Script to identify segments generating redologs

SELECT to_char(begin_interval_time,’YY-MM-DD HH24′) snap_time, 
        dhso.object_name, 
        sum(db_block_changes_delta) BLOCK_CHANGED 
  FROM dba_hist_seg_stat dhss, 
       dba_hist_seg_stat_obj dhso, 
       dba_hist_snapshot dhs 
  WHERE dhs.snap_id = dhss.snap_id 
    AND dhs.instance_number = dhss.instance_number 
    AND dhss.obj# = dhso.obj# 
    AND dhss.dataobj# = dhso.dataobj# 
    AND begin_interval_time BETWEEN to_date(’12-02-07 12:00′,’YY-MM-DD HH24:MI’)  
                                AND to_date(’12-02-07 16:00′,’YY-MM-DD HH24:MI’) 
  GROUP BY to_char(begin_interval_time,’YY-MM-DD HH24′), 
           dhso.object_name 
  HAVING sum(db_block_changes_delta) > 0 
ORDER BY sum(db_block_changes_delta) desc ;