DISTRIBUTED DATABASEMANAGEMENT SYSTEMS

A Practical Approach

SAEED K. RAHIMIUniversity of St. Thomas

FRANK S. HAUGUniversity of St. Thomas

A JOHN WILEY & SONS, INC., PUBLICATION

DISTRIBUTED DATABASEMANAGEMENT SYSTEMS

DISTRIBUTED DATABASEMANAGEMENT SYSTEMS

A Practical Approach

SAEED K. RAHIMIUniversity of St. Thomas

FRANK S. HAUGUniversity of St. Thomas

A JOHN WILEY & SONS, INC., PUBLICATION

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To my mother, Behjat, and my father, Mohammadthough they were not giventhe opportunity to attend or finish school, they did everything they

could to make sure that all of their seven children obtained college degrees.S. K. R.

To my mother who taught me to love reading, learning, and books;my father who taught me to love mathematics, science, and computers;and the rest of my family who put up with me while we wrote this book

this would not have been possible without you.F. S. H.

CONTENTS

Preface xxv

1 Introduction 1

1.1 Database Concepts, 21.1.1 Data Models, 21.1.2 Database Operations, 21.1.3 Database Management, 31.1.4 DB Clients, Servers, and Environments, 3

1.2 DBE Architectural Concepts, 41.2.1 Services, 41.2.2 Components and Subsystems, 51.2.3 Sites, 5

1.3 Archetypical DBE Architectures, 61.3.1 Required Services, 61.3.2 Basic Services, 71.3.3 Expected Services, 81.3.4 Expected Subsystems, 91.3.5 Typical DBMS Services, 101.3.6 Summary Level Diagrams, 11

1.4 A New Taxonomy, 131.4.1 COS Distribution and Deployment, 131.4.2 COS Closedness or Openness, 141.4.3 Schema and Data Visibility, 151.4.4 Schema and Data Control, 16

1.5 An Example DDBE, 171.6 A Reference DDBE Architecture, 18

1.6.1 DDBE Information Architecture, 181.6.2 DDBE Software Architecture, 20

vii

viii CONTENTS

1.6.2.1 Components of the Application Processor, 211.6.2.2 Components of the Data Processor, 23

1.7 Transaction Management in Distributed Systems, 241.8 Summary, 311.9 Glossary, 32

References, 33

2 Data Distribution Alternatives 35

2.1 Design Alternatives, 382.1.1 Localized Data, 382.1.2 Distributed Data, 38

2.1.2.1 Nonreplicated, Nonfragmented, 382.1.2.2 Fully Replicated, 382.1.2.3 Fragmented or Partitioned, 392.1.2.4 Partially Replicated, 392.1.2.5 Mixed Distribution, 39

2.2 Fragmentation, 392.2.1 Vertical Fragmentation, 402.2.2 Horizontal Fragmentation, 42

2.2.2.1 Primary Horizontal Fragmentation, 422.2.2.2 Derived Horizontal Fragmentation, 44

2.2.3 Hybrid Fragmentation, 472.2.4 Vertical Fragmentation Generation Guidelines, 49

2.2.4.1 Grouping, 492.2.4.2 Splitting, 49

2.2.5 Vertical Fragmentation Correctness Rules, 622.2.6 Horizontal Fragmentation Generation Guidelines, 62

2.2.6.1 Minimality and Completeness of HorizontalFragmentation, 63

2.2.7 Horizontal Fragmentation Correctness Rules, 662.2.8 Replication, 68

2.3 Distribution Transparency, 682.3.1 Location Transparency, 682.3.2 Fragmentation Transparency, 682.3.3 Replication Transparency, 692.3.4 Location, Fragmentation, and Replication

Transparencies, 692.4 Impact of Distribution on User Queries, 69

2.4.1 No GDDNo Transparency, 702.4.2 GDD Containing Location InformationLocation

Transparency, 722.4.3 Fragmentation, Location, and Replication

Transparencies, 732.5 A More Complex Example, 73

2.5.1 Location, Fragmentation, and ReplicationTransparencies, 75

2.5.2 Location and Replication Transparencies, 76

CONTENTS ix

2.5.3 No Transparencies, 772.6 Summary, 782.7 Glossary, 78

References, 79Exercises, 80

3 Database Control 83

3.1 Authentication, 843.2 Access Rights, 853.3 Semantic Integrity Control, 86

3.3.1 Semantic Integrity Constraints, 883.3.1.1 Relational Constraints, 88

3.4 Distributed Semantic Integrity Control, 943.4.1 Compile Time Validation, 973.4.2 Run Time Validation, 973.4.3 Postexecution Time Validation, 97

3.5 Cost of Semantic Integrity Enforcement, 973.5.1 Semantic Integrity Enforcement Cost in Distributed

System, 983.5.1.1 Variables Used, 1003.5.1.2 Compile Time Validation, 1023.5.1.3 Run Time Validation, 1033.5.1.4 Postexecution Time Validation, 104

3.6 Summary, 1063.7 Glossary, 106

References, 107Exercises, 107

4 Query Optimization 111

4.1 Sample Database, 1124.2 Relational Algebra, 112

4.2.1 Subset of Relational Algebra Commands, 1134.2.1.1 Relational Algebra Basic Operators, 1144.2.1.2 Relational Algebra Derived Operators, 116

4.3 Computing Relational Algebra Operators, 1194.3.1 Computing Selection, 120

4.3.1.1 No Index on R, 1204.3.1.2 B + Tree Index on R, 1204.3.1.3 Hash Index on R, 122

4.3.2 Computing Join, 1234.3.2.1 Nested-Loop Joins, 1234.3.2.2 SortMerge Join, 1244.3.2.3 Hash-Join, 126

4.4 Query Processing in Centralized Systems, 1264.4.1 Query Parsing and Translation, 1274.4.2 Query Optimization, 128

4.4.2.1 Cost Estimation, 129

x CONTENTS

4.4.2.2 Plan Generation, 1334.4.2.3 Dynamic Programming, 1354.4.2.4 Reducing the Solution Space, 141

4.4.3 Code Generation, 1444.5 Query Processing in Distributed Systems, 145

4.5.1 Mapping Global Query into Local Queries, 1464.5.2 Distributed Query Optimization, 150

4.5.2.1 Utilization of Distributed Resources, 1514.5.2.2 Dynamic Programming in Distributed

Systems, 1524.5.2.3 Query Trading in Distributed Systems, 1564.5.2.4 Distributed Query Solution Space

Reduction, 1574.5.3 Heterogeneous Database Systems, 170

4.5.3.1 Heterogeneous Database SystemsArchitecture, 170

4.5.3.2 Optimization in Heterogeneous Databases, 1714.6 Summary, 1724.7 Glossary, 173

References, 175Exercises, 178

5 Controlling Concurrency 183

5.1 Terminology, 1835.1.1 Database, 183

5.1.1.1 Database Consistency, 1845.1.2 Transaction, 184

5.1.2.1 Transaction Redefined, 1885.2 Multitransaction Processing Systems, 189

5.2.1 Schedule, 1895.2.1.1 Serial Schedule, 1895.2.1.2 Parallel Schedule, 189

5.2.2 Conflicts, 1915.2.2.1 Unrepeatable Reads, 1915.2.2.2 Reading Uncommitted Data, 1915.2.2.3 Overwriting Uncommitted Data, 192

5.2.3 Equivalence, 1925.2.4 Serializable Schedules, 193

5.2.4.1 Serializability in a Centralized System, 1945.2.4.2 Serializability in a Distributed System, 1955.2.4.3 Conflict Serializable Schedules, 1965.2.4.4 View Serializable Schedules, 1965.2.4.5 Recoverable Schedules, 1975.2.4.6 Cascadeless Schedules, 197

5.2.5 Advanced Transaction Types, 1975.2.5.1 Sagas, 1985.2.5.2 ConTracts, 199

CONTEN