Data Warehouse

Data Warehouse – Kimball and Inmon method

Data warehouse – Kimball or Inmon

Understanding the basics of 2 different approach in Data warehouse modeling:

HISTORY OF DATA WAREHOUSE:

  • In 1990 Inmon wrote a book “Building the Data Warehouse”
    • Inmon defines architecture for collection of disparate sources into detailed, time variant data store( The top down approach)
  • In 1996 Kimball wrote “The Data Warehouse Toolkit”
    • Kimball updates book and defines multiple databases called data-marts that are organized by business processes, but use Data bus architecture (The bottom-up approach)

Data Warehouse VS Data Mart:

  • A Data warehouse is a collection of Enterprise wide data across line of business and subject areas
    • Data is integrated using a massive database
    • Provides complete organizational view of the information needed to run the business
  • A Data mart provides departmental view of information specific and subject oriented
    • Build multiple data-marts using dimensional architecture
    • Provides Fact based information integrated with multiple dimensions


Inmon Model:

  • Bill Inmon: A data warehouse is a subject-oriented and the data in the database is organized with data elements relating and linking together.
    • Time-variant: The changes to the data in the database are tracked and recorded showing changes over time;
    • Non-volatile: Data in the database is never over-written or deleted – once committed, the data is static, read-only, but retained for future Database: The database contains data from all operational applications, and that this data is made consistent
    • The data warehouse should be designed from the top-down to include all corporate data. In this methodology, data marts are created only after the complete data warehouse has been created.

Kimball Model:

  • Ralph Kimball: A proponent of the dimensional modelling and approach to building data warehouse through data marts.
    • The data warehouse is nothing more than the union of all the data-marts,
    • Kimball indicates a bottom-up approach for data warehousing
    • Individual data marts are created providing views into the organizational data in chunks
    • Eventually an Enterprise Data warehouse is create by combining the data marts together using Bus architecture.


Inmon Model and Kimball Model (Diagram):


 


 

Inmon versus Kimball Model:



 

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