The owner of the data warehouse must decide how to respond to the changes in the descriptions of dimensional entities like Employee, Customer, Product, Supplier, Location and others. In 30 years of studying this issue, I have found that only three different kinds of responses are needed. I call these slowly changing dimension (SCD) Types […]

Students often blur the concepts of snowflakes, outriggers, and bridges. In this Design Tip, I’ll try to reduce the confusion surrounding these embellishments to the standard dimensional model. When a dimension table is snowflaked, the redundant many-to-one attributes are removed into separate dimension tables. For example, instead of collapsing hierarchical rollups such as brand and category into columns […]