public void processGroup(int tag) throws HiveException {
    if (CollectionUtils.isNotEmpty(childOperators)) {
      for (int i = 0; i < childOperatorsArray.length; i++) {
        childOperatorsArray[i].processGroup(childOperatorsTag[i]);
      }
    }
  }
Process the row.

@param row
         The object representing the row.
@param tag
         The tag of the row usually means which parent this row comes from.
         Rows with the same tag should have exactly the same rowInspector
         all the time.
ql/src/java/org/apache/hadoop/hive/ql/exec/Operator.java