Hi,
I am having a high contention for undo header. I used the following queries to find that out.

Do i need to increase the rollback segment size or increase the number of rollback segments to tune this.

Also what is Undo Header??


select class, count
2 from v$waitstat
3 where class in ('system undo header', 'system undo block',
4 'undo header', 'undo block' ) ;

CLASS COUNT
------------------ ----------
system undo header 0
system undo block 0
undo header 62579
undo block 2

select 'Contention for undo header = '||
2 (round(count/(&xxv1+0.00000000001),4)) * 100||'%'
3 from v$waitstat
4 where class = 'undo header' ;
old 2: (round(count/(&xxv1+0.00000000001),4)) * 100||'%'
new 2: (round(count/( 85473+0.00000000001),4)) * 100||'%'

Contention for undo header = 73.21%


Thanks
Anurag