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