final protected void evaluateChildren(VectorizedRowBatch vrg) throws HiveException {
    if (childExpressions != null) {
      for (VectorExpression ve : childExpressions) {
        ve.evaluate(vrg);
      }
    }
  }
Evaluate the child expressions on the given input batch.
@param vrg {@link VectorizedRowBatch}
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/VectorExpression.java