How to increase rollback segment

Question

hi,
I am using oracle8i in solaris
I got a situation to increase rollback segment but i dont know how to do so?
can any one help me in solving this..........
I also want to know wat is the maximum max_extents size we can keep.....
This is my rollback segments
SQL> select segment_name, max_extents,TABLESPACE_NAME FROM dba_rollback_segs;
SEGMENT_NAME MAX_EXTENTS TABLESPACE_NAME
SYSTEM 121 SYSTEM
RBS 121 SYSTEM
RBS1 121 RBS
RBS2 121 RBS
RBS3 121 RBS
RBS4 121 RBS
RBS99 32765 RBS1
7 rows selected.
With Regards
Boo

Answer 1

If you have metalink access, there are really couple of good notes on how to tune and create optimal rollback segments.
Rollback Segment Configuration Tips Doc ID:      Note:69464.1
Regarding the size of the rollback segment, it is depends on the nature of the application and the transaction size, whether short transaction or lenghty transactions.
If oltp with very small transaction, create rollback segment with very small value and make minextents 20, so that you dont need to have recursive call to create extents initially.
ORA-01628: max # extents (121) reached for rollback segment RBS1Make the extent unlimited.
ALTER ROLLBACK SEGMENT RBS1
STORAGE ( MAXEXTENTS UNLIMITED)
2) how many rollback segment can we hav?1 rollback segment = 4 concurrent transactions.
Now you decide, how many concurrent transaction do you have.
.3) what is the maximum extent size we can set?I would recommend to set the extent size according to nature of your application.
<<1) if there is more than one rollback segment in that, i want to know which one is active how to know this....... where to check this.........
SELECT r.name "RB NAME ", p.pid "ORACLE PID",
p.spid "SYSTEM PID ", NVL (p.username, 'NO TRANSACTION') "OS USER",
p.terminal
FROM v$lock l, v$process p, v$rollname r, v$session s
WHERE l.sid = s.sid(+)
AND s.paddr = p.addr
AND TRUNC (l.id1(+)/65536) = r.usn
AND l.type(+) = 'TX'
AND l.lmode(+) = 6
ORDER BY r.name;
Jaffar