关于ORACLE的锁表与解锁总结

总结1：Oracle的锁表与解锁
select
s.username,
decode(l.type,'tm','table lock','tx','row lock',null) lock_level,
o.owner,
o.object_name,
o.object_type,
s.sid,
s.serial#,
s.terminal,
s.machine,
s.program,
s.osuser
from v$session s,v$lock l,dba_objects o
where l.sid = s.sid
and l.id1 = o.object_id(+)
and s.username is not null;

--kill session语句
alter system kill session'50,492';
--以下几个为相关表
SELECT * FROM v$lock;
SELECT * FROM v$sqlarea;
SELECT * FROM v$session;
SELECT * FROM v$process ;
SELECT * FROM v$locked_object;
SELECT * FROM all_objects;
SELECT * FROM v$session_wait;
--1.查出锁定object的session的信息以及被锁定的object名
SELECT l.session_id sid, s.serial#, l.locked_mode,l.oracle_username,
l.os_user_name,s.machine, s.terminal, o.object_name, s.logon_time
FROM v$locked_object l, all_objects o, v$session s
WHERE l.object_id = o.object_id
AND l.session_id = s.sid
ORDER BY sid, s.serial# ;
--2.查出锁定表的session的sid, serial#,os_user_name, machine name, terminal和执行的语句
--比上面那段多出sql_text和action
SELECT l.session_id sid, s.serial#, l.locked_mode, l.oracle_username, s.user#,
l.os_user_name,s.machine, s.terminal,a.sql_text, a.action
FROM v$sqlarea a,v$session s, v$locked_object l
WHERE l.session_id = s.sid
AND s.prev_sql_addr = a.address
ORDER BY sid, s.serial#;
--3.查出锁定表的sid, serial#,os_user_name, machine_name, terminal，锁的type,mode
SELECT s.sid, s.serial#, s.username, s.schemaname, s.osuser, s.process, s.machine,
s.terminal, s.logon_time, l.type
FROM v$session s, v$lock l
WHERE s.sid = l.sid
AND s.username IS NOT NULL
ORDER BY sid;

这个语句将查找到数据库中所有的DML语句产生的锁，还可以发现，
任何DML语句其实产生了两个锁，一个是表锁，一个是行锁。
杀锁命令
alter system kill session 'sid,serial#'
SELECT /*+ rule */ s.username,
decode(l.type,'TM','TABLE LOCK',
'TX','ROW LOCK',
NULL) LOCK_LEVEL,
o.owner,o.object_name,o.object_type,
s.sid,s.serial#,s.terminal,s.machine,s.program,s.osuser
FROM v$session s,v$lock l,dba_objects o
WHERE l.sid = s.sid
AND l.id1 = o.object_id(+)
AND s.username is NOT NULL
如果发生了锁等待，我们可能更想知道是谁锁了表而引起谁的等待
以下的语句可以查询到谁锁了表，而谁在等待。
以上查询结果是一个树状结构，如果有子节点，则表示有等待发生。
如果想知道锁用了哪个回滚段，还可以关联到V$rollname，其中xidusn就是回滚段的USN
col user_name format a10
col owner format a10
col object_name format a10
col object_type format a10
select lpad(' ',decode(l.xidusn ,0,3,0))||l.oracle_username user_name,
o.owner,o.object_name,o.object_type,s.sid,s.serial#
from v$locked_object l,dba_objects o,v$session s
where l.object_id=o.object_id
and l.session_id=s.sid
order by o.object_id,xidusn desc

总结2：一个有用查找脚本：

column sid format 999;
column b format 9;
column object_name format a30;
column locktype format a20;
select v$lock.sid,
decode(v$lock.type,
        'MR', 'Media Recovery',
        'RT','Redo Thread',
        'UN','User Name',
        'TX', 'Transaction',
        'TM', 'DML',
        'UL', 'PL/SQL User Lock',
        'DX', 'Distributed Xaction',
        'CF', 'Control File',
        'IS', 'Instance State',
        'FS', 'File Set',
        'IR', 'Instance Recovery',
        'ST', 'Disk Space Transaction',
        'TS', 'Temp Segment',
        'IV', 'Library Cache Invalida-tion',
        'LS', 'Log Start or Switch',
        'RW', 'Row Wait',
        'SQ', 'Sequence Number',
        'TE', 'Extend Table',
        'TT', 'Temp Table',
        'Unknown') LockType,
         rtrim(owner) || '.' || object_name object_name,
decode(lmode,   0, 'None',
                1, 'Null',
                2, 'Row-S',
                3, 'Row-X',
                4, 'Share',
                5, 'S/Row-X',
                6, 'Exclusive','Unknown') LockMode,
decode(request, 0, 'None',
                1, 'Null',
                2, 'Row-S',
                3, 'Row-X',
                4, 'Share',
                5, 'S/Row-X',
                6, 'Exclusive', 'Unknown') RequestMode,
ctime, block b
from v$lock, all_objects
where sid > 6
and v$lock.id1 = all_objects.object_id;


找到某表的锁 所属的sid.
alter system kill session 'sid,serial#';
即可

select object_id,session_id,serial#,oracle_username,os_user_name,s.process
from v$locked_object a,v$session s
where a.session_id=s.sid;
查出被lock 的对象
然后 alter system kill session 'sid,serial#';

知识点3：

LOCK   TABLE 
  语法： 
  LOCK   TABLE   table_1   [,table_2,   ...,   table_n]   IN   lock_mode   MODE 
  NOWAIT 
  变量： 
  table_1,...,table_n:   一系列你想通过使用LOCK   TABLE语句锁住的数据库表。 
  lock_mode:   对于某一数据库表你要设定的锁定模式。你可以从如下的锁定模式中任选一个。 
  EXCLUSIVE 
  SHARE   ROW   EXCLUSIVE 
  SHARE 
  SHARE   UPDATE 
  ROW   SHARE 
  ROW   EXCLUSIVE 
  NOWAIT:   Oracle   will   not   wait   to   lock   the   given   Table(s),   if   the   Table(s)   is(are)   not 
  available 
  例子： 
  SQL 
  LOCK   TABLE   loan   IN   SHARE   MODE   ; 
  LOCK   TABLE   region   IN   EXCLUSIVE   MODE   NOWAIT; 
  LOCK   TABLE   acct   IN   SHARE   UPDATE   MODE; 
  LOCK   TABLE   bank   IN   ROW   EXCLUSIVE   MODE   NOWAIT; 
  LOCK   TABLE   user   IN   SHARE   ROW   EXCLUSIVE   MODE; 
  LOCK   TABLE   branch   IN   ROW   SHARE   MODE   NOWAIT; 
  
  commit 
  /