Ok... I've ran this test case on both a 8.1.6.0 and a 8.1.7.3 database...
I've ran it with both public and private rollback segments (just in case)...
I've looked at rssize in v$rollstat and sum(bytes) from dba_segments...
And, in all cases, it allows me to shrink the segment to less then both
optimal and min_extents*extent_size even though
optimal=min_extents*extent_size... Is there something wrong in the test
case? Has anyone ran this on one of their test databases? I'm confused
since the test case seems straight forward... The way I read, it allows me
to perform the shrink and the resulting segment is actually the size I
specify... Am I doing something stupid in the test case?
Thanks
Tim
PS - Here is the test case again...
column segment_name format a30
create public rollback segment tim tablespace rbs storage ( initial 1M next
1M minextents 20 maxextents 100 optimal 20M );
alter rollback segment tim online;
select segment_name, min_extents, initial_extent, next_extent
from dba_segments
where segment_name = 'TIM';
select rs.extents, rs.rssize/1048576 , rs.optsize/1048576
from dba_rollback_segs drs,
v$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$rollstat rs
where drs.segment_name = 'TIM'
and drs.segment_id = rs.usn;
alter rollback segment tim offline;
drop rollback segment tim;
-----Original Message-----
Sent: Wednesday, January 30, 2002 2:31 PM
To: Multiple recipients of list ORACLE-L
Um... Must be version differences... Here is a test case I ran on my
8.1.7.3 machine...
SQL> create public rollback segment tim tablespace rbs storage ( initial 1M
next 1M minextents 20 maxextents 100 optimal 20M );
Rollback segment created.
SQL> alter rollback segment tim online;
Rollback segment altered.
SQL> select segment_name, min_extents, initial_extent, next_extent
2 from dba_segments
3 where segment_name = 'TIM';
SEGMENT_NAME MIN_EXTENTS INITIAL_EXTENT NEXT_EXTENT
------------------------------ ----------- -------------- -----------
TIM 20 1048576 1048576
SQL> select rs.extents, rs.rssize/1048576 , rs.optsize/1048576
2 from dba_rollback_segs drs,
3 v$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.
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Johnston, Tim
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