DROP INDEX

    1. CREATE TABLE t1 (id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, c1 INT NOT NULL);
    1. Query OK, 0 rows affected (0.10 sec)
    1. INSERT INTO t1 (c1) VALUES (1),(2),(3),(4),(5);
    1. EXPLAIN SELECT * FROM t1 WHERE c1 = 3;
    1. +-------------------------+----------+-----------+---------------+--------------------------------+
    2. | id                      | estRows  | task      | access object | operator info                  |
    4. | └─Selection_6           | 10.00    | cop[tikv] |               | eq(test.t1.c1, 3)              |
    5. |   └─TableFullScan_5     | 10000.00 | cop[tikv] | table:t1      | keep order:false, stats:pseudo |
    6. +-------------------------+----------+-----------+---------------+--------------------------------+
    7. 3 rows in set (0.00 sec)
    1. CREATE INDEX c1 ON t1 (c1);
    1. EXPLAIN SELECT * FROM t1 WHERE c1 = 3;
    1. +------------------------+---------+-----------+------------------------+---------------------------------------------+
    3. +------------------------+---------+-----------+------------------------+---------------------------------------------+
    4. | └─IndexRangeScan_5     | 0.01    | cop[tikv] | table:t1, index:c1(c1) | range:[3,3], keep order:false, stats:pseudo |
    5. +------------------------+---------+-----------+------------------------+---------------------------------------------+
    6. 2 rows in set (0.00 sec)
    1. ALTER TABLE t1 DROP INDEX c1;
    • 不支持删除 CLUSTERED 类型的 。要了解关于 CLUSTERED 主键的详细信息，请参考聚簇索引。