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A top-down approach to answering queries using views


A top-down approach to answering queries using views

Mohajerin, Nima (2008) A top-down approach to answering queries using views. Masters thesis, Concordia University.

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The problem of answering queries using views is concerned with finding answers to a query using only answers to a set of views. In the context of data integration with LAV approach, this problem translates to finding maximally contained rewriting for a query using a set of views. When both query and views are in conjunctive form, rewritings generated by existing bottom-up algorithms in this context are generally expensive to evaluate. As a result, they often require costly post-processing to improve efficiency of computing the answer tuples. In this dissertation, we propose a top-down approach to the rewriting problem of conjunctive queries. We first present a graph-based analysis of the problem and identify conditions that must be satisfied to ensure maximal containment of rewriting. We then present TreeWise, a novel algorithm that uses our top-down approach to efficiently generate maximally contained rewritings that are generally less expensive to evaluate. Our experiments confirm that TreeWise generally produces better quality rewritings, with a performance comparable to the most efficient of previously proposed algorithms

Divisions:Concordia University > Gina Cody School of Engineering and Computer Science > Computer Science and Software Engineering
Item Type:Thesis (Masters)
Authors:Mohajerin, Nima
Pagination:x, 123 leaves : ill. ; 29 cm.
Institution:Concordia University
Degree Name:M. Comp. Sc.
Program:Computer Science and Software Engineering
Thesis Supervisor(s):Constantinides, Constantinos
Identification Number:LE 3 C66C67M 2008 M64
ID Code:975902
Deposited By: Concordia University Library
Deposited On:22 Jan 2013 16:17
Last Modified:13 Jul 2020 20:09
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