Challenge III - Changing Sites
One of the hardest problems is dealing with changing sites - all our I.I.D assumptions do not hold!
It is very easy to change personalization rules (cross-sells/up-sells), images shown, messages, etc
Sites changes their registration forms
New products are introduced, old ones are deleted (especially with perishable products such as wines) or change attributes
How do we deal with slowly changing dimensions? (or quickly changing?)