Processing XML Queries with Structural and Full-Text Constraints.

Efficient query processing on XML data is an important task for querying the data web. In this paper, we consider the XML query which can be represented as a query tree with twig patterns, and also consists of complex full-text constraints. Two approaches are proposed. The structure-first approach will first identify the elements which satisfy the tag constraint, and then process the full-text constraint on the terms represented within each element. The satisfied elements will be combined to meet the complete twig constraints. On the other hand, the keyword-first approach will first identify the elements which represent the required keywords, and then return the elements which satisfy the given full-text predicates and structural constraints. We demonstrate, via an extensive experimental study, that the two approaches have their own merits. [ABSTRACT FROM AUTHOR]