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: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Euler Taveira <euler@eulerto.com>, Greg Nancarrow <gregn4422@gmail.com>, "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>, 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: 2021-11-30T10:25:45Z
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, Nov 30, 2021 at 11:37 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Tue, Nov 30, 2021 at 10:26 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Mon, Nov 29, 2021 at 8:40 PM Euler Taveira <euler@eulerto.com> wrote:
> > >
> > > 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.
> > >
> >
> > We can try that way but I think we should still be able to combine in
> > many cases like where all the operations are specified for
> > publications having the table or maybe pubactions are same. So, we
> > should not give up on those cases. We can do this new logic only when
> > we find that pubactions are different and probably store them as
> > independent expressions and corresponding pubactions for it at the
> > current location in the v42* patch (in pgoutput_row_filter). It is
> > okay to combine them at a later stage during execution when we can't
> > do it at the time of forming cache entry.
>
> What about the initial table sync? during that, we are going to
> combine all the filters or we are going to apply only the insert
> filters?
>

AFAIK, currently, initial table sync doesn't respect publication
actions so it should combine all the filters. What do you think?

-- 
With Regards,
Amit Kapila.