oracle rollback 时间查询

查询大表回滚剩余时间

select a.sid,A.USERNAME,T.USED_UBLK,T.USED_UREC,
T.XIDUSN  from v$transaction t,v$session a where A.SADDR=T.SES_ADDR and A.USERNAME = 'RPT' order by t.USED_UBLK desc;