Star Schema

As discussed in the topic i.e., Data Warehouse or Data Mart, Star schema and Snowflake Schema both refer to Ralph Kimball Data Warehousing approach.

As per Ralph Kimball, we MUST use Dimensional Modelling for Data Warehousing and Data Marts consisting of Star and Snowflake Schemas.

In Star Schema, the model has a Fact table in the middle and all the Dimensions are joined with the Fact. For example, there is a Fact table called Sales and there can be many dimensions like Time, Location, Product, Categories etc. The Primary Key of the Fact table consists of all the foreign key columns coming from Dimensions. This way when a report or a query is created, there is always one direct join with any Dimension.