MySql-如果列的索引被定义为唯一的,那么它是多余的吗?

如果表被定义为对列具有唯一约束,那么如果我们希望对该列进行索引以进行快速查找,是否还需要在该列上定义单独的索引?

例如,给定以下表索引:

mysql> show index from FRONTIER;
+----------+------------+-------------------------+--------------+--------------+-----------+-------------+----------+--------+------+-------------+---------+
| Table    | Non_unique | Key_name                | Seq_in_index | Column_name  | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+----------+------------+-------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+
| FRONTIER |          0 | PRIMARY                 |            1 | ID           | A         |           0 |     NULL | NULL   |      | BTREE      |         |
| FRONTIER |          0 | uniq_cnstr              |            1 | HOST_ID      | A         |           0 |     NULL | NULL   |      | BTREE      |         |
| FRONTIER |          0 | uniq_cnstr              |            2 | HASH_PATHQRY | A         |           0 |     NULL | NULL   |      | BTREE      |         |
| FRONTIER |          1 | I_FRONTIER_HASH_PATHQRY |            1 | HASH_PATHQRY | A         |           0 |     NULL | NULL   |      | BTREE      |         |
+----------+------------+-------------------------+--------------+--------------+-----------+-------------+----------+--------+------+------------+---------+

给定唯一约束“uniq_constr”,索引“I_FRONTIER_HASH_PATHQRY”是否冗余?

(请注意,唯一约束跨越两列)