1. A computer implemented method for conversion of units of measure during data stream processing, the method comprising: receiving one or more input streams to be processed by a query, wherein the query is associated with one or more expected input stream types and an expected output stream type; pre-processing the one or more input streams to match the one or more expected input stream types, wherein the pre-processing comprises conversion of one or more units of measure of the one or more input streams; processing the pre-processed one or more input streams according to the query to generate a result output stream; post-processing the result output stream to match the expected output stream type defined by the query; and generating an output stream with the expected output stream type.