Um... Must be version differences... Here is a test case I ran on my
8.1.7.3 machine...
SQL> create public rollback segment tim tablespace rbs storage ( initial 1M
next 1M minextents 20 maxextents 100 optimal 20M );
Rollback segment created.
SQL> alter rollback segment tim online;
Rollback segment altered.
SQL> select segment_name, min_extents, initial_extent, next_extent
2 from dba_segments
3 where segment_name = 'TIM';
SEGMENT_NAME MIN_EXTENTS INITIAL_EXTENT NEXT_EXTENT
------------------------------ ----------- -------------- -----------
TIM 20 1048576 1048576
SQL> select rs.extents, rs.rssize/1048576 , rs.optsize/1048576
2 from dba_rollback_segs drs,
3 v$rollstat rs
4 where drs.segment_name = 'TIM'
5 and drs.segment_id = rs.usn;
EXTENTS RS.RSSIZE/1048576 RS.OPTSIZE/1048576
---------- ----------------- ------------------
20 20.296875 20
SQL> alter rollback segment TIM shrink to 10M;
Rollback segment altered.
SQL> select segment_name, min_extents, initial_extent, next_extent
2 from dba_segments
3 where segment_name = 'TIM';
SEGMENT_NAME MIN_EXTENTS INITIAL_EXTENT NEXT_EXTENT
------------------------------ ----------- -------------- -----------
TIM 20 1048576 1048576
SQL> select rs.extents, rs.rssize, rs.optsize
2 from dba_rollback_segs drs,
3 v$rollstat rs
4 where drs.segment_name = 'TIM'
5 and drs.segment_id = rs.usn;
EXTENTS RSSIZE OPTSIZE
---------- ---------- ----------
10 10633216 20971520
SQL> alter rollback segment tim offline;
Rollback segment altered.
SQL> drop rollback segment tim;
Rollback segment dropped.
SQL>
What version is your test running on?
Tim
PS - Here is my test case if you want to run it...
column segment_name format a30
create public rollback segment tim tablespace rbs storage ( initial 1M next
1M minextents 20 maxextents 100 optimal 20M );
alter rollback segment tim online;
select segment_name, min_extents, initial_extent, next_extent
from dba_segments
where segment_name = 'TIM';
select rs.extents, rs.rssize/1048576 , rs.optsize/1048576
from dba_rollback_segs drs,
v$rollstat rs
where drs.segment_name = 'TIM'
and drs.segment_id = rs.usn;
alter rollback segment TIM shrink to 10M;
select segment_name, min_extents, initial_extent, next_extent
from dba_segments
where segment_name = 'TIM';
select rs.extents, rs.rssize, rs.optsize
from dba_rollback_segs drs,
v$rollstat rs
where drs.segment_name = 'TIM'
and drs.segment_id = rs.usn;
alter rollback segment tim offline;
drop rollback segment tim;
-----Original Message-----
Sent: Wednesday, January 30, 2002 2:17 PM
To: Multiple recipients of list ORACLE-L
testing....
if the initial extent*min_extents is less than the optimal, yes you can
shrink below optimal.
if initial*minextents = optimal, you can execute an alter rollback
segment statement that lists a shrink size that is less than optimal
AND less than initial*minextents and it will not fail. But if you LOOK
at the size it shrinks to, it's initial*minextents.
so you can "kinda" shrink below optimal, the statement won't fail, but
Oracle will ignore the number you give it.
--- "Johnston, Tim" <[EMAIL PROTECTED]> wrote:
> You know what? I thought the same thing... But, the curious side of
> me
> decided to give it a try to be sure... And guess what... It works?
> Learn
> something new everyday...
>
> SQL> select segment_name,sum(bytes) from dba_segments where
> tablespace_name
> = 'RBS' and segment_name
> = 'RBS17' group by segment_name;
>
> SEGMENT_NAME SUM(BYTES)
> ------------------------ ----------
> RBS17 22364160
>
>
> SQL> select rs.optsize, rs.extents
> 2 from dba_rollback_segs drs,
> 3 v$rollstat rs
> 4 where drs.segment_name = 'RBS17'
> 5 and drs.segment_id = rs.usn;
>
> OPTSIZE EXTENTS
> ---------- ----------
> 22020096 21
>
> SQL> alter rollback segment RBS17 shrink to 10M;
>
> Rollback segment altered.
>
> SQL> select segment_name,sum(bytes) from dba_segments where
> tablespace_name
> = 'RBS' and segment_name
> = 'RBS17' group by segment_name;
>
> SEGMENT_NAME SUM(BYTES)
> ------------------------- ----------
> RBS17 10649600
>
>
> SQL> select rs.optsize, rs.extents
> 2 from dba_rollback_segs drs,
> 3 v$rollstat rs
> 4 where drs.segment_name = 'RBS17'
> 5 and drs.segment_id = rs.usn;
>
> OPTSIZE EXTENTS
> ---------- ----------
> 22020096 10
>
> SQL>
>
> 8.1.7.3 on Solaris 2.8
>
> Tim
>
> -----Original Message-----
> Sent: Wednesday, January 30, 2002 10:26 AM
> To: Multiple recipients of list ORACLE-L
>
>
> no, you can't shrink a rollback segment below the optimal value
>
> --- Sinard Xing <[EMAIL PROTECTED]> wrote:
> > Hi,
> >
> >
> > Assume
> > INITIAL * MINEXTENT = 2M and also = OPTIMAL
> >
> > Do you think
> > ALTER ROLLBACK SEGMENT rbs SHRINK TO 1M;
> >
> > will work ?
> >
> >
> >
> > Thanks,
> >
> > Sinardy
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.com
> > --
> > Author: Sinard Xing
> > INET: [EMAIL PROTECTED]
> >
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INET: [EMAIL PROTECTED]
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