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Home -> Community -> Usenet -> c.d.o.misc -> Re: Rollback Contention
> Can anyone please tell me a quick and easy way of establishing if he is
> right. My rollback segments are configured as follows:-
You can query V$WAITSTAT to see if there is contention for rollback segments. Try this:
SELECT class,SUM(count) FROM v$waitstat GROUP BY class;
If you see SUM(count)>0 for the following classes: undo header, undo block, system undo header, system undo block then you have rollback contention. Increase the number of rollback segments.
> No of Rollback segments 35
Oracle recommends no more than 50 rollback segments (according to the Rule of 4).
> Initial Extent 1M Next 1M
You don't say what the MINEXTENTS and MAXEXTENTS parameters are.
> Optimal Size 10M
You might want to V$ROLLSTAT to make sure that your rollback segments aren't experiencing high levels of extending and shrinking.
HTH,
Brian
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