Besides the time dimension, Slowly Changing Dimension (SCD) is the most common kind of dimension used. SCD are dimensions where changes may occur from time to time. Typical examples of SCD are regions, customers, and products.
Suppose that you have a dimension with products. It may happen that the description of a product changes. If you don't care about the old description and, in your dimension, you just overwrite the attribute with the new description, then your product dimension is called a Type I SCD.
In general, if you don't preserve historical values when you update an SCD dimension, the dimension is called Type I slowly changing dimension (Type I SCD).
The next tutorial explains ...
