On solving efficiently the view selection problem under bag-semantics

Afrati, F; Damigos, M; Gergatsoulis, M

dc.contributor.author	Afrati, F	en
dc.contributor.author	Damigos, M	en
dc.contributor.author	Gergatsoulis, M	en
dc.date.accessioned	2014-03-01T02:52:05Z
dc.date.available	2014-03-01T02:52:05Z
dc.date.issued	2009	en
dc.identifier.issn	18651348	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/35831
dc.subject.other	Binary relation	en
dc.subject.other	Conjunctive queries	en
dc.subject.other	Optimal solutions	en
dc.subject.other	Optimality	en
dc.subject.other	Optimum solution	en
dc.subject.other	Path queries	en
dc.subject.other	Search spaces	en
dc.subject.other	Sub-expressions	en
dc.subject.other	View selection	en
dc.subject.other	View selection problem	en
dc.subject.other	Optimal systems	en
dc.subject.other	Semantics	en
dc.title	On solving efficiently the view selection problem under bag-semantics	en
heal.type	conferenceItem	en
heal.identifier.primary	10.1007/978-3-642-03422-0_2	en
heal.identifier.secondary	http://dx.doi.org/10.1007/978-3-642-03422-0_2	en
heal.publicationDate	2009	en
heal.abstract	In this paper, we investigate the problem of view selection for workloads of conjunctive queries under bag semantics. In particular we aim to limit the search space of candidate viewsets. In that respect we start delineating the boundary between query workloads for which certain restricted search spaces suffice. They suffice in the sense that they do not compromise optimality in that they contain at least one of the optimal solutions. We start with the general case, where we give a tight condition that candidate views can satisfy and still the search space (thus limited) does contain at least one optimal solution. Preliminary experiments show that this reduces the size of the search space significantly. Then we study special cases. We show that for chain query workloads, taking only chain views may miss all optimum solutions, whereas, if we further limit the queries to be path queries (i.e., chain queries over a single binary relation), then path views suffice. This last result shows that in the case of path queries, taking query subexpressions suffice. © 2009 Springer Berlin Heidelberg.	en
heal.journalName	Lecture Notes in Business Information Processing	en
dc.identifier.doi	10.1007/978-3-642-03422-0_2	en
dc.identifier.volume	27 LNBIP	en
dc.identifier.spage	12	en
dc.identifier.epage	28	en