oracle解除锁表【原】

在日常操作中,经常会有不小心被锁表的情况发生

一般造成原因有:

• 开发人员不小心执行了 for update 查询语句后,没有解锁
• 不合理代码中开启事务(begin transaction)后,没有关闭(close)或回滚(rollback)该事务.

此时我们必须拥有dba的权限才能对被锁的表进行解锁操作.而锁表的时如果突然断网或断电那么可能会报如下异常:

Exception in thread "Thread-4" org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: java.sql.SQLException: Io 异常: Connection reset
### The error may exist in file [D:applicationeclipse64eeworkspace.metadata.pluginsorg.eclipse.wst.server.core	mp7wtpwebappsiscWEB-INFclassescom	estdemopcisiscdaoLockMapper.xml]
### The error may involve com.testdemo.pcis.isc.dao.LockMapper.queryLockTableForUpdate-Inline
### The error occurred while setting parameters
### SQL: SELECT T.C_PK_ID as cId, T.C_IP as cIP,T.C_MEMO as cMemo ,T.T_CRT_TM as tCrtTm FROM WEB_ISC_LOCK T  FOR UPDATE
### Cause: java.sql.SQLException: Io 异常: Connection reset
    at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
    at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:128)
    at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:68)
    at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53)
    at com.sun.proxy.$Proxy24.queryLockTableForUpdate(Unknown Source)
    at com.testdemo.pcis.isc.threadpool.MasterSlaveThread.judgeMasterNewCode(MasterSlaveThread.java:73)
    at com.testdemo.pcis.isc.threadpool.MasterSlaveThread.run(MasterSlaveThread.java:54)
Caused by: java.sql.SQLException: Io 异常: Connection reset
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:146)
    at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:255)
    at oracle.jdbc.driver.T4CPreparedStatement.executeForDescribe(T4CPreparedStatement.java:829)
    at oracle.jdbc.driver.OracleStatement.executeMaybeDescribe(OracleStatement.java:1049)
    at oracle.jdbc.driver.T4CPreparedStatement.executeMaybeDescribe(T4CPreparedStatement.java:854)
    at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1154)
    at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3370)
    at oracle.jdbc.driver.OraclePreparedStatement.execute(OraclePreparedStatement.java:3476)
    at org.apache.commons.dbcp.DelegatingPreparedStatement.execute(DelegatingPreparedStatement.java:172)
    at org.apache.commons.dbcp.DelegatingPreparedStatement.execute(DelegatingPreparedStatement.java:172)
    at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:63)
    at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:79)
    at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:63)
    at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:325)
    at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
    at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)
    at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83)
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148)
    ... 7 more

创造锁表情景:

SELECT * FROM STUDENT FOR UPDATE;

现在查看有哪些表被锁了

执行以下语句必须有oracle管理员权限,不然会报错 "ORA-00942:表或视图不存在"

SELECT OBJECT_NAME, MACHINE, S.SID, S.SERIAL#
  FROM GV$LOCKED_OBJECT L, DBA_OBJECTS O, GV$SESSION S
 WHERE L.OBJECT_ID　 = O.OBJECT_ID
   AND L.SESSION_ID = S.SID;

解除被锁定的表

ALTER SYSTEM KILL SESSION '219,59457'; -- 219为SID,59457为SERIAL

继续查看哪些表被锁了

SELECT OBJECT_NAME, MACHINE, S.SID, S.SERIAL#
  FROM GV$LOCKED_OBJECT L, DBA_OBJECTS O, GV$SESSION S
 WHERE L.OBJECT_ID　 = O.OBJECT_ID
   AND L.SESSION_ID = S.SID;

　　

在我自己的mybatis3项目中

如果用select * from tableName where id='XXX' for update 锁表后不 rollback() 或 commit() ,那么只会锁 id = 'XXX' 这一数据行

查看表被锁的其它形式语句

   SELECT OBJECT_ID,
          SESSION_ID,
          SERIAL# AS SERIAL,
          ORACLE_USERNAME,
          OS_USER_NAME,
          S.PROCESS
     FROM V$LOCKED_OBJECT A, V$SESSION S
    WHERE A.SESSION_ID = S.SID
      AND SYSDATE - S.LOGON_TIME > 0.5

其它参考

查询Oracle正在执行的sql语句 

 ORACLE脚本之锁表时 查询谁锁了表而又引起谁的等待--https://blog.csdn.net/haiross/article/details/17223295

其它相关语句

查看oracle中的锁的情况.
SESSION_ID, USERNAME, MODE_HELD, MODE_REQUESTED, OBJECT_NAME, LOCK_TYPE, LOCK_ID
分别是 拥有锁的SESSION_ID,拥有锁的USERNAME,锁的执行模式MODE_HELD,锁的请求MODE_REQUESTED,锁所在的数据库对象名,锁的类型,锁的ID

SELECT S.SID SESSION_ID,
       S.USERNAME,
       DECODE(LMODE,
              0,
              'None',
              1,
              'Null',
              2,
              'Row-S (SS)',
              3,
              'Row-X (SX)',
              4,
              'Share',
              5,
              'S/Row-X (SSX)',
              6,
              'Exclusive',
              TO_CHAR(LMODE)) MODE_HELD,
       DECODE(REQUEST,
              0,
              'None',
              1,
              'Null',
              2,
              'Row-S (SS)',
              3,
              'Row-X (SX)',
              4,
              'Share',
              5,
              'S/Row-X (SSX)',
              6,
              'Exclusive',
              TO_CHAR(REQUEST)) MODE_REQUESTED,
       O.OWNER || '.' || O.OBJECT_NAME || ' (' || O.OBJECT_TYPE || ')',
       S.TYPE LOCK_TYPE,
       L.ID1 LOCK_ID1,
       L.ID2 LOCK_ID2
  FROM V$LOCK L, SYS.DBA_OBJECTS O, V$SESSION S
 WHERE L.SID = S.SID
   AND L.ID1 = O.OBJECT_ID
   AND S.USERNAME = 'bobo';