1. A method, with an information processing system, for reducing message flow on a message bus, the method comprising: determining if at least one logical operator in a plurality of logical operators requires processing on a given physical processing node in a group of physical nodes; pinning, in response to determining that the logical operator requires processing on the given physical processing node, the logical operator to the given physical processing node; assigning each logical operator in the plurality of logical operators to an initial physical processing node in the group of physical processing nodes on a message bus; determining a message flow rate associated with each logical operator in the plurality of logical operators, wherein the message flow rate is determined based on statistics, observations, and assumptions; determining a total initial message flow cost associated with the assigning each logical operator in the plurality of logical operators to a respective initial physical processing node, wherein the total initial message flow cost comprises a summation of message flow rates associated with each logical operator that transmits a message to the initial physical processing node; determining, for at least one logical operator in the plurality of logical operators, if a sum of a set of input message flow rates associated with the logical operator is at least one of greater than and equal to a sum of a set of output message flow rates associated with the logical operator; assigning, in response to the sum of the set of input message flow rates being one of greater than and equal to the sum of the set of output message flow rates, the logical operator to a preceding physical processing node situated at a position on the message bus for a given message flow sequence preceding the physical processing node to which the logical operator is currently associated therewith, wherein the assigning further comprises: determining if the preceding physical processing node comprises available resources to satisfy a resource requirement of the logical operator; and assigning, in response to the preceding physical processing node comprising available resources, the logical operator to the preceding physical processing node situated at the position on the message bus preceding the physical processing node to which the logical operator is currently associated therewith; assigning, in response to the sum of the set of input message flow rates being less than the sum of the set of output message flow rates, the logical operator to a subsequent processing node situated at a subsequent position on the message bus for the given message flow sequence to the physical processing node to which the logical operator is currently associated therewith; determining if at least one logical operator in the plurality of logical operators is a parent of at least one other logical operator; determining, in response to the logical operator being a parent, if the logical operator is assigned to a preceding physical processing node situated at a position on the message bus for the given message flow sequence preceding the physical processing node to which a child logical operator of the logical operator is assigned to; reassigning, in response to the logical operator being on the preceding physical processing node, the logical operator to the physical processing node to which the child logical operator is assigned to therewith; determining a total subsequent message flow cost associated with assigning each logical operator in the plurality of logical operators to one of each preceding physical processing node and each subsequent physical processing node, respectively, wherein the total subsequent message flow cost comprises a summation of message flow rates associated with each logical operator that transmits a message to a preceding physical processing node and a subsequent physical processing node, respectively determining if the total subsequent message flow cost is lower than the initial total message flow cost; and selecting, in response to the total subsequent message flow cost being lower than the total initial message flow cost, an assignment of the logical operators associated with the subsequent message flow cost.