Horton

Re: row filtering for logical replication

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Ajin Cherian <itsajin@gmail.com>, Euler Taveira <euler@eulerto.com>, Peter Smith <smithpb2250@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>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, Amit Langote <amitlangote09@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-09-21T11:42:20Z
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 Tue, Sep 21, 2021 at 4:29 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> Some more comments,
>
> In pgoutput_row_filter_update(), first, we are deforming the tuple in
> local datum, then modifying the tuple, and then reforming the tuple.
> I think we can surely do better here.  Currently, you are reforming
> the tuple so that you can store it in the scan slot by calling
> ExecStoreHeapTuple which will be used for expression evaluation.
> Instead of that what you need to do is to deform the tuple using
> tts_values of the scan slot and later call ExecStoreVirtualTuple(), so
> advantages are 1) you don't need to reform the tuple 2) the expression
> evaluation machinery doesn't need to deform again for fetching the
> value of the attribute, instead it can directly get from the value
> from the virtual tuple.
>

I have one more question, while looking into the
ExtractReplicaIdentity() function, it seems that if any of the "rep
ident key" fields is changed then we will write all the key fields in
the WAL as part of the old tuple, not just the changed fields.  That
means either the old tuple will be NULL or it will be having all the
key attributes.  So if we are supporting filter only on the "rep ident
key fields" then is there any need to copy the fields from the new
tuple to the old tuple?

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com