1. Paper Presentation Prepared by Dindar Öz
‘‘Research Problems in Data Warehousing,, Jennifer Widom Department of Computer Science Stanford University
Paper Presentation
Prepared by Dindar Öz

2. What is Datawarehousing?
The collection of architecture , algorithms and tools for bringing together selected data from multiple databases or other information sources into single repository
which is called “data warehouse”

3. Why do we need Datawarehousing?

4. Our business challenges
Decisions need to be made quickly.
Users are businessman not computer experts.
Fast increase in database sizes.
Increasing importance of business intelligence,and strategy.(Decision Support)

5. What does Datawarehousing offer?
Locating the right information
Presentation of information (reports ,graphs)
Testing of hypothesis
Discovery of information
Sharing the analysis

6. Architecture

7. Main Components
Wrapper
Integrator
Information Sources
Data Warehouse

8. Main Approaches Lazy(on-demand) Approach Eager(in-advance) Approach
Traditional approach
Eager(in-advance) Approach
Actually this is datawarehousing.

9. Lazy Approach When Rapidly changing data Requirement of recent data
Unpredictable query requests
Large number of information sources

10. Eager Approach When... Query range specified and predictable
Requirement of fast data
Information sources are busy(Do not want to be interrupted by DW users too often)
Private copies of the clients needed.

11. Research Problems Related with... Wrapper Monitor Integrator
Warehouse Specification
Optimization

12. Research Problems/Wrapper
Translation
Translating the structure of information sources to that
of datawarehouse
Change Detection ***
Monitoring the Information Sources for changes.

13. Change Detection Strategies
Periodic Full-copy propagation. (Offline)
Cooperative Sources (Triggers ,Active Database)
Logged Sources (Log Analysis)
Queryable Sources (Query Polling)
Snapshot Sources (Comparison of Snapshots)

14. Research Problems/Integrator
View Maintenance
- Information sources do not care view maintenance.Integrator are loosely coupled with I.S.s
- Some of the warehouse views can not be supported by base sources such as historical view of a certain data.

15. Some Optimizations Update Filtering Self-Maintainability
Multiple View Optimization

16. Conclusion
Datawarehousing is an indispensible technology and a research area for its numerous benefits.
There still open research problems related with Datawarehousing.

17. Any Question?

18. Thank You!