A database executes logical queries against in-flight data in a data streaming application. The data streaming application returns results representing in-flight data matching the parameters of the logical queries. Preferably, the streaming application produces data tuples for input to at least one table of the database. A user submitting queries may define the query scope to include in-flight data in the streaming application, causing the database manager to forward the query to the streaming application. A streaming application manager invokes database agents in respective nodes of the streaming application, which query in-flight data in respective buffers of the streaming application. The responses are provided back to the stream manager and the database manager. Profiling data obtained by trace analysis may be used to predict tuples which will be produced for the database.