ITPub博客

Oracle DBA值得去读的书1.Expert Oracle Database Architecture: 9i and 10g Programming Techniques and Solutions by Thomas Kyte2.Expert Oracle Database 10g Administration by Sam Alapati3.Unix for Oracle DBAs Pocket Reference by Donald Burleson4.Cost-Based Oracle Fundamentals by Jonathan Lewis5.Oracle PL/SQL Programming by Steven Feuerstein6.Oracle Wait Interface: A Practical Guide to Performance Diagnostics&Tuning by Richmond Shee, Kirtikumar Deshpande, and K. Gopalakrishnan你读完几本？:)[@more@

create index时对表加的什么锁[@more@]SQL> create index idx_1 on A02 (owner, object_name, subobject_name);Index createdSQL> select sid from v$mystat where rownum<2;SID----------16select rpad(oracle_username, 10) o_name,session_id sid,decode(locked_mode,0,'None',1,'Null',2,'Row share',3,'Row Exclusive',4,'Share',5,'Share Row Exclusive',6,'Exclusive') lock_type,object_name,xidusn,xidslot,xidsqnfrom v$locked_object, all_objectswhere v$locked_object.object_id = all_objects.object_id;O_NAME SI

转自wanghai的blog(http://wzwanghai.spaces.live.com),比较值得我们注意。[@more@]说起library cache lock wait event就必须先说一下library cache lock是什么东西，library lock是oracle用来对library cache object进行并发控制的两种数据结构之一，另外一种数据结构是pin，lock将会在pin之前获得，并被加载到library cache handle上。library cache lock有3种形式，share,null,exclusive，具体的library cache lock的分析请看我的另一篇帖子。 通常我们举的关于library cache lock wait event的例子都是用procedure来模拟的，eygle发表

参考了eygle的文章。[@more@]Shared Pool的Free list管理Shared Pool通过Free list管理free内存块(Free chunk),根据Free chunk的大小，被划分到不同的Bucket中进行管理。关于Shared Pool中有多少个Bucket和每个Bucket中管理多大的Free chunk可以通过设置event来查看。alter session set events 'immediate trace name heapdump level 2'9i之前和9i及以后的Bucket管理的free chunk的大小范围有较大改变，所以9i及以后设置较大的Shared Pool，会增加更多的Bucket来管理大量的free chunk,使每个Bucket管理的free chunk数量变少，提高了查找效