Common Dimensional Modeling Mistakes to Avoid
As we close this final chapter on dimensional modeling techniques, we thought it would be helpful to establish boundaries beyond which designers should not go. Thus far in this book, we’ve presented concepts by positively stating dimensional modeling best practices. Now rather than reiterating the to-dos, we focus on not-to-dos by elaborating on dimensional modeling techniques that should be avoided. We’ve listed the not-to-dos in reverse order of importance; be aware, however, that even the less important mistakes can seriously compromise your DW/BI system.
Mistake 10: Place Text Attributes in a Fact Table
The process of creating a dimensional model is always a kind of triage. The numeric measurements delivered from an operational business process source belong in the fact table. The descriptive textual attributes comprising the context of the measurements go in dimension tables. In nearly every case, if an attribute is used...