1. A real-time stream computing system comprising one or more computers and one or more storage devices storing instructions that are operable, when executed by the one or more computers, to cause the one or more computers to perform operations comprising: receiving, by the real-time stream computing system, a query; identifying, in the query by the real-time stream computing system, one or more reserved terms that each correspond to a function prototype for a dynamic post-processing node of a stream computing topology; identifying, in the query by the real-time stream computing system, a base query that specifies one or more search criteria; generating a stream computing topology definition that specifies: one or more source nodes and at least one processing node, wherein the processing node is specified in the topology to receive, from the one or more source nodes, one or more streams of data object identifiers of data objects that satisfy the one or more search criteria of the base query; and a respective post-processing node for each function prototype identified in the query, wherein the topology specifies that each post-processing node receives a stream of data objects output by the processing node and performs one or more operations on the received data objects according to the function prototype; and allocating, by the real-time stream computing system, a plurality of computing nodes to implement the nodes of the stream computing topology definition generated from the received query.