Management of heterogeneous and autonomous database systems

Management of Heterogeneous and Autonomous Database Systems Edited by Ahmed Elmagarmid Marek Rusinkiewicz Amit Sheth Morgan Kaufmann Publishers, Inc. San Francisco, California Contents Preface xiii 1 An Overview of Multidatabase Systems: Past and Present Athman Bouguettaya, Boualern Benatallah, and Ahmed Elmagarmid 1.1 Terminology 1.1.1 Distribution. 1.1.2 Heterogeneity 1.1.3 Autonomy 1.1.4 Interoperability ; 1.2 Architecture of Heterogeneous Distributed Databases 1.2.1 Global Schema Integration 1.2.2 Federated Database Systems (FDBSs) 1.2.3 Multidatabase Language Approach 1.3 Research Issues in Multidatabase Systems 1.3.1 Schema and Language Translation 1.3.2 Schema Integration 1.3.3 Multidatabase Consistency and Dependencies - 1.3.4 Workflow Management Systems 1.3.5 Transaction Processing 1.4 Multidatabase Prototypes 1.5 Summary Bibliography 2 Local Autonomy and Its Effects on Multidatabase Systems Ahmed Elmagarmid, Weimin Du, and Rafi Ahmed 2.1 Schema Integration 2.1.1 Heterogeneous Data Models 2.1.2 Resolution ofjkhematic Discrepancies 2.1.3 Reconciliation of Data Values 2.1.4 Query and Update Translation 2.2 Query Processing 2.2.1 Unification Decomposition 1 4 4 4 5 5 6 7 8 11 12 12 13 15 16 17 20 24 24 33 38 38 39 40 41 41 41 viii Contents 2.2.2 Optimization 2.3 Transaction Management 2.3.1 Concurrency Control 2.3.2 Commitment and Recovery 2.3.3 Replication Control 2.4 Summary Bibliography 3 Semantic Similarities Between Objects in Multiple Databases Vipul Kashyap and Amit Sheth 3.1 Semantics: Perspectives and Representation 3.1.1 Context: The Semantic Component 3.1.2 Abstractions/Mappings: The Structural Component . . 3.1.3 Modeling Uncertainty, Inconsistency, and Incompleteness 3.2 Semantic Proximity: A Model for Representing Semantic Similarities 3.2.1 Context(s) of the Two Objects: The Semantic Component 3.2.2 Issues of Representation and Reasoning 3.2.3 The Vocabulary Problem 3.2.4 The Structural Components 3.2.5 Modeling Uncertainty: Fuzzy Strengths as a Function of Semantic Proximity 3.2.6 A Semantic Classification of Object Similarities 3.3 Context Building Approach 3.3.1 Context-Dependent Interpretation 3.3.2 Context Management Using a Truth Maintenance System 3.3.3 Discussion 3.4 Context Interchange Approach 3.4.1 Context and Metadata 3.4.2 Data Conversion (Conversion Functions) 3.4.3 Discussion 3.5 Common Concepts: An Approach to Determine Attribute Similarities 3.5.1 Representation of Attribute Semantics by Common Concepts 3.5.2 Establishing Attribute Relationships 3.5.3 Discussion 3.6 Semantic Abstractions Approach 3.6.1 The Semantic Enrichment Phase 3.6.2 The Detection Phase 3.6.3 Discussion 3.7 Semantic Similarity Based on Fuzzy Knowledge 3.7.1 Terminological Knowledge 42 44 45 48 50 52 52 57 59 59 59 60 61 62 63 63 64 65 66 70 70 72 74 74 74 75 76 76 77 78 79 79 79 81 82 82 82 Contents ix 3.7.2 Semantic Similarity of Classes 3.7.3 Discussion 3.8 Related Work Bibliography 83 85 85 85 Resolution of Representational Diversity in Multidatabase Systems 91 Joachim Hammer and Dennis McLeod 4.1 Related Research 4.2 Heterogeneity in a Collaborative Sharing Environment 4.2.1 A Spectrum of Representational Heterogeneities . . . . 4.2.2 Causes of Representational Diversities 4.3 Remote-Exchange Architecture 4.3.1 Core Object Data Model 4.3.2 Remote Sharing Language 4.3.3 Local Lexicon . . . .<• 4.3.4 Semantic Dictionary 4.4 Resolving Representational Heterogeneity in Remote-Exchange 4.4.1 Relationships among Objects 4.4.2 Common Concepts 4.4.3 Related Concepts 4.4.4 Strategy for Resolving Object Relationships 4.5 Sharing in Remote-Exchange 4.6 Summary Bibliography 92 94 94 97 99 99 101 102 104 104 106 107 108 108 110 110 112 Schema Integration: Past, Present, and Future 119 Sudha Ram and V. Ramesh 5.1 Framework for Schema Integration 5.1.1 Steps in Schema Integration 5.1.2 Classification of Schema Integration Strategies 5.2 Interschema Relationship Identification and Integrated Schema Generation 5.2.1 Interschema Relationship Identification 5.2.2 Integrated Schema Generation 5.2.3 Schema Mapping Generation 5.3 Automating Schema Integration 5.3.1 Schema Integration Toolkits 5.4 Future Directions in Schema Integration 5.4.1 Improving Interschema Relationship Identification . . . 5.4.2 Improving Integrated Schema Generation 5.5 Summary Bibliography 122 122 126 133 133 136 139 140 140 145 145 147 148 149 Contents Schema and Language Translation 157 Bogdan Czejdo and Le Gruenwald 6.1 Schema Translations into the Relational Model 6.2 Schema Translations into an ER Model 6.3 Schema Translations into a Functional Model 6.4 Schema Translations into an Object-Oriented Model 6.5 Example of a Schema Translation 6.6 Language Translation 6.7 Translations Using an Intermediate Language 6.8 Translations Involving Rule-Based Languages 6.9 Using a Metamodel in the Language Translation Process . . . . 6.10 General Query Transformation Systems 6.11 Example of Language Translations 6.12 Summary Bibliography v 158 159 159 160 161 162 163 164 165 165 167 170 171 Multidatabase Languages 175 Paolo Missier, Marek Rusinkiewicz, and W. Jin 7.1 Classification of Semantic Heterogeneity 177 7.1.1 Semantic Heterogeneity 177 7.1.2 Summary of Semantic Heterogeneity Conflicts 178 7.1.3 Semantic Heterogeneity Resolution Methodologies . . . 180 7.1.4 Summary 182 7.2 Functionalities of Multidatabase Query Languages 183 7.2.1 Historical Perspective 183 7.2.2 Design Principles 185 7.2.3 Multinational Algebra 186 7.3 MSQL+ Approach 187 7.3.1 Example Database Schemas . . 187 7.3.2 Data Definition Language 189 7.3.3 Data Manipulation Language 190 7.3.4 Multiquery Evaluation 204 7.4 Updates in Multidatabase Languages 208 7.4.1 Updates in MSQL and Multitransactions 208 Bibliography 212 Interdependent Database Systems George Karabatis, Marek Rusinkiewicz, and Amit Sheth 8.1 Current Approaches to the Management of Interdependent Data 8.2 Research Problems 8.2.1 The Problem of Specifying Interdependent Data . . . . 8.2.2 An Execution Model for Consistency-Restoring Procedures 8.3 Specification of Interdependent Data 217 223 224 224 225 226 Contents xi Aeolos: A System for the Management of Interdependent Data 8.4.1 Interdependent Database Systems (IDBSs) 8.4.2 Architecture of Aeolos 8.4.3 Data Distribution in Aeolos 8.4.4 Components of a Dependency Subsystem 8.4.5 The IDS Manager 8.4.6 Monitors in Aeolos 8.4.7 Measures of Consistency 8.4.8 Consistency Manager 8.4.9 Recovery Manager 8.4.10 Execution Agent 8.5 Active Database Systems and Interdependent Data 8.5.1 Active Database Systems 8.5.2 Differences between IDBSs and Active DBMSs 8.6 Detecting Events in Aeolos 8.6.1 Detecting Events on LDBSs That Provide Triggering Capabilities 8.6.2 Detecting Events on LDBSs Without Triggering Capabilities 8.7 Summary Bibliography 229 229 231 231 233 234 235 236 239 240 240 241 241 244 244 8.4 9 Correctness Criteria and Concurrency Control Panos K. Chrysanthis and Krithi Ramamritham 9.1 Databases, Multidatabases, and Transactions 9.2 Correctness of Concurrent Executions 9.3 Application-Independent Criteria 9.3.1 Global Serializability 9.3.2 Achieving Global Serializability 9.3T3 Achieving Relaxations of Global Serializability 9.4 Application-Dependent Criteria 9.5 Summary Bibliography 10 Transaction Management in Multidatabase Systems: Current Technologies and Formalisms Ken Barker and Ahmed Elmagarmid 10.1 Transaction Management Review 10.2 Unique Transaction Properties Found in Multidatabase Systems 10.3 Modeling Issues in Multidatabase Systems 10.4 Examples of Advanced Transaction Models 10.4.1 Formalizing Transaction Models 10.4.2 MDBS-Specific Transaction Models 10.4.3 Adapting Other Transaction Models to the MDBS . . . 245 246 246 247 253 254 257 260 260 262 264 267 269 270 277 278 282 283 285 287 287 296 xii Contents 10.5 Summary Bibliography 11 Transaction-Based Recovery Jari Veijalainen and Antoni Wolski 11.1 Basic Concepts 11.1.1 Architecture 11.1.2 Failure Types 11.1.3 Basic Recovery Techniques for Heterogeneous Autonomous Databases 11.1.4 Dealing with Transactionless Data Servers 11.1.5 Comparing Recovery Techniques 11.2 A Formal Recovery Model 11.2.1 Recoverability and Serializability in the R-W Model . . 11.2.2 A General Framework Model 11.2.3 Correctness Criteria for Sx !• 11.2.4 Computation Model for Heterogeneous Transaction Management in Srw 11.2.5 Completeness and Correctness Predicates for Heterogeneous Transaction Management in Srw 11.2.6 Correct Transaction Scheduling in a Heterogeneous Autonomous Environment Under Rigorousness 11.2.7 Recovery under FMSS Serializability 11.2.8 Generalizing FMSS 11.2.9 Enforcing DLRP 11.3 Related Work 11.3.1 MSS Orientation Due to Backward Recovery 11.3.2 MSS Orientation Due to Forward Recovery 11.3.3 SSS Orientation, Two-Phased LTMs 11.4 Summary Bibliography 297 297 301 303 303 309 310 312 313 313 314 320 324 328 329 331 334 337 338 340 340 341 342 343 344 Bibliography 351 Index 391