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Re: Column Filtering in Logical Replication

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Justin Pryzby <pryzby@telsasoft.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Rahila Syed <rahilasyed90@gmail.com>, Peter Smith <smithpb2250@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-01-07T13:08:58Z
Lists: pgsql-hackers 
On Fri, Jan 7, 2022 at 5:16 PM Peter Eisentraut
<peter.eisentraut@enterprisedb.com> wrote:
>
> src/backend/commands/tablecmds.c:
>
> ATExecReplicaIdentity(): Regarding the question of how to handle
> REPLICA_IDENTITY_NOTHING: I see two ways to do this.  Right now, the
> approach is that the user can set the replica identity freely, and we
> decide later based on that what we can replicate (e.g., no updates).
>

+1. This is what we are trying to do with the row filter patch. It
seems Hou-San has also mentioned the same on this thread [1].

> For this patch, that would mean we don't restrict what columns can be
> in the column list, but we check what actions we can replicate based
> on the column list.  The alternative is that we require the column
> list to include the replica identity, as the patch is currently doing,
> which would mean that REPLICA_IDENTITY_NOTHING can be allowed since
> it's essentially a set of zero columns.
>
> I find the current behavior a bit weird on reflection.  If a user
> wants to replicate on some columns and only INSERTs, that should be
> allowed regardless of what the replica identity columns are.
>

Right, I also raised the same point [2] related to INSERTs.

[1] - https://www.postgresql.org/message-id/OS0PR01MB5716330FFE3803DF887D073C94789%40OS0PR01MB5716.jpnprd01.prod.outlook.com
[2] - https://www.postgresql.org/message-id/CAA4eK1%2BFoJ-J7wUG5s8zCtY0iBuN9LcjQcYhV4BD17xhuHfoug%40mail.gmail.com

-- 
With Regards,
Amit Kapila.

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Doc: Explain about Column List feature.

  2. Doc: fix column list vs. replica identity rules.

  3. Prohibit combining publications with different column lists.

  4. Fix the check to limit sync workers.

  5. Wait for subscription to sync in t/031_column_list.sql

  6. Move prattrs to the pg_publication_rel section in docs

  7. Allow specifying column lists for logical replication

  8. Fix row filters with multiple publications

  9. Fix publish_as_relid with multiple publications

  10. Add some additional tests for row filters in logical replication.

  11. Add index on pg_publication_rel.prpubid

  12. Avoid using DefElemAction in AlterPublicationStmt

  13. Small cleanups related to PUBLICATION framework code

  14. Add PublicationTable and PublicationRelInfo structs

  15. Fix various concurrency issues in logical replication worker launching