code: @Override
  	public boolean next() {
  		if (prodScan == null)
  			return false;
  		while (!prodScan.next())
  			if (!useNextChunk())
  				return false;
  		return true;
  	}
docs: Moves to the next record in the current scan. If there are no more
  records in the current chunk, then move to the next LHS record and the
  beginning of that chunk. If there are no more LHS records, then move to
  the next chunk and begin again.
  
  @see Scan#next()