如何设置数据库的LC_COLLATE, LC_CTYPE, ENCODING, TEMPLATE

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背景

PostgreSQL实例支持创建多个数据库,创建数据库时,可以指定模板库,并为每个数据库设置不同的字符集、本地化collate, 货币等属性。

接下来举例讲述CREATE DATABASE的具体使用方法。

一、CREATE DATABASE语法

Command:     CREATE DATABASE  
Description: create a new database  
Syntax:  
CREATE DATABASE name  
    [ [ WITH ] [ OWNER [=] user_name ]  
           [ TEMPLATE [=] template ]  
           [ ENCODING [=] encoding ]  
           [ LC_COLLATE [=] lc_collate ]  
           [ LC_CTYPE [=] lc_ctype ]  
           [ TABLESPACE [=] tablespace_name ]  
           [ CONNECTION LIMIT [=] connlimit ] ]  

二、克隆模板库(从指定模板创建数据库)

例子

以test数据库为模板,克隆一个名为test01的数据库。

test=> create database test01 with template test;  
CREATE DATABASE  

如果不指定模板,则默认的模板为template1。

注意

从指定模板库创建数据库,除了当前连接,不能有其他用户连在对应的模板库上面。

如果有其他用户连在test库,可能会报类似这样的错误

test=> create database test01 with template test;  
ERROR:  source database "test" is being accessed by other users  
DETAIL:  There is 1 other session using the database.  

三、创建数据库时,如何指定encoding

PostgreSQL支持哪些encoding

用户可以参考PostgreSQL的官方文档,有对应的字符集支持列表

https://www.postgresql.org/docs/9.6/static/multibyte.html

Server=Yes表示该字符集支持用于create database。否则只支持作为客户端字符集。

Name Description Language Server? Bytes/Char Aliases
BIG5 Big Five Traditional Chinese No 1-2 WIN950, Windows950
EUC_CN Extended UNIX Code-CN Simplified Chinese Yes 1-3 -
EUC_JP Extended UNIX Code-JP Japanese Yes 1-3 -
EUC_JIS_2004 Extended UNIX Code-JP, JIS X 0213 Japanese Yes 1-3 -
EUC_KR Extended UNIX Code-KR Korean Yes 1-3 -
EUC_TW Extended UNIX Code-TW Traditional Chinese, Taiwanese Yes 1-3 -
GB18030 National Standard Chinese No 1-4 -
GBK Extended National Standard Simplified Chinese No 1-2 WIN936, Windows936
ISO_8859_5 ISO 8859-5, ECMA 113 Latin/Cyrillic Yes 1 -
ISO_8859_6 ISO 8859-6, ECMA 114 Latin/Arabic Yes 1 -
ISO_8859_7 ISO 8859-7, ECMA 118 Latin/Greek Yes 1 -
ISO_8859_8 ISO 8859-8, ECMA 121 Latin/Hebrew Yes 1 -
JOHAB JOHAB Korean (Hangul) No 1-3 -
KOI8R KOI8-R Cyrillic (Russian) Yes 1 KOI8
KOI8U KOI8-U Cyrillic (Ukrainian) Yes 1 -
LATIN1 ISO 8859-1, ECMA 94 Western European Yes 1 ISO88591
LATIN2 ISO 8859-2, ECMA 94 Central European Yes 1 ISO88592
LATIN3 ISO 8859-3, ECMA 94 South European Yes 1 ISO88593
LATIN4 ISO 8859-4, ECMA 94 North European Yes 1 ISO88594
LATIN5 ISO 8859-9, ECMA 128 Turkish Yes 1 ISO88599
LATIN6 ISO 8859-10, ECMA 144 Nordic Yes 1 ISO885910
LATIN7 ISO 8859-13 Baltic Yes 1 ISO885913
LATIN8 ISO 8859-14 Celtic Yes 1 ISO885914
LATIN9 ISO 8859-15 LATIN1 with Euro and accents Yes 1 ISO885915
LATIN10 ISO 8859-16, ASRO SR 14111 Romanian Yes 1 ISO885916
MULE_INTERNAL Mule internal code Multilingual Emacs Yes 1-4 -
SJIS Shift JIS Japanese No 1-2 Mskanji, ShiftJIS, WIN932, Windows932
SHIFT_JIS_2004 Shift JIS, JIS X 0213 Japanese No 1-2 -
SQL_ASCII unspecified (see text) any Yes 1 -
UHC Unified Hangul Code Korean No 1-2 WIN949, Windows949
UTF8 Unicode, 8-bit all Yes 1-4 Unicode
WIN866 Windows CP866 Cyrillic Yes 1 ALT
WIN874 Windows CP874 Thai Yes 1 -
WIN1250 Windows CP1250 Central European Yes 1 -
WIN1251 Windows CP1251 Cyrillic Yes 1 WIN
WIN1252 Windows CP1252 Western European Yes 1 -
WIN1253 Windows CP1253 Greek Yes 1 -
WIN1254 Windows CP1254 Turkish Yes 1 -
WIN1255 Windows CP1255 Hebrew Yes 1 -
WIN1256 Windows CP1256 Arabic Yes 1 -
WIN1257 Windows CP1257 Baltic Yes 1 -
WIN1258 Windows CP1258 Vietnamese Yes 1 ABC, TCVN, TCVN5712, VSCII

创建指定encoding的数据库

例子

创建一个UTF-8字符集的数据库

test=> create database test02 with encoding 'UTF-8';  
CREATE DATABASE  

注意

1. 指定的字符集必须是模板库字符集的超集,否则会报错。

2. 指定的lc_ctype和lc_collate必须与目标字符集兼容。

例子,template1是默认模板库,它的字符集为UTF8。

test=> \l template1  
                                  List of databases  
   Name    |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges     
-----------+----------+----------+-------------+-------------+-----------------------  
 template1 | xxxxxxxx | UTF8     | zh_CN.UTF-8 | zh_CN.UTF-8 | =c/xxxxxxxx          +  
           |          |          |             |             | xxxxxxxx=CTc/xxxxxxxx  
(1 row)  

创建一个EUC_CN字符集的数据库

报错1,EUC_CN字符集与模板库的lc_collate,lc_ctype不兼容。

test=> create database test03 with encoding 'EUC_CN';  
ERROR:  encoding "EUC_CN" does not match locale "zh_CN.UTF-8"  
DETAIL:  The chosen LC_CTYPE setting requires encoding "UTF8".  

报错2,EUC_CN字符集与模板库的字符集UTF-8不兼容。

test=> create database test03 with encoding 'EUC_CN' lc_collate='C' lc_ctype='C';  
ERROR:  new encoding (EUC_CN) is incompatible with the encoding of the template database (UTF8)  
HINT:  Use the same encoding as in the template database, or use template0 as template.  

四、如何获取字符集支持的LC_COLLATE, LC_CTYPE信息

使用如下SQL可以查询系统表pg_collation得到字符集支持的lc_collate和lc_ctype。

其中encoding为空时,表示这个collation支持所有的字符集。

test=> select pg_encoding_to_char(collencoding) as encoding,collname,collcollate,collctype from pg_collation ;  
  encoding  |       collname        |      collcollate      |       collctype         
------------+-----------------------+-----------------------+-----------------------  
            | default               |                       |   
            | C                     | C                     | C  
            | POSIX                 | POSIX                 | POSIX  
 UTF8       | aa_DJ                 | aa_DJ.utf8            | aa_DJ.utf8  
 LATIN1     | aa_DJ                 | aa_DJ                 | aa_DJ  
 LATIN1     | aa_DJ.iso88591        | aa_DJ.iso88591        | aa_DJ.iso88591  
 UTF8       | aa_DJ.utf8            | aa_DJ.utf8            | aa_DJ.utf8  
 UTF8       | aa_ER                 | aa_ER                 | aa_ER  
 UTF8       | aa_ER.utf8            | aa_ER.utf8            | aa_ER.utf8  
.......  
 EUC_CN     | zh_CN                 | zh_CN                 | zh_CN  
 UTF8       | zh_CN                 | zh_CN.utf8            | zh_CN.utf8  
 EUC_CN     | zh_CN.gb2312          | zh_CN.gb2312          | zh_CN.gb2312  
 UTF8       | zh_CN.utf8            | zh_CN.utf8            | zh_CN.utf8  
 UTF8       | zh_HK                 | zh_HK.utf8            | zh_HK.utf8  
 UTF8       | zh_HK.utf8            | zh_HK.utf8            | zh_HK.utf8  
 EUC_CN     | zh_SG                 | zh_SG                 | zh_SG  
 UTF8       | zh_SG                 | zh_SG.utf8            | zh_SG.utf8  
 EUC_CN     | zh_SG.gb2312          | zh_SG.gb2312          | zh_SG.gb2312  
 UTF8       | zh_SG.utf8            | zh_SG.utf8            | zh_SG.utf8  
 EUC_TW     | zh_TW                 | zh_TW.euctw           | zh_TW.euctw  
 UTF8       | zh_TW                 | zh_TW.utf8            | zh_TW.utf8  
 EUC_TW     | zh_TW.euctw           | zh_TW.euctw           | zh_TW.euctw  
 UTF8       | zh_TW.utf8            | zh_TW.utf8            | zh_TW.utf8  
 UTF8       | zu_ZA                 | zu_ZA.utf8            | zu_ZA.utf8  
 LATIN1     | zu_ZA                 | zu_ZA                 | zu_ZA  
 LATIN1     | zu_ZA.iso88591        | zu_ZA.iso88591        | zu_ZA.iso88591  
 UTF8       | zu_ZA.utf8            | zu_ZA.utf8            | zu_ZA.utf8  
(869 rows)  

五、创建数据库时指定LC_COLLATE, LC_CTYPE

例子

创建一个数据库,lc_collate, lc_ctype分别为zh_CN.utf8

test=> create database test05 with encoding 'UTF-8' template template0 lc_collate='zh_CN.utf8' lc_ctype='zh_CN.utf8';  
CREATE DATABASE  

注意

如果指定的lc_collate, lc_ctype与模板库的collate,ctype不兼容,会报错。

test=> create database test04 with encoding 'UTF-8' lc_collate='zh_CN.utf8' lc_ctype='zh_CN.utf8';  
ERROR:  new collation (zh_CN.utf8) is incompatible with the collation of the template database (zh_CN.UTF-8)  
HINT:  Use the same collation as in the template database, or use template0 as template.  

解决办法1,使用兼容的collate和ctype。

test=> create database test04 with encoding 'UTF-8' lc_collate='zh_CN.UTF-8' lc_ctype='zh_CN.UTF-8';  
CREATE DATABASE  

解决办法2,使用template0作为模板库。

test=> create database test05 with encoding 'UTF-8' template template0 lc_collate='zh_CN.utf8' lc_ctype='zh_CN.utf8';  
CREATE DATABASE  

六、如何修改已有数据库的collate,ctype

目前无法直接通过alter database的语法进行修改,用户可以使用创建新的数据库,导出,再导入的方式。

例子

1. 创建新数据库,指定目标collate和ctype

2. 使用pg_dump或其他客户端工具逻辑导出源数据库的数据

3. 使用pg_restore或其他客户端工具,将第二步导出数据导入新数据库

参考

https://www.postgresql.org/docs/9.6/static/sql-createdatabase.html

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