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The Soul of the Data Warehouse, Part 1: Drilling Down
Although data warehouses come in many shapes and sizes and deal with many different subject areas, every data warehouse must embody a few fundamental themes. The three most important are drilling...
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The Soul of the Data Warehouse, Part 2: Drilling Across
The three fundamental themes that make up the soul of every data warehouse are drilling down, drilling across, and handling time. In Part One of “The Soul of the Data Warehouse,” I showed that...
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Fables and Facts
Do you know the difference between dimensional modeling truth and fiction? According to Merriam-Webster, fables are fictitious statements. Unfortunately, fables about dimensional modeling circulate...
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Design Tip #107 Using the SQL MERGE Statement for Slowly Changing Dimension...
Most ETL tools provide some functionality for handling slowly changing dimensions. Every so often, when the tool isn’t performing as needed, the ETL developer will use the database to identify new and...
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The 10 Essential Rules of Dimensional Modeling
A student attending one of Kimball Group’s recent onsite dimensional modeling classes asked me for a list of “Kimball’s Commandments” for dimensional modeling. We’ll refrain from using religious...
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Industry Standard Data Models Fall Short
Industry-standard data models are an appealing concept at first blush, but they aren’t the time savers they are cracked up to be. What’s more, these prebuilt models may inhibit data warehouse project...
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Design Tip #128 Selecting Default Values for Nulls
Design Tip #43 Dealing with Nulls in the Dimensional Model describes two cases where null values should be avoided in a dimensional model; in these situations, we recommend using default values rather...
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Design Tip #156 An Excel Macro for Drilling Across
Drilling across separate business processes is one of the most powerful applications in a data warehouse. We often describe drilling across as magic: separately open connections to the dimensional...
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Design Tip #168 What’s in a Name?
It seems like a small thing, but names are important. Good names for tables and columns are particularly important for ad hoc users of the DW/BI system who need to find the objects they’re looking...
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Design Tip #176 Dimensional Models – Logical or Physical?
Dimensional data models have been around for a very long time, almost certainly tracing their lineage back to the original Data Cube project between Dartmouth and General Mills in the late 1960s. The...
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