start, serialize all the changes of the transaction.
> +			 *
> +			 * Start a transaction on stream start, this transaction will
> be
> 
> 
> It seems that the following comment can be removed after using switch case.
> +			 * Since no parallel apply worker is used for the first
> stream
> +			 * start, serialize all the changes of the transaction.

Removed.

> 2.
> +	switch (apply_action)
> +	{
> +		case TRANS_LEADER_SERIALIZE:
> +			if (!in_streamed_transaction)
> +				ereport(ERROR,
> +
> 	(errcode(ERRCODE_PROTOCOL_VIOLATION),
> +						 errmsg_internal("STREAM STOP
> message without STREAM START")));
> 
> In apply_handle_stream_stop(), I think we can move this check to the beginning
> of
> this function, to be consistent to other functions.

Improved as suggested.

> 3. I think the some of the changes in 0005 patch can be merged to 0001 patch,
> 0005 patch can only contain the changes about new column 'apply_leader_pid'.

Merged changes not related to 'apply_leader_pid' into patch 0001.

> 4.
> + * ParallelApplyWorkersList. After successfully, launching a new worker it's
> + * information is added to the ParallelApplyWorkersList. Once the worker
> 
> Should `it's` be `its` ?

Fixed.

Attach the new patch set.

Regards,
Wang wei

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.