Horton

Re: row filtering for logical replication

Peter Smith <smithpb2250@gmail.com>

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From: Peter Smith <smithpb2250@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Euler Taveira <euler@eulerto.com>, Greg Nancarrow <gregn4422@gmail.com>, vignesh C <vignesh21@gmail.com>, Ajin Cherian <itsajin@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, Dilip Kumar <dilipbalaut@gmail.com>, Rahila Syed <rahilasyed90@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Önder Kalacı <onderkalaci@gmail.com>, japin <japinli@hotmail.com>, Michael Paquier <michael@paquier.xyz>, David Steele <david@pgmasters.net>, Craig Ringer <craig@2ndquadrant.com>, Amit Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-02-03T08:29:54Z
Lists: pgsql-hackers

Commits

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  1. Release cache tuple when no longer needed

  2. Add some additional tests for row filters in logical replication.

  3. Fix one of the tests introduced in commit 52e4f0cd47.

  4. Allow specifying row filters for logical replication of tables.

  5. Move scanint8() to numutils.c

  6. Replace Test::More plans with done_testing

  7. Reduce relcache access in WAL sender streaming logical changes

  8. Small cleanups related to PUBLICATION framework code

  9. Add a view to show the stats of subscription workers.

  10. Allow publishing the tables of schema.

  11. Doc: improve documentation of CREATE/ALTER SUBSCRIPTION.

  12. Add PublicationTable and PublicationRelInfo structs

  13. Remove unused argument "txn" in maybe_send_schema().

  14. Add prepare API support for streaming transactions in logical replication.

  15. Unify PostgresNode's new() and get_new_node() methods

  16. Use l*_node() family of functions where appropriate

  17. Add support for prepared transactions to built-in logical replication.

  18. Restore the portal-level snapshot after procedure COMMIT/ROLLBACK.

  19. Rename a parse node to be more general

  20. Remove unused column atttypmod from initial tablesync query

  21. SEARCH and CYCLE clauses

Attachments

On Sat, Jan 29, 2022 at 11:31 AM Andres Freund <andres@anarazel.de> wrote:
>
> Hi,
>
> Are there any recent performance evaluations of the overhead of row filters? I
> think it'd be good to get some numbers comparing:
>
> 1) $workload with master
> 2) $workload with patch, but no row filters
> 3) $workload with patch, row filter matching everything
> 4) $workload with patch, row filter matching few rows
>
> For workload I think it'd be worth testing:
> a) bulk COPY/INSERT into one table
> b) Many transactions doing small modifications to one table
> c) Many transactions targetting many different tables
> d) Interspersed DDL + small changes to a table
>

Here are performance data results for the workload case (c):

HEAD 105.75
v74 no filters 105.86
v74 allow 100% 104.94
v74 allow 75% 97.12
v74 allow 50% 78.92
v74 allow 25% 69.71
v74 allow 0% 59.70

This was tested using patch v74 and synchronous pub/sub.
There are 100K INSERTS/UPDATES over 5 tables (all published)
The PUBLICATIONS use differing amounts of row filtering (or none).

Observations:
- We see pretty much the same pattern as for workloads "a" and "b"
- There seems insignificant row-filter overheads (e.g. viz no filter
and 100% allowed versus HEAD).
- The elapsed time decreases as more % data is filtered out (i.e as
replication happens).

PSA workload "c" test files for details.

------
Kind Regards,
Peter Smith.
Fujitsu Australia.