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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: <CAHGQGwFJKg-aT5vajSU1v_B4K129u_SjZ3EGGHFSBhW967gcMA@mail.gmail.com>
Date: Thu, 26 Feb 2026 13:07:06 +0800
Cc: Jim Jones <jim.jones@uni-muenster.de>,
 PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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 <CAHGQGwFJKg-aT5vajSU1v_B4K129u_SjZ3EGGHFSBhW967gcMA@mail.gmail.com>
To: Fujii Masao <masao.fujii@gmail.com>
Archived-At: <https://www.postgresql.org/message-id/5BBBA7F3-2268-4E0C-96D7-59AA664699C0%40gmail.com>
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> 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

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.

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