Distributed Database Management Systems: Lecture 3
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Distributed database
Management Systems
Lecture 03
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Resembling Setups
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Distributed Files: A collection of files
stored on different computers of a
network; not a DDBS
DDBS is logically related, common
structure among files, and accessed via
same interface
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3
Resembling Setups
Multiprocessor System: multiple
processors that share some form of
memory Processor Processor Processor
Unit
Unit
Unit
Memory
Shared Everything
Tight Coupling
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I/O System
4
Resembling Setups
Computer
System
Computer
System
Computer
System
CPU
CPU
CPU
Memory
Memory
Memory
Shared Everything
Loose Coupling
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Shared
Secondary
Memory
5
Resembling Setups
Computer
System
Computer
System
Computer
System
CPU
CPU
CPU
Memory
Memory
Memory
Switch
Shared Nothing
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6
Resembling Setups
DDBS is also different from a
centralized system having C/S
system involving network
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7
Reasons for DDBS
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Local units want control over data.
Consolidate data for integrated
decisions
Reduce telecommunication costs.
Reduce the risk of
telecommunication failures.
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9
Global User
Local User
Global User
Distributed DBMS
Global
Schema
Node 1
Node n
DBMS 1
DBMS 1
• • • •
DBMS n
Local User
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10
Promises of DDBSs
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Transparency
User View
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System View
12
Data Independence
Two types, Logical Data
Independence and Physical Data
Independence
A transparent system hides the
implementation details from its
users
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13
Network Transparency
User should not only be free from
network management activities rather
it should be unaware of even
existence of the network
Location Transparency and Naming
Transparency
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14
Thanks
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