private boolean canPushLimitToReduceSink(WindowTableFunctionDef wTFn) {
      for(WindowFunctionDef wFnDef : wTFn.getWindowFunctions() ) {
        if ( (wFnDef.getWFnEval() instanceof GenericUDAFRankEvaluator) ||
            (wFnDef.getWFnEval() instanceof GenericUDAFDenseRankEvaluator )  ||
            (wFnDef.getWFnEval() instanceof GenericUDAFLeadEvaluator ) ) {
          continue;
        }
        WindowFrameDef wdwFrame = wFnDef.getWindowFrame();
        BoundaryDef end = wdwFrame.getEnd();
        if (wdwFrame.getWindowType() == WindowType.RANGE) {
          return false;
        }
        if ( end.getDirection() == Direction.FOLLOWING ) {
          return false;
        }
      }
      return true;
    }
Processor for Script Operator Prevents any predicates being pushed.
ql/src/java/org/apache/hadoop/hive/ql/ppd/OpProcFactory.java