mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-12-03 08:00:21 +08:00
327 lines
9.8 KiB
Plaintext
327 lines
9.8 KiB
Plaintext
PostgreSQL 7.0.1 multi-byte (MB) support README May 20 2000
|
|
|
|
Tatsuo Ishii
|
|
ishii@postgresql.org
|
|
http://www.sra.co.jp/people/t-ishii/PostgreSQL/
|
|
|
|
[註] 1. 感謝石井達夫 (Tatsuo Ishii) 先生!
|
|
2. 註釋部份原文所無, 中譯若有錯誤, 請聯絡 cch@cc.kmu.edu.tw
|
|
|
|
|
|
0. 簡介
|
|
|
|
MB 支援是為了讓 PostgreSQL 能處理多位元組字元 (multi-byte character),
|
|
例如: EUC (Extended Unix Code), Unicode (統一碼) 和 Mule internal code
|
|
(多國語言內碼). 在 MB 的支援下, 你可以在正規表示式 (regexp), LIKE 及
|
|
其他一些函式中使用多位元組字元. 預設的編碼系統可取決於你安裝 PostgreSQL
|
|
時的 initdb(1) 命令, 亦可由 createdb(1) 命令或建立資料庫的 SQL 命令決定.
|
|
所以你可以有多個不同編碼系統的資料庫.
|
|
|
|
MB 支援也解決了一些 8 位元單位元組字元集 (包含 ISO-8859-1) 的相關問題,
|
|
(我並沒有說所有的相關問題都解決了, 我只是確認了迴歸測試執行成功,
|
|
而一些法語字元在 MB 修補下可以使用. 如果你在使用 8 位元字元時發現了
|
|
任何問題, 請通知我)
|
|
|
|
1. 如何使用
|
|
|
|
編譯 PostgreSQL 前, 執行 configure 時使用 multibyte 的選項
|
|
|
|
% ./configure --enable-multibyte[=encoding_system]
|
|
% ./configure --enable-multibyte[=編碼系統]
|
|
|
|
其中的編碼系統可以指定為下面其中之一:
|
|
|
|
SQL_ASCII ASCII
|
|
EUC_JP Japanese EUC
|
|
EUC_CN Chinese EUC
|
|
EUC_KR Korean EUC
|
|
EUC_TW Taiwan EUC
|
|
UNICODE Unicode(UTF-8)
|
|
MULE_INTERNAL Mule internal
|
|
LATIN1 ISO 8859-1 English and some European languages
|
|
LATIN2 ISO 8859-2 English and some European languages
|
|
LATIN3 ISO 8859-3 English and some European languages
|
|
LATIN4 ISO 8859-4 English and some European languages
|
|
LATIN5 ISO 8859-5 English and some European languages
|
|
KOI8 KOI8-R
|
|
WIN Windows CP1251
|
|
ALT Windows CP866
|
|
|
|
例如:
|
|
|
|
% ./configure --enable-multibyte=EUC_JP
|
|
|
|
如果省略指定編碼系統, 那麼預設值就是 SQL_ASCII.
|
|
|
|
2. 如何設定編碼
|
|
|
|
initdb 命令定義 PostgresSQL 安裝後的預設編碼, 例如:
|
|
|
|
% initdb -E EUC_JP
|
|
|
|
將預設的編碼設定為 EUC_JP (Extended Unix Code for Japanese), 如果你喜歡
|
|
較長的字串, 你也可以用 "--encoding" 而不用 "-E". 如果沒有使用 -E 或
|
|
--encoding 的選項, 那麼編繹時的設定會成為預設值.
|
|
|
|
你可以建立使用不同編碼的資料庫:
|
|
|
|
% createdb -E EUC_KR korean
|
|
|
|
這個命令會建立一個叫做 "korean" 的資料庫, 而其採用 EUC_KR 編碼.
|
|
另外有一個方法, 是使用 SQL 命令, 也可以達到同樣的目的:
|
|
|
|
CREATE DATABASE korean WITH ENCODING = 'EUC_KR';
|
|
|
|
在 pg_database 系統規格表 (system catalog) 中有一個 "encoding" 的欄位,
|
|
就是用來紀錄一個資料庫的編碼. 你可以用 psql -l 或進入 psql 後用 \l 的
|
|
命令來查看資料庫採用何種編碼:
|
|
|
|
$ psql -l
|
|
List of databases
|
|
Database | Owner | Encoding
|
|
---------------+---------+---------------
|
|
euc_cn | t-ishii | EUC_CN
|
|
euc_jp | t-ishii | EUC_JP
|
|
euc_kr | t-ishii | EUC_KR
|
|
euc_tw | t-ishii | EUC_TW
|
|
mule_internal | t-ishii | MULE_INTERNAL
|
|
regression | t-ishii | SQL_ASCII
|
|
template1 | t-ishii | EUC_JP
|
|
test | t-ishii | EUC_JP
|
|
unicode | t-ishii | UNICODE
|
|
(9 rows)
|
|
|
|
3. 前端與後端編碼的自動轉換
|
|
|
|
[註: 前端泛指客戶端的程式, 可能是 psql 命令解譯器, 或採用 libpq 的 C
|
|
程式, Perl 程式, 或者是透過 ODBC 的視窗應用程式. 而後端就是指 PostgreSQL
|
|
資料庫的伺服程式]
|
|
|
|
PostgreSQL 支援某些編碼在前端與後端間做自動轉換: [註: 這裡所謂的自動
|
|
轉換是指你在前端及後端所宣告採用的編碼不同, 但只要 PostgreSQL 支援這
|
|
兩種編碼間的轉換, 那麼它會幫你在存取前做轉換]
|
|
|
|
encoding of backend available encoding of frontend
|
|
--------------------------------------------------------------------
|
|
EUC_JP EUC_JP, SJIS
|
|
|
|
EUC_TW EUC_TW, BIG5
|
|
|
|
LATIN2 LATIN2, WIN1250
|
|
|
|
LATIN5 LATIN5, WIN, ALT
|
|
|
|
MULE_INTERNAL EUC_JP, SJIS, EUC_KR, EUC_CN,
|
|
EUC_TW, BIG5, LATIN1 to LATIN5,
|
|
WIN, ALT, WIN1250
|
|
|
|
在啟動自動編碼轉換之前, 你必須告訴 PostgreSQL 你要在前端採用何種編碼.
|
|
有好幾個方法可以達到這個目的:
|
|
|
|
o 在 psql 命令解譯器中使用 \encoding 這個命令
|
|
|
|
\encoding 這個命令可以讓你馬上切換前端編碼, 例如, 你要將前端編碼切換為 SJIS,
|
|
那麼請打:
|
|
|
|
\encoding SJIS
|
|
|
|
o 使用 libpq [註: PostgreSQL 資料庫的 C API 程式庫] 的函式
|
|
|
|
psql 的 \encoding 命令其實只是去呼叫 PQsetClientEncoding() 這個函式來達到目的.
|
|
|
|
int PQsetClientEncoding(PGconn *conn, const char *encoding)
|
|
|
|
上式中 conn 這個參數代表一個對後端的連線, encoding 這個參數要放你想用的編碼,
|
|
假如它成功地設定了編碼, 便會傳回 0 值, 失敗的話傳回 -1. 至於目前連線的編碼可
|
|
利用以下函式查知:
|
|
|
|
int PQclientEncoding(const PGconn *conn)
|
|
|
|
這裡要注意的是: 這個函式傳回的是編碼的代號 (encoding id, 是個整數值),
|
|
而不是編碼的名稱字串 (如 "EUC_JP"), 如果你要由編碼代號得知編碼名稱,
|
|
必須呼叫:
|
|
|
|
char *pg_encoding_to_char(int encoding_id)
|
|
|
|
o 使用 PGCLIENTENCODING 這個環境變數
|
|
|
|
如果前端底設定了 PGCLIENTENCODING 這一個環境變數, 那麼後端會做編碼自動轉換.
|
|
|
|
[註] PostgreSQL 7.0.0 ~ 7.0.3 有個 bug -- 不認這個環境變數
|
|
|
|
o 使用 SET CLIENT_ENCODING TO 這個 SQL 的命令
|
|
|
|
要設定前端的編碼可以用以下這個 SQL 命令:
|
|
|
|
SET CLIENT_ENCODING TO 'encoding';
|
|
|
|
你也可以使用 SQL92 的語法 "SET NAMES" 達到同樣的目的:
|
|
|
|
SET NAMES 'encoding';
|
|
|
|
查詢目前的前端編碼可以用以下這個 SQL 命令:
|
|
|
|
SHOW CLIENT_ENCODING;
|
|
|
|
切換為原來預設的編碼, 用以下這個 SQL 命令:
|
|
|
|
RESET CLIENT_ENCODING;
|
|
|
|
[註] 使用 psql 命令解譯器時, 建議不要用這個方法, 請用 \encoding
|
|
|
|
4. 關於 Unicode (統一碼)
|
|
|
|
統一碼和其他編碼間的轉換可能要在 7.1 版後才會實現.
|
|
|
|
5. 如果無法轉換會發生什麼事?
|
|
|
|
假設你在後端選擇了 EUC_JP 這個編碼, 前端使用 LATIN1, (某些日文字元無法轉換成
|
|
LATIN1) 在這個狀況下, 某個字元若不能轉成 LATIN1 字元集, 就會被轉成以下的型式:
|
|
|
|
(十六進位值)
|
|
|
|
6. 參考資料
|
|
|
|
These are good sources to start learning various kind of encoding
|
|
systems.
|
|
|
|
ftp://ftp.ora.com/pub/examples/nutshell/ujip/doc/cjk.inf
|
|
Detailed explanations of EUC_JP, EUC_CN, EUC_KR, EUC_TW
|
|
appear in section 3.2.
|
|
|
|
Unicode: http://www.unicode.org/
|
|
The homepage of UNICODE.
|
|
|
|
RFC 3629
|
|
UTF-8 is defined here.
|
|
|
|
5. History
|
|
|
|
May 20, 2000
|
|
* SJIS UDC (NEC selection IBM kanji) support contributed
|
|
by Eiji Tokuya
|
|
* Changes above will appear in 7.0.1
|
|
|
|
Mar 22, 2000
|
|
* Add new libpq functions PQsetClientEncoding, PQclientEncoding
|
|
* ./configure --with-mb=EUC_JP
|
|
now deprecated. use
|
|
./configure --enable-multibyte=EUC_JP
|
|
instead
|
|
* Add SQL_ASCII regression test case
|
|
* Add SJIS User Defined Character (UDC) support
|
|
* All of above will appear in 7.0
|
|
|
|
July 11, 1999
|
|
* Add support for WIN1250 (Windows Czech) as a client encoding
|
|
(contributed by Pavel Behal)
|
|
* fix some compiler warnings (contributed by Tomoaki Nishiyama)
|
|
|
|
Mar 23, 1999
|
|
* Add support for KOI8(KOI8-R), WIN(CP1251), ALT(CP866)
|
|
(thanks Oleg Broytmann for testing)
|
|
* Fix problem with MB and locale
|
|
|
|
Jan 26, 1999
|
|
* Add support for Big5 for fronend encoding
|
|
(you need to create a database with EUC_TW to use Big5)
|
|
* Add regression test case for EUC_TW
|
|
(contributed by Jonah Kuo <jonahkuo@mail.ttn.com.tw>)
|
|
|
|
Dec 15, 1998
|
|
* Bugs related to SQL_ASCII support fixed
|
|
|
|
Nov 5, 1998
|
|
* 6.4 release. In this version, pg_database has "encoding"
|
|
column that represents the database encoding
|
|
|
|
Jul 22, 1998
|
|
* determine encoding at initdb/createdb rather than compile time
|
|
* support for PGCLIENTENCODING when issuing COPY command
|
|
* support for SQL92 syntax "SET NAMES"
|
|
* support for LATIN2-5
|
|
* add UNICODE regression test case
|
|
* new test suite for MB
|
|
* clean up source files
|
|
|
|
Jun 5, 1998
|
|
* add support for the encoding translation between the backend
|
|
and the frontend
|
|
* new command SET CLIENT_ENCODING etc. added
|
|
* add support for LATIN1 character set
|
|
* enhance 8 bit cleaness
|
|
|
|
April 21, 1998 some enhancements/fixes
|
|
* character_length(), position(), substring() are now aware of
|
|
multi-byte characters
|
|
* add octet_length()
|
|
* add --with-mb option to configure
|
|
* new regression tests for EUC_KR
|
|
(contributed by "Soonmyung. Hong" <hong@lunaris.hanmesoft.co.kr>)
|
|
* add some test cases to the EUC_JP regression test
|
|
* fix problem in regress/regress.sh in case of System V
|
|
* fix toupper(), tolower() to handle 8bit chars
|
|
|
|
Mar 25, 1998 MB PL2 is incorporated into PostgreSQL 6.3.1
|
|
|
|
Mar 10, 1998 PL2 released
|
|
* add regression test for EUC_JP, EUC_CN and MULE_INTERNAL
|
|
* add an English document (this file)
|
|
* fix problems concerning 8-bit single byte characters
|
|
|
|
Mar 1, 1998 PL1 released
|
|
|
|
Appendix:
|
|
|
|
[Here is a good documentation explaining how to use WIN1250 on
|
|
Windows/ODBC from Pavel Behal. Please note that Installation step 1)
|
|
is not necceary in 6.5.1 -- Tatsuo]
|
|
|
|
Version: 0.91 for PgSQL 6.5
|
|
Author: Pavel Behal
|
|
Revised by: Tatsuo Ishii
|
|
Email: behal@opf.slu.cz
|
|
Licence: The Same as PostgreSQL
|
|
|
|
Sorry for my Eglish and C code, I'm not native :-)
|
|
|
|
!!!!!!!!!!!!!!!!!!!!!!!!! NO WARRANTY !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
|
|
|
|
Instalation:
|
|
------------
|
|
1) Change three affected files in source directories
|
|
(I don't have time to create proper patch diffs, I don't know how)
|
|
2) Compile with enabled locale and multibyte set to LATIN2
|
|
3) Setup properly your instalation, do not forget to create locale
|
|
variables in your profile (environment). Ex. (may not be exactly true):
|
|
LC_ALL=cs_CZ.ISO8859-2
|
|
LC_COLLATE=cs_CZ.ISO8859-2
|
|
LC_CTYPE=cs_CZ.ISO8859-2
|
|
LC_MONETARY=cs_CZ.ISO8859-2
|
|
LC_NUMERIC=cs_CZ.ISO8859-2
|
|
LC_TIME=cs_CZ.ISO8859-2
|
|
4) You have to start the postmaster with locales set!
|
|
5) Try it with Czech language, it have to sort
|
|
5) Install ODBC driver for PgSQL into your M$ Windows
|
|
6) Setup properly your data source. Include this line in your ODBC
|
|
configuration dialog in field "Connect Settings:" :
|
|
SET CLIENT_ENCODING = 'WIN1250';
|
|
7) Now try it again, but in Windows with ODBC.
|
|
|
|
Description:
|
|
------------
|
|
- Depends on proper system locales, tested with RH6.0 and Slackware 3.6,
|
|
with cs_CZ.iso8859-2 loacle
|
|
- Never try to set-up server multibyte database encoding to WIN1250,
|
|
always use LATIN2 instead. There is not WIN1250 locale in Unix
|
|
- WIN1250 encoding is useable only for M$W ODBC clients. The characters are
|
|
on thy fly re-coded, to be displayed and stored back properly
|
|
|
|
Important:
|
|
----------
|
|
- it reorders your sort order depending on your LC_... setting, so don't be
|
|
confused with regression tests, they don't use locale
|
|
- "ch" is corectly sorted only in some newer locales (Ex. RH6.0)
|
|
- you have to insert money as '162,50' (with comma in aphostrophes!)
|
|
- not tested properly
|