MySQL索引原理及慢查询优化 http://blog.jobbole.com/86594/
细说mysql索引 https://www.cnblogs.com/chenshishuo/p/5030029.html
MySQL的btree索引和hash索引的区别 https://www.cnblogs.com/vicenteforever/articles/1789613.html
Mysql几种索引类型的区别及适用情况 https://www.cnblogs.com/yuan-shuai/p/3225417.html
慢查询分析MySQL Explain详解 MySQL Explain详解

sql优化总结 http://www.cnblogs.com/shamo89/p/6758476.html