Horton

Re: Skipping schema changes in publication

vignesh C <vignesh21@gmail.com>

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From: vignesh C <vignesh21@gmail.com>
To: Shlok Kyal <shlok.kyal.oss@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, YeXiu <1518981153@qq.com>, Ian Lawrence Barwick <barwick@gmail.com>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-09-29T15:30:14Z
Lists: pgsql-hackers

Commits

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  1. Fix miscellaneous issues in EXCEPT publication clause.

  2. Change syntax of EXCEPT TABLE clause in publication commands.

  3. Add support for EXCEPT TABLE in ALTER PUBLICATION.

  4. Allow table exclusions in publications via EXCEPT TABLE.

  5. Add wait_for_subscription_sync for TAP tests.

On Sat, 27 Sept 2025 at 01:20, Shlok Kyal <shlok.kyal.oss@gmail.com> wrote:
>
> Thanks for reviewing the patch.
> I have addressed the comments and attached the updated version.

If all columns are excluded, we do not publish the changes. However,
when a table has no columns, the data is still replicated. Should we
make this behavior consistent?
@@ -1482,6 +1525,13 @@ pgoutput_change(LogicalDecodingContext *ctx,
ReorderBufferTXN *txn,
        relentry = get_rel_sync_entry(data, relation);
+       /*
+        * If all columns of a table are present in column list specified with
+        * EXCEPT, skip publishing the changes.
+        */
+       if (relentry->all_cols_excluded)
+               return;

Steps to check the above issue:
-- pub
create table t1();
create table t2(c1 int, c2 int);
create publication pub1 FOR table t1;
create publication pub2 FOR table t2 except(c1, c2);

--sub
create table t1(c1 int);
create table t2(c1 int, c2 int);
create subscription sub1 connection 'dbname=postgres host=localhost
port=5432' publication pub1,pub2;

--pub
postgres=# insert into t1 default values ;
INSERT 0 1
postgres=# insert into t2 default values;
INSERT 0 1

--sub
-- In case of table having no columns, data is replicated
postgres=# select * from t1;
 c1
----

(1 row)

-- In case of table having all columns excluded, data is not replicated
postgres=# select * from t2;
 c1 | c2
----+----
(0 rows)

Thoughts?

Regards,
Vignesh