Certain example embodiments concern an analysis system for analyzing at least one continuous query for at least one input data stream. The at least one input data stream includes a sequence of events captured by at least one sensor. The debugging system includes an analyzer for executing the at least one continuous query and at least one modified continuous query on the at least one input data stream, for comparing at least one output data stream produced by the at least one continuous query with at least one second output data stream produced by the at least one modified continuous query, and for indicating at least one difference between the at least one output data stream and the at least one second output data stream. The analyzer synchronizes the execution of the at least one continuous query and the at least one modified continuous query.