SHOW LOCKS
提供当前正在持有表锁的活跃事务列表，可以显示当前用户在其所有会话中的锁，或 TiDB Cloud Lake 系统内所有用户的锁。锁是一种同步机制，用于限制对共享资源（如表）的访问，确保 TiDB Cloud Lake 系统中的进程或线程之间以有序且受控的方式进行交互，从而维护数据一致性并防止冲突。
UPDATE、DELETE、OPTIMIZE TABLE、RECLUSTER TABLE 和 ALTER TABLE 等操作都可能导致系统中出现表锁。表锁功能默认启用。发生资源冲突时，你可以使用该命令查看具体详情。若要禁用此功能，请执行 set enable_table_lock=0;。
语法
SHOW LOCKS [IN ACCOUNT] [WHERE <expr>]
输出
该命令以表格形式返回锁信息，包含以下列：
示例
SHOW LOCKS IN ACCOUNT;
+----------+----------+-------+---------+------+------------------------+--------------------------------------+----------------------------+----------------------------+------------+
| table_id | revision | type | status | user | node | query_id | created_on | acquired_on | extra_info |
+----------+----------+-------+---------+------+------------------------+--------------------------------------+----------------------------+----------------------------+------------+
| 57 | 4517 | TABLE | HOLDING | root | xzi6pRbLUYasuA9QFB36m6 | d7989971-d5ec-4764-8e37-afe38ebc13e2 | 2023-12-13 09:56:47.295684 | 2023-12-13 09:56:47.310805 | |
+----------+----------+-------+---------+------+------------------------+--------------------------------------+----------------------------+----------------------------+------------+
SHOW LOCKS;
+----------+----------+-------+---------+------+------------------------+--------------------------------------+----------------------------+----------------------------+------------+
| table_id | revision | type | status | user | node | query_id | created_on | acquired_on | extra_info |
+----------+----------+-------+---------+------+------------------------+--------------------------------------+----------------------------+----------------------------+------------+
| 57 | 4517 | TABLE | HOLDING | root | xzi6pRbLUYasuA9QFB36m6 | d7989971-d5ec-4764-8e37-afe38ebc13e2 | 2023-12-13 09:56:47.295684 | 2023-12-13 09:56:47.310805 | |
| 57 | 4521 | TABLE | WAITING | zzq | xzi6pRbLUYasuA9QFB36m6 | 4bc78044-d4fc-4fe1-a5c5-ff6ab1e3e372 | 2023-12-13 09:56:48.419774 | NULL | |
+----------+----------+-------+---------+------+------------------------+--------------------------------------+----------------------------+----------------------------+------------+
SHOW LOCKS WHERE STATUS = 'HOLDING';
+----------+----------+-------+---------+------+------------------------+--------------------------------------+----------------------------+----------------------------+------------+
| table_id | revision | type | status | user | node | query_id | created_on | acquired_on | extra_info |
+----------+----------+-------+---------+------+------------------------+--------------------------------------+----------------------------+----------------------------+------------+
| 57 | 4517 | TABLE | HOLDING | root | xzi6pRbLUYasuA9QFB36m6 | d7989971-d5ec-4764-8e37-afe38ebc13e2 | 2023-12-13 09:56:47.295684 | 2023-12-13 09:56:47.310805 | |
+----------+----------+-------+---------+------+------------------------+--------------------------------------+----------------------------+----------------------------+------------+