Dimensions

• Dimension is a collection of reference information about a measurable event. 
• Dimensions categorize and describe data warehouse facts and measures in ways that support meaningful answers to business questions.  They form the very core of dimensional modeling.  

A data warehouse organizes descriptive attributes as columns in dimension tables. 

A dimension table has a primary key column that uniquely identifies each dimension record (row).  The dimension table is associated with a fact table using this key.  Data in the fact table can be filtered and grouped (“sliced and diced”) by various combinations of attributes.