Horton

Re: row filtering for logical replication

Peter Smith <smithpb2250@gmail.com>

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From: Peter Smith <smithpb2250@gmail.com>
To: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
Cc: Ajin Cherian <itsajin@gmail.com>, Greg Nancarrow <gregn4422@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Euler Taveira <euler@eulerto.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>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Amit Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-11-05T05:27:45Z
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

On Thu, Nov 4, 2021 at 2:21 PM houzj.fnst@fujitsu.com
<houzj.fnst@fujitsu.com> wrote:
>
> Thanks for the patches.
> I started to review the patches and here are a few comments.
>
> 1)
>                 /*
>                  * ALTER PUBLICATION ... ADD TABLE provides a PublicationTable List
>                  * (Relation, Where clause). ALTER PUBLICATION ... DROP TABLE provides
>                  * a Relation List. Check the List element to be used.
>                  */
>                 if (IsA(lfirst(lc), PublicationTable))
>                         whereclause = true;
>                 else
>                         whereclause = false;
>
> I am not sure about the comments here, wouldn't it be better to always provides
> PublicationTable List which could be more consistent.

Fixed in v37-0001 [1].

>
> 2)
> +                                       if ($3)
> +                                       {
> +                                               $$->pubtable->whereClause = $3;
> +                                       }
>
> It seems we can remove the if ($3) check here.
>

Fixed in v37-0001 [1].

>
> 3)
>
> +                                       oldctx = MemoryContextSwitchTo(CacheMemoryContext);
> +                                       rfnode = stringToNode(TextDatumGetCString(rfdatum));
> +                                       exprstate = pgoutput_row_filter_init_expr(rfnode);
> +                                       entry->exprstates = lappend(entry->exprstates, exprstate);
> +                                       MemoryContextSwitchTo(oldctx);
> +                               }
>
> Currently in the patch, it save and execute each expression separately. I was
> thinking it might be better if we can use "AND" to combine all the expressions
> into one expression, then we can initialize and optimize the final expression
> and execute it only once.

Yes, thanks for this suggestion - it is an interesting idea. I had
thought the same as this some time ago but never acted on it. I will
try implementing this idea as a separate new patch because it probably
needs to be performance tested against the current code just in case
the extra effort to combine the expressions outweighs any execution
benefits.

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[1] https://www.postgresql.org/message-id/CAHut%2BPtRdXzPpm3qv3cEYWWfVUkGT84EopEHxwt95eo_cG_3eQ%40mail.gmail.com

Kind Regards,
Peter Smith.
Fujitsu Australia.