Horton

Re: row filtering for logical replication

Euler Taveira <euler@eulerto.com>

View thread
From: "Euler Taveira" <euler@eulerto.com>
To: "Dilip Kumar" <dilipbalaut@gmail.com>, "Tomas Vondra" <tomas.vondra@enterprisedb.com>
Cc: "Amit Kapila" <amit.kapila16@gmail.com>, "Alvaro Herrera" <alvherre@alvh.no-ip.org>, "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: 2021-07-14T16:30:33Z
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 Wed, Jul 14, 2021, at 11:48 AM, Dilip Kumar wrote:
> On Wed, Jul 14, 2021 at 8:04 PM Tomas Vondra
> <tomas.vondra@enterprisedb.com> wrote:
> >
> 
> > Perhaps the best way forward is to stick to the approach that INSERT
> > uses new, DELETE uses old and UPDATE works as DELETE+INSERT (probably),
> > and leave anything fancier (like being able to reference both versions
> > of the row) for a future patch.
> 
> If UPDATE works as DELETE+ INSERT, does that mean both the OLD row and
> the NEW row should satisfy the filter, then only it will be sent?
> That means if we insert a row that is not satisfying the condition
> (which is not sent to the subscriber) and later if we update that row
> and change the values such that the modified value matches the filter
> then we will not send it because only the NEW row is satisfying the
> condition but OLD row doesn't.  I am just trying to understand your
> idea.  Or you are saying that in this case, we will not send anything
> for the OLD row as it was not satisfying the condition but the
> modified row will be sent as an INSERT operation because this is
> satisfying the condition?
That's a fair argument for the default UPDATE behavior. It seems we have a
consensus that UPDATE operation will use old row. If there is no objections, I
will change it in the next version.

We can certainly discuss the possibilities for UPDATE operations. It can choose
which row to use: old, new or both (using an additional publication argument or
OLD and NEW placeholders to reference old and new rows are feasible ideas).


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