@Override
  public void forward(Object row, ObjectInspector rowInspector)
      throws HiveException {
    // Because we need to revert the tag of a row to its old tag and
    // we cannot pass new tag to this method which is used to get
    // the old tag from the mapping of newTagToOldTag, we bypass
    // this method in MuxOperator and directly call process on children
    // in process() method..
  }
Calls initialize on each of the children with outputObjetInspector as the
output row format.
ql/src/java/org/apache/hadoop/hive/ql/exec/MuxOperator.java