方法一：通過MySQL的information_schema數據庫 查找重復與冗余索引

SELECT a.table_schema AS ‘數據庫‘, a.table_name AS ‘表名‘, a.index_name AS ‘索引1‘, b.index_name AS ‘索引2‘, a.column_name AS ‘重復列名‘
FROM information_schema.statistics a
    JOIN statistics b ON a.table_schema = b.table_schema
        AND a.table_name = b.table_name
        
 
AND a.seq_in_index = b.seq_in_index
        AND a.column_name = b.column_name
WHERE a.seq_in_index = 1
    AND a.index_name != b.index_name

方法二：通過工具

用pt-duplicate-key-checker 工具檢查重復及冗余索引
使用方法 pt-duplicate-key-checker -hxxx -uxxx -pxxx

查找重復與冗余索引

參考慕課網：http://www.imooc.com/video/3998

MySQL索引的維護與優化——查找重復及冗余索引