Re: enq: IV - contention

Hi

It looks like this patch is not included in the PSU. It seems to me that some very specific bugs dont get fixed in the PSU. I came to this conclusion because my RAC PSU was from July 2016 and this bug was fixed back in 2014.

Thanks

On Thu, Dec 21, 2017 at 2:34 PM, Uwe K <uwe_at_kuechler.org> wrote:

> Hi Ls,
> thanks for the hint to bug 19771961.
> Looking at OPatch output, it seems like this patch is not applied here.
> Maybe because the bug doesn't affect Oracle on Windows, but I'll check back
> with support.
>
> Cheers,
> Uwe
>
> -------
>
>
> On 21.12.2017 13:41, Ls Cheng wrote:
>
>> Hi
>>
>> I have a four nodes RAC DWH running in 11.2.0.4, it is a very busy DWH
>> peaking 180 active session per second and we had very tough time when
>> running partition maintenance operations such as splitting and
>> dropping partitions, some of them takes as long as 24 hours to split
>> 6000 partitions and it was caused by two events, ENQ-IV CONTENTION and
>> reliable message (reliable message seems effect of IV contention).
>>
>> I applied a merge patch for both Bug 19771961 and 15985351 almost 3
>> weeks ago and the contention dropped by great magnitude, the operation
>> which used to take hours and hours (8 to 24 hours) now takes roughly 1
>> hour. Is your system patched with 19771961 (15985351 seems be included
>> in 12.1.0.1)?
>>
>> Thanks
>>
>> On Thu, Dec 21, 2017 at 11:42 AM, Uwe K <uwe_at_kuechler.org> wrote:
>>
>> Dear oracle-l'ers,
>>>
>>> I'm interested to see whether some of you ever experienced the wait
>>> event "enq: IV - contention" being an issue on an Oracle RAC. To me,
>>> this is an exotic event and it is far from well documented.
>>> Reason: I have an open SR for five months now and no resolution to
>>> the issue yet. But before I describe the SR history in full length,
>>> i thought I'd make a short poll.
>>>
>>> My scenario very briefly described:
>>>
>>> - Windows 2012R2
>>> - Two nodes
>>> - Oracle Grid Infrastructure and DB 12.1.0.2, CpuOct17
>>> (but for a while the effect can also be seen on another system
>>> running 11.2.0.4 CpuOct17)
>>> - Batch Job running
>>> - "Delete from" several tables (housekeeping)
>>> - gather_schema_stats( cascade=>false )
>>> - Index rebuild
>>> - All DDL run in serial
>>> - Application Servers shut down during batch runs (to avoid
>>> concurrency with apps)
>>>
>>> Comparing earlier run times of this job on the 11.2 production, in
>>> 12.1 they were around twice as high.
>>> Top wait by far is "enq: IV - contention" during the time span when
>>> gather stats and index rebuilds run.
>>>
>>> I've already tried to confine the job to a service that runs on one
>>> instance only to avoid cluster-related waits (also top waits). That
>>> didn't change the top waits.
>>> The only thing that helps was shutting down the other instance
>>> completely.
>>>
>>> Any ideas?
>>>
>>> Cheers,
>>> Uwe
>>> --
>>> http://www.freelists.org/webpage/oracle-l [1]
>>>
>>
>>
>>
>> Links:
>> ------
>> [1] http://www.freelists.org/webpage/oracle-l
>>
>

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