if you don't have optimal set, you need to manually monitor the size of
your rollback segments or you can hit maxextents on them or run out of
room in your rollback tablespace.
It's best to size the rollback segments so that most of the time they
don't need to extend. Then when you add optimal, it shrinks them back
for the unusual cases (like one shot major loads) that extends them
past the size you've set.
- Sinard Xing <sinardyxing_at_bcs-ach.com.sg> wrote:
> Oracle said, optimal value will automatically shrink your rbs (with
> continuous extents off course).
> Since this is the case do you think is good to add the value of
> optimal.
>
>
> Sinardy
>
> -----Original Message-----
> Tim
> Sent: 01 February 2002 12:30
> To: Multiple recipients of list ORACLE-L
>
>
> Can what cause a ORA-1555? A shrink? If that is the question...
> The
> answer is yes...
>
> Tim
>
> -----Original Message-----
> Sent: Thursday, January 31, 2002 11:00 PM
> To: Multiple recipients of list ORACLE-L
>
>
> Will this cause ora 1555 ?
>
> -----Original Message-----
> Tim
> Sent: 31 January 2002 03:31
> 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.
>
>
> --- "Johnston, Tim" <TJohnston_at_quallaby.com> 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
> > ---------- ----------
>
=== message truncated ===
Do You Yahoo!?
Great stuff seeking new owners in Yahoo! Auctions!
http://auctions.yahoo.com
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rachel Carmichael
INET: wisernet100_at_yahoo.com
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
Received on Fri Feb 01 2002 - 08:25:22 CST
