Re: Disallow UPDATE/DELETE on table with unpublished generated column as REPLICA IDENTITY - Mailing list pgsql-hackers

From vignesh C
Subject Re: Disallow UPDATE/DELETE on table with unpublished generated column as REPLICA IDENTITY
Date
Msg-id CALDaNm0=Na3v2tcf3srZ4x1uO_oGTRqS38deu8G-9cyXsAVKwg@mail.gmail.com
Whole thread Raw
In response to Re: Disallow UPDATE/DELETE on table with unpublished generated column as REPLICA IDENTITY  (Amit Kapila <amit.kapila16@gmail.com>)
List pgsql-hackers
On Sat, 16 Nov 2024 at 00:10, Shlok Kyal <shlok.kyal.oss@gmail.com> wrote:
>
> Thanks for providing the comments. I have fixed all the comments and
> attached the updated patch.

Few comments:
1) The replident_has_valid_gen_cols flag is set when either an update
or delete operation is published by the publication.
+               /*
+                * Check if all columns which are part of the REPLICA
IDENTITY is
+                * published.
+                */
+               if (!pubform->pubgencols &&
+                       (pubform->pubupdate || pubform->pubdelete) &&
+                       replident_has_unpublished_gen_col(pubid,
relation, ancestors,
+
                   pubform->pubviaroot))
+                       pubdesc->replident_has_valid_gen_cols = false;

You should create two separate flags—one for updates and one for
deletes—and set them accordingly, based on the operation being
published. This is similar to how the cols_valid_for_update and
cols_valid_for_delete flags are handled for column lists.

As shown in the test below, the delete operation fails even though the
delete operation is not published by the pub_gencol publication:
CREATE TABLE testpub_gencol (a INT, b INT GENERATED ALWAYS AS (a + 1)
STORED NOT NULL);
CREATE UNIQUE INDEX testpub_gencol_idx ON testpub_gencol (b);
ALTER TABLE testpub_gencol REPLICA IDENTITY USING index testpub_gencol_idx;

CREATE PUBLICATION pub_gencol FOR TABLE testpub_gencol with ( PUBLISH
= 'update');

-- This should be successful, since the publication is not publishing delete:
postgres=# delete from testpub_gencol ;
ERROR:  cannot delete from table "testpub_gencol"
DETAIL:  Replica identity consists of an unpublished generated column.

2) Since the code in replident_has_unpublished_gen_col and
pub_collist_contains_invalid_column is largely identical, we can
consolidate them into a single function that handles both column lists
and relation columns. The function name, header comments, and internal
comments should be updated accordingly.

Regards,
Vignesh



pgsql-hackers by date:

Previous
From: Tomas Vondra
Date:
Subject: Re: logical replication: restart_lsn can go backwards (and more), seems broken since 9.4
Next
From: Shlok Kyal
Date:
Subject: Re: Improve the error message for logical replication of regular column to generated column.