Consider the ER diagram shown in Figure 3.22 for part of a BANK database (also below for reference). Each bank can have multiple branches, and each branch can have multiple acc

FUNDAMENTALS OF

Database Systems SEVENTH EDITION

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FUNDAMENTALS OF

Database Systems SEVENTH EDITION

Ramez Elmasri Department of Computer Science and Engineering The University of Texas at Arlington

Shamkant B. Navathe College of Computing Georgia Institute of Technology

Boston Columbus Indianapolis New York San Francisco Hoboken

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ISBN-10: 0-13-397077-9 ISBN-13: 978-0-13-397077-7

Copyright © 2016, 2011, 2007 by Ramez Elmasri and Shamkant B. Navathe. All rights reserved. Manufactured in the United States of America. This publication is protected by Copyright and permissions should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. To obtain permission(s) to use materials from this work, please submit a written request to Pearson Higher Education, Permissions Department, 221 River Street, Hoboken, NJ 07030.

Many of the designations by manufacturers and seller to distinguish their products are claimed as trademarks. Where those designations appear in this book, and the publisher was aware of a trademark claim, the designations have been printed in initial caps or all caps.

The author and publisher of this book have used their best efforts in preparing this book. These efforts include the development, research, and testing of theories and programs to determine their effectiveness. The author and publisher make no warranty of any kind, expressed or implied, with regard to these programs or the documentation contained in this book. The author and publisher shall not be liable in any event for incidental or consequential damages with, or arising out of, the furnishing, performance, or use of these programs.

Microsoft and/or its respective suppliers make no representations about the suitability of the information contained in the documents and related graphics published as part of the services for any purpose. All such documents and related graphics are provided “as is” without warranty of any kind. Microsoft and/or its respective suppliers hereby disclaim all warranties and conditions with regard to this information, including all warranties and conditions of merchantability. Whether express, implied or statutory, fitness for a particular purpose, title and non-infringement. In no event shall microsoft and/or its respective suppliers be liable for any special, indirect or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract. Negligence or other tortious action, arising out of or in connection with the use or performance of information available from the services.

The documents and related graphics contained herein could include technical inaccuracies or typographical errors. Changes are periodically added to the information herein. Microsoft and/or its respective suppliers may make improvements and/or changes in the product(s) and/or the program(s) described herein at any time. Partial screen shots may be viewed in full within the software version specified.

Library of Congress Cataloging-in-Publication Data on File

10 9 8 7 6 5 4 3 2 1

To Amalia and

to Ramy, Riyad, Katrina, and Thomas

R. E.

To my wife Aruna for her love, support, and understanding and

to Rohan, Maya, and Ayush for bringing so much joy into our lives

S.B.N.

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This book introduces the fundamental concepts necessary for designing, using, and implementing

database systems and database applications. Our presentation stresses the funda- mentals of database modeling and design, the languages and models provided by the database management systems, and database system implementation techniques. The book is meant to be used as a textbook for a one- or two-semester course in database systems at the junior, senior, or graduate level, and as a reference book. Our goal is to provide an in-depth and up-to-date presentation of the most important aspects of database systems and applications, and related technologies. We assume that readers are familiar with elementary programming and data-structuring con- cepts and that they have had some exposure to the basics of computer organization.

New to This Edition The following key features have been added in the seventh edition:

■ A reorganization of the chapter ordering (this was based on a survey of the instructors who use the textbook); however, the book is still organized so that the individual instructor can choose to follow the new chapter ordering or choose a different ordering of chapters (for example, follow the chapter order from the sixth edition) when presenting the materials.

■ There are two new chapters on recent advances in database systems and big data processing; one new chapter (Chapter 24) covers an introduction to the newer class of database systems known as NOSQL databases, and the other new chapter (Chapter 25) covers technologies for processing big data, including MapReduce and Hadoop.

■ The chapter on query processing and optimization has been expanded and reorganized into two chapters; Chapter 18 focuses on strategies and algo- rithms for query processing whereas Chapter 19 focuses on query optimiza- tion techniques.

■ A second UNIVERSITY database example has been added to the early chap- ters (Chapters 3 through 8) in addition to our COMPANY database example from the previous editions.

■ Many of the individual chapters have been updated to varying degrees to include newer techniques and methods; rather than discuss these enhancements here,

Preface

vii

viii Preface

we will describe them later in the preface when we discuss the organization of the seventh edition.

The following are key features of the book:

■ A self-contained, flexible organization that can be tailored to individual needs; in particular, the chapters can be used in different orders depending on the instructor’s preference.

■ A companion website (http://www.pearsonhighered.com/cs-resources) includes data to be loaded into various types of relational databases for more realistic student laboratory exercises.

■ A dependency chart (shown later in this preface) to show which chapters depend on other earlier chapters; this can guide the instructor who wants to tailor the order of presentation of the chapters.

■ A collection of supplements, including a robust set of materials for instruc- tors and students such as PowerPoint slides, figures from the text, and an instructor’s guide with solutions.

Organization and Contents of the Seventh Edition There are some organizational changes in the seventh edition as well as improve- ment to the individual chapters. The book is now divided into 12 parts as follows:

■ Part 1 (Chapters 1 and 2) describes the basic introductory concepts neces- sary for a good understanding of database models, systems, and languages. Chapters 1 and 2 introduce databases, typical users, and DBMS concepts, terminology, and architecture, as well as a discussion of the progression of database technologies over time and a brief history of data models. These chapters have been updated to introduce some of the newer technologies such as NOSQL systems.

■ Part 2 (Chapters 3 and 4) includes the presentation on entity-relationship modeling and database design; however, it is important to note that instruc- tors can cover the relational model chapters (Chapters 5 through 8) before Chapters 3 and 4 if that is their preferred order of presenting the course materials. In Chapter 3, the concepts of the Entity-Relationship (ER) model and ER diagrams are presented and used to illustrate conceptual database design. Chapter 4 shows how the basic ER model can be extended to incorpo- rate additional modeling concepts such as subclasses, specialization, gener- alization, union types (categories) and inheritance, leading to the enhanced-ER (EER) data model and EER diagrams. The notation for the class diagrams of UML are also introduced in Chapters 7 and 8 as an alternative model and diagrammatic notation for ER/EER diagrams.

■ Part 3 (Chapters 5 through 8) includes a detailed presentation on relational databases and SQL with some additional new material in the SQL chapters to cover a few SQL constructs that were not in the previous edition. Chapter 5

Preface ix

describes the basic relational model, its integrity constraints, and update operations. Chapter 6 describes some of the basic parts of the SQL standard for relational databases, including data definition, data modification opera- tions, and simple SQL queries. Chapter 7 presents more complex SQL que- ries, as well as the SQL concepts of triggers, assertions, views, and schema modification. Chapter 8 describes the formal operations of the relational algebra and introduces the relational calculus. The material on SQL (Chap- ters 6 and 7) is presented before our presentation on relational algebra and calculus in Chapter 8 to allow instructors to start SQL projects early in a course if they wish (it is possible to cover Chapter 8 before Chapters 6 and 7 if the instructor desires this order). The final chapter in Part 2, Chapter 9, covers ER- and EER-to-relational mapping, which are algorithms that can be used for designing a relational database schema from a conceptual ER/EER schema design.

■ Part 4 (Chapters 10 and 11) are the chapters on database programming tech- niques; these chapters can be assigned as reading materials and augmented with materials on the particular language used in the course for program- ming projects (much of this documentation is readily available on the Web). Chapter 10 covers traditional SQL programming topics, such as embedded SQL, dynamic SQL, ODBC, SQLJ, JDBC, and SQL/CLI. Chapter 11 introduces Web database programming, using the PHP scripting language in our exam- ples, and includes new material that discusses Java technologies for Web database programming.

■ Part 5 (Chapters 12 and 13) covers the updated material on object-relational and object-oriented databases (Chapter 12) and XML (Chapter 13); both of these chapters now include a presentation of how the SQL standard incorpo- rates object concepts and XML concepts into more recent versions of the SQL standard. Chapter 12 first introduces the concepts for object databases, and then shows how they have been incorporated into the SQL standard in order to add object capabilities to relational database systems. It then covers the ODMG object model standard, and its object definition and query lan- guages. Chapter 13 covers the XML (eXtensible Markup Language) model and languages, and discusses how XML is related to database systems. It presents XML concepts and languages, and compares the XML model to traditional database models. We also show how data can be converted between the XML and relational representations, and the SQL commands for extracting XML documents from relational tables.

■ Part 6 (Chapters 14 and 15) are the normalization and relational design theory chapters (we moved all the formal aspects of normalization algo- rithms to Chapter 15). Chapter 14 defines functional dependencies, and the normal forms that are based on functional dependencies. Chapter 14 also develops a step-by-step intuitive normalization approach, and includes the definitions of multivalued dependencies and join dependencies. Chapter 15 covers normalization theory, and the formalisms, theories,

x Preface

and algorithms developed for relational database design by normaliza- tion, including the relational decomposition algorithms and the relational synthesis algorithms.

■ Part 7 (Chapters 16 and 17) contains the chapters on file organizations on disk (Chapter 16) and indexing of database files (Chapter 17). Chapter 16 describes primary methods of organizing files of records on disk, including ordered (sorted), unordered (heap), and hashed files; both static and dynamic hashing techniques for disk files are covered. Chapter 16 has been updated to include materials on buffer management strategies for DBMSs as well as an overview of new storage devices and standards for files and mod- ern storage architectures. Chapter 17 describes indexing techniques for files, including B-tree and B+-tree data structures and grid files, and has been updated with new examples and an enhanced discussion on indexing, including how to choose appropriate indexes and index creation during physical design.

■ Part 8 (Chapters 18 and 19) includes the chapters on query processing algo- rithms (Chapter 18) and optimization techniques (Chapter 19); these two chapters have been updated and reorganized from the single chapter that covered both topics in the previous editions and include some of the newer techniques that are used in commercial DBMSs. Chapter 18 presents algo- rithms for searching for records on disk files, and for joining records from two files (tables), as well as for other relational operations. Chapter 18 con- tains new material, including a discussion of the semi-join and anti-join operations with examples of how they are used in query processing, as well as a discussion of techniques for selectivity estimation. Chapter 19 covers techniques for query optimization using cost estimation and heuristic rules; it includes new material on nested subquery optimization, use of histograms, physical optimization, and join ordering methods and optimization of typical queries in data warehouses.

■ Part 9 (Chapters 20, 21, and 22) covers transaction processing concepts; concurrency control; and database recovery from failures. These chapters have been updated to include some of the newer techniques that are used in some commercial and open source DBMSs. Chapter 20 introduces the techniques needed for transaction processing systems, and defines the concepts of recoverability and serializability of schedules; it has a new sec- tion on buffer replacement policies for DBMSs and a new discussion on the concept of snapshot isolation. Chapter 21 gives an overview of the var- ious types of concurrency control protocols, with a focus on two-phase locking. We also discuss timestamp ordering and optimistic concurrency control techniques, as well as multiple-granularity locking. Chapter 21 includes a new presentation of concurrency control methods that are based on the snapshot isolation concept. Finally, Chapter 23 focuses on database recovery protocols, and gives an overview of the concepts and techniques that are used in recovery.

■ Part 10 (Chapters 23, 24, and 25) includes the chapter on distributed data- bases (Chapter 23), plus the two new chapters on NOSQL storage systems for big data (Chapter 24) and big data technologies based on Hadoop and MapReduce (Chapter 25). Chapter 23 introduces distributed database concepts, including availability and scalability, replication and fragmenta- tion of data, maintaining data consistency among replicas, and many other concepts and techniques. In Chapter 24, NOSQL systems are categorized into four general categories with an example system in each category used for our examples, and the data models, operations, as well as the replica- tion/distribution/scalability strategies of each type of NOSQL system are discussed and compared. In Chapter 25, the MapReduce programming model for distributed processing of big data is introduced, and then we have presentations of the Hadoop system and HDFS (Hadoop Distributed File System), as well as the Pig and Hive high-level interfaces, and the YARN architecture.

■ Part 11 (Chapters 26 through 29) is entitled Advanced Database Models, Systems, and Applications and includes the following materials: Chapter 26 introduces several advanced data models including active data- bases/triggers (Section 26.1), temporal databases (Section 26.2), spatial data- bases (Section 26.3), multimedia databases (Section 26.4), and deductive databases (Section 26.5). Chapter 27 discusses information retrieval (IR) and Web search, and includes topics such as IR and keyword-based search, comparing DB with IR, retrieval models, search evaluation, and ranking algorithms. Chapter 28 is an introduction to data mining including over- views of various data mining methods such as associate rule mining, cluster- ing, classification, and sequential pattern discovery. Chapter 29 is an overview of data warehousing including topics such as data warehousing models and operations, and the process of building a data warehouse.

■ Part 12 (Chapter 30) includes one chapter on database security, which includes a discussion of SQL commands for discretionary access control (GRANT, REVOKE), as well as mandatory security levels and models for including mandatory access control in relational databases, and a discussion of threats such as SQL injection attacks, as well as other techniques and methods related to data security and privacy.

Appendix A gives a number of alternative diagrammatic notations for displaying a conceptual ER or EER schema. These may be substituted for the notation we use, if the instructor prefers. Appendix B gives some important physical parameters of disks. Appendix C gives an overview of the QBE graphical query language, and Appendixes D and E (available on the book’s Companion Website located at http://www.pearsonhighered.com/elmasri) cover legacy database systems, based on the hierarchical and network database models. They have been used for more than thirty years as a basis for many commercial database applications and transaction- processing systems.

Preface xi

Guidelines for Using This Book There are many different ways to teach a database course. The chapters in Parts 1 through 7 can be used in an introductory course on database systems in the order that they are given or in the preferred order of individual instructors. Selected chap- ters and sections may be left out and the instructor can add other chapters from the rest of the book, depending on the emphasis of the course. At the end of the open- ing section of some of the book’s chapters, we list sections that are candidates for being left out whenever a less-detailed discussion of the topic is desired. We suggest covering up to Chapter 15 in an introductory database course and including selected parts of other chapters, depending on the background of the students and the desired coverage. For an emphasis on system implementation techniques, chapters from Parts 7, 8, and 9 should replace some of the earlier chapters.

Chapters 3 and 4, which cover conceptual modeling using the ER and EER models, are important for a good conceptual understanding of databases. However, they may be partially covered, covered later in a course, or even left out if the emphasis is on DBMS implementation. Chapters 16 and 17 on file organizations and indexing may also be covered early, later, or even left out if the emphasis is on database mod- els and languages. For students who have completed a course on file organization, parts of these chapters can be assigned as reading material or some exercises can be assigned as a review for these concepts.

If the emphasis of a course is on database design, then the instructor should cover Chapters 3 and 4 early on, followed by the presentation of relational databases. A total life-cycle database design and implementation project would cover conceptual design (Chapters 3 and 4), relational databases (Chapters 5, 6, and 7), data model mapping (Chapter 9), normalization (Chapter 14), and application programs implementation with SQL (Chapter 10). Chapter 11 also should be covered if the emphasis is on Web database programming and applications. Additional documen- tation on the specific programming languages and RDBMS used would be required. The book is written so that it is possible to cover topics in various sequences. The following chapter dependency chart shows the major dependencies among chap- ters. As the diagram illustrates, it is possible to start with several different topics following the first two introductory chapters. Although the chart may seem com- plex, it is important to note that if the chapters are covered in order, the dependen- cies are not lost. The chart can be consulted by instructors wishing to use an alternative order of presentation.

For a one-semester course based on this book, selected chapters can be assigned as reading material. The book also can be used for a two-semester course sequence. The first course, Introduction to Database Design and Database Systems, at the sophomore, junior, or senior level, can cover most of Chapters 1 through 15. The second course, Database Models and Implementation Techniques, at the senior or first-year graduate level, can cover most of Chapters 16 through 30. The two- semester sequence can also be designed in various other ways, depending on the preferences of the instructors.

xii Preface

Supplemental Materials Support material is available to qualified instructors at Pearson’s instructor resource center (http://www.pearsonhighered.com/irc). For access, contact your local Pearson representative.

■ PowerPoint lecture notes and figures.

■ A solutions manual.

Acknowledgments It is a great pleasure to acknowledge the assistance and contributions of many indi- viduals to this effort. First, we would like to thank our editor, Matt Goldstein, for his guidance, encouragement, and support. We would like to acknowledge the excellent work of Rose Kernan for production management, Patricia Daly for a

1, 2 Introductory

3, 4 ER, EER Models

5 Relational

Model

8 Relational Algebra

9 ER-, EER-to-

Relational

16, 17 File Organization,

Indexing

28, 29 Data Mining, Warehousing

10, 11 DB, Web

Programming

30 DB

Security

14, 15 FD, MVD,

Normalization

23, 24, 25 DDB, NOSQL,

Big Data

20, 21, 22 Transactions, CC, Recovery

12, 13 ODB, ORDB,

XML

26, 27 Advanced Models, IR

6, 7 SQL

18, 19 Query Processing,

Optimization

Preface xiii

thorough copy editing of the book, Martha McMaster for her diligence in proofing the pages, and Scott Disanno, Managing Editor of the production team. We also wish to thank Kelsey Loanes from Pearson for her continued help with the project, and reviewers Michael Doherty, Deborah Dunn, Imad Rahal, Karen Davis, Gilliean Lee, Leo Mark, Monisha Pulimood, Hassan Reza, Susan Vrbsky, Li Da Xu, Weining Zhang and Vincent Oria.

Ramez Elmasri would like to thank Kulsawasd Jitkajornwanich, Vivek Sharma, and Surya Swaminathan for their help with preparing some of the material in Chap- ter 24. Sham Navathe would like to acknowledge the following individuals who helped in critically reviewing and revising various topics. Dan Forsythe and Satish Damle for discussion of storage systems; Rafi Ahmed for detailed re-organization of the material on query processing and optimization; Harish Butani, Balaji Palanisamy, and Prajakta Kalmegh for their help with the Hadoop and MapReduce technology material; Vic Ghorpadey and Nenad Jukic for revision of the Data Warehousing material; and finally, Frank Rietta for newer techniques in database security, Kunal Malhotra for various discussions, and Saurav Sahay for advances in information retrieval systems.

We would like to repeat our thanks to those who have reviewed and contributed to previous editions of Fundamentals of Database Systems.

■ First edition. Alan Apt (editor), Don Batory, Scott Downing, Dennis Heimbinger, Julia Hodges, Yannis Ioannidis, Jim Larson, Per-Ake Larson, Dennis McLeod, Rahul Patel, Nicholas Roussopoulos, David Stemple, Michael Stonebraker, Frank Tompa, and Kyu-Young Whang.

■ Second edition. Dan Joraanstad (editor), Rafi Ahmed, Antonio Albano, David Beech, Jose Blakeley, Panos Chrysanthis, Suzanne Dietrich, Vic Ghorpadey, Goetz Graefe, Eric Hanson, Junguk L. Kim, Roger King, Vram Kouramajian, Vijay Kumar, John Lowther, Sanjay Manchanda, Toshimi Minoura, Inderpal Mumick, Ed Omiecinski, Girish Pathak, Raghu Ramakrishnan, Ed Robertson, Eugene Sheng, David Stotts, Marianne Winslett, and Stan Zdonick.

■ Third edition. Maite Suarez-Rivas and Katherine Harutunian (editors); Suzanne Dietrich, Ed Omiecinski, Rafi Ahmed, Francois Bancilhon, Jose Blakeley, Rick Cattell, Ann Chervenak, David W. Embley, Henry A. Etlinger, Leonidas Fegaras, Dan Forsyth, Farshad Fotouhi, Michael Franklin, Sreejith Gopinath, Goetz Craefe, Richard Hull, Sushil Jajodia, Ramesh K. Karne, Harish Kotbagi, Vijay Kumar, Tarcisio Lima, Ramon A. Mata-Toledo, Jack McCaw, Dennis McLeod, Rokia Missaoui, Magdi Morsi, M. Narayanaswamy, Carlos Ordonez, Joan Peckham, Betty Salzberg, Ming-Chien Shan, Junping Sun, Rajshekhar Sunderraman, Aravindan Veerasamy, and Emilia E. Villareal.

■ Fourth edition. Maite Suarez-Rivas, Katherine Harutunian, Daniel Rausch, and Juliet Silveri (editors); Phil Bernhard, Zhengxin Chen, Jan Chomicki, Hakan Ferhatosmanoglu, Len Fisk, William Hankley, Ali R. Hurson, Vijay Kumar, Peretz Shoval, Jason T. L. Wang (reviewers); Ed Omiecinski (who contributed to Chapter 27). Contributors from the University of Texas at

xiv Preface

Arlington are Jack Fu, Hyoil Han, Babak Hojabri, Charley Li, Ande Swathi, and Steven Wu; Contributors from Georgia Tech are Weimin Feng, Dan For- sythe, Angshuman Guin, Abrar Ul-Haque, Bin Liu, Ying Liu, Wanxia Xie, and Waigen Yee.

■ Fifth edition. Matt Goldstein and Katherine Harutunian (editors); Michelle Brown, Gillian Hall, Patty Mahtani, Maite Suarez-Rivas, Bethany Tidd, and Joyce Cosentino Wells (from Addison-Wesley); Hani Abu-Salem, Jamal R. Alsabbagh, Ramzi Bualuan, Soon Chung, Sumali Conlon, Hasan Davulcu, James Geller, Le Gruenwald, Latifur Khan, Herman Lam, Byung S. Lee, Donald Sanderson, Jamil Saquer, Costas Tsatsoulis, and Jack C. Wileden (reviewers); Raj Sunderraman (who contributed the laboratory projects); Salman Azar (who contributed some new exercises); Gaurav Bhatia, Fari- borz Farahmand, Ying Liu, Ed Omiecinski, Nalini Polavarapu, Liora Sahar, Saurav Sahay, and Wanxia Xie (from Georgia Tech).

■ Sixth edition. Matt Goldstein (editor); Gillian Hall (production manage- ment); Rebecca Greenberg (copy editing); Jeff Holcomb, Marilyn Lloyd, Margaret Waples, and Chelsea Bell (from Pearson); Rafi Ahmed, Venu Dasigi, Neha Deodhar, Fariborz Farahmand, Hariprasad Kumar, Leo Mark, Ed Omiecinski, Balaji Palanisamy, Nalini Polavarapu, Parimala R. Pranesh, Bharath Rengarajan, Liora Sahar, Saurav Sahay, Narsi Srinivasan, and Wanxia Xie.

Last, but not least, we gratefully acknowledge the support, encouragement, and patience of our families.

R. E.

S.B.N.

Preface xv

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Contents

Preface vii About the Authors xxx

■ part 1 Introduction to Databases ■

chapter 1 Databases and Database Users 3 1.1 Introduction 4 1.2 An Example 6 1.3 Characteristics of the Database Approach 10 1.4 Actors on the Scene 15 1.5 Workers behind the Scene 17 1.6 Advantages of Using the DBMS Approach 17 1.7 A Brief History of Database Applications 23 1.8 When Not to Use a DBMS 27 1.9 Summary 27 Review Questions 28 Exercises 28 Selected Bibliography 29

chapter 2 Database System Concepts and Architecture 31

2.1 Data Models, Schemas, and Instances 32 2.2 Three-Schema Architecture and Data Independence 36 2.3 Database Languages and Interfaces 38 2.4 The Database System Environment 42 2.5 Centralized and Client/Se

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