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

Yu Shi (Fujitsu) <shiy.fnst@fujitsu.com>

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From: "shiy.fnst@fujitsu.com" <shiy.fnst@fujitsu.com>
To: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>, Peter Smith <smithpb2250@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-12-14T06:34:19Z
Lists: pgsql-hackers

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Hi,

I did some performance tests for this patch, based on v59-0001 and v59-0002
patch.

This test used synchronous logical replication, and compared SQL execution times
before and after applying the patch.

Two cases are tested by varying logical_decoding_work_mem:
a) Bulk insert.
b) Rollback to savepoint. (Different percentage of changes in the transaction
are rolled back).

The test was performed ten times, and the average of the middle eight was taken.

The results are as follows. The bar charts are attached.
(The steps are the same as before.[1])

RESULT - bulk insert (5kk)
---------------------------------------------------------------
logical_decoding_work_mem   64kB        256kB       64MB
HEAD                        51.655      51.694      51.262
patched                     31.104      31.234      31.711
Compare with HEAD           -39.79%     -39.58%     -38.14%

RESULT - rollback 10% (5kk)
---------------------------------------------------------------
logical_decoding_work_mem   64kB        256kB       64MB
HEAD                        43.908      43.358      42.874
patched                     31.924      31.343      29.102
Compare with HEAD           -27.29%     -27.71%     -32.12%

RESULT - rollback 20% (5kk)
---------------------------------------------------------------
logical_decoding_work_mem   64kB        256kB       64MB
HEAD                        40.561      40.599      40.015
patched                     31.562      32.116      29.680
Compare with HEAD           -22.19%     -20.89%     -25.83%

RESULT - rollback 30% (5kk)
---------------------------------------------------------------
logical_decoding_work_mem   64kB        256kB       64MB
HEAD                        38.092      37.756      37.142
patched                     31.631      31.236      28.783
Compare with HEAD           -16.96%     -17.27%      -22.50%

RESULT - rollback 50% (5kk)
---------------------------------------------------------------
logical_decoding_work_mem   64kB        256kB       64MB
HEAD                        33.387      33.056      32.638
patched                     31.272      31.279      29.876
Compare with HEAD           -6.34%      -5.38%      -8.46%

(If "Compare with HEAD" is a positive number, it means worse than HEAD; if it is
a negative number, it means better than HEAD.)

Summary:
In the case of bulk insert, it takes about 30% ~ 40% less time, which looks good
to me.
In the case of rollback to savepoint, the larger the amount of data rolled back,
the smaller the improvement compared to HEAD. But as such cases won't be often,
this should be okay.

[1] https://www.postgresql.org/message-id/OSZPR01MB63103AA97349BBB858E27DEAFD499%40OSZPR01MB6310.jpnprd01.prod.outlook.com

Regards,
Shi yu

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.