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ID #1047

What is star schema grouping?

A star schema grouping is an arrangement of database tables where you have a fact table in "the center", and many dimension tables linking directly to it. For example, a student-course-load fact table might be measured by dimensions such as semester, date, department, student home state, and so on.

The tricky part comes when you have several different fact tables that share dimensions. For example your student-course-load fact and your grades fact, plus even your student-head-count fact, can all be measured by semester and by department.

The main thing is to make sure you roll up your summaries to the same level of granularity. That is, if you're summarizing head-count by division, then you should also roll up course-load by division, in the same query. Otherwise you'll be double-counting all kinds of stuff.

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Last update: 2010-11-16 07:54
Author: will trillich
Revision: 1.2

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