STAR SCHEMA

Star Schema Modelling

A Dimensional modelling technique in which a detail fact table is linked to dimension tables. The data in data warehouses and data marts is accessed by end-users.

The information contained in the data warehouse/data mart must be easy for the end-user to use and access. Denormalized designs are easier for end-users to use than highly normalized designs, however these designs are more difficult to design and maintain.

The Star Schema diagram graphically models the end-user's view (i.e., the denormalized view) of how the information is accessed.


Components of a Star Schema Diagram

The diagram has three main components:

· Fact Table and its contents: metric attributes and the foreign keys necessary to join to the dimension tables,

· Dimension Tables and their contents: reference attributes, hierarchical attributes, and metric attributes. The dimension tables are highly denormalized,

· The lines that link the Dimension Tables to the Fact Table.

Star Schema Model

This diagram is a model of a star schema diagram.










Star Schema Example

The following is an example of a star schema for sales items.