借助 MySQLTuner 优化 MySQL 性能（转载的一篇文章）

MySQLTuner 是一个 Perl 脚本，可以用来分析您的 MySQL 性能，并且基于收集到的信息给出相应的优化建议。这样子，您就可以调整 my.cnf 从而优化您的 MySQL 设置。

这边只是介绍使用方法，不保证说 MySQLTuner 对您就是绝对有效。

首先需要下载 MySQLTuner

# wget https://raw.github.com/major/MySQLTuner-perl/master/mysqltuner.pl

设置权限为可执行

# chmod +x mysqltuner.pl

然后就可以直接运行了

# ./mysqltuner.pl

如果遇到错误 Unable to find mysqladmin in your $PATH 可以输入

# PATH=$PATH:/usr/local/mysql/bin

PS：把 /usr/local/mysql/bin 改为您 MySQL 程序 mysqladmin 的路径

运行后的内容如下：

 >>  MySQLTuner 1.2. - MySQL High Performance Tuning Script
 >>  Bug reports, feature requests, and downloads at http://mysqltuner.com/
 >>  Run with '--help' for additional options and output filtering
 Please enter your MySQL administrative login: <-- root
 Please enter your MySQL administrative password: <-- yourrootsqlpassword

 -------- General Statistics --------------------------------------------------
 [--] Skipped version check for MySQLTuner script
 [!!] Your MySQL version 4.1.-Debian_etch1-log is EOL software!  Upgrade soon!
 [OK] Operating on -bit architecture with less than 2GB RAM

 -------- Storage Engine Statistics -------------------------------------------
 [--] Status: +Archive -BDB -Federated +InnoDB +ISAM -NDBCluster
 [--] Data in MyISAM tables: 301M (Tables: )
 [--] Data in HEAP tables: 379K (Tables: )
 [!!] InnoDB is enabled but isn't being used
 [!!] ISAM is enabled but isn't being used
 [!!] Total fragmented tables: 

 -------- Performance Metrics -------------------------------------------------
 [--] Up for: 12d 18h 33m 30s (1B q [1K qps], 185K conn, TX: 3B, RX: 377M)
 [--] Reads / Writes: % / %
 [--] Total buffers: 2.6M per thread and 58.0M global
 [OK] Maximum possible memory usage: 320.5M (% of installed RAM)
 [OK] Slow queries: % (/1B)
 [OK] Highest usage of available connections: % (/)
 [OK] Key buffer size / total MyISAM indexes: 16.0M/72.3M
 [OK] Key buffer hit rate: 99.9%
 [OK] Query cache efficiency: 99.9%
 [!!] Query cache prunes per day:
 [OK] Sorts requiring temporary tables: %
 [!!] Temporary tables created on disk: %
 [OK] Thread cache hit rate: %
 [!!] Table cache hit rate: %
 [OK] Open file limit used: %
 [OK] Table locks acquired immediately: %
 [!!] Connections aborted: %

 -------- Recommendations -----------------------------------------------------
 General recommendations:
     Add skip-innodb to MySQL configuration to disable InnoDB
     Add skip-isam to MySQL configuration to disable ISAM
     Run OPTIMIZE TABLE to defragment tables for better performance
     Enable the slow query log to troubleshoot bad queries
     When making adjustments, make tmp_table_size/max_heap_table_size equal
     Reduce your SELECT DISTINCT queries without LIMIT clauses
     Increase table_cache gradually to avoid file descriptor limits
     Your applications are not closing MySQL connections properly
 Variables to adjust:
     query_cache_size (> 16M)
     tmp_table_size (> 32M)
     max_heap_table_size (> 16M)
     table_cache (> )

浏览输出的结果，特别是末尾的 Recommendations ，里面一般会提到您需要在 my.cnf 修改的内容。修改 my.cnf 后记得重启 MySQL 。重启后再运行 MySQLTuner 检查。另外需要注意的是 MySQL 需要启动 24 小时候再运行 MySQLTuner ，不然有些内容会不准。