Oracle Database Tuning ADDM
ADDM (Automatic Database Diagnostic Monitor) implements the Oracle performance method and analyzes statistics to provide automatic diagnosis of major performance problems. Because ADDM can significantly shorten the time required to improve the performance of a system, it is one of the most used performance tuning tools of Oracle database.
1. Run some operations on your database instance.
First, start your database instance and do the database operations (select, update, delete...) which will be optimized. e.g. run a script to make some queries in database:
sh run.sh -r rdf1mm-performance -t p -f p3.txt
2. Login to EM
Login to Database EM home page (https://:5500/em), click Performance tab.
3. Run ADDM
Click Button "Run ADDM Now", and click "Yes" on the confirmation page. After a while, we will see the ADDM analysis page.
Database Activity chart shows the database activity during the ADDM analysis period.
In the ADDM Performance Analysis table, ADDM findings are listed in descending order, from highest to least impact. The Informational Findings section lists areas that have no performance impact and are for information only.
4. Implement ADDM recommendations
Click the ADDM findings that has the impact on performance. e.g. Top SQL Statements.
The Category column displays the category of recommendation. The Benefit column displays the estimated benefit of implementing the recommendation.
If we click "Run Advisor Now", SQL tuning advisor will give us some recommendations on how to tune the SQLs.
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oracle做查询语句的时候，类似select id in (xxxx,xxxx.....)这样的语句最大只支持2000个值，如果对应得值上万行，如该如何处理了。
这时候应该采用临时表。建一个临时表，把数据导入进去。查询时候联表查询既可。（以上是我工作中遇到的一个需求) ......
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http://www.itsoba.com/Article.asp?id=847
视频介绍：
本套ORACLE视频教程为传智播客内部经典教学视频的一集，后续视频正在录制和整理中，敬请关注。
讲师介绍：
王治国，有多年软件开发经验和教学经验，先后在多家软件公司担任软件工程师、项目经理，精通J2SE、J2ME、J2EE、Linux、Oracle、SqlS ......
17:00:59 SQL> desc dbms_random;
Element Type
---------- ---------
SEED PROCEDURE
VALUE FUNCTION
NORMAL FUNCTION
STRING FUNCT ......
单值函数在查询中返回单个值，可被应用到select，where子句，start with以及connect by 子句和having子句。
(一).数值型函数(Number Functions)
数值型函数输入数字型参数并返回数值型的值。多数该类函数的返回值支持38位小数点，诸如：COS, COSH, EXP, LN, LOG,
SIN, SINH, SQRT, TAN, and TANH � ......
很不幸，建立的表被某人误删了，，，
还好可以通过这样恢复。
select * from user_recyclebin where original_name like 'FINANCE_%' order by droptime desc;
FLASHBACK TABLE FINANCE_CASE_FEE_ITEM TO BEFORE DROP
即所有drop的表都在 user_recyclebin 这个oracle回收站里面的，再通过flashback命 ......
