Re: row filtering for logical replication

Euler Taveira <euler@eulerto.com>

From: "Euler Taveira" <euler@eulerto.com>
To: "Amit Kapila" <amit.kapila16@gmail.com>, "Greg Nancarrow" <gregn4422@gmail.com>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, "vignesh C" <vignesh21@gmail.com>, "Peter Smith" <smithpb2250@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, "Ajin Cherian" <itsajin@gmail.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: 2021-11-29T15:10:09Z
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 Mon, Nov 29, 2021, at 7:11 AM, Amit Kapila wrote:
> I don't think it is a good idea to combine the row-filter from the
> publication that publishes just 'insert' with the row-filter that
> publishes 'updates'. We shouldn't apply the 'insert' filter for
> 'update' and similarly for publication operations. We can combine the
> filters when the published operations are the same. So, this means
> that we might need to cache multiple row-filters but I think that is
> better than having another restriction that publish operation 'insert'
> should also honor RI columns restriction.
That's exactly what I meant to say but apparently I didn't explain in details.
If a subscriber has multiple publications and a table is part of these
publications with different row filters, it should check the publication action
*before* including it in the row filter list. It means that an UPDATE operation
cannot apply a row filter that is part of a publication that has only INSERT as
an action. Having said that we cannot always combine multiple row filter
expressions into one. Instead, it should cache individual row filter expression
and apply the OR during the row filter execution (as I did in the initial
patches before this caching stuff). The other idea is to have multiple caches
for each action.  The main disadvantage of this approach is to create 4x
entries.

I'm experimenting the first approach that stores multiple row filters and its
publication action right now. Unfortunately we cannot use the
relentry->pubactions because it aggregates this information if you have
multiple entries. It seems a separate array should store this information that
will be used later while evaluating the row filter -- around
pgoutput_row_filter_exec_expr() call.


--
Euler Taveira
EDB   https://www.enterprisedb.com/