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In this paper we deal with the problem of finding an optimal query execution plan in database systems. We improve the analysis of a polynomial-time approximation algorithm due to Makino et al. for designing query execution plans with almost optimal number of parallel steps. This algorithm is based on the concept of edge ranking of graphs. We use a new upper bound for the edge ranking number of a tree to derive a better worst-case performance guarantee for this algorithm. We also present some experimental results obtained during the tests of the algorithm on random graphs in order to compare the quality of both approximation ratios on average. Both theoretical analysis and experimental results indicate the superiority of our approach.
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Czasopismo
Rocznik
Tom
Strony
273--285
Opis fizyczny
bibliogr. 18 poz.
Twórcy
autor
autor
- Department of Algorithms and System Modeling Faculty of Electronics, Telecommunications and Informatics Gdańsk University of Technology Narutowicza 11/12, 80-952 Gdańsk, Poland, deren,kubale@eti.pg.gda.pl
Bibliografia
- [1] Chaudhuri, S.: An overview of query optimization in relational systems, Proc. PODS, Seattle (WA), USA, 1998.
- [2] de la Torre, P., Greenlaw, R., Schäffer,A. A.: Optimal edge ranking of trees in polynomial time, Algorithmica, 13, 1995, 529-618.
- [3] Dereniowski, D., Kubale, M.: Parallel query processing and edge ranking of graphs, Proceedings of the Sixth International Conference on Parallel Processing and AppliedMathematics, Poznan, Poland, September 2005, (to appear).
- [4] Furer, M., Raghavachari, B.: Approximating the minimum-degree Steiner tree to within one of optimal, J. Algorithms, 17, 1994, 409-423.
- [5] Ibaraki, T., Kameda, T.: On the optimal nesting order for computing N-relational joins, ACM Transactions on Database Systems, 9, 1984, 482-502.
- [6] Kremer, M., Gryz, J.: A survey of query optimization in parallel databases, Technical Report CS-1999-04 York University, 1999.
- [7] Lam, T. W., Yue, F. L.: Optimal edge ranking of trees in linear time, Proc. of the 9th Annual ACM-SIAM Symposium on Discrete Algorithms, 1998, 436-445.
- [8] Makino, K., Uno, Y., Ibaraki, T.: On minimum edge ranking spanning trees, J. Algorithms, 38, 2001, 411-437.
- [9] Makino, K., Uno, Y., Ibaraki, T.: Minimum edge ranking spanning trees of threshold graphs, LNCS, 2518, 2002, 428-440.
- [10] Ullman, J. D.: Principles of Database and Knowledge-Base Systems, Vol. 1. Computer Science Press, Maryland, 1990.
- [11] Yu, P. S., Chen, M.-S., Wolf, J. L., Turek, J.: Parallel query processing, in: N.R. Adam, B.K. Bhargava, editors, Advanced Database Systems LNCS, Springer-Verlag, 759, 1993.
Typ dokumentu
Bibliografia
Identyfikator YADDA
bwmeta1.element.baztech-article-BUS2-0009-0036