Research Problems in Data Warehousing,, Jennifer Widom Department of Computer Science Stanford Unive

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Research Problems in Data Warehousing,,Jennifer
WidomDepartment of Computer Science Stanford
University

• Paper Presentation
• Prepared by Dindar Öz

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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

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Why do we need Datawarehousing?
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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)

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What does Datawarehousing offer?

• Locating the right information
• Presentation of information (reports ,graphs)
• Testing of hypothesis
• Discovery of information
• Sharing the analysis

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Architecture
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Main Components

• Wrapper
• Integrator
• Information Sources
• Data Warehouse

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Main Approaches

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

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Lazy Approach

• When
• Rapidly changing data
• Requirement of recent data
• Unpredictable query requests
• Large number of information sources

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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.

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Research Problems

• Related with...
• Wrapper Monitor
• Integrator
• Warehouse Specification
• Optimization

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Research Problems/Wrapper

• Translation
• Translating the structure of information
  sources to that
• of datawarehouse
• Change Detection
• Monitoring the Information Sources for
  changes.

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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)

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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.

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Some Optimizations

• Update Filtering
• Self-Maintainability
• Multiple View Optimization

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Conclusion

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

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Any Question?
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Thank You!