MySQL架构优化之字符集


MySQL应用于大中小企业当中，字符集标准化也是MySQL架构优化中重要的一部分。通常建议中英文混合环境建议选择utf8字符集。
1.操作系统Linuxcat /etc/sysconfig/i18n => LANG="en_US.UTF-8"
2.MySQL客户端cat /etc/my.cnf => [client] default-character-set=utf8
3.MySQL服务端cat /etc/my.cnf => [mysqld] character-set-server=utf8 collation-server=utf8_bin
4.库、表字符集一致 默认库、表字符集与MySQL服务端保持一致；所以，默认库、表字符集均为utf8
5.程序 选择统一的utf8程序安装包


1.操作系统Linux字符集
[root@db12cvm1 ~]# cat /etc/sysconfig/i18n
LANG="en_US.UTF-8"
SYSFONT="latarcyrheb-sun16"


2.MySQL客户端字符集
[root@db12cvm1 ~]# cat /etc/my.cnf
[client]
default-character-set=utf8


3.MySQL服务端字符集
[root@db12cvm1 ~]# cat /etc/my.cnf
[mysqld]
character-set-server=utf8
collation-server=utf8_bin


4.库、表字符集一致 默认库、表字符集与MySQL服务端保持一致
mysql> show databases;
+--------------------+
| Database|
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test|
+--------------------+
4 rows in set (0.00 sec)


mysql> create database dbadoudou;
Query OK, 1 row affected (0.00 sec)


mysql> show create database dbadoudou\G;
*************************** 1. row ***************************
Database: dbadoudou
Create Database: CREATE DATABASE `dbadoudou` /*!40100 DEFAULT CHARACTER SET utf8 COLLATE utf8_bin */
1 row in set (0.00 sec)


ERROR:
No query specified
## DATABASE DEFAULT CHARACTER SET utf8 COLLATE utf8_bin and [mysqld] character-set-server=utf8
## collation-server=utf8_bin the same


mysql> use dbadoudou;
Database changed
mysql> create table dbadoudou
-> (
-> id int(4) not null auto_increment,
-> name char(20) not null,
-> primary key (id)
-> );
Query OK, 0 rows affected (4.36 sec)


mysql> show create table dbadoudou;
+-----------


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


-------------------------------------------------------------------------------------+
| Table | Create Table


|
+-----------


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


-------------------------------------------------------------------------------------+
| dbadoudou | CREATE TABLE `dbadoudou` (
`id` int(4) NOT NULL AUTO_INCREMENT,
`name` char(20) COLLATE utf8_bin NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin |
+-----------


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


-------------------------------------------------------------------------------------+
1 row in set (0.00 sec)


## TABLE DEFAULT CHARSET=utf8 COLLATE=utf8_bin AND [mysqld] character-set-server=utf8
## collation-server=utf8_bin the same


mysql> insert into dbadoudou (name) values('dbadoudou'),('ocmxiaoyu'),('ocmdream');
ERROR 1665 (HY000): Cannot execute statement: impossible to write to binary log since BINLOG_FORMAT =


STATEMENT and at least one table uses a storage engine limited to row-based logging. InnoDB is limited


to row-logging when transaction isolation level is READ COMMITTED or READ UNCOMMITTED.
## CAUSE: ERROR 1665 (HY000) SOLUTION: SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;


mysql> show global variables like 'binlog_format';
+---------------+-----------+
| Variable_name | Value |
+---------------+-----------+
| binlog_format | STATEMENT |
+---------------+-----------+
1 row in set (0.00 sec)
mysql> SELECT @@session.tx_isolation, @@global.tx_isolation;
+------------------------+-----------------------+
| @@session.tx_isolation | @@global.tx_isolation |
+------------------------+-----------------------+
| READ-COMMITTED | READ-COMMITTED|
+------------------------+-----------------------+
1 row in set (0.00 sec)
mysql> SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;
Query OK, 0 rows affected (0.00 sec)


mysql> SELECT @@session.tx_isolation, @@global.tx_isolation;
+------------------------+-----------------------+
| @@session.tx_isolation | @@global.tx_isolation |
+------------------------+-----------------------+
| REPEATABLE-READ| READ-COMMITTED|
+------------------------+-----------------------+
1 row in set (0.00 sec)
mysql> insert into dbadoudou (name) values('dbadoudou'),('ocmxiaoyu'),('ocmdream');
Query OK, 3 rows affected (0.01 sec)
Records: 3 Duplicates: 0 Warnings: 0


mysql> select * from dbadoudou;
+----+-----------+
| id | name |
+----+-----------+
| 1 | dbadoudou |
| 2 | ocmxiaoyu |
| 3 | ocmdream |
+----+-----------+
3 rows in set (0.00 sec)
## reference:MOS (文档 ID 1433907.1)


5.处理MySQL乱码
上面讲到字符集要标准化保持一致。如果出现不一致，怎么解决乱码问题呢？
临时解决:
set names utf8;
永久解决：
vi /etc/my.cnf
[mysqld]
character-set-server=utf8
collation-server=utf8_bin