📣

TiDB Cloud Serverless 现已更名为
Starter
!此页面由 AI 自动翻译,英文原文请见
此处。

DROP INDEX

该语句用于从指定的表中删除索引,在 TiKV 中释放空间。

概要

DropIndexStmt
DROPINDEXIfExistsIdentifierONTableNameIndexLockAndAlgorithmOpt
IfExists
IFEXISTS
IndexLockAndAlgorithmOpt
LockClauseAlgorithmClauseAlgorithmClauseLockClause

示例

mysql> CREATE TABLE t1 (id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, c1 INT NOT NULL); Query OK, 0 rows affected (0.10 sec) mysql> INSERT INTO t1 (c1) VALUES (1),(2),(3),(4),(5); Query OK, 5 rows affected (0.02 sec) Records: 5 Duplicates: 0 Warnings: 0 mysql> EXPLAIN SELECT * FROM t1 WHERE c1 = 3; +-------------------------+----------+-----------+---------------+--------------------------------+ | id | estRows | task | access object | operator info | +-------------------------+----------+-----------+---------------+--------------------------------+ | TableReader_7 | 10.00 | root | | data:Selection_6 | | └─Selection_6 | 10.00 | cop[tikv] | | eq(test.t1.c1, 3) | | └─TableFullScan_5 | 10000.00 | cop[tikv] | table:t1 | keep order:false, stats:pseudo | +-------------------------+----------+-----------+---------------+--------------------------------+ 3 rows in set (0.00 sec) mysql> CREATE INDEX c1 ON t1 (c1); Query OK, 0 rows affected (0.30 sec) mysql> EXPLAIN SELECT * FROM t1 WHERE c1 = 3; +------------------------+---------+-----------+------------------------+---------------------------------------------+ | id | estRows | task | access object | operator info | +------------------------+---------+-----------+------------------------+---------------------------------------------+ | IndexReader_6 | 0.01 | root | | index:IndexRangeScan_5 | | └─IndexRangeScan_5 | 0.01 | cop[tikv] | table:t1, index:c1(c1) | range:[3,3], keep order:false, stats:pseudo | +------------------------+---------+-----------+------------------------+---------------------------------------------+ 2 rows in set (0.00 sec) mysql> DROP INDEX c1 ON t1; Query OK, 0 rows affected (0.30 sec)

MySQL 兼容性

  • 不支持删除 CLUSTERED 类型的主键。关于 CLUSTERED 类型主键的更多细节,请参考 clustered index

相关链接

文档内容是否有帮助?