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Dimensional data modelling

Data Warehouse Dimensional Modelling

When designing a new data warehouse it's vital to firstly determine the overall architecture and approach that will be used.

Ralph Kimball Bill Inmon

There are two primary schools of thought for data warehouse theory;
Ralph Kimball and Bill Inmon.

 

The details of each are very often misunderstood. Kimball is often referred to as advocating a 'Bottom Up' denormalised approach with Inmon recommending a 'Top Down' normalised method. Although largely inaccurate, this is a generalisation that most people are content with.

 

Kimball or Inmon?

The Purple Frog team have designed many data warehouses over the years using both design methodologies, in fact a large number of our solutions take elements from both, being combined into the most suitable model for the problem at hand.

We pride ourselves on being experts in both schools, not just through real-world experience, but with some of our consultants having even studied data warehouse architecture theory at MSc level, and indeed delivered our own training seminars on the subject.

Despite having a foot in both camps, our focus for most data warehouse projects is based primarily in Kimball design methodology, modelling the core warehouse as a series of dimensional star schemas.

In our experience one of the biggest cause of data warehouse project failure is not the technical implementation, budget or poor project management, but a lack of adoption throughout the business. In almost all cases this is because users find the information difficult to retrieve. This comes down to one cause; bad dimensional modelling.

Data Warehouse Dimensional ModellingDesigning a star schema data model is not simply about denormalising data from the source system. The main focus must be remodelling the data so that it fundamentally mirrors how business users perceive the organisation. Only then will users be able to easily get answers to their questions.

The only way to ensure a good data model is for the designer to understand the business. Our job as data warehouse consultants is not simply to design a data warehouse, but to make sure that what we design is right for your organisation. We will spend time with your users and management, learning what they do and how they do it in order to create a Kimball dimensional model that truly represents your company.

With our wide diversity of industry experience the chances are we'll already have the necessary understanding of your industry processes and terminology, we'll make sure that we go deeper than this and understand your individual processes and staff.