Decomposition and processing strategies of global XQuery queries over distributed environments

Abstract

The global XML view concept for integrating distributed heterogeneous data sources over the Internet makes it possible to deal with such data as a single XML document. The global XQuery queries based on a global XML view can search heterogeneous data seamlessly, being distributed in the local systems. In distributed relational databases, one of the important techniques for processing global SQL queries was the decomposition. So, it is natural to consider how the decomposition technique for SQL queries can be applied to processing global XQuery queries. Compared to well-structured relational data, however, XML data is not structured since it is like trees. So the XQuery language reflects this characteristic and its syntax is very complex. For example, the structure-based operations such as the FOR clauses are very specific and is not supported by SQL. Therefore, this paper proposes a method for decomposing a global XQuery query into local XQuery queries and also gives query processing strategies based on the decomposition. © 2008 Springer-Verlag Berlin Heidelberg.