Distributed and Parallel Databases

, Volume 5, Issue 1, pp 77–114 | Cite as

Multidatabase Query Optimization

  • Cem Evrendilek
  • Asuman Dogac
  • Sena Nural
  • Fatma Ozcan


A multidatabase system (MDBS) allows the users to simultaneously access heterogeneous,and autonomous databases using an integrated schema and a single global query language. The query optimization problem in MDBSs is quite different from the query optimization problem in distributed homogeneous databases due to schema heterogeneity and autonomy of local database systems.

In this work, we consider the optimization of query distribution in case of data replication and the optimization of intersite joins, that is, the join of the results returned by the local sitesin response to the global subqueries. The algorithms presented for the optimization of intersite joins try to maximize the parallelism in execution and take the federated nature of the problem into account. It has also been shown through a comparativeperformance study that the proposed intersite join optimization algorithms are efficient.The approach presented can easily be generalized to any operation required for intersite query processing.

The query optimization scheme presentedin this paper is being implemented within the scopeof a multidatabase system which is based on OMG‘sobject management architecture.

Multidatabases query optimization heterogeneity 


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  1. 1.
    E. I. Chong. “Query Optimization in Distributed Database Systems and Multidatabase Systems”, Ph.D Thesis, Northwestern University, 1994.Google Scholar
  2. 2.
    U. Dayal. ”Processing Queries over Generalization Hierarchies in a Multidatabase System”, in Proc. of VLDB Conference, 1983.Google Scholar
  3. 3.
    U. Dayal. ”Query Processing in a Multidatabase System”, Query Processing: Database Systems, eds. Kim, et al., pp.81–108, Springer-Verlag, New York, 1985.Google Scholar
  4. 4.
    A. Dogac, et. al. ”METU Object-Oriented Database System”, Demo Description in Proceedings of ACM SIGMOD Intl. Conf. on Management of Data, pp. 513, Minneapolis, May 1994.Google Scholar
  5. 5.
    A. Dogac, C. Dengi, E. Kilic, G. Ozhan, F. Ozcan, S. Nural, C. Evrendilek, U. Halici, B. Arpinar, P. Koksal, N. Kesim, and S. Mancuhan. ”METU Interoperable Database System”, ACM SIGMOD Record, 24(3),pp. 56–61, September, 1995.Google Scholar
  6. 6.
    A. Dogac, U. Halici, E. Kilic, G. Ozhan, F. Ozcan, S. Nural, C. Dengi, S. Mancuhan, B. Arpinar, P. Koksal, C. Evrendilek. ”METU Interoperable Database System”, Demo Description, In Proc. of ACM Sigmod Intl. Conf. on Management of Data, pp 552, Montreal, June 1996.Google Scholar
  7. 7.
    W. Du, R. Krishnamurthy, M-C. Shan. ”Query Optimization in Heterogeneous DBMS”, Proc. of the 18th Int'l Conf. Very Large Data Bases, pp. 277–291, August 1992.Google Scholar
  8. 8.
    A. Dogac, C. Dengi, T. Ozsu. ”Building Interoperable Databases on Distributed Object Management Platforms”, Communications of the ACM (to appear).Google Scholar
  9. 9.
    W. Du, M-C Shan and U. Dayal. ”Reducing Multidatabase Query Response Time by Tree Balancing”, In ACM SIGMOD Intl. Conf. on Management of Data, pp. 293–303, 1995.Google Scholar
  10. 10.
    C. Evrendilek, A. Dogac, S. Nural, F. Ozcan, ”Query Optimization in Multidatabase Systems”, in Proc. of Next Generation Information Technologies and Systems, pp. 49–58, Israel, June 1995.Google Scholar
  11. 11.
    C. Evrendilek. ”Multidatabase Query Processing and Optimization”, Ph. D. Thesis, Middle East Technical University, in Preparation, 1995.Google Scholar
  12. 12.
    M. R. Garey, and D. S. Johnson. Computers and Intractability: A Guide to the Theory of NP-Completeness, Freeman and Co., San Francisco, 1979.Google Scholar
  13. 13.
    E. Horowitz, S. Sahni. Fundamentals of Data Structures in Pascal, Pitman Publishing Limited, 1984.Google Scholar
  14. 14.
    W. Hong, M. Stonebraker. ”Optimization of Parallel Query Execution Plans in XPRS”, Journal of Distributed and Parallel Databases, Vol. 1, No. 1, pp. 9–32, Kluwer Academic Publishers, January, 1993.Google Scholar
  15. 15.
    T. Ibaraki, T. Kameda. ”On the Optimal Nesting Order for Computing N-Relational Joins”, ACM Trans. on Database Systems, Vol. 9, No. 3, pp. 482–502, September 1984.Google Scholar
  16. 16.
    E. Kilic, G. Ozhan, C. Dengi, N. Kesim, P. Koksal and A. Dogac, ”Experiences in Using CORBA in a Multidatabase Implementation”, in Proc. of 6th Intl.Workshop on Database and Expert System Applications, pp. 223–230, London, Sept. 1995.Google Scholar
  17. 17.
    H. Lu, B-C Ooi, C-H Goh. ”On Global Multidatabase Query Optimization”, Sigmod Record, Vol.21, No. 4, pp. 6–11, December 1992.Google Scholar
  18. 18.
    G.M. Lohman, C. Mohan, L.M. Haas, B.G. Lindsay, P.G. Selinger, P.F. Wilms, and D. Daniels, ”Query Processing in R* ”, Query Processing in Database Systems, pp. 31–47, Springer-Verlag, 1985.Google Scholar
  19. 19.
    E-P. Lim and J. Srivastava. ”Query optimization/processing in federated database systems”, Technical Report 92-68, Dept. of Comp. Sc., University of Minnesota.Google Scholar
  20. 20.
    H. Lu, M. Shan, K. Tan. ”Optimization of Multi-way Join Queries for Parallel Execution”, In Proc. of the 17th Intl. Conf. on Very Large Data Bases, pp. 549–560, Barcelona, September, 1991.Google Scholar
  21. 21.
    A. Dogac, C. Dengi, E. Kilic, G. Ozhan, F. Ozcan, S. Nural, C. Evrendilek, U. Halici, B. Arpinar, P. Koksal, N. Kesim, S. Mancuhan. ”A Multidatabase System Implementation on CORBA”, 6th Intl. Workshop on Research Issues in Data Engineering (RIDE-NDS '96), pp. 2–11, New Orleans, February 1996.Google Scholar
  22. 22.
    G. Ozhan, A. Dogac, E. Kilic, F. Ozcan, S. Nural, C. Dengi, U. Halici, B. Arpinar, P. Koksal, S. Mancuhan, C. Evrendilek. ”Making Oracle7, Sybase and Adabas D Interoperable through CORBA: MIND Project”, in Proc. of European Oracle User Group Conference, pp. 1047–1058, Amsterdam, April 1996.Google Scholar
  23. 23.
    W. Meng, C. Yu. ”Query Processing in Multidatabase Systems”, in Modern Database Systems (Edtr. Won Kim), pp. 551–572, ACM Press 1995.Google Scholar
  24. 24.
    S. Nural, P. Koksal, F. Ozcan, A. Dogac. ”Query decomposition and Processing in Multidatabase Systems”, Object Oriented Database Symposium of the 3rd European Joint Conference on Engineering Systems Design and Analysis, pp. 41–52, France, 1996.Google Scholar
  25. 25.
    C. Ozkan, A. Dogac, M. Altinel. ”A Cost Model for Path Expressions in Object-Oriented Queries”, Journal of Database Management, Vol.7, No. 3, pp. 25–33, June 1996.Google Scholar
  26. 26.
    C. Ozkan, A. Dogac, C. Evrendilek. ”A Heuristic Approach for Optimization of Path Expressions”, in Proc. of 6th Intl. Conf. on Database and Expert System Applications, pp. 522–534, London, September 1995.Google Scholar
  27. 27.
    F. Ozcan, S. Nural, P. Koksal, C. Evrendilek, A. Dogac. ”Dynamic Query Optimization on a Distributed Object Management Platform”, 5th Intl. Conf. on Information and Knowledge Management, pp. 117–124, USA, 1996.Google Scholar
  28. 28.
    A. Rosenthal, D. Reiner. ”Extending the Algebraic Framework of Query Processing to Handle Outerjoins”, in Proc. of the 10th VLDB Conference, pp. 334–341, Singapore, 1984.Google Scholar
  29. 29.
    B. Salzberg. File Structures: An Analytical Approach, Prentice Hall Inc., 1988.Google Scholar
  30. 30.
    R. M. Soley. Object Management Architecture Guide, OMG, Second Edition, 1992.Google Scholar
  31. 31.
    S. Salza, G. Barone, T. Morzy. ”Distributed Query Optimization in Loosely Coupled Multidatabase Systems”, Proc. of Intl. Conf. on Database Theory, 1995.Google Scholar
  32. 32.
    P. Scheurmann and E. Chong. ”Role-based Query Processing in Multidatabase Systems”, in Proc. of EDBT, 1994.Google Scholar
  33. 33.
    P.G. Selinger, M.M. Astrahan, D.D. Chamberlin, R.A. Lorie, and T.G. Price, ”Access Path Selection in a Relational Database Management System”, Proc. of ACM-SIGMOD, 1979.Google Scholar
  34. 34.
    A. Wilschut, P. Apers. Dataflow Query Execution in a Parallel Main-Memory Environment,Journal of Distributed and Parallel Databases, Vol. 1, No. 1, pp. 103–128, Kluwer Academic Publishers, January, 1993.Google Scholar
  35. 35.
    A. Wilschut, J. Flokstra, P. Apers. Parallel Evaluation of Multi-Join Queries, Technical Report, University of Twente, the Netherlands, 1994.Google Scholar

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • Cem Evrendilek
    • 1
  • Asuman Dogac
    • 1
  • Sena Nural
    • 1
  • Fatma Ozcan
    • 1
  1. 1.Software Research and Development CenterMiddle East Technical University (METU)AnkaraTurkiye

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