实践MySQL(mysqld)多实例/多版本同时运行
摘要：
在RedHat 9.0 (2.4.20-8 )中，实践MySQL的
(1) 单版本多实例,
(2) 多版本单实例运行
(3) 多版本多实例运行。
实现目标：
1) 同一版本的多个实例同时运行。
两个4.1.9的实例分别于3301，3302端口监听并提供服务。
2) 不同版本的单个实例同时运行。
4.1.9和5.0.2的实例分别于3304，3305端口监听并提供服务。
3) 不同版本的多个实例同时运行。
4.1.9的2个实例分别于3301，3302端口监听并提供服务。
5.0.2的2个实例分别于3308，3309端口监听并提供服务。
必要准备：
1) 运行环境：
[root@trydofor]#cat /proc/version
Linux version 2.4.20-8 (bhcompile@porky.devel.redhat.com)(gcc version
3.2.2 20030222(Red Hat Linux 3.2.2-5))#1 Thu Mar 13 17:54:28 EST 2003
[root@trydofor]#ls -l |grep mysql|awk '{print $5,$9}'
33368998 mysql-max-5.0.2-alpha-pc-linux-i686.tar.gz
28195102 mysql-standard-4.1.9-pc-linux-gnu-i686.tar.gz
[注] 获得mysql二进制包
2) 理论基础：
mysqld 读取配置文件的顺序：
1./etc/my.cnf, Global options.
2.$DATADIR/my.cnf, Server-specific options.
3.defaults-extra-file,
The file specified with --defaults-extra-file=path, if any
4.~/.my.cnf, User-specific options.
mysqld 多进程运行的必要条件：
至少要使 pid-file, datadir, socket, port 是独立分开。
实现策略：
1) 安装与准备
[注] 添加mysql组和用户
# groupadd mysql
# useradd -g mysql mysql
[注] 解包到/usr/local
# tar -xzf mysql-standard-4.1.9-pc-linux-gnu-i686.tar.gz -C /usr/local
# tar -xzf mysql-max-5.0.2-alpha-pc-linux-i686.tar.gz -C /usr/local
[注] 建立软链接，方便操作
# cd /usr/local
# ln -s mysql-standard-4.1.9-pc-linux-gnu-i686 mysql4
# ln -s mysql-max-5.0.2-alpha-pc-linux-i686 mysql5
[注] 初始化data,更改文件属性
# cd mysql4
# scripts/mysql_install_db --user=mysql
# chown -R root .
# chown -R mysql data
# chgrp -R mysql .
[注] 复制data，以供单版本多实例分配
cp -a data data_1
cp -a data data_2
[注] 初始化data,更改文件属性
# cd ../mysql5
# scripts/mysql_install_db --user=mysql
# chown -R root .
# chown -R mysql data
# chgrp -R mysql .
[注] 复制data，以供单版本多实例分配
cp -a data data_1
cp -a data data_2
2) 配置与测试
2.1) 单版本多实例的实现
[注] 本目标利用 $MYSQL/bin/mysqld_multi 脚本来实现。
其实，通过启动多个 $MYSQL/bin/mysqld_safe 脚本也实现，
不过 mysqld_multi 提供了更方便更简单的途径，不用有点可惜：）
2.1.1) 配置mysql
#pwd
/usr/local/mysql4
#cat >;my_multi.cnf
[mysqld_multi]
mysqld = /usr/local/mysql4/bin/mysqld_safe
mysqladmin = /usr/local/mysql4/bin/mysqladmin
user = root
[mysqld1]
socket = /tmp/mysql_4_1.sock
port = 3301
pid-file = /usr/local/mysql4/data_1/hostname.pid
datadir = /usr/local/mysql4/data_1
log = /usr/local/mysql4/data_1/hostname.log
user = mysql
[mysqld2]
socket = /tmp/mysql_4_2.sock
port = 3302
pid-file = /usr/local/mysql4/data_2/hostname.pid
datadir = /usr/local/mysql4/data_2
log = /usr/local/mysql4/data_2/hostname.log
user = mysql
CTRL+D
2.1.2) 启动mysql
#pwd
/usr/local/mysql4
[注] 启动mysqld2个实例 (GNR1和GNR2)
# bin/mysqld_multi --config-file=./my_multi.cnf start 1,2
Starting mysqld daemon with databases from /usr/local/mysql4/data_1
Starting mysqld daemon with databases from /usr/local/mysql4/data_2
[注] 查看端口是否被监听
# netstat -lt |grep 33
tcp 0 0 *:3301 *:* LISTEN
tcp 0 0 *:3302 *:* LISTEN
2.1.3) 测试mysql
#pwd
/usr/local/mysql4
[注] 通过mysql_4_1.sock连接3001端口的mysql(GNR1)
# bin/mysql -u root -S /tmp/mysql_4_1.sock -e "SELECT @@VERSION;"
[注] 停止3001端口的mysql(GNR1)
# bin/mysqld_multi --config-file=./my_multi.cnf stop 1
STOPPING server from pid file /usr/local/mysql4/data_1/hostname.pid
050223 08:56:04 mysqld ended
[注] 再次连接(GNR4),系统会提示错误
# bin/mysql -u root -S /tmp/mysql_4_1.sock -e "SELECT @@VERSION;"
ERROR 2002 (HY000):
Can't connect to local MySQL server through socket '/tmp/mysql_4_1.sock' (2)
[注] 相同的步骤测试3002端口的mysql(GNR2)，输出与上相同
# bin/mysql -u root -S /tmp/mysql_4_2.sock -e "SELECT @@VERSION;"
# bin/mysqld_multi --config-file=./my_multi.cnf stop 2
# bin/mysql -u root -S /tmp/mysql_4_2.sock -e "SELECT @@VERSION;"
2.2) 多版本单实例的实现
[注] 本目标利用启动多个 $MYSQL/bin/mysqld_safe 脚本实现
2.2.1) 配置mysql
[注] 在mysql4/data目录中添加配置文件my.cnf (也可以通过命令行参数实现)
#pwd
/usr/local/mysql4
#cat >;data/my.cnf
[mysqld]
socket = /tmp/mysql_4_4.sock
port = 3304
basedir = /usr/local/mysql4
default-character-set = gbk
CTRL+D
[注] 在mysql5/data目录中添加配置文件my.cnf (也可以通过命令行参数实现)
#pwd
/usr/local/mysql5
#cat >;data/my.cnf
[mysqld]
socket = /tmp/mysql_5_5.sock
port = 3305
basedir = /usr/local/mysql5
default-character-set = gbk
CTRL+D
2.2.2) 启动与测试
[注] 分别启动mysql4和mysql5
# cd /usr/local/mysql4
# bin/mysqld_safe --user=mysql --pid-file=data/hostname.pid --datadir=data &
# cd /usr/local/mysql5
# bin/mysqld_safe --user=mysql --pid-file=data/hostname.pid --datadir=data &
[注] 查看端口是否被监听
# netstat -lp|grep 33
tcp 0 0 *:3304 *:* LISTEN
tcp 0 0 *:3305 *:* LISTEN
[注] 查看mysql版本
# bin/mysql -u root -S /tmp/mysql_4_4.sock -e "SELECT @@VERSION;"
# bin/mysql -u root -S /tmp/mysql_5_5.sock -e "SELECT @@VERSION;"
[注] 检测mysql5
# bin/mysql -u root -S /tmp/mysql_5_5.sock
[注] 利用文末 注意事项 4)的sql语句可以检测msyql5版本
[注] 停止mysql
# bin/mysqladmin -u root -S /tmp/mysql_4_4.sock shutdown
# bin/mysqladmin -u root -S /tmp/mysql_5_5.sock shutdown
2.3) 多版本多实例的实现
[注] 利用启动多个 $MYSQL/bin/mysqld_multi 脚本实现，其方法同目标1。
2.3.1) 配置mysql
[注] 仿造目标1)方法，创建mysql5的配置
#pwd
/usr/local/mysql5
#cat >;my_multi.cnf
[mysqld_multi]
mysqld = /usr/local/mysql5/bin/mysqld_safe
mysqladmin = /usr/local/mysql5/bin/mysqladmin
user = root
[mysqld1]
socket = /tmp/mysql_5_8.sock
port = 3308
pid-file = /usr/local/mysql5/data_1/hostname.pid
datadir = /usr/local/mysql5/data_1
log = /usr/local/mysql5/data_1/hostname.log
user = mysql
[mysqld2]
socket = /tmp/mysql_5_9.sock
port = 3309
pid-file = /usr/local/mysql5/data_2/hostname.pid
datadir = /usr/local/mysql5/data_2
log = /usr/local/mysql5/data_2/hostname.log
user = mysql
CTRL+D
2.3.2) 启动mysql
#cd /usr/local/mysql4
# bin/mysqld_multi --config-file=./my_multi.cnf start 1,2
Starting mysqld daemon with databases from /usr/local/mysql4/data_1
Starting mysqld daemon with databases from /usr/local/mysql4/data_2
# netstat -lt |grep 33
tcp 0 0 *:3301 *:* LISTEN
tcp 0 0 *:3302 *:* LISTEN
tcp 0 0 *:3308 *:* LISTEN
tcp 0 0 *:3309 *:* LISTEN
2.3.3) 测试mysql
# bin/mysql -u root -S /tmp/mysql_4_1.sock -e "SELECT @@VERSION;"
# bin/mysql -u root -S /tmp/mysql_4_1.sock -e "SELECT @@VERSION;"
# bin/mysql -u root -S /tmp/mysql_5_8.sock -e "SELECT @@VERSION;"
# bin/mysql -u root -S /tmp/mysql_5_9.sock -e "SELECT @@VERSION;"
[注] 利用文末 注意事项 4)的sql语句可以检测msyql5版本
# bin/mysql -u root -S /tmp/mysql_5_8.sock
注意事项：
1) 系统环境变量的设定
很多linux发行版都把/usr/local/mysql加入了$PATH，同时/usr/bin/下
还有很多mysql命令和脚本。如果不注意，可能启动了错误版本的命令。
2) $MYSQL/scripts/mysql_install_db 初始化不成功
这时要停掉系统中运行的mysqld，否则就要修改mysql_install_db
才能成功运行。---- 我是没有成功修改过
3) $MYSQL/bin/mysqld_multi 启动多本版可能不正确
即，把msyql4和mysql5写在一个配置文件指定不同的中通过一个mysqld_multi启动。
[mysqld_multi]
user = root
[mysqld4]
socket = /tmp/mysql_4_4.sock
port = 3304
pid-file = /usr/local/mysql4/data/hostname.pid
datadir = /usr/local/mysql4/data
log = /usr/local/mysql4/data/hostname.log
user = mysql
[mysqld5]
socket = /tmp/mysql_5_5.sock
port = 3305
pid-file = /usr/local/mysql5/data/hostname.pid
datadir = /usr/local/mysql5/data
log = /usr/local/mysql5/data/hostname.log
user = mysql
当用mysql5中的mysqld_multi启动时，查看mysql版本都显示5的信息
使用4)中的语句测试，都不通过。原因尚在调查中...
4) 下面语句在mysql5上可以成功通过（主要是最后一句）
use test;
drop table if exists t3;
create table t3 ( userid bigint(20) not null default 0 );
drop procedure if exists bug8116;
create procedure bug8116(in _userid int)
select * from t3 where userid = _userid;
call bug8116(42);
参考资料：
Using Option Files
The mysqld_multi Program for Managing Multiple MySQL Servers
Running Multiple Servers on Unix
MySQL Lists: internals: bk commit into 5.0 tree (pem:1.1857) BUG#8116
