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DMBoK Figure 40 Axis Notation for Dimensional Models

The concept of dimensional modeling started from a joint research project conducted by General Mills and Dartmouth College in the 1960's. In dimensional models, data is structured to optimize the query and analysis of large amounts of data. In contrast, operational systems that support transaction processing are optimized for fast processing of individual transactions.


Dimensional data models capture business questions focused on a particular business process. The process being measured on this dimensional model is Admissions. Admissions can be viewed by the Zone the student is from, School Name, Semester, and whether the student is receiving financial aid. Navigation can be made from Zone up to Region and Country, from Semester up to Year, and from School Name up to School Level.


The diagramming notation used to build this model - the 'axis notation' - can be a very effective communication tool with those who prefer not to read traditional data modeling syntax.


Both the relational and dimensional conceptual data models can be based on the same business processes (as in this example with Admissions). The difference is in the meaning of the relationships, where on the relational model the relationship lines capture business rules, and on the dimensional model, they capture the navigation paths needed to answer business questions.

DAMA Data Management Body of Knowledge 2nd Edition, 2017, Print.

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