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1、数据仓库,杭诚方 教授,What is Data Warehouse,Data warehouse is a very large database that stores integrated data of one or more business subject areas Data warehouse is built to support data analysis for decision making Integrated customer data warehouse is a necessary step to the success of the business inte
2、lligence strategy Data warehouses are also used for many other purposes such as product manufacturing data warehouses Data warehouses become the focal point in the enterprise-wide IT infrastructure,What is Data Warehouse?,What is Data Warehouse,A data warehouse is simply a single,complete,and consis
3、tent store of data obtained from a variety of sources and made available to end users in a way they can understand and use in a business context.,What is Data Warehouse,Data Warehouse Definitions,The key elements in the definitions:Subject-Oriented:Presentation as business subjects,not as computer f
4、iles.Integrated:A single source of information for and about the business.Non-Volatile:Stable information that doesnt change each time an operational process is executed.Time-Variant:Containing a history of the business,as well as current business information.Accessible:The primary purpose of a data
5、 warehouse is to provide readily accessible information to business people.,Subject-Oriented,Integrated,Integrated,Non-Volatile,Time Variant,Accessible,Data Warehouse Characteristics,Data warehouse separates functions from operational systems.,Data Warehouse Characteristics,Data warehouse serves as
6、a central repository for recording everything about the business for information retrieval.Data is loaded from internal business operational system,and external systems.,Data Warehouse Characteristics,A data warehouse has a fundamental effect on how the users see the data available about the organiz
7、ation,what to do with it and how to use it for decision making.,Data Warehouse Characteristics,Data Warehouse Characteristics,A data warehouse is not a single software or hardware product you purchase to strategic.It is a computing environment where users can find strategic information to make bette
8、r decisions.It is a user-centric environment.,Data Warehouse Characteristics,Data warehouse is a blend of many different technologies needed for supporting the various functions of a data warehouse environment.These different technologies all work together in a data warehouse environment.,Enterprise
9、 Data Warehouse,Enterprise data warehouses are funded on a corporate basis.Enterprise data warehouse covers the entire business(corporation),incorporating data from all operational systems.Information is extracted from the operational environment,cleansed,and transformed into a central,integrated en
10、terprise-wide data warehouse environment,so that all the departments and other internal organizations of the corporation can benefit from a consistent,integrated source of decision support information.,Data Mart,Data marts are often funded on a departmental basis.Data mart is a collection of data ta
11、ilored to the DSS processing needs of a particular department.It is a subset of a enterprise data warehouse that has been customized to fit the needs of a department.Data marts serve users at a specific level,or for a specific department.,Data Warehouse versus Data Mart,Data Mart,Data Mart,Control:A
12、 department can completely control the data and processing that occurs inside a data mart.Cost:The cost of storage and processing is less,because the data marts machine is smaller than DWsCustomization:The data marts data is customized to suit the peculiar needs of the department.,Data Mart,Data Mar
13、t,Data Mart,Dependent Data Mart:The source is the data warehouse.The extraction,transformation,and loading process is easy.The data mart is part of the enterprise plan.Independent Data Mart:The source are operational system external source.The extraction,transformation,and loading process is difficu
14、lt.The data mart is built to satisfy analytical needs.,Operational Data Store(ODS),Integrate information from the production system.Relieve the production systems reporting and analysis demands.Provide access to current data.,ODS,ODS,ODS looks very much like a data warehouse,such as subject-oriented
15、,and integration.However,the remaining characteristics of an ODS are quite different from a data warehouse:Volatile:An ODS can be updated as a normal part of processing.Current-Values:An ODS typically contains daily,weekly,or even monthly data,but the data ages very quickly.Detailed Data:An ODS cont
16、ains detailed data only.,Different Classes of the ODS,Class I:A synchronous interface in which a very,very small amount of time lapses between an applications transaction and the reflection of the transaction in the ODS.Class II:If an hour or two passes from the time a transaction is created and int
17、eracted in the application environment until that transaction is reflected in the ODS.Class III:There may be a time lag between 12 hours and a day as transaction data is collected in the I&T interface.Class IV:The data is fed into the ODS directly from the data warehouse.,Determining the Class,Speed
18、 of movement of data into the ODSVolume of data that must be movedVolume of data that must be stored in intermediate location during I&T processingUpdate of data and integrity of transaction processingThe time of day the movement needs to occur,Data Architecture,Operational Data Store ODS,Operationa
19、l Data Store ODS,Call Center,Email,ATM,Support Operational CRM,Support Analytical CRM,Example:The Content of a Customer ODS,数据仓库系统的体系结构,两层架构（Generic Two-Level Architecture）独立型数据集市（Independent Data Mart）依赖型数据集市和操作型数据存储（Dependent Data Mart and Operational Data Store）,两层数据仓库体系结构,基于独立数据集市的数据仓库体系结构,基于依赖型数据集市和操作型数据存储(ODS)的数据仓库体系结构,
