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Modeling and Querying Multidimensional
Databases: an Overview by Patrick Marcel
Presented By: Amani Al-Ajlan Asma Al-Saleh
King Saud UniversityThe College of Computer & Information Science
Computer Science Department
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Outlines
• Multidimensional Database query2
• Introduction
• Multidimensional DB VS Relational DB
• On-Line Analytical Processing (OLAP)
• Multidimensional Database modeling
• Multidimensional Database operations
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Outlines
• Multidimensional Database query3
• Introduction
• Multidimensional DB VS Relational DB
• On-Line Analytical Processing (OLAP)
• Multidimensional Database modeling
• Multidimensional Database operations
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• MDD is a database designed to allow efficient storageand retrieval of large volumes of data that is viewed andanalyzed from different perspectives.
• Use when the objective is to analyze data rather than toperform online transactions.
• MDD is a key factor in the interactive analysis of large
amounts of data for decision-making purposes.
Introduction
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Outlines
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• Introduction
• Multidimensional DB VS Relational DB
• On-Line Analytical Processing (OLAP)
• Multidimensional Database modeling
• Multidimensional Database operations
• Multidimensional Database query
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Multidimensional DB VS Relational DB
Relational DB MDD
Many different tables all linkedand joined together in a variety
of ways
Not good at retrieving a largenumber of records and
summarizing them on the fly
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Structured in specificdimensions, not tables
Many relationships areprecalculated, this greatly
speeds response andcomputation time
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Multidimensional DB VS Relational DB
Region Time
Product
Answer Answer
Multidimensional DBRelational DB
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Multidimensional DB VS Relational DB
Sales 1996(Relational)
Sales 1996(2-dimintional)
Simple Example:
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MDD Advantages
1. Fast retrieval
2. Fast calculation
3. Storage is very efficient
4. Fast query response time
5. Ease of Data Presentation and Navigation
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MDD Limitations
1. This research area is very recent, and several workshave appeared, but no commonly agreed frameworkhas emerged
2. Not used in one-to-one relationship
1
3
2
4 M a n
a g e r
Department
1 40
80 50
59 33
90 50 4
Region
P r o
d u c
t
10(One-to-One) (Many-to-Many)
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Outlines
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• Introduction
• Multidimensional DB VS Relational DB
• On-Line Analytical Processing (OLAP)
• Multidimensional Database modeling
• Multidimensional Database operations
• Multidimensional Database query
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• Is an approach to quickly providinganswers to analytical queries that are
multidimensional in nature
Online Analytical Processing(OLAP)
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Outlines
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• Introduction
• Multidimensional DB VS Relational DB
• On-Line Analytical Processing (OLAP)
• Multidimensional Database modeling
• Multidimensional Database operations
• Multidimensional Database query
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Database Modeling Categories:
1. Two-dimensional databases
2. Full multidimensional (hypercube) models
3. Multidimensional models based on relations
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2.Full multidimensional(hypercube) models
cells
measure
dimens ion
members
The cube sales
F sales (1994,nuts,north) = 10
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Example:
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3.Multidimensional models based on relations
Example:
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Dimension
Relations
Measure
Relation
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Dimension Hierarchy
• Organizing the information into a hierarchy, to be able to examine it at different levels of detail
• Levels are described by a graph that indicatehow members of some level are grouped
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Example:
Dimension Hierarchy
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Example Cont.: Sale result can be viewed at region level or at cities
level.
Region level Cities level
Dimension Hierarchy Cont.
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• Group ing relat ion : used to model part of the hierarchies associated with the cube sales . It represents how citiesare grouped to form regions.
•
this relation can be used to compute the cube sales fromthe cube sales cities
Dimension Hierarchy Cont.
(Grouping relation)
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