public List<String> getActualAggregationNames(boolean isPartial) {
    List<String> outputAggregationNames = new ArrayList<>();
    if (isPartial) {
      switch (aggregationType) {
        case AVG:
          outputAggregationNames.add(SqlConstant.COUNT);
          outputAggregationNames.add(SqlConstant.SUM);
          break;
        case FIRST_VALUE:
          outputAggregationNames.add(FIRST_VALUE);
          outputAggregationNames.add(SqlConstant.MIN_TIME);
          break;
        case LAST_VALUE:
          outputAggregationNames.add(SqlConstant.LAST_VALUE);
          outputAggregationNames.add(SqlConstant.MAX_TIME);
          break;
        case TIME_DURATION:
          outputAggregationNames.add(SqlConstant.MAX_TIME);
          outputAggregationNames.add(SqlConstant.MIN_TIME);
          break;
        case STDDEV:
          outputAggregationNames.add(addPartialSuffix(STDDEV));
          break;
        case STDDEV_POP:
          outputAggregationNames.add(addPartialSuffix(SqlConstant.STDDEV_POP));
          break;
        case STDDEV_SAMP:
          outputAggregationNames.add(addPartialSuffix(SqlConstant.STDDEV_SAMP));
          break;
        case VARIANCE:
          outputAggregationNames.add(addPartialSuffix(SqlConstant.VARIANCE));
          break;
        case VAR_POP:
          outputAggregationNames.add(addPartialSuffix(SqlConstant.VAR_POP));
          break;
        case VAR_SAMP:
          outputAggregationNames.add(addPartialSuffix(SqlConstant.VAR_SAMP));
          break;
        case MAX_BY:
          outputAggregationNames.add(addPartialSuffix(SqlConstant.MAX_BY));
          break;
        case MIN_BY:
          outputAggregationNames.add(addPartialSuffix(SqlConstant.MIN_BY));
          break;
        case UDAF:
          outputAggregationNames.add(addPartialSuffix(aggregationFuncName));
          break;
        default:
          outputAggregationNames.add(aggregationFuncName);
      }
    } else {
      outputAggregationNames.add(aggregationFuncName);
    }
    return outputAggregationNames;
  }
Keep the lower case of function name for partial result, and origin value for others.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/planner/plan/parameter/AggregationDescriptor.java