Data Warehouse Design - Bill Inmon Vs Ralph Kimball Approach

The two common approaches to design a Data Warehouse are the approaches introduced by Bill Inmon and Ralph Kimball. We often discuss as to which method is the best approach to design the data warehouse databases. But a clear cut answer has never been arrived upon, as both philosophies have their own advantages and differentiating factors, and enterprises continue to use either of these.

Inmon's Approach :-

Bill Inmon’s enterprise data warehouse approach is the Top-Down design approach. According to him, the data warehouse should operate in a relational format and store all of the organization’s atomized data. Once the data warehouse is fully designed and put in place, only then can small data marts be added for different departments to query data from the central data warehouse and store it in various dimensions & facts.

Inmon's Approach

Inmon defines the data warehouse in the following terms:

1. Subject-oriented: The data in the data warehouse is organized so that all the data elements relating to the same real-world event or object are linked together

2. Time-variant: The changes to the data in the database are tracked and recorded so that reports can be produced showing changes over time

3. Non-volatile: Data in the data warehouse is never over-written or deleted -- once committed, the data is static, read-only, and retained for future reporting

4. Integrated: The database contains data from most or all of an organization's operational applications, and that this data is made consistent

Kimball's Approach :-

Ralph Kimball’s dimensional design approach is the Bottom-Up Approach. Kimball suggests suggests that an organization should first build small data marts for each department. The data marts should contain facts and dimensions relevant to the business area and store them in a star or snowflake schema. As Kimball's approach  is concerned, the data warehouse is essentially a union of all the data marts.

Kimball's Approach

Inmon Vs Kimball Approach :-

Pros & Cons :-

Inmon Vs Kimball Approach for various Sectors :-

• Insurance: It is vital to get the overall picture with respect to individual clients, groups, history of claims, mortality rate tendencies, demography, profitability of each plan and agents, etc. All aspects are inter-related and therefore suited for the Inmon’s approach.
• Marketing: This is a specialized division, which does not call for enterprise warehouse. Only data marts are required. Hence, Kimball’s approach is an ideal approach.
• CRM in banks: The focus is on parameters such as products sold, up-sell and cross-sell at a customer-level. It is not necessary to get an overall picture of the business. You can go for Kimball’s method. However, if the entire processes and divisions in the bank are to be linked, the obvious choice is Inmon’s design vs. Kimball’s.
• Manufacturing:  Inmon’s method is ideal as multiple functions are involved in the manufacturing industries.