Multiple Materialized View Selection for XPath Query Rewriting

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Multiple Materialized View Selection for XPath Query Rewriting

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by Nan Tang , M. Tamer Özsu , Byron Choi , Kam-fai Wong

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BibTeX

@MISC{Tang_multiplematerialized,
    author = {Nan Tang and M. Tamer Özsu and Byron Choi and Kam-fai Wong},
    title = {Multiple Materialized View Selection for XPath Query Rewriting},
    year = {}
}

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Abstract

Abstract — We study the problem of answering XPATH queries using multiple materialized views. Despite the efforts on answering queries using single materialized view, answering queries using multiple views remains relatively new. We address two important aspects of this problem: multiple-view selection and equivalent multiple-view rewriting. With regards to the first problem, we propose an NFA-based approach (called VFILTER) to filter views that cannot be used to answer a given query. We then present the criterion for multiple view/query answerability. Based on the output of VFILTER, we further propose a heuristic method to identify a minimal view set that can answer a given query. For the problem of multiple-view rewriting, we first refine the materialized fragments of each selected view (like pushing selection), we then join the refined fragments utilizing an encoding scheme. Finally, we extract the result of the query from the materialized fragments of a single view. Experiments show the efficiency of our approach.

Keyphrases

xpath query multiple materialized view selection materialized fragment encoding scheme single view heuristic method multiple-view rewriting multiple view multiple view query answerability refined fragment multiple-view selection first problem important aspect minimal view equivalent multiple-view rewriting multiple materialized view nfa-based approach

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