Containment of partially specified tree-pattern queries in the presence of dimension graphs

Theodoratos, D; Placek, P; Dalamagas, T; Souldatos, S; Sellis, T

dc.contributor.author	Theodoratos, D	en
dc.contributor.author	Placek, P	en
dc.contributor.author	Dalamagas, T	en
dc.contributor.author	Souldatos, S	en
dc.contributor.author	Sellis, T	en
dc.date.accessioned	2014-03-01T01:30:01Z
dc.date.available	2014-03-01T01:30:01Z
dc.date.issued	2009	en
dc.identifier.issn	1066-8888	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/19456
dc.subject	Partial tree-pattern query	en
dc.subject	Query containment	en
dc.subject	Tree-structured data	en
dc.subject	XML	en
dc.subject.classification	Computer Science, Hardware & Architecture	en
dc.subject.classification	Computer Science, Information Systems	en
dc.subject.other	Experimental evaluations	en
dc.subject.other	Extracting informations	en
dc.subject.other	Heuristic approaches	en
dc.subject.other	In trees	en
dc.subject.other	Multiple data sources	en
dc.subject.other	Necessary and sufficient conditions	en
dc.subject.other	Partial specifications	en
dc.subject.other	Partial tree-pattern query	en
dc.subject.other	Query containment	en
dc.subject.other	Query times	en
dc.subject.other	Structural informations	en
dc.subject.other	Tree patterns	en
dc.subject.other	Tree structures	en
dc.subject.other	Tree-structured data	en
dc.subject.other	Data structures	en
dc.subject.other	Linguistics	en
dc.subject.other	Markup languages	en
dc.subject.other	Query languages	en
dc.subject.other	Query processing	en
dc.subject.other	Specification languages	en
dc.subject.other	Specifications	en
dc.subject.other	XML	en
dc.subject.other	Trees (mathematics)	en
dc.title	Containment of partially specified tree-pattern queries in the presence of dimension graphs	en
heal.type	journalArticle	en
heal.identifier.primary	10.1007/s00778-008-0097-y	en
heal.identifier.secondary	http://dx.doi.org/10.1007/s00778-008-0097-y	en
heal.language	English	en
heal.publicationDate	2009	en
heal.abstract	Nowadays, huge volumes of data are organized or exported in tree-structured form. Querying capabilities are provided through tree-pattern queries. The need for querying tree-structured data sources when their structure is not fully known, and the need to integrate multiple data sources with different tree structures have driven, recently, the suggestion of query languages that relax the complete specification of a tree pattern. In this paper, we consider a query language that allows the partial specification of a tree pattern. Queries in this language range from structureless keyword-based queries to completely specified tree patterns. To support the evaluation of partially specified queries, we use semantically rich constructs, called dimension graphs, which abstract structural information of the tree-structured data. We address the problem of query containment in the presence of dimension graphs and we provide necessary and sufficient conditions for query containment. As checking query containment can be expensive, we suggest two heuristic approaches for query containment in the presence of dimension graphs. Our approaches are based on extracting structural information from the dimension graph that can be added to the queries while preserving equivalence with respect to the dimension graph. We considered both cases: extracting and storing different types of structural information in advance, and extracting information on-the-fly (at query time). Both approaches are implemented, validated, and compared through experimental evaluation. © 2008 Springer-Verlag.	en
heal.publisher	SPRINGER	en
heal.journalName	VLDB Journal	en
dc.identifier.doi	10.1007/s00778-008-0097-y	en
dc.identifier.isi	ISI:000262317000010	en
dc.identifier.volume	18	en
dc.identifier.issue	1	en
dc.identifier.spage	233	en
dc.identifier.epage	254	en