Chang, C. and Garcia-Molina, H. (1999) Mind Your Vocabulary: Query Mapping Across Heterogeneous Information Sources. In: International Conference on Management of Data (SIGMOD 1999), May 31 - June 3, 1999, Philadephia, Pennsylvania.
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Abstract
In this paper we present a mechanism for translating constraint queries, i.e., Boolean expressions of constraints, across heterogeneous information sources. Integrating such systems is difcult in part because they use a wide range of constraints as the vocabulary for formulating queries. W e describe algorithms that apply userprovided mapping rules to translate query constraints into ones that are understood and supported in another context, e.g., that use the proper operators and value formats. W e show that the translated queries minimally subsume the original ones. Furthermore, the translated queries are also the most compact possible. Unlike other query mapping work, we effectively consider inter-dependencies among constraints, i.e., we handle constraints that cannot be translated independently . Furthermore, when constraints are not fully supported, our framework explores relaxations (semantic rewritings) into the closest supported version. Our most sophisticated algorithm (Algorithm TDQM ) does not blindly convert queries to DNF (which would be easier to translate, but expensivinstead it performs a top-down mapping of a query tree, and does local query structure conversion only when necessary .
Item Type: | Conference or Workshop Item (Paper) | |
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Uncontrolled Keywords: | constraint mapping, query translation, constraint dependencies query subsumption, heterogeneity, information integration | |
Subjects: | Computer Science > Digital Libraries Computer Science > Query Processing | |
Projects: | Digital Libraries | |
Related URLs: | Project Homepage | http://www-diglib.stanford.edu/diglib/pub/ |
ID Code: | 408 | |
Deposited By: | Import Account | |
Deposited On: | 25 Feb 2000 16:00 | |
Last Modified: | 27 Dec 2008 16:41 |
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