docs: public int getAggregationDistinctColumnIndex(final int derivedSumIndex) {
          for (Entry<Integer, Integer> entry : aggregationDistinctColumnIndexAndSumColumnIndexes.entrySet()) {
              if (entry.getValue().equals(derivedSumIndex)) {
                  return entry.getKey();
              }
          }
          throw new ShardingException("Can not get aggregation distinct column index.");
      }