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见过这么高并发( logons current)的数据库么?
作者：eygle |【转载时请以超链接形式标明文章出处和作者信息及本声明】链接：http://www.eygle.com/archives/2009/05/huge_logons_current.html
今天在客户这里，在9206 RAC的集群环境中，偶然发现数据库的Logons Current指标超高。
高得超乎寻常，可以让我们直接判断为Bug，看看以下数据。
数据库环境：
SQL> select * from v$version;
BANNER
----------------------------------------------------------------
Oracle9i Enterprise Edition Release 9.2.0.6.0 - 64bit Production
PL/SQL Release 9.2.0.6.0 - Production
CORE 9.2.0.6.0 Production
TNS for Solaris: Version 9.2.0.6.0 - Production
NLSRTL Version 9.2.0.6.0 - Production
看看logons current输出为：1.8447E+19
SQL> select name,value from v$sysstat where name like 'logons%';改变列宽显示，这个天文数字呈现出来：
NAME VALUE
---------------------------------------------------------------- ----------
logons cumulative 8674656
logons current 1.8447E+19
SQL> col name for a40
SQL> col value for 9999999999999999999999
SQL> select name,value from v$sysstat where name like 'logons%';
NAME VALUE
---------------------------------------- -----------------------
logons cumulative 8674700
logons current 18446744073709550949
那么当前数据库有多少会话呢？
SQL> select count(*) from v$session;819个，logons current的统计数据会随着会话的变化而继续增加，并非停滞的溢出：
COUNT(*)
----------
819
SQL> select name,value from v$sysstat where name like 'logons%';
NAME VALUE
---------------------------------------- -----------------------
logons cumulative 8674708
logons current 18446744073709550952
SQL> select name,value from v$sysstat where name like 'logons%';
NAME VALUE
---------------------------------------- -----------------------
logons cumulative 8674722
logons current 18446744073709550958
在Metalink上确认的Bug号是：2960012，在10.1中被修正。Bug的描述为：
When running in a RAC cluster, select from gv$sysstat can show a huge
value (1.8447E+19) for 'logons current' or 'logons cumulative'.
logons cumulative---Total number of logons since the instance started. Useful only in V$SYSSTAT. It gives an instance overview of all processes that logged on.
logons current-------Total number of current logons. Useful only in V$SYSSTAT.
那么这个天大的数字 18446744073709550958 ，该怎么读出口呢？
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By eygle on 2009-05-11 13:50 | Comments (4) | Posted to Case | FAQ | Edit |
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留言 (4)
天文数字,呵呵
Posted by: dd_macle at May 11, 2009 8:42 PM
没见过啊
Posted by: 家常菜 at May 11, 2009 10:39 PM
4g^2
=18446744073709551616
Posted by: l1t at May 13, 2009 11:23 AM
We are looking for experienced large scale, high performance MySQL DB Architect, any name you could recommend? Email me.
Thanks in advance for your help!
Diane
Posted by: Diane at May 14, 2009 11:49 AM