RE: About Unicode IVS - Graham Myers

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From: Graham Myers <gmyers@retailexpress.com>
To: 荒井元成 <n2029@ndensan.co.jp>
To: David G. Johnston <david.g.johnston@gmail.com>
Cc: pgsql-admin@lists.postgresql.org
Subject: RE: About Unicode IVS
Date: Tue, 29 Mar 2022 09:26:09 +0100
Message-ID: <d60efdf8caa7379a7483cd530ba5098e@mail.gmail.com> (raw)
In-Reply-To: <011201d84345$f704a1f0$e50de5d0$@ndensan.co.jp>
References: <00e201d8431c$cb38eb40$61aac1c0$@ndensan.co.jp>
	<CAKFQuwYCTmp5t5_7n+qRoKZArnBvv309CSi4XVdONXxQL6OX0Q@mail.gmail.com>
	<00f601d84326$5367cf00$fa376d00$@ndensan.co.jp>
	<ed987a765304d836fb05a9190eac46bf@mail.gmail.com>
	<011201d84345$f704a1f0$e50de5d0$@ndensan.co.jp>

Thanks you for the explanation, Unicode always blows my mind 😊  The
problems is that postgres is counting code points which in your example is
two.

*From:* 荒井元成 <n2029@ndensan.co.jp>
*Sent:* 29 March 2022 09:21
*To:* 'Graham Myers' <gmyers@retailexpress.com>; 'David G. Johnston' <
david.g.johnston@gmail.com>
*Cc:* pgsql-admin@lists.postgresql.org
*Subject:* RE: About Unicode IVS

thank you for your reply.

This is because two characters display one character.

This includes Unicode Variant Selectors and Combining Characters.

Moto.

*From:* Graham Myers <gmyers@retailexpress.com>
*Sent:* Tuesday, March 29, 2022 4:46 PM
*To:* 荒井元成 <n2029@ndensan.co.jp>; David G. Johnston <
david.g.johnston@gmail.com>
*Cc:* pgsql-admin@lists.postgresql.org
*Subject:* RE: About Unicode IVS

Why do you expect the concatenation of two characters to return a length of
one?

Graham Myers

*From:* 荒井元成 <n2029@ndensan.co.jp>
*Sent:* 29 March 2022 05:35
*To:* 'David G. Johnston' <david.g.johnston@gmail.com>
*Cc:* pgsql-admin@lists.postgresql.org
*Subject:* RE: About Unicode IVS

thank you for your reply.

It will be 2 characters.

select char_length(U&'\+008FBA' || U&'\+0E0102');

char_length

-------------

           2

(1 行)

select length('辺󠄂');

length

--------

      2

(1 行)

select char_length('辺󠄂');

char_length

-------------

           2

(1 行)

$ psql -l

                                      データベース一覧

   名前    | 所有者  | エンコーディング | 照合順序 | Ctype(変換演算子) |    アクセス権限

-----------+---------+------------------+----------+-------------------+---------------------

D209007   | D209007 | UTF8             | C        | C                 |

postgres  | D209007 | UTF8             | C        | C                 |

template0 | D209007 | UTF8             | C        | C                 |
=c/D209007         +

           |         |                  |          |                   |
D209007=CTc/D209007

template1 | D209007 | UTF8             | C        | C                 |
=c/D209007         +

           |         |                  |          |                   |
D209007=CTc/D209007

(4 行)

$ cat pgdata/PG_VERSION

13

Moto.

*From:* David G. Johnston <david.g.johnston@gmail.com>
*Sent:* Tuesday, March 29, 2022 12:38 PM
*To:* 荒井元成 <n2029@ndensan.co.jp>
*Cc:* pgsql-admin@lists.postgresql.org
*Subject:* Re: About Unicode IVS

Graham Myers

On Monday, March 28, 2022, 荒井元成 <n2029@ndensan.co.jp> wrote:

Hi,

In the Length () function, it will be 2 characters where you want it to be
1 character.

Is it possible to respond by changing the settings such as changing
the collation setting like SQL Server?

Also, if you understand how to deal with it (eg, create your own
function), it would be helpful if you could provide as much
information as you can.

Try char_length(text) instead.

David J.

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