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Message-ID: <e08cb97f-0364-4002-9cda-3c16b42e4136@uni-muenster.de>
Date: Thu, 12 Feb 2026 11:11:58 +0100
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Content-Language: de-DE, en-GB
From: Jim Jones <jim.jones@uni-muenster.de>
Subject: COMMENTS are not being copied in CREATE TABLE LIKE
To: "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Cc: Matheus Alcantara <matheusssilv97@gmail.com>
Archived-At: <https://www.postgresql.org/message-id/e08cb97f-0364-4002-9cda-3c16b42e4136%40uni-muenster.de>
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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:


psql (19devel)
Type "help" for help.

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 | table comment | table comment
(1 row)


Thoughts?

Best, Jim

1 -
https://www.postgresql.org/message-id/flat/DG7Y34A6VBEG.76L7K1OML5DI%40gmail.com
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