Distributed Database Management Systems: Lecture 1

In the name of 
Allah
Virtual University of Pakistan


Distributed Database
Management Systems
Lecture - 01
Virtual University of Pakistan

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References
1­Distributed Database Systems (2nd 
Edition) by T.M., Ozsu, P. Valdusiez

2­ Distributed Database Systems. 
By D. Bell, J. Grimson, Addison­
Wesley, 1992 

 
  

Virtual University of Pakistan

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References
3­ Distributed Systems: Concepts and   

Design, 4th Edition,  by G. Coulouris, 
J. Dollimore, T. Kindberg, Addison­
Wesley
Prerequisites: Database Management 
Systems, Computer Networks 
Virtual University of Pakistan

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Course of Course
Introduction to database and Distributed 
Systems in general
Architectures and Design Issues of 
DDBS
Technological Treatment
Theoretical Aspects of the topic
Virtual University of Pakistan

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Little bit of History
Traditional File Processing 
System: the very first form of 
business data processing 
Each program contains data 
description that it manipulates
Redundancy of data
Problems in maintenance

Virtual University of Pakistan

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Examination

Registration

Library
Applications

Examination
Applications

Registration
Applications

Library
Data
Files

Examination
Data
Files

Registration
Data
Files

Library

Program and Data Interdependence
Virtual University of Pakistan

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File Processing Systems
Library

Exam

Registration

Reg_Number

Reg_Number

Reg_Number

Name

Name

Name

Father Name

Address

Father Name

Books Issued

Class

Phone

Fine

Semester

Address

Grade

Class

Duplication of Data
Vulnerable to Inconsistency
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History continues
  Database Approach: (Also called 
centralized database) Database is a 
shared collection of logically related 

data

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Database Approach
PROGRAM 1
PROGRAM 2
PROGRAM 3

Data
Description
Data
Manipulation

Database

….

Takes care of all major drawbacks of File
System Environment plus more
Virtual University of Pakistan

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Distributed Computing System
A number of autonomous processing 

elements that are connected through a 
computer network and that cooperate 
in performing their assigned tasks

Virtual University of Pakistan

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Distributed Computing Systems
Distributed System Software enables 
computers to coordinate and share 
The thing being distributed?
– Processing logic
– Functions
– Data
– Control; All are relevant and important here
Virtual University of Pakistan

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Classifications of DCS
Degree of Coupling
– How closely systems are connected
– May be the measured as ratio of 
messages interchanged to the local 
processing
– Could be Weak (over the network) or 
Strong (if components are shared)

Virtual University of Pakistan

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Classifications of DCS
Interconnection structure
– Could be point to point or a common 
interconnection channel

Interdependence of Components
Synchronization
Factors are not totally independent 
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Why DCS?
Suits some of the Organizational 
Structures; more reliable and 
responsive
Nature of some applications
Technological Push
Virtual University of Pakistan

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DCS’s Alerts

Information Islands and Lack of 
Standards
Difficulties in Large Application 
Design
Too Many Options Available
Virtual University of Pakistan

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