public static PTFRollingPartition createRolling(Configuration cfg,
      AbstractSerDe serDe,
      StructObjectInspector inputOI,
      StructObjectInspector outputOI,
      int precedingSpan,
      int followingSpan)
      throws HiveException {
    return new PTFRollingPartition(cfg, serDe, inputOI, outputOI, precedingSpan, followingSpan);
  }
This can be used for functions with no parameters.
next() function in this impl does not fetch anything from rowContainer, thus saving IO.
It just increments the pointer to maintain iterator contract.
ql/src/java/org/apache/hadoop/hive/ql/exec/PTFPartition.java