@Override
  public void shallowCopyTo(ColumnVector otherCv) {
    DateColumnVector other = (DateColumnVector) otherCv;
    super.shallowCopyTo(other);
    other.vector = vector;
  }
Don't use this except for testing purposes.

@param len the number of rows
storage-api/src/java/org/apache/hadoop/hive/ql/exec/vector/DateColumnVector.java