The acronym, SCD, is a keyword in a dimensional modeler’s vernacular. As most of you know, SCD is short-hand for slowly changing dimensions. There are several well-documented techniques for dealing with slowly changing dimension attributes. Briefly, with SCD Type 1, the attribute value is overwritten with the new value, obliterating the historical attribute values. For example, when the […]

By Margy Ross and Bob Becker During the past year, we’ve repeatedly observed a pattern with maturing data warehouses. Despite significant effort and investment, some data warehouses have fallen off course. Project teams (or their user communities) are dissatisfied with the warehouse deliverables – the data’s too confusing, it’s not consistent, queries are too slow, etc. Teams have […]

One of the most prevalent fallacies in our industry is that data marts are defined by business department. We’ve seen countless data warehouse architecture diagrams with boxes labeled “Marketing Data Mart,” “Sales Data Mart,” and “Finance Data Mart.” After reviewing business requirements from these departments, you’d inevitably learn that all three organizations want the same core information, such as […]