Cost Framework for a Heterogeneous Distributed Semi-structured Environment

This paper proposes a generic cost framework for query optimization in an XML-based mediation system called XLive. which integrates distributed, heterogeneous and autonomous data sources. Our approach relies on cost annotation on an XQuery logical representation called Tree Graph View (TGV). A generic cost communication language is used to give an XML-based uniform format for cost communication within the XLive system. This cost framework is suitable for various search strategies to choose the best execution plan for the sake of minimizing the execution cost.