// create POGlobalRearrange
POGlobalRearrange gr = new POGlobalRearrange(new OperatorKey(scope,nig.getNextNodeId(scope)), rp);
// Skewed join has its own special partitioner
gr.setResultType(DataType.TUPLE);
gr.visit(this);
if(gr.getRequestedParallelism() > curMROp.requestedParallelism)
curMROp.requestedParallelism = gr.getRequestedParallelism();
compiledInputs = new MapReduceOper[] {curMROp};
// create POPakcage