Database Systems – Discussion

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

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Copyright © 2016, 2011, 2007 by Ramez Elmasri and Shamkant B. Navathe. All rights reserved. Manufactured
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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 ing (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 ing
or choose a different ing of chapters (for example, follow the chapter
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 s 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 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 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 ). 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
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
ed (sorted), un ed (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 ing 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 ing 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
that they are given or in the preferred 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 , the dependen-
cies are not lost. The chart can be consulted by instructors wishing to use an
alternative 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/Server Architectures for DBMSs 46
2.6 Classification of Database Management Systems 51
2.7 Summary 54
Review Questions 55
Exercises 55
Selected Bibliography 56

xvii

xviii Contents

■ part 2
Conceptual Data Modeling and Database Design ■

chapter 3 Data Modeling Using the Entity–Relationship (ER)
Model 59

3.1 Using High-Level Conceptual Data Models
for Database Design 60

3.2 A Sample Database Application 62
3.3 Entity Types, Entity Sets, Attributes, and Keys 63
3.4 Relationship Types, Relationship Sets, Roles, and Structural

Constraints 72
3.5 Weak Entity Types 79
3.6 Refining the ER Design for the COMPANY Database 80
3.7 ER Diagrams, Naming Conventions, and Design Issues 81
3.8 Example of …