Alyoubi, K.H. and Helmer, S. and Wood, Peter T. (2015) Ordering selection operators under partial ignorance. In: UNSPECIFIED (ed.) Proceedings of the 24th ACM International on Conference on Information and Knowledge Management. New York, U.S.: Association For Computing Machinery, pp. 1521-1530. ISBN 9781450337946.
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Abstract
Optimising queries in real-world situations under imperfect conditions is still a problem that has not been fully solved. We consider finding the optimal order in which to execute a given set of selection operators under partial ignorance of their selectivities. The selectivities are modelled as intervals rather than exact values and we apply a concept from decision theory, the minimisation of the maximum regret, as a measure of optimality. The associated decision problem turns out to be NP-hard, which renders a brute-force approach to solving it impractical. Nevertheless, by investigating properties of the problem and identifying special cases which can be solved in polynomial time, we gain insight that we use to develop a novel heuristic for solving the general problem. We also evaluate minmax regret query optimisation experimentally, showing that it outperforms a currently employed strategy of optimisers that uses mean values for uncertain parameters.
Metadata
| Item Type: | Book Section |
|---|---|
| Additional Information: | CIKM'15 24th ACM International Conference on Information and Knowledge Management; Melbourne, VIC, Australia — October 19 - 23, 2015 |
| School: | Birkbeck Faculties and Schools > Faculty of Science > School of Computing and Mathematical Sciences |
| Research Centres and Institutes: | Birkbeck Knowledge Lab |
| Depositing User: | Peter Wood |
| Date Deposited: | 21 Oct 2015 16:14 |
| Last Modified: | 18 Mar 2025 11:32 |
| URI: | https://eprints.bbk.ac.uk/id/eprint/13120 |
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