Re: Skipping schema changes in publication

From: Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>
To: vignesh C <vignesh21(at)gmail(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Shlok Kyal <shlok(dot)kyal(dot)oss(at)gmail(dot)com>, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>, shveta malik <shveta(dot)malik(at)gmail(dot)com>, "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Peter Smith <smithpb2250(at)gmail(dot)com>, "Zhijie Hou (Fujitsu)" <houzj(dot)fnst(at)fujitsu(dot)com>, YeXiu <1518981153(at)qq(dot)com>, Ian Lawrence Barwick <barwick(at)gmail(dot)com>, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Skipping schema changes in publication
Date: 2026-02-25 08:22:37
Message-ID: 0DDF38E7-3033-47E1-98C1-49A1378526B3@gmail.com
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> On Feb 25, 2026, at 15:04, vignesh C <vignesh21(at)gmail(dot)com> wrote:
>
> On Mon, 23 Feb 2026 at 16:46, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>>
>> On Mon, Feb 23, 2026 at 11:37 AM Shlok Kyal <shlok(dot)kyal(dot)oss(at)gmail(dot)com> wrote:
>>>
>>> I have also modified the error message as suggested by Shveta in [2].
>>> Attached the latest v48 patch.
>>>
>>
>> I see that the second patch (0002) brings complexity in the patch to
>> deal with following points: (a) The first complexity is if one of the
>> partitions is specified then how to compute the initial set of
>> relations to copy when pubviaroot is true. This is complex because we
>> need to exclude the partitions specified. (b) The other complexity is
>> combining Except list containing partitions and other publications
>> specifying partitions or partitioned tables both during replication
>> and probably during initial sync.
>>
>> I think it will be better if for the first version, we allow only root
>> partitioned table to be specified in the Except Table list. This would
>> mean that if the user tries to attach that root partition table to
>> another root then we should give an error. If we go via this route, it
>> will be important to allow users to remove some tables from the Except
>> list, so we can provide Alter Publication <pub_name> Set Except Table
>> (table_names).
>
> The attached patch has the changes for the same i.e.a) Raises an error
> when attempting to attach a partition to a root partitioned table if
> that table is referenced in an EXCEPT clause of any publication. b)
> Adds support for dropping excluded tables using: ALTER PUBLICATION ...
> DROP EXCEPT TABLE. c) Adds support for replacing the exclusion list
> using ALTER PUBLICATION ... SET EXCEPT TABLE.
> The changes related to DROP EXCEPT TABLE and SET EXCEPT TABLE have
> been kept separately into patch 0002 for easier review.
>
> The comments from [1] are also addressed in the attached patch.
> [1] - https://www.postgresql.org/message-id/CAA4eK1KESu4%3DW6j4CQkKv5nzNJgtJyYBsg3E5K%2BLcwOr3t0WKw%40mail.gmail.com
>
> Regards,
> Vignesh
> <v49-0001-Skip-publishing-the-tables-specified-in-EXCEPT-T.patch><v49-0002-Support-DROP-and-SET-EXCEPT-TABLE-in-ALTER-PUBLI.patch>

I quickly went through the code change and haven’t actually played the new feature yet. A few small comments:

1 - 0001 - subscriptioncmds.c
```
+ GetPublicationsStr(except_publications, &pubnames, false);
+
+ pfree(except_publications);
```

except_publications is a list, so we should use list_free(except_publications) instead of pfree().

2 - 0002
```
+ will be removed. The <literal>ADD</literal> clauses will add one or more
+ tables/schemas from the publication. The <literal>DROP</literal> clauses
```

I guess “from the publication” should be “to the publication”.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/

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