@Override
  public boolean isDistanceGreater(Object v1, Object v2, int amt) {
    throw new UnsupportedOperationException("Only unbounded ranges supported");
  }
Simply returns the Object[] returned by VectorPTFGroupBatches.getAt(i), which contains the
value of the ordering columns.
ql/src/java/org/apache/hadoop/hive/ql/udf/ptf/ValueBoundaryScanner.java