Horton

Re: row filtering for logical replication

Ajin Cherian <itsajin@gmail.com>

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From: Ajin Cherian <itsajin@gmail.com>
To: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Euler Taveira <euler@eulerto.com>, vignesh C <vignesh21@gmail.com>, Greg Nancarrow <gregn4422@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: 2021-12-20T03:52:13Z
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 Mon, Dec 20, 2021 at 12:51 PM houzj.fnst@fujitsu.com
<houzj.fnst@fujitsu.com> wrote:
>
> I think it might not be hard to predict the current behavior. User only need to be
> aware of that:
> 1) pubaction and row filter on different publications are combined with 'OR'.
> 2) FOR UPDATE, we execute the fiter for both OLD and NEW tuple and would change
>    the operation type accordingly.
>
> For the example mentioned:
> create table tbl1 (a int primary key, b int);
> create publication A for table tbl1 where (b<2) with(publish='insert');
> create publication B for table tbl1 where (a>1) with(publish='update');
>
> If we follow the rule 1) and 2), I feel we are able to predict the following
> conditions:
> --
> WHERE (action = 'insert' AND b < 2) OR (action = 'update' AND a > 1)
> --
>
> So, it seems acceptable to me.
>
> Personally, I think the current design could give user more flexibility to
> handle some complex scenario. If user want some simple setting for publication,
> they can also set same row filter for the same table in different publications.
> To avoid confusion, I think we can document about these rules clearly.
>
> BTW, From the document of IBM, I think IBM also support this kind of complex
> condition [1].
> [1] https://www.ibm.com/docs/en/idr/11.4.0?topic=rows-log-record-variables

Yes, I agree with this. It's better to give users more flexibility
while warning him on what the consequences are rather than restricting
him with constraints.
We could explain this in the documentation so that users can better
predict the effect of having pubaction specific filters.

regards,
Ajin Cherian
Fujitsu Australia