XQuery containment in presence of variable binding dependencies
Li Chen, Elke Angelika Rundensteiner · 2005
Semantic caching is an important technology for improving the response time of future user queries specified over re-mote servers. This paper deals with the fundamental query containment problem in an XQuery-based semantic caching system. To our best knowledge, the impact of subtle dif-ferences in XQuery semantics caused by different ways of specifying variables on query containment has not yet been studied. We introduce the concept of variable binding de-pendencies for representing the hierarchical element depen-dencies preserved by an XQuery. We analyze the problem of XQuery containment in the presence of such dependencies. We propose a containment mapping technique for nested XQuery in presence of variable binding dependencies. The implication of the nested block structure on XQuery con-tainment is also considered. We mention the performance gains achieved by a semantic caching system we build based on the proposed technique.