Using multi-query optimization for sharing common work among multiple queries requires the identification of shareable query components. This kind of optimization is particularly effective in distributed data stream management systems (DSMSs) with multiple continuous queries running concurrently over long periods of time. In this paper, we introduce an abstract property tree (APT) and its extension, an abstract property forest (APF), for representing, matching, and merging XQuery-based queries and XML data streams in a distributed DSMS to enable the sharing of potentially preprocessed data streams among multiple queries. The presented techniques thus allow for efficient resource usage and provide for an increased number of queries that can be processed concurrently.     «

Using multi-query optimization for sharing common work among multiple queries requires the identification of shareable query components. This kind of optimization is particularly effective in distributed data stream management systems (DSMSs) with multiple continuous queries running concurrently over long periods of time. In this paper, we introduce an abstract property tree (APT) and its extension, an abstract property forest (APF), for representing, matching, and merging XQuery-based queries a...     »