Stars and Cubes -- <Two> Fact Table Features

Every fact table represents a business process by capturing measurements that describe it. The level of detail at which the fact table records information is referred to as its grain. It is important to identify the grain of each fact table clearly and avoid situations of mixed grain. Fact tables do not contain rows for every combination of dimension values. Instead, they exhibit a characteristic called sparsity.

Fact Tables and Processes
The fact table is the engine for business process measurement. It is the locus for storage of the detailed measurements that describe the process. The facts are accompanied by foreign keys that provide dimensional context for each measurement.

If dimension tables are wide, fact tables are deep. The compact nature of fact table rows enables the table to accumulate a large number of rows without generating inordinate storage requirements.

 

To be continued...