On rewriting Xpath Queries Using Views

Afrati, F; Chirkova, R; Gergatsoulis, M; Kimelfeld, B; Pavlaki, V; Sagiv, Y

dc.contributor.author	Afrati, F	en
dc.contributor.author	Chirkova, R	en
dc.contributor.author	Gergatsoulis, M	en
dc.contributor.author	Kimelfeld, B	en
dc.contributor.author	Pavlaki, V	en
dc.contributor.author	Sagiv, Y	en
dc.date.accessioned	2014-03-01T02:46:15Z
dc.date.available	2014-03-01T02:46:15Z
dc.date.issued	2009	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/32627
dc.subject	Materialized Views	en
dc.subject	Upper Bound	en
dc.subject.other	Complexity bounds	en
dc.subject.other	Containment test	en
dc.subject.other	Materialized view	en
dc.subject.other	Novel techniques	en
dc.subject.other	Rewriting algorithm	en
dc.subject.other	Upper Bound	en
dc.subject.other	XPath queries	en
dc.subject.other	Computability and decidability	en
dc.subject.other	Database systems	en
dc.title	On rewriting Xpath Queries Using Views	en
heal.type	conferenceItem	en
heal.identifier.primary	10.1145/1516360.1516381	en
heal.identifier.secondary	http://dx.doi.org/10.1145/1516360.1516381	en
heal.publicationDate	2009	en
heal.abstract	The problem of rewriting a query using a materialized view is studied for a well known fragment of XPath that includes the following three constructs: wildcards, descendant edges and branches. In earlier work, determining the existence of a rewriting was shown to be coNP-hard, but no tight complexity bound was given. While it was argued that Σ3p is an upper bound, the proof was based on results that have recently been refuted. Consequently, the exact complexity (and even decidability) of this basic problem has been unknown, and there have been no practical rewriting algorithms if the query and the view use all the three constructs mentioned above. It is shown that under fairly general conditions, there are only two candidates for rewriting and hence, the problem can be practically solved by two containment tests. In particular, under these conditions, determining the existence of a rewriting is coNP-complete. The proofs utilize various novel techniques for reasoning about XPath patterns. For the general case, the exact complexity remains unknown, but it is shown that the problem is decidable. Copyright 2009 ACM.	en
heal.journalName	Proceedings of the 12th International Conference on Extending Database Technology: Advances in Database Technology, EDBT'09	en
dc.identifier.doi	10.1145/1516360.1516381	en
dc.identifier.spage	168	en
dc.identifier.epage	179	en