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Oracle操作Session的方法

时间:2021-07-01 10:21:17 帮助过:36人阅读

1.如何查看session级的等待事件? 当我们对数据库的性能进行调整时,一个最重要的参考指标就是系统等待事 件。$system_event,v$session_event,v$session_wait这三个视图里记录的就是系统级和session级的等待 事件,通过查询这些视图你可以发现数据库的一些操

1.如何查看session级的等待事件?

当我们对数据库的性能进行调整时,一个最重要的参考指标就是系统等待事 件。$system_event,v$session_event,v$session_wait这三个视图里记录的就是系统级和session级的等待 事件,通过查询这些视图你可以发现数据库的一些操作到底在等待什么?是磁盘I/O,缓冲区忙,还是插锁等等。

通过如下sql你可以查询你的每个应用程序到底在等待什么,从而针对这些信息对数据库的性能进行调整。
Select s.username,s.program,s.status,se.event,se.total_waits,se.total_timeouts,se.time_waited,se.average_wait
from v$session s, v$session_event se
Where s.sid=se.sid And se.event not like 'SQl*Net%' And s.status ='ACTIVE' And s.username is not null

2.oracle中查询被锁的表并释放session
SELECT A.OWNER,A.OBJECT_NAME,B.XIDUSN,B.XIDSLOT,B.XIDSQN,B.SESSION_ID,B.ORACLE_USERNAME, B.OS_USER_NAME,B.PROCESS, B.LOCKED_MODE, C.MACHINE,C.STATUS,C.SERVER,C.SID,C.SERIAL#,C.PROGRAM
FROM ALL_OBJECTS A,V$LOCKED_OBJECT B,SYS.GV_$SESSION C
WHERE ( A.OBJECT_ID = B.OBJECT_ID ) AND (B.PROCESS = C.PROCESS ) ORDER BY 1,2

释放session Sql:
alter system kill session 'sid, serial#'
alter system kill session '379, 21132'
alter system kill session '374, 6938'

3.查看占用系统io较大的session
SELECT se.sid,se.serial#,pr.SPID,se.username,se.status,se.terminal,se.program,se.MODULE,se.sql_address,st.event,st.p1text,si.physical_reads,si.block_changes
FROM v$session se, v$session_wait st,v$sess_io si,v$process pr
WHERE st.sid=se.sid  AND st.sid=si.sid AND se.PADDR=pr.ADDR AND se.sid>6 AND st.wait_time=0 AND st.event NOT LIKE '%SQL%' ORDER BY physical_reads DESC

4.找出耗cpu较多的session
select a.sid,spid,status,substr(a.program,1,40) prog,a.terminal,osuser,value/60/100 value
from v$session a,v$process b,v$sesstat c
where c.statistic#=12 and c.sid=a.sid and a.paddr=b.addr order by value desc

5.查询session被锁的sql可以用一下语句

select sys.v_$session.osuser,sys.v_$session.machine,v$lock.sid,

  sys.v_$session.serial#,

  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(object_type) || ' ' || 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$lock, all_objects, sys.v_$session

  where v$Lock.sid > 6

  and sys.v_$session.sid = v$lock.sid

  and v$lock.id1 = all_objects.object_id;

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