数据仓库及应用-数据仓库

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 cons

3、istent 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 compu

4、ter files. 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 pur

5、pose of a data 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 wareho

6、use serves as 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 a

7、bout the organization, 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 informa

8、tion to make better 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 env

9、ironment.,Enterprise 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 in

10、to a central, integrated enterprise-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 m

11、art is a collection of data tailored 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 M

12、art,Data Mart,Data Mart,Control: A 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 DWs Customization: The data marts data is customized to suit the peculiar need

13、s of the department.,Data Mart,Data Mart,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 extractio

14、n, transformation, and loading process is difficult. 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 ver

15、y much like a data warehouse, such as subject-oriented, 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 monthl

16、y data, but the data ages very quickly. Detailed Data: An ODS contains 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: I

17、f an hour or two passes from the time a transaction is created and interacted 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

18、into the ODS directly from the data warehouse.,Determining the Class,Speed of movement of data into the ODS Volume of data that must be moved Volume of data that must be stored in intermediate location during I & T processing Update of data and integrity of transaction processing The time of day the movement needs to occur,Data Architecture,Operational Data Store ODS,Operational Data Store ODS,Call Center,Email,ATM,Supp