梦想有多远

今天是2008年1月16日，比较有意思的一天，BEA被ORACLE以85亿美元收购了，而MYSQL则以10亿美元被SUN收购了。

 http://www.tech-ex.com/network/resources/manufactory/00405272.html ORACLE+BEA

http://www.sun.com/aboutsun/pr/2008-01/sunflash.20080116.1.xml MYSQL+SUN

用dbms_stats包收集统计数据                                      

dbms_stats包问世以后，Oracle专家可通过一种简单的方式来为CBO收集统计数据。目前，已经不再推荐你使用老式的分析表和dbms_utility方法来生成CBO统计数据。那些古老的方式甚至有可能危及SQL的性能，因为它们并非总是能够捕捉到有关表和索引的高质量信息。CBO使用对象统计，为所有SQL语句选择最佳的执行计划。

dbms_stats能良好地估计统计数据（尤其是针对较大的分区表），并能获得更好的统计结果，最终制定出速度更快的SQL执行计划。

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这几天一致在关注JY的事情，为主人公所惋惜，无法想想她那两个月的生活 ，从其博客中了解了一些，我只希望不要在发生这种悲剧，无论做人和做事一定要厚道。

祝福JY在另一个世界能过的开心，没有烦恼，也希望他们的家人身体健康。

http://orionchris.spaces.live.com/ 主人的博客地址

载入中……

这是主人公很喜欢的一首歌

Join Me In Death  

Baby join me in death…Baby join me in death…Baby join me in death…

We are so young,  Our lives have just begun
But already we’re considering, Escape from this world

And we’ve waited for so long, For this moment to come
We’re so anxious to be together,Together in death

Won’t you die tonight for love?Baby join me in death
Won’t you die?Baby join me in death
Won’t you die tonight for love?Baby join me in death

This world is a cruel place, And we’re here only to lose
So before life tears us apart,Let death bless me with you

Won’t you die tonight for love? Baby join me in death
Won’t you die? Baby join me in death
Won’t you die tonight for love? Baby join me in death

This life ain’t worth living…This life ain’t worth living…

This life ain’t worth living…This life ain’t worth living…

Won’t you die tonight for love? Baby join me in death
Won’t you die? Baby join me in death
Won’t you die tonight for love? Baby join me in death

Baby join me in death…

Bad Connection Management

The application connects and disconnects for each database interaction. This problem is common with stateless middleware in application servers. It has over two orders of magnitude impact on performance, and it is totally unscalable.

Bad Use of Cursors and the Shared Pool

Not using cursors results in repeated parses. If bind variables are not used, then there is hard parsing of all SQL statements. This has an order of magnitude impact in performance, and it is totally unscalable. Use cursors with bind variables that open the cursor and execute it many times. Be suspicious of applications generating dynamic SQL.

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1.检查并跟踪数据库进程

诊断时是晚上,无用户访问
在前台点击相关页面,同时进行进程跟踪

查询v$session视图,获取进程信息
PHP code:——————————————————————————–
SQL> select sid,serial#,username from v$session;

       SID    SERIAL# USERNAME
———- ———- ——————————
         1          1
         2          1
         3          1
         4          1
         5          1
         6          1
         7        284 IFLOW
        11        214 IFLOW
        12        164 SYS
        16       1042 IFLOW

10 rows selected.——————————————————————————–
启用相关进程sql_trace

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