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Subject: Re: Show comments in \dRp+, \dRs+, and \dX+ psql meta-commands
From: Chao Li <li.evan.chao@gmail.com>
In-Reply-To: <5BBBA7F3-2268-4E0C-96D7-59AA664699C0@gmail.com>
Date: Thu, 26 Feb 2026 14:13:44 +0800
Cc: Jim Jones <jim.jones@uni-muenster.de>,
 PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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To: Fujii Masao <masao.fujii@gmail.com>
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> On Feb 26, 2026, at 13:07, Chao Li <li.evan.chao@gmail.com> wrote:
>=20
>=20
>=20
>> On Feb 26, 2026, at 11:32, Fujii Masao <masao.fujii@gmail.com> wrote:
>>=20
>>=20
>>> One unrelated thing caught my attention though: NULLs and empty =
strings
>>> are both displayed as NULL, which is expected according to
>>> CreateComments() in comment.c
>>>=20
>>> ...
>>> /* Reduce empty-string to NULL case */
>>> if (comment !=3D NULL && strlen(comment) =3D=3D 0)
>>> comment =3D NULL;
>>> ...
>>>=20
>>> However, I couldn't find anything in the docs that clearly says that
>>> it's going to be the case -- at least not in comment.sgml.
>>>=20
>>> CREATE SEQUENCE s1;
>>> COMMENT ON SEQUENCE s1 IS '';
>>> CREATE SEQUENCE s2;
>>> COMMENT ON SEQUENCE s2 IS NULL;
>>>=20
>>> postgres=3D# \ds+
>>> List of sequences
>>> -[ RECORD 1 ]-----------
>>> Schema      | public
>>> Name        | s1
>>> Type        | sequence
>>> Owner       | jim
>>> Persistence | permanent
>>> Size        | 8192 bytes
>>> Description | (null)
>>> -[ RECORD 2 ]-----------
>>> Schema      | public
>>> Name        | s2
>>> Type        | sequence
>>> Owner       | jim
>>> Persistence | permanent
>>> Size        | 8192 bytes
>>> Description | (null)
>>>=20
>>> Is it perhaps an undocumented behaviour?
>>=20
>> I'm not sure why this behavior isn't documented, but it seems worth
>> addressing in a separate documentation patch.
>>=20
>=20
> Actually, I am right about to post a doc patch for that. I noticed =
that while reviewing the other patch about comment before the holiday =
vacation. My patch will be out today or tomorrow.
>=20
> Best regards,
> --
> Chao Li (Evan)
> HighGo Software Co., Ltd.
> https://www.highgo.com/
>=20

Hi Fujii-san,

This is the tiny patch to enhance the doc of COMMON ON command. Would =
you please take a look? Thanks a lot.

=
https://www.postgresql.org/message-id/26476097-B1C1-4BA8-AA92-0AD0B8EC7190=
%40gmail.com

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