Snowflake Schema

A snowflake schema is a star schema structure normalized through the use of outrigger tables. Though normalizing data is useful in entity relationship modeling, it reduces database efficiency in dimensional modeling. In a dimensional model, the primary objective is to create a database that supports high performance browsing and querying. A snowflake schema typically hinders performance because it requires multiple joins to return a simple query result set, which increases the query response time.

In the following example, the REVENUE fact table is joined to the dimension tables: Customer, Movie, Market, and Time, which are joined to two outrigger tables.

More information:

Outrigger Table