Re: enq: SV - contention on RAC EXADATA

Have you tried running SQL trace (10046)? Oracle support search yields the following information:

Bug 12842402 "enq: SV - contention" using ORDERED Sequences in RAC

So, are your sequences ordered? Ordered sequences have been a bane of RAC application since the time immemorial, since Oracle 8i and OPS. Also, do you have any enq HW waits? It's a high water mark wait, a sign that your sequence cache is too small. In any case, I would run 10046 trace on the application. AWR and oracle-l are not sufficient in this case.

Regards

On 6/14/2016 5:14 AM, Pawel Smolarz wrote:
> Hi,
>
> Hi,
>
> On Exadata RAC database 12.1.0.2.0 we have problems with queries:
>
> SELECT schema.sequence_name.NEXTVAL
> FROM DUAL CONNECT BY ROWNUM <= :v1
>
> huge waits on Foreground Events:
> Event Waits Total Wait Time (sec) Wait Avg(ms) % DB time Wait Class
> DB CPU 2.1M 37.5
> resmgr:cpu quantum 1.1E+08 1.2M 11.21 21.6 Scheduler
> enq: SV - contention 83,224,234 1.1M 12.91 18.8 Other
>
> I know that is BUG but fix has been included in 12.1.0.1
>
> Anyone has a experience with this type of event?
> A lot of CPU has been consume by these sessions .
>
> Regards,
> Pawel
> --
> http://www.freelists.org/webpage/oracle-l
>
>

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Mladen Gogala
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