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From: Matheus Alcantara <[email protected]>
To: Jim Jones <[email protected]>
To: [email protected] <[email protected]>
Cc: Matheus Alcantara <[email protected]>
Subject: Re: COMMENTS are not being copied in CREATE TABLE LIKE
Date: Thu, 12 Feb 2026 11:36:26 -0300
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

Hi, thanks for checking this.

On Thu Feb 12, 2026 at 7:11 AM -03, Jim Jones wrote:
> Hi,
>
> While reviewing another patch[1] I saw that COMMENTS on tables are being
> ignored in CREATE TABLE LIKE:
>
> psql (18.1 (Debian 18.1-1.pgdg13+2))
> Type "help" for help.
>
> postgres=# \pset null '(null)'
> Null display is "(null)".
> postgres=# CREATE TABLE t1 (id int, name text);
> COMMENT ON TABLE t1 IS 'table comment';
> CREATE TABLE t2 (LIKE t1 INCLUDING ALL);
> CREATE TABLE t3 (LIKE t1 INCLUDING COMMENTS);
>
> SELECT
>   obj_description('t1'::regclass, 'pg_class') AS t1_comment,
>   obj_description('t2'::regclass, 'pg_class') AS t2_comment,
>   obj_description('t3'::regclass, 'pg_class') AS t3_comment;
> CREATE TABLE
> COMMENT
> CREATE TABLE
> CREATE TABLE
>   t1_comment   | t2_comment | t3_comment
> ---------------+------------+------------
>  table comment | (null)     | (null)
> (1 row)
>
>
> v1 attached attempts to fix it by expanding expandTableLikeClause() to
> retrieve and copy the table-level comment when the INCLUDING COMMENTS
> [ALL] option is specified:
>

The patch fix the issue and it seems correct to me.

This bug seems to also happen on 14.20:
postgres=# select version();
                                                           version
------------------------------------------------------------------------------------------------------------------------------
 PostgreSQL 14.20 (Homebrew) on aarch64-apple-darwin24.6.0, compiled by Apple clang version 17.0.0 (clang-1700.4.4.1), 64-bit
(1 row)

postgres=# CREATE TABLE t(a int, b text);
CREATE TABLE
postgres=# COMMENT ON TABLE t IS 'foo';
COMMENT
postgres=# CREATE TABLE t2(LIKE t INCLUDING ALL);
CREATE TABLE
postgres=# SELECT obj_description('t'::regclass, 'pg_class') as t_comment, obj_description('t2'::regclass, 'pg_class') AS t2_comment;
 t_comment | t2_comment
-----------+------------
 foo       |
(1 row)

So I think that we need to backport.

--
Matheus Alcantara
EDB: https://www.enterprisedb.com

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