Re: row filtering for logical replication

Alexey Zagarin <zagarin@gmail.com>

From: Alexey Zagarin <zagarin@gmail.com>
To: a.kondratov@postgrespro.ru, Euler Taveira <euler@timbira.com.br>
Cc: Andres Freund <andres@anarazel.de>, Petr Jelinek <petr.jelinek@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Suzuki Hironobu <hironobu@interdb.jp>
Date: 2019-09-01T05:25:41Z
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

I think that I also have found one shortcoming when using the setup described by Alexey Kondratov. The problem that I face is that if both (cloud and remote) tables already have data the moment I add the subscription, then the whole table is copied in both directions initially. Which leads to duplicated data and broken replication because COPY doesn't take into account the filtering condition. In case there are filters in a publication, the COPY command that is executed when adding a subscription (or altering one to refresh a publication) should also filter the data based on the same condition, e.g. COPY (SELECT * FROM ... WHERE ...) TO ...

The current workaround is to always use WITH copy_data = false when subscribing or refreshing, and then manually copy data with the above statement.

Alexey Zagarin
On 1 Sep 2019 12:11 +0700, Euler Taveira <euler@timbira.com.br>, wrote:
> Em ter, 27 de ago de 2019 às 18:10, <a.kondratov@postgrespro.ru> escreveu:
> >
> > Do you have any plans for continuing working on this patch and
> > submitting it again on the closest September commitfest? There are only
> > a few days left. Anyway, I will be glad to review the patch if you do
> > submit it, though I didn't yet dig deeply into the code.
> >
> Sure. See my last email to this thread. I appreciate if you can review it.
>
> > Although almost all new tests are passed, there is a problem with DELETE
> > replication, so 1 out of 10 tests is failed. It isn't replicated if the
> > record was created with is_cloud=TRUE on cloud, replicated to remote;
> > then updated with is_cloud=FALSE on remote, replicated to cloud; then
> > deleted on remote.
> >
> That's because you don't include is_cloud in PK or REPLICA IDENTITY. I
> add a small note in docs.
>
>
> --
> Euler Taveira Timbira -
> http://www.timbira.com.br/
> PostgreSQL: Consultoria, Desenvolvimento, Suporte 24x7 e Treinamento
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