public void reset(){
    this.state = State.INIT;
    if (childOperators != null) {
      for (Operator<? extends OperatorDesc> o : childOperators) {
        o.reset();
      }
    }
  }
Replace one parent with another at the same position. Chilren of the new
parent are not updated

@param parent
         the old parent
@param newParent
         the new parent
ql/src/java/org/apache/hadoop/hive/ql/exec/Operator.java