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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: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>, Rahila Syed <rahilasyed90@gmail.com>, Peter Smith <smithpb2250@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2021-12-17T04:47:33Z
Lists: pgsql-hackers 
On Wed, Dec 15, 2021 at 1:05 AM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> On 2021-Dec-14, Tomas Vondra wrote:
>
> > Yeah. I think it's not clear if this should behave more like an index or a
> > view. When an indexed column gets dropped we simply drop the index. But if
> > you drop a column referenced by a view, we fail with an error. I think we
> > should handle this more like a view, because publications are externally
> > visible objects too (while indexes are pretty much just an implementation
> > detail).
>
> I agree -- I think it's more like a view than like an index.  (The
> original proposal was that if you dropped a column that was part of the
> column list of a relation in a publication, the entire relation is
> dropped from the view,
>

I think in the above sentence, you mean to say "dropped from the
publication". So, IIUC, you are proposing that if one drops a column
that was part of the column list of a relation in a publication, an
error will be raised. Also, if the user specifies CASCADE in Alter
Table ... Drop Column, then we drop the relation from publication. Is
that right? BTW, this is somewhat on the lines of what row_filter
patch is also doing where if the user drops the column that was part
of row_filter for a relation in publication, we give an error and if
the user tries to drop the column with CASCADE then the relation is
removed from the publication.

-- 
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