Horton

Re: row filtering for logical replication

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Peter Smith <smithpb2250@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Euler Taveira <euler@eulerto.com>, Greg Nancarrow <gregn4422@gmail.com>, vignesh C <vignesh21@gmail.com>, Ajin Cherian <itsajin@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: 2022-02-01T02:57:36Z
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 Sat, Jan 29, 2022 at 6:01 AM Andres Freund <andres@anarazel.de> wrote:
>
>
> > +     if (has_filter)
> > +     {
> > +             /* Create or reset the memory context for row filters */
> > +             if (entry->cache_expr_cxt == NULL)
> > +                     entry->cache_expr_cxt = AllocSetContextCreate(CacheMemoryContext,
> > +                                                                                                               "Row filter expressions",
> > +                                                                                                               ALLOCSET_DEFAULT_SIZES);
> > +             else
> > +                     MemoryContextReset(entry->cache_expr_cxt);
>
> I see this started before this patch, but I don't think it's a great idea that
> pgoutput does a bunch of stuff in CacheMemoryContext. That makes it
> unnecessarily hard to debug leaks.
>
> Seems like all this should live somwhere below ctx->context, allocated in
> pgoutput_startup()?
>

Agreed.

> Consider what happens in a long-lived replication connection, where
> occasionally there's a transient error causing streaming to stop. At that
> point you'll just loose all knowledge of entry->cache_expr_cxt, no?
>

I think we will lose knowledge because the WALSender exits on ERROR
but that would be true even when we allocate it in this new allocated
context. Am, I missing something?

-- 
With Regards,
Amit Kapila.