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Copyright © 2004 Pearson Education, Inc.
Chapter 25
Distributed Databases
and Client-Server
Architectures
Copyright © 2004 Pearson Education, Inc.
FIGURE 25.1
Some different database system architectures. (a) Shared
nothing architecture.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-3
FIGURE 25.1 (continued)
Some different database system architectures. (b) A
networked architecture with a centralized database at one of
the sites.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-4
FIGURE 25.1 (continued)
Some different database system architectures. (c) A truly
distributed database architecture.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-5
FIGURE 25.2
Data distribution and replication among distributed
databases.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-6
FIGURE 25.3
Allocation of fragments to sites. (a) Relation fragments at site
2 corresponding to department 5.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-7
FIGURE 25.3 (continued)
Allocation of fragments to sites. (b) Relation fragments at site
3 corresponding to department 4.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-8
FIGURE 25.4
Complete and disjoint fragments of the WORKS_ON
relation. (a) Fragments of WORKS_ON for employees working in department
5 (C=[ESSN IN (SELECT SSN FROM EMPLOYEE WHERE DNO=5)]).
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-9
FIGURE 25.4 (continued)
Complete and disjoint fragments of the WORKS_ON
relation. (b) Fragments of WORKS_ON for employees working in department
4 (C=[ESSN IN (SELECT SSN FROM EMPLOYEE WHERE DNO=4)]).
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-10
FIGURE 25.4 (continued)
Complete and disjoint fragments of the WORKS_ON
relation. (c) Fragments of WORKS_ON for employees working in department
1 (C=[ESSN IN (SELECT SSN FROM EMPLOYEE WHERE DNO=1)]).
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-11
FIGURE 25.5
The five-level
schema
architecture in a
federated
database system
(FDBS). Source:
Adapted from Sheth
and Larson, Federated
Database Systems for
Managing Distributed
Heterogeneous
Autonomous
Databases. ACM
Computing Surveys
(Vol. 22: No. 3,
September 1990).
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-12
FIGURE 25.6
Examples to illustrate volume of data transferred.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-13
FIGURE 25.7
Guard conditions and attributes lists for fragments. (a) Site 2
fragments.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-14
FIGURE 25.7 (continued)
Guard conditions and attributes lists for fragments. (b) Site 3
fragments.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-15
FIGURE 25.8
The three-tier client-server architecture.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-16
FIGURE 25.9
Oracle distributed
database systems.
Source: From Oracle
(1997a). Copyright  Oracle
Corporation 1997. All rights
reserved.
Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition
Copyright © 2004 Pearson Education, Inc.
Slide 25-17