1. A computer-implemented method for operator fusion management in a stream computing environment, the method comprising: establishing a topology model which indicates: a set of stream operators, a set of connections between the set of stream operators, and a set of stream operator attributes for the set of stream operators; determining, based on the topology model, a set of operator fusion management operations to combine the set of stream operators into a set of processing elements, wherein determining, based on the topology model, the set of operator fusion management operations includes using a set of deployment cluster characteristics, and wherein the set of deployment cluster characteristics includes both a compute host quantity factor and a compute host size factor; detecting, using the topology model, a familial subset of the set of stream operators which indicates one or more stream operators that have a fusion-related mandate; building a single processing element that includes the familial subset of the set of stream operators; constructing, by performing the set of operator fusion management operations, the set of processing elements, wherein the establishing, the determining, and the constructing each occur in an automated fashion without user intervention; receiving a stream of tuples to be processed by the set of processing elements operating on a pool of compute hosts; and processing, using the set of processing elements operating on the pool of compute hosts, the stream of tuples.