Re: row filtering for logical replication

Amit Kapila <amit.kapila16@gmail.com>

From: Amit Kapila <amit.kapila16@gmail.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Peter Smith <smithpb2250@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, Euler Taveira <euler@eulerto.com>, Greg Nancarrow <gregn4422@gmail.com>, vignesh C <vignesh21@gmail.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: 2022-01-20T13:33:27Z
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, Jan 20, 2022 at 6:43 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> And the actual reason I was looking at this code, is that I had stumbled
> upon the new GetRelationPublicationInfo() function, which has an even
> weirder API:
>
> >  * Get the publication information for the given relation.
> >  *
> >  * Traverse all the publications which the relation is in to get the
> >  * publication actions and validate the row filter expressions for such
> >  * publications if any. We consider the row filter expression as invalid if it
> >  * references any column which is not part of REPLICA IDENTITY.
> >  *
> >  * To avoid fetching the publication information, we cache the publication
> >  * actions and row filter validation information.
> >  *
> >  * Returns the column number of an invalid column referenced in a row filter
> >  * expression if any, InvalidAttrNumber otherwise.
> >  */
> > AttrNumber
> > GetRelationPublicationInfo(Relation relation, bool validate_rowfilter)
>
> "Returns *an* invalid column referenced in a RF if any"?  That sounds
> very strange.  And exactly what info is it getting, given that there is
> no actual returned info?
>

It returns an invalid column referenced in an RF if any but if not
then it helps to form pubactions which is anyway required at a later
point in the caller. The idea is that when we are already traversing
publications we should store/gather as much info as possible. I think
probably the API name is misleading, maybe we should name it something
like ValidateAndFetchPubInfo, ValidateAndRememberPubInfo, or something
along these lines?

>  Maybe this was meant to be "validate RF
> expressions" and return, perhaps, a bitmapset of all invalid columns
> referenced?
>

Currently, we stop as soon as we find the first invalid column.

>  (What is an invalid column in the first place?)
>

A column that is referenced in the row filter but is not part of
Replica Identity.

-- 
With Regards,
Amit Kapila.