Rewriting conjunctive queries determined by views

Afrati, F

dc.contributor.author	Afrati, F	en
dc.date.accessioned	2014-03-01T02:44:56Z
dc.date.available	2014-03-01T02:44:56Z
dc.date.issued	2007	en
dc.identifier.issn	03029743	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/32038
dc.subject	Conjunctive Queries	en
dc.subject.other	Problem solving	en
dc.subject.other	Query processing	en
dc.subject.other	Conjunctive queries	en
dc.subject.other	Equivalent rewriting	en
dc.subject.other	Query equivalence	en
dc.subject.other	Query languages	en
dc.title	Rewriting conjunctive queries determined by views	en
heal.type	conferenceItem	en
heal.identifier.primary	10.1007/978-3-540-74456-6_9	en
heal.identifier.secondary	http://dx.doi.org/10.1007/978-3-540-74456-6_9	en
heal.publicationDate	2007	en
heal.abstract	Answering queries using views is the problem which examines how to derive the answers to a query when we only have the answers to a set of views. Constructing rewritings is a widely studied technique to derive those answers. In this paper we consider the problem of existence of rewritings in the case where the answers to the views uniquely determine the answers to the query, Specifically, we say that a view set V determines a query Q if for any two databases D1, D2 it holds: V(D1) = V(D 2) implies Q(D1) = Q(D2). We consider the case where query and views are defined by conjunctive queries and investigate the question: If a view set V determines a query Q, is there an equivalent rewriting of Q using V? We present here interesting cases where there are such rewritings in the language of conjunctive queries. Interestingly, we identify a class of conjunctive queries, CQpath, for which a view set can produce equivalent rewritings for ""almost all"" queries which are determined by this view set. We introduce a problem which relates determinacy to query equivalence. We show that there are cases where restricted results can carry over to broader classes of queries. © Springer-Verlag Berlin Heidelberg 2007.	en
heal.journalName	Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)	en
dc.identifier.doi	10.1007/978-3-540-74456-6_9	en
dc.identifier.volume	4708 LNCS	en
dc.identifier.spage	78	en
dc.identifier.epage	89	en