Snowflake schema

The snowflake schema is a more complex data warehouse model than a star schema, and is a type of star schema. It is called a snowflake schema because the diagram of the schema resembles a snowflake.

Snowflake schemas Database normalization dimension tables to eliminate redundancy. That is, the dimension data has been grouped into multiple table (database)s instead of one large table. For example, a product dimension table in a star schema might be normalized into a products table, a product_category table, and a product_manufacturer table in a snowflake schema. While this saves space, it increases the number of dimension tables and requires more foreign key join (SQL)s. The result is more complex queries and reduced query performance.

=External links=

[http://citeseer.ist.psu.edu/457156.html Why is the Snowflake Schema a Good Data Warehouse Design] by Mark Levene and George Loizou

*Article [http://intelligententerprise.com/010629/warehouse1_1.jhtml A Trio of Interesting Snowflakes] (Beat three common modeling challenges with extensions of the dimensional model) by Ralph Kimball *[http://learndatamodeling.com/snow_flake.htm Designing Snowflake Schema] *[http://freedatawarehouse.com/tutorials/dmtutorial/Snowflake%20Schema.aspx Snowflake Schema Design] *[http://blogs.msdn.com/bi_systems/articles/164525.aspx Star vs. Snowflake Schemas]