Copyright © 2004 Pearson Education, Inc.

Chapter 25 Distributed Databases and Client-Server Architectures

Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition Copyright © 2004 Pearson Education, Inc. Slide 25-3 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 25-4 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 25-5 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 25-6 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 25-7 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 25-8 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 25-9 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 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 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 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 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 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 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 FIGURE 25.8 The three-tier client-server architecture.

Elmasri and Navathe, Fundamentals of Database Systems, Fourth Edition Copyright © 2004 Pearson Education, Inc. Slide FIGURE 25.9 Oracle distributed database systems. Source: From Oracle (1997a). Copyright  Oracle Corporation All rights reserved.