数据库中的锁查询及相关关系
2009-04-02 10:58
239 查看
1.查询数据库中的锁
select * from v$lock;
select * from v$lock where block=1;
2.查询被锁的对象
select * from v$locked_object;
3.查询阻塞
查被阻塞的会话
select * from v$lock where lmode=0 and type in ('TM','TX');
查阻塞别的会话锁
select * from v$lock where lmode>0 and type in ('TM','TX');
4.查询数据库正在等待锁的进程
select * from v$session where lockwait is not null;
5.查询会话之间锁等待的关系
select a.sid holdsid,b.sid waitsid,a.type,a.id1,a.id2,a.ctime from v$lock a,v$lock b
where a.id1=b.id1 and a.id2=b.id2 and a.block=1 and b.block=0;
6.查询锁等待事件
select * from v$session_wait where event='enqueue';
1.关于V$lock表和相关视图的说明
Column
Datatype
Description
ADDR
RAW(4 | 8)
Address of lock state object
KADDR
RAW(4 | 8)
Address of lock
SID
NUMBER
Identifier for session holding or acquiring the lock
TYPE
VARCHAR2(2)
Type of user or system lock
The locks on the user types are obtained by user applications. Any process that is blocking others is likely to be holding one of these locks. The user type locks are:
TM - DML enqueue
TX - Transaction enqueue
UL - User supplied
--我们主要关注TX和TM两种类型的锁
--UL锁用户自己定义的,一般很少会定义,基本不用关注
--其它均为系统锁,会很快自动释放,不用关注
ID1
NUMBER
Lock identifier #1 (depends on type)
ID2
NUMBER
Lock identifier #2 (depends on type)
---当lock type 为TM时,id1为DML-locked object的object_id
---当lock type 为TX时,id1为usn+slot,而id2为seq。
--当lock type为其它时,不用关注
LMODE
NUMBER
Lock mode in which the session holds the lock:
0 - none
1 - null (NULL)
2 - row-S (SS)
3 - row-X (SX)
4 - share (S)
5 - S/Row-X (SSX)
6 - exclusive (X)
--大于0时表示当前会话以某种模式占有该锁,等于0时表示当前会话正在等待该锁资源,即表示该会话被阻塞。
--往往在发生TX锁时,伴随着TM锁,比如一个sid=9会话拥有一个TM锁,一般会拥有一个或几个TX锁,但他们的id1和id2是不同的,请注意
REQUEST
NUMBER
Lock mode in which the process requests the lock:
0 - none
1 - null (NULL)
2 - row-S (SS)
3 - row-X (SX)
4 - share (S)
5 - S/Row-X (SSX)
6 - exclusive (X)
--大于0时,表示当前会话被阻塞,其它会话占有改锁的模式
CTIME
NUMBER
Time since current mode was granted
BLOCK
NUMBER
The lock is blocking another lock
0, 'Not Blocking', /* Not blocking any other processes */
1, 'Blocking', /* This lock blocks other processes */
2, 'Global', /* This lock is global, so we can't tell */
--该锁是否阻塞了另外一个锁
select * from v$lock;
select * from v$lock where block=1;
2.查询被锁的对象
select * from v$locked_object;
3.查询阻塞
查被阻塞的会话
select * from v$lock where lmode=0 and type in ('TM','TX');
查阻塞别的会话锁
select * from v$lock where lmode>0 and type in ('TM','TX');
4.查询数据库正在等待锁的进程
select * from v$session where lockwait is not null;
5.查询会话之间锁等待的关系
select a.sid holdsid,b.sid waitsid,a.type,a.id1,a.id2,a.ctime from v$lock a,v$lock b
where a.id1=b.id1 and a.id2=b.id2 and a.block=1 and b.block=0;
6.查询锁等待事件
select * from v$session_wait where event='enqueue';
1.关于V$lock表和相关视图的说明
Column
Datatype
Description
ADDR
RAW(4 | 8)
Address of lock state object
KADDR
RAW(4 | 8)
Address of lock
SID
NUMBER
Identifier for session holding or acquiring the lock
TYPE
VARCHAR2(2)
Type of user or system lock
The locks on the user types are obtained by user applications. Any process that is blocking others is likely to be holding one of these locks. The user type locks are:
TM - DML enqueue
TX - Transaction enqueue
UL - User supplied
--我们主要关注TX和TM两种类型的锁
--UL锁用户自己定义的,一般很少会定义,基本不用关注
--其它均为系统锁,会很快自动释放,不用关注
ID1
NUMBER
Lock identifier #1 (depends on type)
ID2
NUMBER
Lock identifier #2 (depends on type)
---当lock type 为TM时,id1为DML-locked object的object_id
---当lock type 为TX时,id1为usn+slot,而id2为seq。
--当lock type为其它时,不用关注
LMODE
NUMBER
Lock mode in which the session holds the lock:
0 - none
1 - null (NULL)
2 - row-S (SS)
3 - row-X (SX)
4 - share (S)
5 - S/Row-X (SSX)
6 - exclusive (X)
--大于0时表示当前会话以某种模式占有该锁,等于0时表示当前会话正在等待该锁资源,即表示该会话被阻塞。
--往往在发生TX锁时,伴随着TM锁,比如一个sid=9会话拥有一个TM锁,一般会拥有一个或几个TX锁,但他们的id1和id2是不同的,请注意
REQUEST
NUMBER
Lock mode in which the process requests the lock:
0 - none
1 - null (NULL)
2 - row-S (SS)
3 - row-X (SX)
4 - share (S)
5 - S/Row-X (SSX)
6 - exclusive (X)
--大于0时,表示当前会话被阻塞,其它会话占有改锁的模式
CTIME
NUMBER
Time since current mode was granted
BLOCK
NUMBER
The lock is blocking another lock
0, 'Not Blocking', /* Not blocking any other processes */
1, 'Blocking', /* This lock blocks other processes */
2, 'Global', /* This lock is global, so we can't tell */
--该锁是否阻塞了另外一个锁
相关文章推荐
- mysql:day3--java访问数据库、CASE...WHEN、无关/相关子查询、表与表之间的关系
- 数据库查询结果、Ibatis的ResultMap与JavaBean的对应关系
- 例题:学习数据库查询。学生信息表的创建,主外键关系,以及45道题的查询实例。主要知识点在讲页45页,和讲页65页
- [数据库]关系数据库的查询优化
- oracle数据库管理--对象、角色相关查询
- 【数据库系统概念】第6章 形式化关系查询语言 知识总结
- 关系数据库的查询优化策略
- 查询数据库的相关信息
- SQLServer 表结构相关查询(快速了解数据库)
- mysql 查询数据库的外键关系
- Oracle与SQL-Server数据库SQL"树查询"对比[按照父子节点关系递归拼接]
- 关系数据库SQL之基本数据查询:子查询、分组查询、模糊查询
- SQL 查询数据库中包含指定字符串的相关表和相关记录
- 任务单2 相关问题 三级模式、数据库对象、关系图创建
- Python开发SQLite3数据库相关操作详解【连接,查询,插入,更新,删除,关闭等】
- 数据库查询性能优化(合理使用索引|避免或简化排序|避免对大型表进行全表顺序扫描|避免使用相关的子查询|避免使用通配符匹配 )
- 11-6数据库加强(子查询(独立子查询,相关子查询),分页显示,开窗函数 over(),join )
- Django数据库查询相关
- 关系数据库SQL之高级数据查询:去重复、组合查询、连接查询、虚拟表
- mysql中相关,无关子查询,表与表之间的关系以及编码和乱码的解决