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Efficient Evaluation of Preference Query Processes Using Twig Caches
BibTeX
@MISC{Cho_efficientevaluation,
author = {Sungran Cho and Wolf-tilo Balke},
title = {Efficient Evaluation of Preference Query Processes Using Twig Caches},
year = {}
}
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Abstract
Abstract — Facing today’s information flood needs efficient means for personalization. Therefore XML query processing over large volumes of data needs to make the most out of already spent processing time by caching common (sub)expressions for reuse. This is especially promising for the new paradigm of personalized preference queries. Here a sequence of possible query relaxations is a-priori determined by the users’ preferences. Structural and value-based preferences thus define a query process where predicates are progressively relaxed until a suitable set of best possible results has been retrieved. To improve evaluation times for such query processes we argue that caching intermediate join results of structural preference queries is especially effective, because subsequent queries will always be subsumed by some previously cached queries to a certain extent. In this paper we propose a structural join-based caching scheme that allows preference queries to reuse the most beneficial structural join results of all previous queries. We first design a twig cache along with effective strategies for cache management. Moreover, we present a selection algorithm for join orders using cached data and the preference-induced sequence of future queries to select optimal query evaluation plans. Our benchmark experiments show that by using our twig caches preference query processing can be essentially sped up. Keywords- XML databases, query processing, preference-based retrieval, caching I.
Keyphrases
efficient evaluation query process user preference subsequent query processing time data need selection algorithm optimal query evaluation plan future query previous query preference-based retrieval therefore xml query processing twig cache twig cache preference query processing effective strategy suitable set new paradigm value-based preference personalized preference query efficient mean possible query relaxation preference-induced sequence cache management evaluation time possible result today information flood large volume structural preference query intermediate join result beneficial structural join result preference query join order query processing certain extent keywords xml database
