Data Warehousing – Star Schema

The Star Schema is a dimensional approach that simplifies the data model to facilitate access. The use of dimensions and fact tables in data warehousing makes the Star Schema the most effective approach to use for the data warehouse database model [1]. It was named Star Schema due to the diagram of dimensions with and the fact table in the middle resembles a star shape.  In one single star schema, there’s a single fact table linked to a number of small dimensional tables in a star shape. A simple example of a star schema fact-dimensional structure:

Star Schema
Figure 1 – Star Schema

If there’s more than one fact table, effectively there is more than one star schema.

A more detailed equivalent diagram to figure 1:

Figure 3 - Star Schema - Indepth
Figure 2 – Star Schema – In-depth

“Fact tables contain transactional records, which over a period of time can come to contain very large numbers of records.” [1].

 

 

References:
  1. Gavin Powell. (2006) Beginning Database Design.