Re: row filtering for logical replication

Peter Smith <smithpb2250@gmail.com>

From: Peter Smith <smithpb2250@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, Ajin Cherian <itsajin@gmail.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, vignesh C <vignesh21@gmail.com>, Greg Nancarrow <gregn4422@gmail.com>, Dilip Kumar <dilipbalaut@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>, Amit Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-12-15T01:17:37Z
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 Tue, Dec 14, 2021 at 10:12 PM Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> On Tue, Dec 14, 2021 at 10:50 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Tue, Dec 14, 2021 at 4:44 AM Peter Smith <smithpb2250@gmail.com> wrote:
> >
> > Few other comments:
> > ===================
>
> Few more comments:
> ==================
> v46-0001/0002
> ===============
> 1. After rowfilter_walker() why do we need
> EXPR_KIND_PUBLICATION_WHERE? I thought this is primarily to identify
> the expressions that are not allowed in rowfilter which we are now
> able to detect upfront with the help of a walker. Can't we instead use
> EXPR_KIND_WHERE?

FYI - I have tried this locally and all tests pass.

~~

If the EXPR_KIND_PUBLICATION_WHERE is removed then there will be some
differences:
- we would get errors for aggregate/grouping functions from the EXPR_KIND_WHERE
- we would get errors for windows functions from the EXPR_KIND_WHERE
- we would get errors for set-returning functions from the EXPR_KIND_WHERE

Actually, IMO this would be a *good* change because AFAIK those are
not all being checked by the row-filter walker. I think the only
reason all tests pass is that there are no specific regression tests
for these cases.

OTOH, there would also be a difference where an error message would
not be as nice. Please see the review comment from Vignesh. [1] The
improved error message is only possible by checking the
EXPR_KIND_PUBLICATION_WHERE.

~~

I think the best thing to do here is to leave the
EXPR_KIND_PUBLICATION_WHERE but simplify code so that the improved
error message remains as the *only* difference in behaviour from the
EXPR_KIND_WHERE. i.e. we should let the other
aggregate/grouping/windows/set function checks give errors exactly the
same as for the EXPR_KIND_WHERE case.

------
[1] https://www.postgresql.org/message-id/CALDaNm08Ynr_FzNg%2BdoHj%3D_nBet%2BKZAvNbqmkEEw7M2SPpPEAw%40mail.gmail.com

Kind Regards,
Peter Smith.
Fujitsu Australia