1. A computer-implemented method, comprising: receiving a continuous input data stream related to an application; generating an input relation from the continuous input data stream, the input relation being a bounded set of data records of the continuous input data stream; storing the input relation as an external data source in a database of historical data; receiving a continuous query that identifies the input relation and a range value window operator associated with the input relation; executing the continuous query to generate an output relation, the continuous query executed by applying the range value window operator on an attribute of the input relation to generate the output relation, the attribute comprising a characteristic of an event associated with the input relation; determining whether the event associated with the input relation occurs within a specified time range defined by the range value window operator; inserting or removing the event with respect to the output relation based at least in part on the determination of whether the event associated with the input relation occurs within the specified time range; and providing data records of the output relation, the output relation comprising at least the event when the event was inserted based at least in part on being within the specified range defined by the range value window operator.