Federated database systems for managing distributed, heterogeneous, and autonomous databases
ACM Computing Surveys (CSUR) - Special issue on heterogeneous databases
DIRECT: a query facility for multiple databases
ACM Transactions on Information Systems (TOIS)
Modern database systems: the object model, interoperability, and beyond
Modern database systems: the object model, interoperability, and beyond
On view support in object-oriented database systems
Modern database systems
Strategic database technology: management for the year 2000
Strategic database technology: management for the year 2000
Data model and query evaluation in global information systems
Journal of Intelligent Information Systems - Special issue: networked information discovery and retrieval
Object orientation in multidatabase systems
ACM Computing Surveys (CSUR)
Object-oriented multidatabase systems: a solution for advanced applications
Object-oriented multidatabase systems: a solution for advanced applications
The impact of transaction management on object-oriented multidatabase views
Object-oriented multidatabase systems
A schema integration facility using object-oriented data model
Object-oriented multidatabase systems
Semantic heterogeneity in multidatabase systems
Object-oriented multidatabase systems
The TSIMMIS Approach to Mediation: Data Models and Languages
Journal of Intelligent Information Systems - Special issue: next generation information technologies and systems
The object database standard: ODMG 2.0
The object database standard: ODMG 2.0
Managing semantic heterogeneity in databases: a theoretical prospective
PODS '97 Proceedings of the sixteenth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems
Object normal forms and dependency constraints for object-oriented schemata
ACM Transactions on Database Systems (TODS)
Principles of distributed database systems (2nd ed.)
Principles of distributed database systems (2nd ed.)
Management of heterogeneous and autonomous database systems
Management of heterogeneous and autonomous database systems
An overview of multidatabase systems: past and present
Management of heterogeneous and autonomous database systems
Local autonomy and its effects on multidatabase systems
Management of heterogeneous and autonomous database systems
Semantic similarities between objects in multiple databases
Management of heterogeneous and autonomous database systems
The object data standard: ODMG 3.0
The object data standard: ODMG 3.0
Distributed Object Management
Query Processing for Advanced Database Systems
Query Processing for Advanced Database Systems
Scaling Access to Heterogeneous Data Sources with DISCO
IEEE Transactions on Knowledge and Data Engineering
The Conceptual Basis for Mediation Services
IEEE Expert: Intelligent Systems and Their Applications
Object Exchange Across Heterogeneous Information Sources
ICDE '95 Proceedings of the Eleventh International Conference on Data Engineering
Don't Scrap It, Wrap It! A Wrapper Architecture for Legacy Data Sources
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
Optimizing Queries Across Diverse Data Sources
VLDB '97 Proceedings of the 23rd International Conference on Very Large Data Bases
Object Fusion in Mediator Systems
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
Calibrating the Query Optimizer Cost Model of IRO-DB, an Object-Oriented Federated Database System
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
The Jupiter System: A Prototype for Multidatabase Interoperability
BNCOD 12 Proceedings of the 12th British National Conference on Databases: Directions in Databases
Federating Object-Oriented and Relational Databases: The IRO-DB Experience
COOPIS '97 Proceedings of the Second IFCIS International Conference on Cooperative Information Systems
Object Identification in Multidatabase Systems
Proceedings of the IFIP WG 2.6 Database Semantics Conference on Interoperable Database Systems (DS-5)
An Object-Oriented Integration Framework for Building Heterogeneous Database Systems
Proceedings of the IFIP WG 2.6 Database Semantics Conference on Interoperable Database Systems (DS-5)
Facilitating Open Communication in Agent Systems: The InfoSleuth Infrastructure
ATAL '97 Proceedings of the 4th International Workshop on Intelligent Agents IV, Agent Theories, Architectures, and Languages
The AQUA Data Model and Algebra
DBLP-4 Proceedings of the Fourth International Workshop on Database Programming Languages - Object Models and Languages
To Form a More Perfect Union (Intersection, Difference)
DBLP-5 Proceedings of the Fifth International Workshop on Database Programming Languages
An adaptive approach to query mediation across heterogeneous information sources
COOPIS '96 Proceedings of the First IFCIS International Conference on Cooperative Information Systems
Managing identity in global object views
RIDE '95 Proceedings of the 5th International Workshop on Research Issues in Data Engineering-Distributed Object Management (RIDE-DOM'95)
Consolidation of Query Results in a Multidatabase Environment: An Object-Oriented Approach
COMPSAC '96 Proceedings of the 20th Conference on Computer Software and Applications
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This paper presents an approach to query decomposition in a multidatabase environment. The unique aspect of this approach is that it is based on performing transformations over an object algebra that can be used as the basis for a global query language. In the paper, we first present our multidatabase environment and semantic framework, where a global conceptual schema based on the Object Data Management Group standard encompasses the information from heterogeneous data sources that include relational databases as well as object-oriented databases and flat file sources. The meta-data about the global schema is enhanced with information about virtual classes as well as virtual relationships and inheritance hierarchies that exist between multiple sources. The AQUA object algebra is used as the formal foundation for manipulation of the query expression over the multidatabase. AQUA is enhanced with distribution operators for dealing with data distribution issues. During query decomposition we perform an extensive analysis of traversals for path expressions that involve virtual relationships and hierarchies for access to several heterogeneous sources. The distribution operators defined in algebraic terms enhance the global algebra expression with semantic information about the structure, distribution, and localization of the data sources relevant to the solution of the query. By using an object algebra as the basis for query processing, we are able to define algebraic transformations and exploit rewriting techniques during the decomposition phase. Our use of an object algebra also provides a formal and uniform representation for dealing with an object-oriented approach to multidatabase query processing. As part of our query processing discussion, we include an overview of a global object identification approach for relating semantically equivalent objects from diverse data sources, illustrating how knowledge about global object identity is used in the decomposition and assembly processes.