There are different parochial interests that need to use data – finance, marketing, sales, finance, engineering, and so forth. The data mart serves the individual need. The data mart is built on the foundation of the dimensional model. The dimensional model consists of star joins and dimension tables. The source of all data for the data mart is the data warehouse. When the data warehouse is the source of data for all data marts, the result is integrity of data in the data marts. It is usually easier to build a new data mart when requirements change than it is to try to do maintenance on an existing data mart. Data marts typically are centered around KPIs.