code: @Override
  	public boolean next() {
  		boolean ok = idx.next();
  		if (ok) {
  			RecordId rid = idx.getDataRecordId();
  			ts.moveToRecordId(rid);
  		}
  		return ok;
  	}
docs: Moves to the next record, which in this case means moving the index to
  the next record satisfying the selection constant, and returning false if
  there are no more such index records. If there is a next record, the
  method moves the tablescan to the corresponding data record.
  
  @see Scan#next()