码迷,mamicode.com
首页 > 数据库 > 详细

Oracle中IMU技术和redo private strand技术

时间:2015-02-24 10:19:46      阅读:357      评论:0      收藏:0      [点我收藏+]

标签:oracle中imu技术   redo private strand技   undo advisor   redo的中读一致性ora-01555错   

oracle030

oracle030

Oracle中IMU技术和redo private strand技术




3、图解Oracle IMU机制
技术分享
     select * from v$sysstat where name like ‘%IMU%‘;
STATISTIC#, NAME,       CLASS, VALUE, STAT_ID
312     IMU commits     128     393     1914489094
313     IMU Flushes     128     88     2099506212

314     IMU contention     128     1     2909373607
315     IMU recursive-transaction flush     128     2     2591100633
316     IMU undo retention flush     128     0     2087226422
317     IMU ktichg flush     128     0     1206609541
318     IMU bind flushes     128     0     2756376339
319     IMU mbu flush     128     0     3723686946
320     IMU pool not allocated     128     0     659017805
321     IMU CR rollbacks     128     114     2225124543
322     IMU undo allocation size     128     1867712     244193920
323     IMU Redo allocation size     128     161408     3945654623
324     IMU- failed to get a private strand     128     0     2412863545

4、图解Oracle private redo strands机制
技术分享
查看回滚段的使用情况,哪个用户正在使用回滚段的资源
select s.username, u.name from v$transaction t,v$rollstat r,
v$rollname u,v$session s where s.taddr=t.addr and
t.xidusn=r.usn and r.usn=u.usn order by s.username;

检查UNDO Segment状态
select usn,xacts,rssize/1024/1024/1024,hwmsize/1024/1024/1024,shrinks
from v$rollstat order by rssize;



确定当前例程正在使用的UNDO表空间
Show parameter undo_tablespace

显示数据库的所有UNDO表空间
SELECT tablespace_name FROM dba_tablespaces WHERE contents=‘UNDO‘;

显示UNDO表空间统计信息
SELECT TO_CHAR(BEGIN_TIME,‘HH24:MI:SS‘) BEGIN_TIME,
TO_CHAR(END_TIME,‘HH24:MI:SS‘) END_TIME,UNDOBLKS
FROM V$UNDOSTAT;

显示UNDO段统计信息
SELECT a.name, b.xacts, b.writes, b.extents
FROM v$rollname a, v$rollstat b
WHERE a.usn=b.usn;

显示活动事务信息
Col username format a10
Col name format a10
SELECT a.username, b.name, c.used_ublk
FROM v$session a, v$rollname b, v$transaction c
WHERE a.saddr=c.ses_addr AND b.usn=c.xidusn
AND a.username=‘HR‘;







V$ROLLSTAT中的常用列

USN            Rollback segment number
EXTENTS      Number of extents in the rollback segment
RSSIZE       Size (in bytes) of the rollback segment.
WRITES       Number of bytes written to the rollback segment
XACTS           Number of active transactions
GETS           Number of header gets
WAITS           Number of header waits
OPTSIZE      Optimal size of the rollback segment
HWMSIZE      High-watermark of rollback segment size
SHRINKS      Number of times the size of a rollback segment decreases
WRAPS           Number of times rollback segment is wrapped
EXTENDS      Number of times rollback segment size is extended
AVESHRINK      Average shrink size
AVEACTIVE      Current size of active extents, averaged over time.
STATUS           Rollback segment status:
               ONLINE
               PENDING OFFLINE
               OFFLINE
               FULL
CUREXT          Current extent
CURBLK          Current block 


5、读一致性
     ORA-01555错误

6、undo advisor
     EM


redo的中读一致性(ORA-01555错误机制问题)问题undo表空间的大小设置

技术分享
技术分享技术分享

解决这样问题:1. 确保undo表空间数据的保留时间至少大于最长sql语句的时间
            2. 增大undo表空间的大小
就是根据时间找大小。

Oracle中IMU技术和redo private strand技术

标签:oracle中imu技术   redo private strand技   undo advisor   redo的中读一致性ora-01555错   

原文地址:http://blog.csdn.net/u011218159/article/details/43924217

(0)
(0)
   
举报
评论 一句话评论(0
登录后才能评论!
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码!