Star Schema

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What Does Star Schema Mean?

A star schema is a data warehousing architecture model where one fact table references multiple dimension tables, which, when viewed as a diagram, looks like a star with the fact table in the center and the dimension tables radiating from it. It is the simplest among the data warehousing schemas and is currently in wide use.

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Techopedia Explains Star Schema

The star schema is the simplest form of a dimensional model used in business intelligence and data warehousing wherein data is arranged in dimensions and facts. In the star schema, there is a single fact table, which is usually expressed in the third normal form (3NF), and multiple de-normalized dimension tables connected to it, radiating out like the points of a star. The star schema has been optimized for querying large data sets and is generally used in data marts and warehouses in order to support OLAP cubes, ad hoc queries, analytic applications and business intelligence.

The fact tables in a star schema usually have two columns: the first is for the foreign keys pointing to the dimension tables, and the second is for the measures that contain numeric facts, hence, the name fact table. The dimension tables are actually structures that are usually composed of multiple hierarchies that categorize data.

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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.