Does the sum of data marts equal to a data warehouse?

1. Does the sum of data marts equal to a data warehouse?

2. I will look at! • Define Data Marts and Data Warehouses • Bill Inmon vs. Ralph Kimball • Structures • Problems with Data Marts

3. Data Marts • A data mart is a repository of data gathered from operational data and other sources that is designed to serve a particular community of knowledge workers.

4. Data Warehouses • A data warehouse is a database geared towards the business intelligence requirements of an organisation. The data warehouse integrates data from the various operational systems and is typically loaded from these systems at regular intervals.

5. Bill Inmon vs. Ralph Kimball • Bill Inmon's paradigm: • One part of the overall business intelligence system • Data marts source their information from the data warehouse • 3rd normal form • Ralph Kimball's paradigm: • Conglomerate of all data marts within the enterprise • dimensional model

6. "...The data warehouse is nothing more than the union of all the data marts...," Ralph Kimball, December 29, 1997.

7. "You can catch all the minnows in the ocean and stack them together and they still do not make a whale," Bill Inmon, January 8, 1998.

9. Departmental • High level of granularity • Star-join structure • Modest amount of historical data • Technology optimal for access and analysis • Each department has a different structure • Highly indexed • Corporate • Lowest level of granularity • Normalized structure • Robust amount of historical data • Technology optimal for holding, managing massive volumes of data • Structure suits corporate understanding of data • Lightly indexed Data Marts Data Warehouses

10. Redundant Data Redundant Data Redundant Data Redundant Data Redundant Data Redundant Data Redundant Data Redundant Data Redundant Data Redundant Data

11. More Problems in Data Marts • No consensus of opinion •  Management is confused • How do you make a decision?? • Is the benefit of building a bunch of data marts a fallacy?

12. More Problems in Data Marts Contd. • A small army of programmers are required • Customized interface • Never ending growth of staff • Interface program has its own unique interpretation of data so that there is no consistency whatsoever in the data that resides in the different data marts.

13. Department's spend money for their needs • Only immediate department needs! • Money on many data marts! • Never turn into a data warehouse • Cost a lot more in the long run

14. Data Warehouse • Data warehouse entails integration • Single point of truth at a granular level  • Atomic, corporate data can be integrated • Represents the corporation, not a department or a subdivision of the corporation

15. In Conclusion • Major , differences between the data mart and the data warehouse • ‘Saying that when a tumbleweed grows large enough that it can be turned into an oak tree’ • Data Mart = $$$$$$$ & Confusion • Data Mart ≠ Data Warehouses

16. ‘When it comes to data mart vendors that tell you that a data mart can be magically turned into a corporate data warehouse, caveat emptor. Only in fairy tales can sows ears be turned into silk purses’ Does the sum of data marts equal to a data warehouse? The sum of data marts is not equal to a data warehouse? Questions