什么是MySQL多实例
MySQL多实例就是在一台机器上开启多个不同的服务端口（如：3306,3307），运行多个MySQL服务进程，通过不同的socket监听不同的服务端口来提供各自的服务:；
Mysql多实例实现的3种方式
mysql 多实例常规来讲，有三种方案可以实现，这三种方案各有利弊，如下：
1、基于多配置文件
通过使用多个配置文件来启动不同的进程，以此来实现多实例。
配置文件：
[client]
port =
socket =/data//mysql.sock
[mysql]
no-auto-rehash
[mysqld]
user = mysql
port =
socket =/data//mysql.sock
basedir =/application/mysql
datadir =/data//data
open_files_limit =
back_log =
max_connections =
max_connect_errors =
table_cache =
external-locking = FALSE
max_allowed_packet =8M
sort_buffer_size =1M
join_buffer_size =1M
thread_cache_size =
thread_concurrency =
query_cache_size =2M
[root@web001 ]# cat my.cnf
[client]
port =
socket =/data//mysql.sock
[mysql]
no-auto-rehash
[mysqld]
user = mysql
port =
socket =/data//mysql.sock
basedir =/application/mysql
datadir =/data//data
open_files_limit =
back_log =
max_connections =
max_connect_errors =
table_cache =
external-locking = FALSE
max_allowed_packet =8M
sort_buffer_size =1M
join_buffer_size =1M
thread_cache_size =
thread_concurrency =
query_cache_size =2M
query_cache_limit =1M
query_cache_min_res_unit =2k
#default_table_type = InnoDB
thread_stack =192K
#transaction_isolation = READ-COMMITTED
tmp_table_size =2M
max_heap_table_size =2M
#long_query_time =
#log_long_format
#log-error = /data//error.log
#log-slow-queries = /data//slow.log
pid-file =/data//mysql.pid
#log-bin = /data//mysql-bin
relay-log =/data//relay-bin
relay-log-info-file =/data//relay-log.info
binlog_cache_size =1M
max_binlog_cache_size =1M
max_binlog_size =2M
expire_logs_days =
key_buffer_size =16M
read_buffer_size =1M
read_rnd_buffer_size =1M
bulk_insert_buffer_size =1M
#myisam_sort_buffer_size = 1M
#myisam_max_sort_file_size = 10G
#myisam_max_extra_sort_file_size = 10G
#myisam_repair_threads =
#myisam_recover
lower_case_table_names =
skip-name-resolve
slave-skip-errors =,
replicate-ignore-db=mysql
server-id =
innodb_additional_mem_pool_size =4M
innodb_buffer_pool_size =32M
innodb_data_file_path = ibdata1:128M:autoextend
innodb_file_io_threads =
innodb_thread_concurrency =
innodb_flush_log_at_trx_commit =
innodb_log_buffer_size =2M
innodb_log_file_size =4M
innodb_log_files_in_group =
innodb_max_dirty_pages_pct =
innodb_lock_wait_timeout =
innodb_file_per_table =
[mysqldump]
quick
max_allowed_packet =2M
[mysqld_safe]
log-error=/data//mysql_oldboy3307.err
pid-file=/data//mysqld.pid
View
优点：逻辑简单，配置简单
缺点：管理起来不方便
mysql启动停止脚本。
#！/bin/sh #init port=
mysql_user="root"
mysql_pwd=""
CmdPath="/application/mysql/bin"
mysql_sock="/data/${port}/mysql.sock" function_start_mysql()
{
if [ ! -e "$mysql_sock" ];then
printf "Starting MySql...\n"
/bin/sh ${CmdPath}/mysqld_safe --defaults-file=/data/${port}/my.cnf >& >/dev/null & else
printf "Mysql is running...\n"
exit
fi
} #stop function
function_stop_mysql()
{
if [ ! -e "$mysql_sock" ];then
printf "MySql is stopped...\n"
exit
else
printf "Stoping MySQL...\n"
${CmdPath}/mysqladmin -u ${mysql_user} -p${mysql_pwd} -S /data/${port}/mysql.sock shutdown
fi
} #restart function
function_restart_mysql()
{
printf "Restarting Mysql...\n"
function_stop_mysql
sleep
function_start_mysql } case $ in
start)
function_start_mysql
;;
stop)
function_stop_mysql
;;
restart)
function_restart_mysql
;;
*)
printf "Usage /data/${port}/mysql {start|stop|restart}\n"
;;
esac
2、基于mysqld_multi
通过官方自带的 mysqld_multi 工具，使用单独配置文件来实现多实例
优点： 便于集中管理管理
缺点： 不方便针对每个实例配置进行定制
3、基于IM
使用 MySQL 实例管理器（MYSQLMANAGER），这个方法好像比较好不过也有点复杂
优点：便于集中管理
缺点：耦合度高。IM一挂，实例全挂
不方便针对每个实例配置进行定制