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Estimate TEMP usage without running SQL
I decided to post this tip for a while but each time I distracted with something and I forgot that. Yesterday a client called me with an issue on TEMP tablespace. Client was running a big merge statement on warehouse database but each time job failed because ...
Overview
If you've been developing applications on Oracle for a while, you've no doubt come across the concept of «Bind Variables». Bind variables are one of those Oracle concepts that experts frequently cite as being key to application performance, but it's often not all that easy to pin down ...
外关联是Oracle数据库的专有语句
Left Outer Join则是SQL-92的标准语句
通常认为这两个SQL是可以等效的，但还是有些细微的差别。
一般说来，外关联的等值条件等效于Left Outer Join中的on语句；两个where中其他语句是一样的。
但是Left Outer Join中的其他条件（非表连接）出现在On关键词后面还是出现在Where关键词后面是不一样的，这样的语句很难用外关联进行同义转义。
Oracle中组合索引的使用详解
在Oracle中可以创建组合索引，即同时包含两个或两个以上列的索引。在组合索引的使用方面，Oracle有以下特点：
1、 当使用基于规则的优化器（RBO）时，只有当组合索引的前导列出现在SQL语句的where子句中时，才会使用到该索引；
2、 在使用Oracle9i之前的基于成本的优化器（CBO）时， 只有当组合索引的前导列出现在SQL语句的where子句中时，才可能会使用到该索引，这取决于优化器计算的使用索引的成本和使用全表扫描的成本，Oracle会自动选择成本低的访问路径（请见下面的测试1和测试2）；
3、 从Oracle ...
http://www.oracleonlinux.cn/2012/09/oracle-splitting-partitions/
本文简单记录在Oracle 10g数据库上对范围分区表的Splitting Partitions测试过程和结论，并不涉及到Oracle数据库中分区技术的详细描述。
1 测试环境及平台：
OS：
1
[root@localhost ~]# uname -rm
2
2.6.18-164.el5 x86_64
3
[root@localhost ~]#
Oracle：
...
Optimizing SPLIT PARTITION and SPLIT SUBPARTITION Operations
Oracle Database implements a SPLIT PARTITION operation by creating two newpartitions and redistributing the rows from the partition being split into the two newpartitions. This is an expensive operation because it is necessary ...
（一）相关类
class A ...{ public String show(D obj)...{ return ("A and D"); }
Java debugging tutorial - 10 tips on debugging in java with example
How to debug java program in Eclipse
Debugging is a must have skill for any java developer. Having ability to debug java program enables to find you any subtle bug which is not visible during code review or comes when ...
10 Interview questions on Singleton Pattern in JavaSingleton pattern in Java is one of the most common patterns available and it’s also used heavily in Java. This is also one of my favorite interview question and has lots of interesting follow-up to dig into details , this not only check the knowled ...
Top 30 Programming interview questions
Programming questions are integral part of any java or C++ programmer or software analyst interview. No matter on which language you have expertise it’s expected that you are familiar with fundamental of programming and can solve problems without taking help ...
Top 20 Core Java Interview questions asked in Investment Bank
This is a new series of sharing core Java interview question on Finance domain and mostly on Big Investment bank. Anybody who is preparing for any Java developer Interview on any Investment bank can be benefited from these se ...
Servlet Questions Asked in Interview
Question 1: In web.xml file <load-on-startup>1</load-on-startup> is defined between <servlet></servlet> tag what does it means.
Ans: whenever we request for any servlet the servlet container will initialize the servlet and load it whi ...
Source Code Control System (SCCS)
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Introduction
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The Source Code Control System (SCCS) is a tool for controlling changes
to text files. It is usually used with source code and documentation
of software systems.
SCCS looks after your files for ...
Understanding Oracle QUERY PLAN
What is Query Execution Plan?
When you fire an SQL query to Oracle, Oracle first comes up with a query execution plan in order to fetch the desired data from the physical tables. This query execution plan is crucial as different execution plan take different time ...
Oracle AUTOTRACE Explained
AUTOTRACE is a beautiful utility in Oracle that can help you gather vital performance statistics for a SQL Query. You need to understand and use it for SQL Query Tuning. Here is how!
When you fire an SQL query to Oracle, database performs a lot of tasks like PARSI ...