my.cnf是mysql的windows版的配置文件（linux下通常叫my.ini）。首先my.cnf是mysql能够运行的前提，或者更准确一点说，如果这个文件没有就位或者设置不对（一般就是basedir和datadir的路径不对），则mysql访问无法启动。

另外，这个文件确定了mysql的配置参数，而mysql的配置参数对mysql的性能会有较大影响。

另外就是其他区段的设置会对相应部分起作用。

[mysqld]

datadir=/var/lib/mysql

socket=/var/lib/mysql/mysql.sock

skip-locking

set-variable = key_buffer=16M

set-variable = max_allowed_packet=1M

set-variable = thread_stack=64K

set-variable = record_buffer=1M

set-variable = table_cache=1024

set-variable = sort_buffer=4M

set-variable = net_buffer_length=8K

set-variable = max_connect_errors=100

set-variable = max_connections=1024

server-id = 1 
 
[mysqldump]

quick

set-variable = max_allowed_packet=16M 
 

[mysql]

no-auto-rehash

# Remove the next comment character if you are not familiar with SQL

#safe-updates 
 

[isamchk]

set-variable = key_buffer=20M

set-variable = sort_buffer=20M 
 

[myisamchk]

set-variable = key_buffer=20M

set-variable = sort_buffer=20M 
 

[mysqlhotcopy]

interactive-timeout 
 

[mysql.server]

user=mysql

basedir=/var/lib 
 

[safe_mysqld]

err-log=/var/log/mysqld.log

pid-file=/var/run/mysqld/mysqld.pid