Wide fact table vs. multiple fact tables
Posted on 2008-06-24
I am currently developing a data warehouse for a telecom company.
We collect several different measures (100+) from the network elements on an hourly basis.
I'm wondering what the optimal data warehouse design would be:
1) Since all measures bear the same granularity (1 hour), and originate from similar network elements, it would make sense to put them all in the same fact table. I would therefore end up with a fact table composed of about 5 dimensions and 100+ fact fields. Does a 100+ field table sound like an acceptable design?
2) I could create several fact tables with each about 5 dimensions and each only a subset of the 100+ facts, grouped in a way likely to be queried by the end users. I would therefore have several fact tables with maximum 25 fact fields (which seems more reasonable?), but I would loose some flexibility in the sense that users could no longer query the data in ways that were unplanned or unexpected.
I would greatly appreciate any advice or comment or field experience with the 2 options proposed (or a 3rd alternative...).