One of my favourite presentation themes is talking about gotchas, blunders and mistakes. Not because I like to focus on the negative, but because there are some wonderful resources out there telling modelers how to model, and so few out there telling us what NOT to do based on lessons learned.
In this slide deck, I focus on physical modeling gotchas based on my reviews of hundreds of great data models that just missed the marks in a few places.
See also: The Three Types of Data Model: Conceptual, Logical and Physical
I also talk about some the process mis-steps that happen.
What other data modeling glitches have you seen? Leave your stories in comments below.