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2 changes: 1 addition & 1 deletion docs/database/MySQL Index.md
Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,7 @@ select * from user where city=xx ; // 无法命中索引

冗余索引指的是索引的功能相同,能够命中 就肯定能命中 ,那么 就是冗余索引如(name,city )和(name )这两个索引就是冗余索引,能够命中后者的查询肯定是能够命中前者的 在大多数情况下,都应该尽量扩展已有的索引而不是创建新索引。

MySQLS.7 版本后,可以通过查询 sys 库的 `schema_redundant_indexes` 表来查看冗余索引
MySQL 5.7 版本后,可以通过查询 sys 库的 `schema_redundant_indexes` 表来查看冗余索引

### Mysql如何为表字段添加索引???

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