1. A computer-implemented method of processing streams of data using continuous queries, the method comprising: receiving an instruction to delete a first continuous query; deleting a second continuous query on which is built a view referenced by the first continuous query, if said view is not referenced by any continuous query other than the first continuous query; compiling by a computer the second continuous query, in response to said deleting; and updating said view to refer to a newly-compiled version of the second continuous query, in response to said compiling; if a predetermined condition is met: de-scheduling execution of an operator used by the first continuous query; freeing any resource owned by the operator; and deleting input data still to be processed by the operator if a queue, holding the input data, is shared with another operator, and alternatively marking the queue for deletion if the queue is not shared.