Multi-Xpath query processing in client-server environment

Abstract

When a client submits a set of XPath queries to an XML database across a network, the answers sent back by the server may include redundancy because of the characteristics of XML and XPath: XML data has a nested structure and XPath query retrieves substructures appearing at arbitrary levels. This kind of redundancy arises in two ways: some elements may appear in more than one answer sets, or some elements may be subelements of other elements. In this thesis, we propose an algorithm to eliminate this kind of redundancy in multi-XPath query processing by replacing redundant data with pointers. In particular, two different approaches are designed for pointer insertion. It is shown in experiments that this approach can substantially reduce the communication costs in multi-XPath query processing in a client-server environment, which is critical in slow networks where the communication cost could easily become a bottleneck.