什么是数据仓库？（基本普及）
各位大哥到底什么是数据仓库，和我们平时的数据库有什么标志性的区别？
能否举例来说明ROLAP，MOLAP的数据结构上的不同，MOLAP如何建立？
针对MOLAP如何进行切片和旋转（对应的sql如何些，还是需要使用工具？）
问题点数：100、回复次数：10Top
1 楼huwei2003（凡）回复于 2006-06-14 11:23:58 得分 0
可以这么说吧，平时用的是前端的，数据仓库是后端的，它可以是各个独立数据库的集合，具体的还是看看书吧，比较系统Top
2 楼bodhi（bodhi）回复于 2006-06-14 15:26:06 得分 0
这几天高手都上哪去了？Top
3 楼longaiatj（）回复于 2006-06-15 22:33:15 得分 0
对呀，哪位高手来解答一下呀，让大家学习学习。Top
4 楼l51（山中人）回复于 2006-06-15 23:14:34 得分 0
数据仓库Data Warehouse，可简写为DW，其实到现在与所谓的 Web2.0 一样并没确却的定义，它只是著名的数据仓库专家W.H.Inmon在其著作《Building the Data Warehouse》一书中给予如下描述——数据仓库（Data Warehouse）是一个面向主题的（Subject Oriented）、集成的（Integrated）、相对稳定的（Non-Volatile）、反映历史变化（Time Variant）的数据集合，用于支持管理决策(Decision Making Support)。
其实，说白了，就是对一些大量的，经历性的、有组织管理的数据库的管理概念化而已。例如，你的公司有固定的销售产品，那么你要为这些产品创建数据库、并建好计量单位、规格、分类、供应商、客户等等资料，但是这些资料因为有它的固定性与资料性，并无数据性、历史性，所以它们可以称之为数据仓库的"仓体"。
现在，当你的公司开始营业了，有了第一笔订单、采购单、入库单、出库单、出货单。。。。。
这些单据数据就购成了前述"仓体"资料的组合数据，请注意，现在我们才称之为"数据"，因为每一个数据都已经存在了数据特性与历史特性。
当然，除了"仓体"与数据，数据仓库的内容还远不止这些，例如到月底了，公司要进行财务结帐，于是乎要进行月统计，也这属于部分决策内容，还有月报年报分析之类的.....，当然它们属于特殊的"数据"，请注意，这是实质的决策内容，并不是普通数据。
最后，其实，目前的任何一个关系型数据库Server，实质上都是一个数据仓库的实例，不信你可以自己去分析一下系统数据库就知道了。
另外：ROLAP 与 MOLAP 是两个不同层面的概念，一个是针对分析运行层，一个是针对数据结构方式，具体你还是 Baidu 一下吧，哈，睡觉去喽~~~~~~~
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5 楼cobejordan（非菲非霏）回复于 2006-06-16 14:50:45 得分 0
放眼本版，满是类似问题：
http://community.csdn.net/Expert/topic/4620/4620342.xml?temp=.5399744
http://community.csdn.net/Expert/topic/4518/4518095.xml?temp=.8373529
http://community.csdn.net/Expert/topic/4634/4634600.xml?temp=.5361444
http://community.csdn.net/Expert/topic/4450/4450233.xml?temp=.9038507
http://community.csdn.net/Expert/topic/4758/4758004.xml?temp=.4151422
http://community.csdn.net/Expert/topic/4620/4620342.xml?temp=.6432306
……
如果楼主懂得“提问的智慧”，解决你的问题并不困难。
何为高手：回复的就是高手？不回复的呢？回复错的呢？想要学习和讨论就要抱着虚心的态度，给大家创造积极向上的氛围。
此类问题发文率很高，却没有FAQ，实属遗憾。如果楼主有意，我愿意和各位朋友一起把这篇帖子推向FAQ。Top
6 楼yangwl（杨威利）回复于 2006-06-21 00:26:11 得分 0
去chinabi.net的知识中心看看Top
7 楼sozdream（Dream.Zhang）回复于 2006-06-21 20:33:20 得分 0
What is a Data Warehouse?
1-2 Oracle9i Data Warehousing Guide
What is a Data Warehouse?
A data warehouse is a relational database that is designed for query and analysis
rather than for transaction processing. It usually contains historical data derived
from transaction data, but it can include data from other sources. It separates
analysis workload from transaction workload and enables an organization to
consolidate data from several sources.
In addition to a relational database, a data warehouse environment includes an
extraction, transportation, transformation, and loading (ETL) solution, an online
analytical processing (OLAP) engine, client analysis tools, and other applications
that manage the process of gathering data and delivering it to business users.
A common way of introducing data warehousing is to refer to the characteristics of
a data warehouse as set forth by William Inmon:
Subject Oriented
Integrated
Nonvolatile
Time Variant
我还没开始学这个, 不过有官方的解释~ 给你Top
8 楼sozdream（Dream.Zhang）回复于 2006-06-21 20:35:04 得分 0
Subject Oriented
Data warehouses are designed to help you analyze data. For example, to learn more
about your company’s sales data, you can build a warehouse that concentrates on
sales. Using this warehouse, you can answer questions like "Who was our best
customer for this item last year?" This ability to define a data warehouse by subject
matter, sales in this case, makes the data warehouse subject oriented.
Integrated
Integration is closely related to subject orientation. Data warehouses must put data
from disparate sources into a consistent format. They must resolve such problems
as naming conflicts and inconsistencies among units of measure. When they achieve
this, they are said to be integrated.Top
9 楼sozdream（Dream.Zhang）回复于 2006-06-21 20:35:43 得分 0
Nonvolatile
Nonvolatile means that, once entered into the warehouse, data should not change.
This is logical because the purpose of a warehouse is to enable you to analyze what
has occurred.
Time Variant
In order to discover trends in business, analysts need large amounts of data. This is
very much in contrast to online transaction processing (OLTP) systems, where
performance requirements demand that historical data be moved to an archive. A
data warehouse’s focus on change over time is what is meant by the term time
variant.
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10 楼TCat（蚊子）回复于 2006-07-03 15:48:27 得分 0
此类问题发文率很高，却没有FAQ，实属遗憾。如果楼主有意，我愿意和各位朋友一起把这篇帖子推向FAQ。
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