What is a data warehouse?

Data warehouse is a subject-oriented, integrated, time-related and unchangeable data set in enterprise management and decision-making.

Data Warehouse, named data warehouse in English, can be abbreviated as DW.

The definition put forward by bill inmon, the father of data warehouse, in the book "Building a Data Warehouse" published by 199 1 is widely accepted. A data warehouse is a subject-oriented, integrated, relatively stable (non-volatile) data set to support decision support.

◆ Topic-oriented: The data organization of the operation database is transaction-oriented, and the business systems are separated, while the data in the data warehouse is organized according to a certain topic domain.

◆ Integration: The data in the data warehouse is obtained through systematic processing, summary and sorting on the basis of extracting and cleaning the original scattered database data. The inconsistency in the source data must be eliminated to ensure that the information in the data warehouse is consistent and is the global information about the whole enterprise.

Relatively stable: the data in the data warehouse is mainly used for enterprise decision analysis, and the data operation involved is mainly data query. Once a certain data enters the data warehouse, it will generally be kept for a long time, that is, there are a lot of query operations in the data warehouse, but there are few modification and deletion operations, and usually it only needs to be loaded and refreshed regularly.

◆ Reflect historical changes: The data in the data warehouse usually contains historical information, which systematically records the information of the enterprise from a certain point in the past (such as the time when the data warehouse was applied) to the present stage. Through this information, we can quantitatively analyze and predict the development process and future trend of enterprises.

Data warehouse is a process rather than a project.

The data warehouse system is an information providing platform. It obtains data from business processing system, organizes data mainly through star model and snowflake model, and provides users with various means to obtain information and knowledge from data.

From the functional structure, the data warehouse system should include at least three key parts: data acquisition, data storage and data access.