Re: row filtering for logical replication

Amit Kapila <amit.kapila16@gmail.com>

From: Amit Kapila <amit.kapila16@gmail.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: 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: 2021-09-09T09:10:36Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →
  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, Sep 9, 2021 at 11:43 AM Peter Smith <smithpb2250@gmail.com> wrote:
>
> PSA my new incremental patch (v28-0002) that introduces row filter
> validation for the publish mode "delete". The validation requires that
> any columns referred to in the filter expression must also be part of
> REPLICA IDENTITY or PK.
>
> [This v28-0001 is identical to the most recently posted rebased base
> patch. It is included again here only so the cfbot will be happy]
>
> ~~
>
> A requirement for some filter validation like this has been mentioned
> several times in this thread [1][2][3][4][5].
>
> I also added some test code for various kinds of replica identity.
>
> A couple of existing tests had to be modified so they could continue
> to work  (e.g. changed publish = "insert" or REPLICA IDENTITY FULL)
>
> Feedback is welcome.
>
> ~~
>
> NOTE: This validation currently only checks when the filters are first
> created. Probably there are many other scenarios that need to be
> properly handled. What to do if something which impacts the existing
> filter is changed?
>
> e.g.
> - what if the user changes the publish parameter using ALTER
> PUBLICATION set (publish="delete") etc?
> - what if the user changes the replication identity?
> - what if the user changes the filter using ALTER PUBLICATION in a way
> that is no longer compatible with the necessary cols?
> - what if the user changes the table (e.g. removes a column referred
> to by a filter)?
> - what if the user changes a referred column name?
> - more...
>
> (None of those are addressed yet - thoughts?)
>

I think we need to remove the filter or the table from publication in
such cases. Now, one can think of just removing the condition related
to the column being removed/changed in some way but I think that won't
be appropriate because it would change the meaning of the filter. We
are discussing similar stuff in the column filter thread and we might
want to do the same for row filters as well. I would prefer to remove
the table in both cases as Rahila has proposed in the column filter
patch.

-- 
With Regards,
Amit Kapila.