Fan Traps and Chasm Traps

posted by Mark @ 5:19pm, Thursday 4 February 2010.

Introduction

Ok, hopefully anyone working in the realm of MIS and BI should have an understanding of what a Fan Trap and Chasm Trap is, unfortunately I suspect that there are a lot of professionals who don’t... or do they?

There are various sources (specifically on the net) that seem to provide only very brief explanations, often leading to an ambiguous understanding based on a very specific scenario.

In my experience the areas that make the most reference to Relationship Traps are ER Modelling and Business Objects Universe Design.

This means that if you have never designed a Business Objects Universes or had any formal training in ER Modelling you may never have come across the terms, except perhaps in passing.

What’s so important about them?

In ER and Data Modelling, you need to be aware of Relationship traps primarily so that you can avoid them in your design in the first place.

I suspect that most professionals in that sort of role already resolve the Traps at design, without actually recognising them as either Fan or Chasm Traps, especially the Chasm Traps (for reasons that will become obvious in my Chasm Trap article).

In Business Objects Universe design, not being aware of the traps could lead to significant statistical errors in the reports based on them, especially if those responsible for the report creation assume the Universes are correct.

Overall, in any situation where data is extracted from a Relational database to gather meaningful information, not being aware of the Traps can cause significant issues.

I work with Relational Databases and have never heard of them?

I suspect that anyone that hand codes SQL to extract information from a Relational Database is probably already aware of the pitfalls of the traps, and how to work around them... you just don’t know them by that name.

This may sound odd, but Fan Traps and Chasm Traps are just putting a name to a problem. That problem existed before it got given a name, so you may well have experienced and addressed, and continue to address the problem yourself, without actually giving it a name.

So what next and why do I need to know?

As I pointed out above, you may already be aware of the Traps and be resolving them as you come across them, however ideally you would know and understand them for what they are and actively look to resolve them while designing databases and producing meaningful information from that data.

You can read my Article on Fan Traps here: Fan Traps

You can read my Article on Chasm Traps here: coming soon

Below is a list of sites I found 'useful' information on the traps from: