pt-duplicate-key-checker 与 mysql information_schema检查冗余索引

pt-duplicate-key-checker

用法：

pt-duplicate-key-checker A=utf8, F=/etc/my.cnf, h=localhost, u=root, P=3306 --ask-pass --databases=voole_vrm --tables=v3a_resumelist

执行结果分析：

# idex_hid is a left-prefix of hid_oemid_mid  说明冗余索引的类型
# Key definitions:  # 以下为两个索引的定义
#   KEY `idex_hid` (`hid`), 
#   KEY `hid_oemid_mid` (`hid`,`oemid`,`mid`) USING BTREE,
# Column types: # 索引对应列的定义
#     `hid` varchar(40) default '' comment '终端硬件id'
#     `oemid` int(11) default '0' comment '终端oemid'
#     `mid` int(11) default '0' comment '影片编号'
# To remove this duplicate index, execute: # 以下为去掉索引要执行的sql
ALTER TABLE `mobileservice_b2c9`.`v3a_resumelist` DROP INDEX `idex_hid`;

说明：

工具很好用，检错冗余索引，在mysql 5.7 中有对应的系统表来查询冗余索引 

mysql information_schema

select * from sys.schema_redundant_indexes\G
              table_schema: voole_ad
                table_name: new_ad_movieinfo
      redundant_index_name: amid
   redundant_index_columns: amid
redundant_index_non_unique: 1
       dominant_index_name: PRIMARY
    dominant_index_columns: amid
 dominant_index_non_unique: 0
            subpart_exists: 0
            sql_drop_index: ALTER TABLE `voole_ad`.`new_ad_movieinfo` DROP INDEX `amid`