mysql ocp 908 中文题库

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Examine these commands and output: mysql>SHOW FULL PROCESSLIST; +----+-----------+------------+---------+------+-------------------+-------------+ | Id | User | Host | db | Command | Time | Info | +----+-----------+------------+---------+------+-------------------+-------------+ | 6 | event_scheduler | | | Waiting on empty queue | NULL | NULL | | 20 | root | | | | NULL | NULL | | 21 | root | | | | NULL | NULL | | 22 | root | | | Waiting for table metadata lock | optimize table test.demo_test | from test.demo_test | | 24 | root | | | | NULL | NULL | | 25 | root | | | | NULL | SHOW FULL PROCESSLIST; | +----+-----------+------------+---------+------+-------------------+-------------+ mysql>SELECT object_type,object_schema,object_name,lock_type,lock_status,owner_thread_id,owner_event_id ->FROM performance_schema.metadata_locks WHERE object_schema!=""; | OBJECT_TYPE | OBJECT_SCHEMA | OBJECT_NAME | LOCK_TYPE | LOCK_STATUS | OWNER_THREAD_ID | OWNER_EVENT_ID | +------------+--------------+-------------+----------+-------------+---------------+---------------+ | TABLE | test | demo_test | SHARED_WRITE | GRANTED | 60 | 9 | | TABLE | test | demo_test | SHARED_EXCLUSIVE | GRANTED | 62 | 6 | | TABLE | test | demo_test | SHARED_NO_READ_WRITE | PENDING | 62 | 6 | +------------+--------------+-------------+----------+-------------+---------------+---------------+ mysql>SELECT thread_id,processlist_id,processlist_user,parent_thread_id ->FROM performance_schema.threads WHERE processlist_user='root'; +------------+-------------+------------------+---------------+ | THREAD_ID | PROCESSLIST_ID | PROCESSLIST_USER | PARENT_THREAD_ID | +------------+-------------+------------------+---------------+ | 60 | 20 | root | NULL | | 61 | 21 | root | NULL | | 62 | 22 | root | 1 | | 64 | 24 | root | 1 | | 65 | 25 | root | NULL | +------------+-------------+------------------+---------------+ Which connection ID is holding the metadata lock? 哪个连接ID持有元数据锁? (缺图)