Guide to Data Warehousing and Business Intelligence
ETL (Extract Transform Load) jobs extract data from the Data Warehouse and populate one or more Data Marts for use by groups of decision makers in the organizations.
Data Marts can be Dimensional (Star Schemas) or relational, depending on how the information is to be used and what "front end" Data Warehousing Tools will be used to present the information.
Each Data Mart can contain different combinations of tables, columns and rows from the Enterprise Data Warehouse.
For example, a business unit or user group that doesn't require a lot of historical data might only need transactions from the current calendar year. The Personnel Department might need to see all details about employees, whereas data such as "salary" or "home address" might not be appropriate for a Data Mart that focuses on Sales.