Flexible Relations - Operational Support of Variant Relational Structures.

Christian Kalus, Peter Dadam: Flexible Relations - Operational Support of Variant Relational Structures. VLDB 1995: 539-550
  author    = {Christian Kalus and
               Peter Dadam},
  editor    = {Umeshwar Dayal and
               Peter M. D. Gray and
               Shojiro Nishio},
  title     = {Flexible Relations - Operational Support of Variant Relational
  booktitle = {VLDB'95, Proceedings of 21th International Conference on Very
               Large Data Bases, September 11-15, 1995, Zurich, Switzerland},
  publisher = {Morgan Kaufmann},
  year      = {1995},
  isbn      = {1-55860-379-4},
  pages     = {539-550},
  ee        = {db/conf/vldb/KalusD95.html},
  crossref  = {DBLP:conf/vldb/95},
  bibsource = {DBLP,}


The relational model is accepted for its simplicity and elegance. At the other side the simplicity causes the problem, that most semantic type constructs are not representable as a simple relation. Variant and heterogeneous structures belong to those constructs not adequatly supported by the simple relational model. In this paper we give an overview of the model of flexible relations that allows to model and process arbitrary heterogeneous structures, while preserving the relational philosophy of operating with a single constructor. As flexible relations support both the modeling and the operational aspectof variant structures seamlessly, our model truly helps to further bridge the gap between semantic and operational data models.

We discuss the structural part of the model and introduce an algebra for flexible relations. Further we examine a subclass of flexible relations, that can be processedas efficiently as the simple relational model, and show that this subclasspossesses desirable structural normal form properties. In addition, we point out that our approach exceeds the object- oriented paradigm in modeling power, typing precision, and query optimization potential.

Copyright © 1995 by the VLDB Endowment. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by the permission of the Very Large Data Base Endowment. To copy otherwise, or to republish, requires a fee and/or special permission from the Endowment.

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Umeshwar Dayal, Peter M. D. Gray, Shojiro Nishio (Eds.): VLDB'95, Proceedings of 21th International Conference on Very Large Data Bases, September 11-15, 1995, Zurich, Switzerland. Morgan Kaufmann 1995, ISBN 1-55860-379-4
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Paolo Atzeni, Giorgio Ausiello, Carlo Batini, Marina Moscarini: Inclusion and Equivalence between Relational Database Schemata. Theor. Comput. Sci. 19: 267-285(1982) BibTeX
Rafiul Ahad, Amit Basu: ESQL: A Query Language for the Relation Model Supporting Image Domains. ICDE 1991: 550-559 BibTeX
Serge Abiteboul, Richard Hull: Restructuring Hierarchical Database Objects. Theor. Comput. Sci. 62(1-2): 3-38(1988) BibTeX
Stefan Benzschawel, Erich Gehlen, Michael Ley, Thomas Ludwig, Albert Maier, Bernd Walter: LILOG-DB: Database Support for Knowledge Based Systems. Text Understanding in LILOG 1991: 501-594 BibTeX
François Bancilhon, Setrag Khoshafian: A Calculus for Complex Objects. J. Comput. Syst. Sci. 38(2): 326-340(1989) BibTeX
Peter Buneman, Atsushi Ohori: A Type System that Reconsiles Classes and Extents. DBPL 1991: 191-202 BibTeX
Kim B. Bruce, Peter Wegner: An Algebraic Model of Subtype and Inheritance. DBPL 1987: 75-96 BibTeX
E. F. Codd: A Relational Model of Data for Large Shared Data Banks. Commun. ACM 13(6): 377-387(1970) BibTeX
Stefano Ceri, Giuseppe Pelagatti: Correctness of Query Execution Strategies in Distributed Databases. ACM Trans. Database Syst. 8(4): 577-607(1983) BibTeX
Luca Cardelli, Peter Wegner: On Understanding Types, Data Abstraction, and Polymorphism. ACM Comput. Surv. 17(4): 471-522(1985) BibTeX
Howard M. Dreizen, Shi-Kuo Chang: Imprecise Schema: A Rationale for Relations with Embedded Subrelations. ACM Trans. Database Syst. 14(4): 447-479(1989) BibTeX
David Eichmann, D. Alton: A Polymorphic Relational Algebra and Its Optimization. ICDE 1991: 680-689 BibTeX
Ralf Hartmut Güting: Gral: An Extensible Relational Database System for Geometric Applications. VLDB 1989: 33-44 BibTeX
Richard Hull, Roger King: Semantic Database Modeling: Survey, Applications, and Research Issues. ACM Comput. Surv. 19(3): 201-260(1987) BibTeX
Richard Hull: Relative Information Capacity of Simple Relational Database Schemata. SIAM J. Comput. 15(3): 856-886(1986) BibTeX
Richard Hull, Chee-Keng Yap: The Format Model: A Theory of database Organization. J. ACM 31(3): 518-544(1984) BibTeX
Christian Kalus, Peter Dadam: Record Subtyping in Flexible Relations by Means of Attribute Dependencies. ICDE 1995: 383-390 BibTeX
William Kent: Limitations of Record-Based Information Models. ACM Trans. Database Syst. 4(1): 107-131(1979) BibTeX
Christophe Lécluse, Philippe Richard, Fernando Vélez: O2, an Object-Oriented Data Model. SIGMOD Conference 1988: 424-433 BibTeX
Thomas Ludwig: A Brief Overview of LILOG-DB. ICDE 1990: 420-427 BibTeX
Thomas Ludwig, Bernd Walter: EFTA: A Database Retrieval Algebra for Feature-Terms. Data Knowl. Eng. 6: 125-149(1991) BibTeX
David Maier: The Theory of Relational Databases. Computer Science Press 1983, ISBN 0-914894-42-0
Contents BibTeX
Jim Melton, Alan R. Simon: Understanding the New SQL: A Complete Guide. Morgan Kaufmann 1993, ISBN 1-55860-245-3
Contents BibTeX
Joan Peckham, Fred J. Maryanski: Semantic Data Models. ACM Comput. Surv. 20(3): 153-189(1988) BibTeX
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