STAR Schema is describes a logical database structure of Data Warehouse or Data Mart. STAR Schema can design with one de-normalized FACT and one or many shared Dimension table(s) that looks like STAR.
STAR Schema often uses in Data warehouse that helps to optimize database query operation. First Normal Form and Second Normal Form rules must apply on Dimension in the STAR Schema. Grain is the base business definition of Fact table that determine measurement of business event.
FACT Table is used to store measurements, metrics or facts or a business process in the Data warehouse. FACT Table is designed with Composite Primary Key to identify unique transaction and those attributes are foreign keys of referenced Dimension tables.
Dimension Table is used to maintain Hierarchy Textual Information of business process that integrated with Fact Table in the Data warehouse. A collection of unordered dimension table's descriptive information is helps to generate Drill down or Roll up Analytical Report that specify how Fact table data should be summarized.
The following STAR Schema is describes a Sales Data Mart that designed with de-normalized Sales_Fact and relevant shared dimension tables to maintain Sales Historical Transaction information.
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