Date: Wed, 11 Feb 2026 15:52:36 +0900 (JST)
Message-Id: <20260211.155236.1457492817322202220.ishii@postgresql.org>
To: thomas.munro@gmail.com
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Do we still need MULE_INTERNAL?
From: Tatsuo Ishii <ishii@postgresql.org>
In-Reply-To: <CA+hUKGKXDXh-FdU0orjfv+F08f=D91BhV3Ra-4zL-q+JmGYqTA@mail.gmail.com>
References: <CA+hUKGKXDXh-FdU0orjfv+F08f=D91BhV3Ra-4zL-q+JmGYqTA@mail.gmail.com>
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Archived-At: <https://www.postgresql.org/message-id/20260211.155236.1457492817322202220.ishii%40postgresql.org>
Precedence: bulk

Hi Thomas,

Thank you for the report. I find it is quite useful, especially the
Emacs 23 internal (new to me). I agree that MULE_INTERNAL has
fulfilled its historic role.

Small comments.

>                                      kanji kana
> MULE_INTERNAL-wrapped-JISX0208/0212: 3     3
> MULE_INTERNAL-wrapped-JISX0201K:     N/A   2
> UTF8:                                3     3
> EUC_JP:                              2     2
> EUC_JIS_2004:                        2     2
> 
> Since there are two encodings for kana characters and MULE's
> superpower is to switch, I guess it depends how you chose to encode it
> and what your ratio of kana to kanji is.

The reason for 2 encodings in MULE for "kana" exist is, it's a nature
of the character sets mule supports. In Japanese there are 2 types of
"kana", one is "hiragana" and the other is "katakana". JIS X0208/0212
includes both types of "kana", while JIS X0201 includes only
"katakana". So why "katakana" appears on those two encodings? Katakana
in JIS X0201 is often rendered on screen in half width comparing with
JIS X 0208 and 0212. Some users find this beneficial.

> UTF8:                                3     3

I thought some of JIS 2004 kanji are mapped to 4-byte UTF8 character.

> Can any Japanese (or other) experts offer any clues?  Concrete questions:

I am not an expert but let me try to answer your questions.

> * Is anyone actually using MULE_INTERNAL today?
> * If so, what prevented migration?

As far as I know, MULE_INTERNAL is not used in production PostgreSQL
databases today. Of course this does not nessary mean nobody is using
MULE_INTERNAL. My perspective is limited.

> * Was it ever actually used outside Japan?

I don't know.

> * Is the lack of interest in the new (22 year old) JIS standard in
> MULE_INTERNAL meaningful?

Maybe because at the time when JIS 2004 was out, quite few users were
trying to adopt it.

Best regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp