MySQL配置优化实例

发现一篇不错的优化MySQL的文章http://blog.haohtml.com/archives/4248，看完记录一下

黑色的表示查询配置和状态，绿色的表示优化原则

清除状态 FLUSH STATUS;

慢查询

       show variables like '%slow%';

show global status like '%slow%';

连接数

         show variables like 'max_connections';

         show global status like'Max_used_connections';

Max_used_connections / max_connections  * 100% ≈ 85%

Key_buffer_size--MyISAM

         show variables like 'key_buffer_size';

show global status like 'key_read%';

key_cache_miss_rate＝ Key_reads / Key_read_requests * 100% <

        show global status like'key_blocks_u%';

        Key_blocks_used / (Key_blocks_unused +Key_blocks_used) * 100% ≈ 80%

临时表

         show variables where Variable_name in('tmp_table_size', 'max_heap_table_size');

         show global status like 'created_tmp%';

Created_tmp_disk_tables / Created_tmp_tables * 100% <= 25%

Open Table情况

         show variables like 'table_cache';à show variables like 'table_open_cache';

         show global status like 'open%tables%';

Open_tables / Opened_tables  * 100% >= 85%
Open_tables / table_cache * 100% <= 95%

进程使用情况

         show variables like'thread_cache_size';

         show global status like 'Thread%';

         Threads_created值不应过大，否则应增加thread_cache_size

查询缓存

         show variables like 'query_cache%';

show global status like 'qcache%';

查询缓存碎片率 = Qcache_free_blocks /Qcache_total_blocks * 100% < 20%

查询缓存利用率 = (query_cache_size - Qcache_free_memory)/ query_cache_size * 100%à 25%-80%

查询缓存命中率 = (Qcache_hits - Qcache_inserts) /Qcache_hits * 100% >

排序使用情况

         show variables like 'Sort_buffer_size';

         show global status like 'sort%';

Sort_merge_passes <

文件打开数

         show variables like 'open_files_limit';

         show global status like 'open_files';

         Open_files / open_files_limit * 100% <=75％

表锁情况

         show global status like 'table_locks%';

         Table_locks_immediate / Table_locks_waited> 5000，最好采用InnoDB引擎，小则MyIASM

表扫描情况

         show global status like 'com_select';

         show global status like'handler_read%';

表扫描率＝ Handler_read_rnd_next / Com_select <

如果表扫描率超过4000，说明进行了太多表扫描，很有可能索引没有建好，增加read_buffer_size值会有一些好处，但最好不要超过 8MB。

最后优化后的my.cnf如下

# Example MySQL config file for large systems.## This is for a large system with memory = 512M where the system runs mainly# MySQL.## MySQL programs look for option files in a set of# locations which depend on the deployment platform.# You can copy this option file to one of those# locations. For information about these locations, see:# http://dev.mysql.com/doc/mysql/en/option-files.html## In this file, you can use all long options that a program supports.# If you want to know which options a program supports, run the program# with the "--help" option.# The following options will be passed to all MySQL clients[client]#password= your_passwordport= 3306socket= /var/lib/mysql/mysql.sock# Here follows entries for some specific programs# The MySQL server[mysqld]port= 3306socket= /var/lib/mysql/mysql.sockskip-lockingkey_buffer_size = 16Mmax_allowed_packet = 1Mtable_open_cache = 256sort_buffer_size = 4Mread_buffer_size = 4Mread_rnd_buffer_size = 8Mmyisam_sort_buffer_size = 64Mthread_cache_size = 8query_cache_size = 32Mlower_case_table_names = 1# Try number of CPU's*2 for thread_concurrencythread_concurrency = 8# Don't listen on a TCP/IP port at all. This can be a security enhancement,# if all processes that need to connect to mysqld run on the same host.# All interaction with mysqld must be made via Unix sockets or named pipes.# Note that using this option without enabling named pipes on Windows# (via the "enable-named-pipe" option) will render mysqld useless!# #skip-networking# Replication Master Server (default)# binary logging is required for replicationlog-bin=mysql-bin# binary logging format - mixed recommendedbinlog_format=mixed# required unique id between 1 and 2^32 - 1# defaults to 1 if master-host is not set# but will not function as a master if omittedserver-id= 1# Replication Slave (comment out master section to use this)## To configure this host as a replication slave, you can choose between# two methods :## 1) Use the CHANGE MASTER TO command (fully described in our manual) -#    the syntax is:##    CHANGE MASTER TO MASTER_HOST=<host>, MASTER_PORT=<port>,#    MASTER_USER=<user>, MASTER_PASSWORD=<password> ;##    where you replace <host>, <user>, <password> by quoted strings and#    <port> by the master's port number (3306 by default).##    Example:##    CHANGE MASTER TO MASTER_HOST='125.564.12.1', MASTER_PORT=3306,#    MASTER_USER='joe', MASTER_PASSWORD='secret';## OR## 2) Set the variables below. However, in case you choose this method, then#    start replication for the first time (even unsuccessfully, for example#    if you mistyped the password in master-password and the slave fails to#    connect), the slave will create a master.info file, and any later#    change in this file to the variables' values below will be ignored and#    overridden by the content of the master.info file, unless you shutdown#    the slave server, delete master.info and restart the slaver server.#    For that reason, you may want to leave the lines below untouched#    (commented) and instead use CHANGE MASTER TO (see above)## required unique id between 2 and 2^32 - 1# (and different from the master)# defaults to 2 if master-host is set# but will not function as a slave if omitted#server-id       = 2## The replication master for this slave - required#master-host     =   <hostname>## The username the slave will use for authentication when connecting# to the master - required#master-user     =   <username>## The password the slave will authenticate with when connecting to# the master - required#master-password =   <password>## The port the master is listening on.# optional - defaults to 3306#master-port     =  <port>## binary logging - not required for slaves, but recommended#log-bin=mysql-bin# Uncomment the following if you are using InnoDB tablesinnodb_data_home_dir = /var/lib/mysqlinnodb_data_file_path = ibdata1:10M:autoextendinnodb_log_group_home_dir = /var/lib/mysql# You can set .._buffer_pool_size up to 50 - 80 %# of RAM but beware of setting memory usage too highinnodb_buffer_pool_size = 256Minnodb_additional_mem_pool_size = 20M# Set .._log_file_size to 25 % of buffer pool sizeinnodb_log_file_size = 64Minnodb_log_buffer_size = 8Minnodb_flush_log_at_trx_commit = 1innodb_lock_wait_timeout = 50[mysqldump]quickmax_allowed_packet = 16M[mysql]no-auto-rehash# Remove the next comment character if you are not familiar with SQL#safe-updates[myisamchk]key_buffer_size = 128Msort_buffer_size = 128Mread_buffer = 2Mwrite_buffer = 2M[mysqlhotcopy]interactive-timeout