Expert modelers always follow these rules:
- Avoid wide tables. Smaller is better.
- Use a star schema. Always.
- Do not use bidirectional relationship unless you have a strong reason to use it.
- Hide all the columns in the fact table. Only show measures in the fact table.
- Expose visible attributes only through dimensions.
- Test your formulas on small sets of data that you can master and understand at a glance.
Expert modelers may decide to override the rules, but they do so with a deep and thorough understanding of what they are dealing with. Inexperienced modelers oftentimes choose to avoid rules. Doing so is exciting, if you want to feel the thrill of wandering into a totally unexplored and dangerous maze of complexity. On the other hand, if you want to deploy a sound model for your customers, then obeying these simple rules is a very good step in the right direction.
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