1. A method of profiling one or more event streams using a profiling computer system that includes at least one hardware processor, the one or more event streams delivered via an event bus that is implemented using the at least one hardware processor, the method comprising: receiving, via the event bus and at the profiling computer system, input events from the one or more event streams emitted to the event bus, the input events also being delivered to at least one production complex event processing (CEP) system; receiving, via the event bus and at the profiling computer system, query registration-related events from a registration event stream emitted to the event bus, the query registration-related events being generated in response to registration of queries with the at least one production CEP system that are executed thereon against specified ones of the one or more event streams using at least one operator, wherein each query registration-related event includes a reference to at least one of the one or more event streams and operator data that corresponds to how a query that corresponds to the query registration-related event will be executed by the production CEP system; developing event-based profiles by subjecting the received input events of the one or more event streams to a profiling complex event processing (CEP) engine that is executing using the at least one hardware processor of the profiling computer system, the event-based profiles including data mining related characteristics and/or statistical characteristics for each of the one or more input event streams; in response to reception of each query registration-related event, generating, using the profiling computer system, a plurality of events, wherein each of the plurality of events is based on a different one of plural operators of the query that corresponds to the query registration-related event; developing query-based profiles by subjecting the generated plurality of events to the profiling CEP engine, the query-based profiles including data indicative of how relevant the queries performed on the one or more input event streams are and/or how those queries are relevant to the one or more input event streams on which they are performed; and storing the event-based profiles and the query-based profiles to a non-transitory computer readable storage medium.