Rewriting queries using views in the presence of arithmetic comparisons

Afrati, F; Li, C; Mitra, P

dc.contributor.author	Afrati, F	en
dc.contributor.author	Li, C	en
dc.contributor.author	Mitra, P	en
dc.date.accessioned	2014-03-01T01:25:05Z
dc.date.available	2014-03-01T01:25:05Z
dc.date.issued	2006	en
dc.identifier.issn	0304-3975	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/17534
dc.subject	Databases	en
dc.subject	Query languages	en
dc.subject	Query rewriting	en
dc.subject.classification	Computer Science, Theory & Methods	en
dc.subject.other	Algebra	en
dc.subject.other	Algorithms	en
dc.subject.other	Computer programming	en
dc.subject.other	Database systems	en
dc.subject.other	Problem solving	en
dc.subject.other	Arithmetic comparisons	en
dc.subject.other	Query containment	en
dc.subject.other	Query rewriting	en
dc.subject.other	Query languages	en
dc.title	Rewriting queries using views in the presence of arithmetic comparisons	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.tcs.2006.08.020	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.tcs.2006.08.020	en
heal.language	English	en
heal.publicationDate	2006	en
heal.abstract	We consider the problem of answering queries using views, where queries and views are conjunctive queries with arithmetic comparisons over dense orders. Previous work only considered limited variants of this problem, without giving a complete solution. We first show that obtaining equivalent rewritings for conjunctive queries with arithmetic comparisons is decidable. Then, we consider the problem of finding maximally contained rewritings (MCRs) where the decidability proof does not carry over. We investigate two special cases of this problem where the query uses only semi-interval comparisons. In both cases decidability of finding MCRs depends on the query containment test. First, we address the case where the homomorphism property holds in testing query containment. In this case decidability is easy to prove but developing an efficient algorithm is not trivial. We develop such an algorithm and prove that it is sound and complete. This algorithm applies in many cases where the query uses only left (or right) semi-interval comparisons. Then, we develop a new query containment test for the case where the containing query uses both left and right semi-interval comparisons but with only one left (or right) semi-interval subgoal. Based on this test, we show how to produce an MCR which is a Datalog query with arithmetic comparisons. The containment test that we develop obtains a result of independent interest. It finds another special case where query containment in the presence of arithmetic comparisons can be tested in nondeterministic polynomial time. (c) 2006 Elsevier B.V. All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE BV	en
heal.journalName	Theoretical Computer Science	en
dc.identifier.doi	10.1016/j.tcs.2006.08.020	en
dc.identifier.isi	ISI:000242872300005	en
dc.identifier.volume	368	en
dc.identifier.issue	1-2	en
dc.identifier.spage	88	en
dc.identifier.epage	123	en