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找出当前session中最高的logical和Physical I/O比率.
下列SQL语句显示了所有连接到数据库的session逻辑、物理读比率(每秒)。logical和physical I/O比率是通过自登陆后的时间消耗计算得出。对于sessions连接到数据库这种长周期操作而言也许不够精确,不过做个示例却足够了。
先获得session逻辑读和物理读统计项的STATISTIC#值:
SELECT name, statistic#
FROM V$STATNAME
WHERE name IN ('session logical reads','physical reads') ;
NAME STATISTIC#
------------------------------ ----------
session logical reads 9
physical reads 40
通过上面获得的STATISTIC#值执行下列语句:
SELECT ses.sid
, DECODE(ses.action,NULL,'online','batch') "User"
, MAX(DECODE(sta.statistic#,9,sta.value,0))
/greatest(3600*24*(sysdate-ses.logon_time),1) "Log IO/s"
, MAX(DECODE(sta.statistic#,40,sta.value,0))
/greatest(3600*24*(sysdate-ses.logon_time),1) "Phy IO/s"
, 60*24*(sysdate-ses.logon_time) "Minutes"
FROM V$SESSION ses
, V$SESSTAT sta
WHERE ses.status = 'ACTIVE'
AND sta.sid = ses.sid
AND sta.statistic# IN (9,40)
GROUP BY ses.sid, ses.action, ses.logon_time
ORDER BY
SUM( DECODE(sta.statistic#,40,100*sta.value,sta.value) )
/ greatest(3600*24*(sysdate-ses.logon_time),1) DESC; |
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