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What are the pros and cons of including non-foreign key attributes in fact tables that are not metrics?

Question: What are the pros and cons (technical and business) of including non-foreign key attributes in fact tables that are not metrics?

 

Chuck Kelley’s Answer:  Generally, I would not do it with a couple exceptions (and not always then): 

  1. A single dimension has the same cardinality as the fact, and
  2. Dates columns that may or may not be present at the time the fact was originally created.
For example, if I were a company that shipped items, I might wish to understand how long things take to be delivered by different carriers. I would not want to wait until notification that the package was delivered before loading that in the data warehouse. Hence, I may create a fact row that has shipped date and received date.

Chuck Kelley is an internationally known expert in database and data warehousing technology. He has 30 years of experience in designing and implementing operational/production systems and data warehouses. Kelley has worked in some facet of the design and implementation phase of more than 50 data warehouses and data marts. He also teaches seminars, co-authored four books on data warehousing and has been published in many trade magazines on database technology, data warehousing and enterprise data strategies. He can be contacted at chuckkelley@usa.net.

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