Basic Concept Of Data WareHause

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Chapter 11:
Chapter 11:
Data Warehousing
Data Warehousing
Chapter 11
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2
Objectives
Objectives
Denition of terms
Denition of terms
Reasons for information gap between
Reasons for information gap between
information needs and availability
information needs and availability
Reasons for need of data warehousing
Reasons for need of data warehousing
Describe three levels of data warehouse
Describe three levels of data warehouse
architectures
architectures
Describe two components of star schema
Describe two components of star schema
Estimate fact table size
Estimate fact table size
Design a data mart
Design a data mart
Develop requirements for a data mart
Develop requirements for a data mart
Chapter 11
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3
Basic Concept
Basic Concept
Data Warehouse
Data Warehouse
:
:
A subject-oriented, integrated, time-variant, non-
A subject-oriented, integrated, time-variant, non-
updatable collection of data used in support of
updatable collection of data used in support of
management decision-making processes
management decision-making processes
Subject-oriented:
Subject-oriented:
e.g. customers, patients,
e.g. customers, patients,
students, products
students, products
Integrated:
Integrated:
Consistent naming conventions, formats,
Consistent naming conventions, formats,
encoding structures; from multiple data sources
encoding structures; from multiple data sources
Time-variant:
Time-variant:
Can study trends and changes
Can study trends and changes
Non-updatable:
Non-updatable:
Read-only, periodically refreshed
Read-only, periodically refreshed
Data Mart
Data Mart
:
:
A data warehouse that is limited in scope
A data warehouse that is limited in scope
Chapter 11
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4
Need for Data Warehousing
Need for Data Warehousing
A busines requires an integrated, company-wide view of
A busines requires an integrated, company-wide view of
high-quality information (from disparate databases)
high-quality information (from disparate databases)
The Information Department must separate information
The Information Department must separate information
for operational systems in order to dramatically improve
for operational systems in order to dramatically improve
performance in managing company data
performance in managing company data
Table 11-1 – Comparison of Operational and Informational Systems
Chapter 11
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5
Need for a Company-Wide
Need for a Company-Wide
View
View
Inconsistent key structures
Inconsistent key structures
Synonyms
Synonyms
Free-form vs. structured elds
Free-form vs. structured elds
Inconsistent data values
Inconsistent data values
Missing data
Missing data
See gure 11-1 (next slide) for example
See gure 11-1 (next slide) for example
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