Appendix : Slowly Changing Dimensions

• Type I

• • Corrections / Updates
  • There is no history kept in dimensions, changes in source are updated in warehouse.

• Type II

• • Historical
  • Multiple “versions” of the customer are kept in the warehouse.
  • Example:
  • • Customer moves from WA  MA. Need to attribute one fact in WA and the other in MA but both from the same customer.

• Type III

• • Old and New Together
  • Typically used for change of classifications/rollups
  • Example:
  • • Reorganization of Sales Organization.
    • New Sales Territory: Pacific, Old Sales Territory: West