One of the basic concepts that makes Business Intelligence work so well is the separation of data into facts (what is being analyzed) and dimensions (how it is analyzed) and organizing those facts and dimensions into a Star Schema. An illustration from my book ‘Business Intelligence Team Handbook’ shows how tables are organized into a star shape.
Star Schema
In this case, you can see how the Sales table is used as the fact table. I was explaining the concept of how dimension tables could be re-used in association with a variety of fact tables to build multiple star schemas. Many of the same dimensions referenced in the star schema above could be used with an Inventory fact table or perhaps with a Foreclosure fact table.
It occurred to me that the resulting design would be a ‘Constellation Schema’. This phrase creates a great mental image of how a Business Intelligence database is organized. It’s more complex than a Star Schema. It’s clearly NOT a Snowflake Schema (thank goodness). It’s a collection of stars.
This is one term that I’m adding to my vocabulary!
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