Inmon and Kimball Approach for Data Models

Bill Inmon supports the Top-Down approach for data warehouse design whereas, Ralph Kimball supports Bottom-Up design. Now let us discuss what each are in detail, but before that it is important to answer the following questions before starting the design of a warehouse-

• Do we need a Top-Down/Bottom-Up approach for our warehouse?
• Should the warehouse be enterprise wide or be departmental?
• What do we create first- Data Mart or the Data Warehouse?
• Should we capture dependent data marts/independent marts?

Whenever a large data warehouse is channeled to small data marts then it’s a Top-Down approach as here the data repository feeds into the local, departmental marts. However, when we have data marts created first and then consolidating them into a repository then it’s called the Bottom-Up approach.

Few Characteristics of both-

Bill Inmon’s Top-Down Approach

1. Has an enterprise wide view of data.
2. Is inherently architected.
3. Has a single, central data storage
4. Has centralized rules and control
5. Gives quick results if implemented with iterations
6. Takes quite a long time to build
7. Has a high risk of failure

Ralph Kimball’s Bottom-Up

1. Has a fast and easy implementation of manageable pieces
2. Has a very less failure risk
3. Id inherently incremented
4. Each data mart has its own narrow view of data
5. Allows redundant data
6. Has inconsistent data
7. Has unmanageable interface
8. But, most severe drawback is Data Fragmentation