ADDING NEW CONTINUOUS QUERIES TO A DATA STREAM MANAGEMENT SYSTEM OPERATING ON EXISTING QUERIES

摘要

A new continuous query to a data stream management system (DSMS) may use a stream or a relation which may or may not be used by continuous queries previously registered in the DSMS. The DSMS is programmed to modify an execution plan to accommodate execution of the new query while continuing to execute the previously registered continuous queries. The modified execution plan may include new operators and/or share existing operators. The DSMS is programmed to cause operators which output a relation to propagate a current state of the relation to each newly-coupled operator that uses the relation. The current state is propagated only to operators that have been newly coupled and have thus not yet received any state information previously. After propagation of current state to newly-coupled operators, results of processing any new data for the relation are supplied to all operators coupled thereto, including newly-coupled operators and existing operators.