Abstract
The optimization problem for a subclass of conjunctive queries which is formed by the union of the class of fan-out free queries and a subclass of typed fan-out queries is investigated. The typed fan-out queries in this class are obtained from simple tableaux by allowing at most one attribute to violate the simple-tableau property. The optimization problem for several restricted subsets of typed fan-out queries is already known to be NP-hard. It is shown that the queries under consideration possess several useful properties which are then used to obtain an O(n2) optimization algorithm based on the implication graph technique. The optimization of typed fan-out queries, obtained from simple tableaux by allowing at most two attributes to violate the simple tableau property, is shown to be NP-hard.
Original language | English |
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Title of host publication | ICDT 1990 - 3rd International Conference on Database Theory, Proceedings |
Editors | Serge Abiteboul, Paris C. Kanetlakis |
Publisher | Springer Verlag |
Pages | 453-469 |
Number of pages | 17 |
ISBN (Print) | 9783540535072 |
DOIs | |
State | Published - 1990 |
Event | 3rd International Conference on Database Theory, ICDT 1990 - Paris, France Duration: 12 Dec 1990 → 14 Dec 1990 |
Publication series
Name | Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) |
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Volume | 470 LNCS |
ISSN (Print) | 0302-9743 |
ISSN (Electronic) | 1611-3349 |
Conference
Conference | 3rd International Conference on Database Theory, ICDT 1990 |
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Country/Territory | France |
City | Paris |
Period | 12/12/90 → 14/12/90 |
Bibliographical note
Publisher Copyright:© Springer-Verlag Berlin Heidelberg 1990.