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数据仓库是面向主题的、集成的、稳定的、不同时间的数据集合，用于支持经营管理中决策制定的过程。
数据库和数据仓库的区别
数据库（DB）
数据仓库（DW）
面向应用
面向主题
数据是详细的
数据是综合的或提炼的 ...
启动SSLEngine 参考http://httpd.apache.org/docs/2.4/ssl/ssl_howto.html
<VirtualHost *:443>
SSLEngine on
SSLCertificateFile /etc/apache2/ssl.key/server.cert
SSLCertificateKeyFile /etc/apache2/ssl.key/server.key
<VirtualHost>
查看openssl版本
openssl version -a
生成 ...
Apache Maven is a software project management and comprehension tool. Based on the concept of a project object model (POM), Maven can manage a project's build, reporting and documentation from a central piece of information.
版本统一仲裁控制
项目的pom.xml中加入
<dependencyManagement>
< ...
HTML5 is the latest and most enhanced version of HTML. Technically, HTML is not aprogramming language, but rather a markup language. This tutorial gives very goodunderstanding on HTML5.HTML5 OverviewHTML5 is the next major revision of the HTML standard superseding HTML 4.01, XHTML 1.0, andXHTML 1.1. ...
jmeter
ApacheBench
ab
Optimizing GROUP BY and DISTINCT
MySQL optimizes these two kinds of queries similarly in many cases, and in fact con-
verts between them as needed internally during the optimization process. Both types
of queries benefit from indexes, as usual, and that’s the single most important way to
optimiz ...
Simple optimizations
You can sometimes use MyISAM’s COUNT(*) optimization to your advantage when you
want to count all but a very small number of rows that are well indexed. The following
example uses the standard world database to show how you can efficiently find the
number of cities whose ID ...
ContextIn a Java 2 Platform, Enterprise Edition (J2EE) application, the server-side businesscomponents are implemented using session beans, entity beans, DAOs, and so forth.Application clients frequently need to access data that is composed from multiple objects.ProblemApplication clients typically ...
ContextThe client requires a list of items from the service for presentation. The number ofitems in the list is unknown and can be quite large in many instances.ProblemMost Java 2 Platform, Enterprise Edition (J2EE) applications have a search and queryrequirement to search and list certain data. In ...
ContextService lookup and creation involves complex interfaces and network operations.ProblemJ2EE clients interact with service components, such as Enterprise JavaBeans (EJB)and Java Message Service (JMS) components, which provide business services andpersistence capabilities. To interact with thes ...
ContextAccess to data varies depending on the source of the data. Access to persistent storage,such as to a database, varies greatly depending on the type of storage (relational databases,object-oriented databases, flat files, and so forth) and the vendor implementation.ProblemMany real-world Java ...
ContextEnterprise beans and other business services need a way to be activatedasynchronously.ProblemWhen a client needs to access an enterprise bean, it first looks up the bean's homeobject. The client requests the Enterprise JavaBeans (EJB) component's home to provide aremote reference to the requ ...
1.保证次变量对所有线程的可见性，这里的“可见性”是指当一条线程修改了这个变量的值，新值对于其他线程来说是可以立即得知的。
2.禁止指令重排优化，普通的变量仅仅会保证在该方法的执行过程中所有依赖赋值结果的地方都获取得到正确的结果，而不能保证变量赋值的顺序与程序代码中的执行顺序一致。
ContextEntity beans are not intended to represent every persistent object in the object model.Entity beans are better suited for coarse-grained persistent business objects.ProblemIn a Java 2 Platform, Enterprise Edition (J2EE) application, clients -- such asapplications, JavaServer Pages (JSP) page ...