Data warehouse consist of both dimensions and measures.
Dimensions are descriptive details about various objects allowing for their detailed analysis. For example time dimension allows us to see object with respect to year, quarter, month, day and hour. And customer dimensions helps in analyzing the customer who affects the business more.
Measures unlike dimensions give the fact numeric value instead of the detailed analysis.
Different type of measures are listed below:
- Additive measures are measures that can be added across all dimensions. For example customer count in numbers can be added across all dimensions.
- Semi-additive measures are measures that can be added across some, but not all dimensions. For example the bank account balance is simply a snapshot in time and cannot be added over time. However you could add multiple accounts of the same customer to get the total balance for that customer.
- Non-additive measures are measures that cannot be added across any dimensions. For example the procurement is simply a snapshot in time and cannot be summed over time. Also you cannot combine procurement for various items.