Advanced Data Stream Sharing

Using multi-query optimization for sharing common work among multiple queries requires theidentification of shareable query components. This kind of optimization is particularly effective indistributed data stream management systems (DSMSs) with multiple continuous queries running con-currently over long periods of time. In this paper, we introduce an abstract property tree (APT) andits 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 potentiallypreprocessed data streams among multiple queries. The presented techniques thus allow for efficientresource usage and provide for an increased number of queries that can be processed concurrently.