摘要：
https://dev.mysql.com/doc/refman/5.6/en/index-btree-hash.html 译文：http://itindex.net/detail/54241-tree-索引-hash https://stackoverflow.com/questions/1687 阅读全文
摘要：
http://blog.csdn.net/linghao00/article/details/8768435 阅读全文