oracle检测回滚剩余时间

操作oracle数据库时，有一个大事务要回滚，非常慢，所以要看一下需要多少时间才能回滚完。在网上找到这样的SQL语句：

select * from v$transaction;

但我执行的时候返回：ORA-00942: 表或视图不存在

原来是这样滴：普通用户下视图v$不可见，conn /as sysdba一下就好了。

再次执行返回：未选定行

下面找的的一段可以看回滚还要用多长时间。

when transaction will finish rollback

-------------------------------------------------------------------------------
--
-- Script:  rolling_back.sql
-- Purpose: to predict when transactions will finish rolling back
-- For: 9.0+
--
-- Copyright:   (c) Ixora Pty Ltd
-- Author:  Steve Adams
--
-------------------------------------------------------------------------------
@save_sqlplus_settings

set serveroutput on
set feedback off
prompt
prompt Looking for transactions that are rolling back ...
prompt

declare
  cursor tx is
select
  s.username,
  t.xidusn,
  t.xidslot,
  t.xidsqn,
  x.ktuxesiz
from
  sys.x$ktuxe  x,
  sys.v_$transaction  t,
  sys.v_$session  s
where
  x.inst_id = userenv('Instance') and
  x.ktuxesta = 'ACTIVE' and
  x.ktuxesiz 1 and
  t.xidusn = x.ktuxeusn and
  t.xidslot = x.ktuxeslt and
  t.xidsqn = x.ktuxesqn and
  s.saddr = t.ses_addr;
  user_name  varchar2(30);
  xid_usnnumber;
  xid_slot   number;
  xid_sqnnumber;
  used_ublk1 number;
  used_ublk2 number;
begin
  open tx;
  loop
fetch tx into user_name, xid_usn, xid_slot, xid_sqn, used_ublk1;
exit when tx%notfound;
if tx%rowcount = 1
then
  sys.dbms_lock.sleep(10);
end if;
select
  sum(ktuxesiz)
into
  used_ublk2
from
  sys.x$ktuxe
where
  inst_id = userenv('Instance') and
  ktuxeusn = xid_usn and
  ktuxeslt = xid_slot and
  ktuxesqn = xid_sqn and
  ktuxesta = 'ACTIVE';
if used_ublk2 < used_ublk1
then
  sys.dbms_output.put_line(
user_name ||
'''s transaction ' ||
xid_usn  || '.' ||
xid_slot || '.' ||
xid_sqn  ||
' will finish rolling back at approximately ' ||
to_char(
  sysdate + used_ublk2 / (used_ublk1 - used_ublk2) / 6 / 60 / 24,
  'HH24:MI:SS DD-MON-YYYY'
)
  );
end if;
  end loop;
  if user_name is null
  then
sys.dbms_output.put_line('No transactions appear to be rolling back.');
  end if;
end;
/

prompt
@restore_sqlplus_settings