1. A computer implemented method for providing load diffusion to perform a join operation over a data stream pair using a distributed stream processing system, the computer implemented method comprising: receiving, by a processing unit, the data stream pair for correlation; partitioning the data stream pair using correlation constraints to form a partitioned data stream pair; partitioning the data stream pair using a single stream partition process or a coupled stream partition process; switching between the single stream partition process and the coupled stream partition process; and distributing the partitioned data stream pair among a set of server nodes for load diffusion in performing the join operation.