Hi devs： At drill,stddev_pop and sum functions once issued together will occur error.The reason is the DrillReduceAggregatesRule leverages Calcite's RexBuilder.addAggCall method to reduce the duplicated functions.But this method only cares about function name and input references ignoring the parameter data type. More details please see https://github.com/apache/drill/pull/1016
But I think it's better to move my judgement logic codes to the RexBuilder's addAggCall method. So what do you think about it ? If it sounds ok ,I will be pleasure to do that.
