Semantic XPath Query Transformation: Opportunities and Performance

Abstract

In this paper we identify the opportunities for the semantic transformation of XPath queries using the structural and explicit semantics defined in an XML schema. Our classification of transformation is the semantic path expression where a path can be semantically contracted, expanded or complemented. Among several applications of such transformations, an obvious one is the semantic optimization of XPath queries. The transformation is likely to result in an improved response time for a given system. We empirically evaluate the gain or loss of performance of the identified transformations with two representative off-the-shelf XML data management systems and XPath query processors.

Using semantics for XPath query transformation

“…Some transformations may produce very promising improvement, thereby providing opportunities for semantic query optimisation. This paper significantly extends the existing work (Le et al, 2007), which was introduced to address only semantic path transformation using a unique path, by more than 90%. The remainder of this paper is organised as follows: Section 2 is an overview of related work on semantic query optimisation in general and of semantic query optimisation for XML query.…”

“…The difference between the earlier semantic path expansion (Le et al, 2007) and this semantic path expansion is that while the former adopted the unique path concept, in the latter we continue using the unique path concept and ensure the accuracy of this transformation by integrating the notion of query tree pattern matching from an XPath query to one or more unique path(s). The normalisation will be applicable for semantic path contraction and semantic path complement.…”

“…The implementation overview of our semantic transformation is designed and shown in Figure 9. On the start-up, the pre-processing schema (Le et al, 2007) system component is called first so that all the constraints/semantics defined in the given schemas are pre-processed. This module is shown by a dash-line rectangle labelled 'Pre-processing schema module'.…”

“…1 We derive a typology of semantic path transformations (Le et al, 2007) including semantic path expansion, semantic path contraction and semantic path complement to transform an XPath query that has no predicate.…”

Automated query transformation for searching semantically rich structured collections

“…And, this signifies that different structured resources need to be addressed accordingly based on their own concepts and structures in its query construction. If we looked at knowledge constructions in query transformation works such as semantic path capturing [4], [2], element types mapping [3] or structures thesaurus [6], each collection has its own knowledge base, for example between DBLP and MONSTER as featured in [3]. This raises the needs of handling collection-dependent knowledge due to heterogeneities (especially information structures, document nature and lexical ambiguity) of these collections.…”