1.如果update 某个表，没有报错，等待很久都没结束，那很有可能是表被锁了。

2.查看被锁的对象

select sid,serial#,username,SCHEMANAME,osuser,MACHINE,terminal,PROGRAM,owner,object_name,object_type,o.object_id
from dba_objects o,v$locked_object l,v$session s
where o.object_id=l.object_id and s.sid=l.session_id;   

 

3.杀掉inactive的锁表的session

alter system kill session '491,47198';

 

4.查看当前的session

select * from v$mystat where rownum = 1