This Design Tip describes how to create and manage mini-dimensions. Recall that a mini-dimension is a subset of attributes from a large dimension that tend to change rapidly, causing the dimension to grow excessively if changes were tracked using the Type 2 technique. By extracting unique combinations of these attribute values into a separate dimension, […]
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People often engage us to conduct dimensional model design reviews. In this column, I’ll provide a laundry list of common design flaws to scout for when performing a review. I encourage you to use this list to critically review your own draft schemas in search of potential improvements. What’s the Grain? When a data warehouse team […]
The Kimball Group has been exposed to hundreds of successful data warehouses. Careful study of these successes has revealed a set of extract, transformation, and load (ETL) best practices. We first described these best practices in an Intelligent Enterprise column three years ago. Since then we have continued to refine the practices based on client […]
Wiley, 2013 Tools and Utilities NOTE: You may need to “Save Link As” to download the files. Chapter 3 Sample date dimension spreadsheet Download Correction to Figure 3-13: The first heading in the lower report shown in Figure 3-13 should read “Calendar Week Ending Date,” just like the top report in that figure. Correction to […]
According to the Webster’s Unabridged Dictionary, a surrogate is an “artificial or synthetic product that is used as a substitute for a natural product.” Thatýs a great definition for the surrogate keys we use in data warehouses. A surrogate key is an artificial or synthetic key that is used as a substitute for a natural […]
In the dimensional modeling world, we try very hard to separate data into two contrasting camps: numerical measurements that we put into fact tables, and textual descriptors that we put into dimension tables as “attributes”. If only life were that easy… Remember that numerical facts usually have an implicit time series of observations, and usually participate in numerical […]
This Design Tip continues my series on implementing common ETL design patterns. These techniques should prove valuable to all ETL system developers, and, we hope, provide some product feature guidance for ETL software companies as well. Recall that a shrunken dimension is a subset of a dimension’s attributes that apply to a higher level of […]