Slowly Changing Dimensions

Submitted by dave on Fri, 05/17/2013 - 13:29

Slowly Changing Dimensions
This is a concept I have encountered in many systems in slightly different forms but never had a name to tie the concept together. I now know that there are techniques to handle Slowly Changing Dimensions to keep track of data that changes infrequently.
Over time the a list of current Countries in the world can change. A person can change their name or they can change positions in the company. It is often important to be able to determine a valid set of data at a point in time. SCDs allow tracking of the original, intermediate, and current values so as data becomes obsolete is is made inactive but never deleted.

Here are some relevant articles:
Ralph Kimball on Slowly Changing Dimensions (part 1)
Ralph Kimball on Slowly Changing Dimensions (part 2)
Wikipedia: Slowly Changing Dimensions
LearnDataModeling.com One-Page on SCDs