星形模型和雪花模型.doc(国外英文资料).doc

星形模型和雪花模型.doc(国外英文资料) Star model and snowflake model The data warehouse is a multidimensional database, it extends to the relational database model, star schema as the main structure, and on the basis of it, the theory of extended snowflake schema and data sign etc., but no matter what kind of structure, dimension table and measure the fact table and the fact table of all components essential 1 star architecture Star model is the most common implementation model of data warehouse design structure, which makes data warehouse form an integrated system, provide reporting services for end users, and provide users with analysis service objects. The star schema supports a variety of decision queries by using a fact table containing a topic and a table of tables containing multiple non formal descriptions of facts. The star model can adopt relational database structure. The core of the model is fact table, and the dimension table is around the fact table. Each dimension table is connected to the central fact table through the fact table that connects various dimension tables. The objects in the dimension table are associated with objects in another dimension table through the fact table, so that the linkages between the various dimension table objects can be established. Each dimension table is connected to the fact table through a primary key. The fact table mainly contains data describing specific business events, that is, the measure of certain business events. In general, data in fact tables is not allowed to change, and new data is simply added to the fact table. The dimension table mainly contains the characteristic data stored in the fact table. Each dimension table using the dimension of keywords from a foreign key constraint in the fact table in the fact table in a row, and relate the fact table, which requires a foreign key in the fact table cannot be empty, and the general database allows for the foreign key space is different. This structure allows users to ea