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：
1 >> MySQLTuner 1.2.0 - MySQL High Performance Tuning Script 2 >> Bug reports, feature requests, and downloads at http://mysqltuner.com/ 3 >> Run with '--help' for additional options and output filtering 4 Please enter your MySQL administrative login: <-- root 5 Please enter your MySQL administrative password: <-- yourrootsqlpassword 6 7 -------- General Statistics -------------------------------------------------- 8 [--] Skipped version check for MySQLTuner script 9 [!!] Your MySQL version 4.1.11-Debian_etch1-log is EOL software! Upgrade soon! 10 [OK] Operating on 32-bit architecture with less than 2GB RAM 11 12 -------- Storage Engine Statistics ------------------------------------------- 13 [--] Status: +Archive -BDB -Federated +InnoDB +ISAM -NDBCluster 14 [--] Data in MyISAM tables: 301M (Tables: 2074) 15 [--] Data in HEAP tables: 379K (Tables: 9) 16 [!!] InnoDB is enabled but isn't being used 17 [!!] ISAM is enabled but isn't being used 18 [!!] Total fragmented tables: 215 19 20 -------- Performance Metrics ------------------------------------------------- 21 [--] Up for: 12d 18h 33m 30s (1B q [1K qps], 185K conn, TX: 3B, RX: 377M) 22 [--] Reads / Writes: 78% / 22% 23 [--] Total buffers: 2.6M per thread and 58.0M global 24 [OK] Maximum possible memory usage: 320.5M (20% of installed RAM) 25 [OK] Slow queries: 0% (17/1B) 26 [OK] Highest usage of available connections: 32% (32/100) 27 [OK] Key buffer size / total MyISAM indexes: 16.0M/72.3M 28 [OK] Key buffer hit rate: 99.9% 29 [OK] Query cache efficiency: 99.9% 30 [!!] Query cache prunes per day: 47549 31 [OK] Sorts requiring temporary tables: 0% 32 [!!] Temporary tables created on disk: 28% 33 [OK] Thread cache hit rate: 99% 34 [!!] Table cache hit rate: 0% 35 [OK] Open file limit used: 12% 36 [OK] Table locks acquired immediately: 99% 37 [!!] Connections aborted: 20% 38 39 -------- Recommendations ----------------------------------------------------- 40 General recommendations: 41 Add skip-innodb to MySQL configuration to disable InnoDB 42 Add skip-isam to MySQL configuration to disable ISAM 43 Run OPTIMIZE TABLE to defragment tables for better performance 44 Enable the slow query log to troubleshoot bad queries 45 When making adjustments, make tmp_table_size/max_heap_table_size equal 46 Reduce your SELECT DISTINCT queries without LIMIT clauses 47 Increase table_cache gradually to avoid file descriptor limits 48 Your applications are not closing MySQL connections properly 49 Variables to adjust: 50 query_cache_size (> 16M) 51 tmp_table_size (> 32M) 52 max_heap_table_size (> 16M) 53 table_cache (> 64)
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。