Concept of Data Warehouse

With the intensification of market competition and the development of the information society, it is increasingly important to extract (retrieve, query, and so on) information from a large amount of data to develop market strategies. This requirement requires both online services and a large amount of Decision-Making data. However, traditional database systems cannot meet this requirement. It is embodied in three aspects:

The historical data volume is large.
Auxiliary Decision-Making Information involves data from many departments, which is difficult to integrate with data from different systems.
Due to insufficient data access capabilities, its access performance to a large amount of data is significantly reduced.

With the maturity of C/S technology and the development of parallel databases, the development trend of information processing technology is to extract data from a large number of transactional databases, clean up and convert it into a new storage format, that is, data is aggregated in a special format for decision-making goals. With the development and improvement of this process, such decision-making and special data storage is called Data Warehouse (DW ).

W. H. Inmon defines a data warehouse as a topic-oriented, integrated, stable, and time-varying data set that supports management decision-making.

A topic is a standard for data classification. Each topic corresponds to an objective analysis field, such as a customer or a store. It can help decision-making to integrate a large amount of data from different departments and systems. A data warehouse contains a large amount of historical data. After integration, the data that enters the Data Warehouse is rarely updated. The data period in a data warehouse is 5 to 10 years. It is mainly used for time trend analysis. The data volume of a data warehouse is large, generally about 10 Gb. It is 100 times the data volume of a general database (100 MB), and the size of a large data warehouse reaches TB.

Data Warehouse is mainly used in two aspects:

Use the browser analysis tool to find useful information in DW.
The data warehouse system supports DW applications to form a Decision Support System (DSS ).