Rewriting Union Queries Using Views

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Title Rewriting Union Queries Using Views
Author Wang, Junhu; Topor, Rodney William; Maher, M.
Journal Name Constraints
Year Published 2005
Place of publication The Netherlands
Publisher Springer
Abstract The problem of finding contained rewritings of queries using views is of great importance in mediated data integration systems. In this paper, we first present a general approach for finding contained rewritings of unions of conjunctive queries with arbitrary built-in predicates. Our approach is based on an improved method for testing conjunctive query containment in this context. Although conceptually simple, our approach generalizes previous methods for finding contained rewritings of conjunctive queries and is more powerful in the sense that many rewritings that can not be found using existing methods can be found by our approach. Furthermore, implication constraints (Zhang, X., & Ozsoyoglu, Z.M. (1997). Implication and referential constraints: A new formal resaoning. IEEE TKDE, 9(6):894–910, Now/Dec.) over the base relations can be easily handled. We then present a simplified approach which is less complete, but is much faster than the general approach, and it still finds maximum rewritings in several special cases. Our general approach finds more rewritings than previous algorithms such as the Bucket and the resolution-based algorithms. Our simplified approach generalizes the U-join and the MiniCon algorithms with no loss of efficiency.
Peer Reviewed Yes
Published Yes
Alternative URI
Volume 10
Page from 219
Page to 251
ISSN 1383-7133
Date Accessioned 2006-03-16
Language en_AU
Research Centre Institute for Integrated and Intelligent Systems
Faculty Faculty of Engineering and Information Technology
Subject PRE2009-Database Management
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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