SQL>
SQL> SELECT b.segment_name, status, sum(bytes) sum_bytes
2 FROM dba_extents a, dba_rollback_segs b
3 WHERE a.segment_name = b.segment_name
4 and rownum < 50
5 AND a.segment_type = 'ROLLBACK'
6 GROUP BY b.segment_name, status
7 ORDER BY status DESC, b.segment_name;
SEGMENT_NAME STATUS SUM_BYTES
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SYSTEM ONLINE 393216
SQL>