Semantics and implementation of schema evolution in object-oriented databases
SIGMOD '87 Proceedings of the 1987 ACM SIGMOD international conference on Management of data
SIGMOD '91 Proceedings of the 1991 ACM SIGMOD international conference on Management of data
SIGMOD '93 Proceedings of the 1993 ACM SIGMOD international conference on Management of data
EDBT '94 Proceedings of the 4th international conference on extending database technology: Advances in database technology
A classification algorithm for supporting object-oriented views
CIKM '94 Proceedings of the third international conference on Information and knowledge management
Towards supporting hard schema changes in TSE
CIKM '95 Proceedings of the fourth international conference on Information and knowledge management
The MultiView OODB view system: design and implementation
Theory and Practice of Object Systems - Special issue on subjectivity in object-oriented systems
A formal model of views for object-oriented database systems
Theory and Practice of Object Systems
A Transparent Schema-Evolution System Based on Object-Oriented View Technology
IEEE Transactions on Knowledge and Data Engineering
A View Mechanism for Object-Oriented Databases
EDBT '92 Proceedings of the 3rd International Conference on Extending Database Technology: Advances in Database Technology
A Propagation Mechanism for Populated Schema Versions
ICDE '97 Proceedings of the Thirteenth International Conference on Data Engineering
Schema Virtualization in Object-Oriented Databases
Proceedings of the Fourth International Conference on Data Engineering
Using Object-Oriented Principles to Optimize Update Propagation to Materialized Views
ICDE '96 Proceedings of the Twelfth International Conference on Data Engineering
Multiview: A Methodology for Supporting Multiple Views in Object-Oriented Databases
VLDB '92 Proceedings of the 18th International Conference on Very Large Data Bases
The Design of an Integrity Consistency Checker (ICC) for an Object-Oriented Database System
ECOOP '91 Proceedings of the European Conference on Object-Oriented Programming
Unified Class Evolution by Object-Oriented Views
ER '92 Proceedings of the 11th International Conference on the Entity-Relationship Approach: Entity-Relationship Approach
Simulation of Schema Change using Views
DEXA '95 Proceedings of the 6th International Conference on Database and Expert Systems Applications
CASCON '96 Proceedings of the 1996 conference of the Centre for Advanced Studies on Collaborative research
Consistent View Removal in Transparent Schema Evolution Systems
RIDE '96 Proceedings of the 6th International Workshop on Research Issues in Data Engineering (RIDE '96) Interoperability of Nontraditional Database Systems
Lazy modular upgrades in persistent object stores
OOPSLA '03 Proceedings of the 18th annual ACM SIGPLAN conference on Object-oriented programing, systems, languages, and applications
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Powerful solutions enabling interoperability must allow applications to evolve and requirements of shared databases to change, while minimizing such changes on other integrated applications. Several approaches, such as the transparent schema evolution system (TSE) by Ra et al., schema versions by Lautemann, and integrated views by Bertino, have been proposed to make interoperability possible by using object-oriented techniques. These approaches may generate a large number of schema versions over time resulting in an excessive build-up of classes and underlying object instances, not all being necessarily still in use. This results in degradation of system performance due to the view maintenance and the storage overhead costs. In this paper, we address the problem of removing obsolete view schemas. We characterize four potential problems of schema consistency that could be caused by removal of a single derived class. We demonstrate that schema version removal is sensitive to the order in which individual classes are processed, and present a formal dependency model that captures all dependencies between classes as logic clauses and manipulates them to make decisions on class deletions and nondeletions while guaranteeing the consistency of the schema. We have also developed and proven consistent a dependency graph (DG) representation of the formal model. Lastly, we present a cost model for evaluating alternative removal patterns on DG to assure selection of the optimal solution. The proposed techniques have been implemented in our Schema View Removal (SVR) tool. Lastly, we report experimental findings for applying our techniques for consistent schema version removal on the MultiView/TSE system.