ak,

Here is a query you can run to see if it is currently in use...

SQL> select b.segment_name, a.xacts, a.shrinks, a.wraps, a.extends
  2  from v$rollstat a, dba_rollback_segs b
  3  where a.usn = b.segment_id
  4  /

SEGMENT_NAME                        XACTS    SHRINKS      WRAPS    EXTENDS
------------------------------ ---------- ---------- ---------- ----------
SYSTEM                                  0          0          0          0
RBS_BIG01                               0          1         46          6
RBS_BIG02                               0          1         57          8
RBS_BIG03                               0          0         31          0
RBS_BIG04                               1          4         86         27
RBS_BIG05                               1          1         43          8

6 rows selected.

------------------------------------------
What you're looking for here is the 'XACTS' column to be zero for the rollback segment 
you want to take offline.
Once you see it is not in use, shrink it: 'alter rollback segment RBSNAME shrink;'.
Then take it offline.  If it is taking up too much space, maybe drop and recreated it 
with smaller extent sizes, but I wouldn't just drop it.  This is a good rollback 
segment to have handy to bring online under special circumstances.  Also, you might 
check any available code to ensure no one is explicitly using this rollback segment in 
their sql code.

Darrell



>>> [EMAIL PROTECTED] 03/14/03 03:53PM >>>
I have recently found that one temporary rollback segment in system tablespace is 
having more then 600 extnets . It looks like previous dba created this rollback 
segment at the time of db creation and forgot to take it offline . 
Now how do I find it this rollback segment is being used actively . I see values in 
gets , writes from v$rollstat view .

What step should I take to drop this rollback segment . What implication might have if 
I take this offline ? I want to relase the space taken by this rollback segment ( >600 
extents ..thats big ) , so just taking offline wont do this.

Are there any views accessible from system( no sys) account which can tell me which 
trasaction is using which rollback segment .


thanks
-ak




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Author: Darrell Landrum
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