Re: Occasional insert slow down with CBC waits.

Yes Jonathan , you are right. This is a RAC database.

On Thu, 14 Apr 2022 at 10:19 PM, Jonathan Lewis <jlewisoracle_at_gmail.com> wrote:

>
> One of the buffers has state PI, which means you must be running RAC, and
> at some recent point in the past another instance has been calling for this
> block. (If you're not running RAC then seeing a PI is probable the problem
> you need to address first).
>
> It's possible that the CBC latch wait is a side effect of having more than
> one instance inserting into the same LOB segment at the same time. Waiting
> for a latch, though, often means that your CPU is overloaded - so perhaps
> the LMS processes are getting too busy and putting pressure on the system
> when the rate of insert gets too high.
>
> Regards
> Jonathan Lewis
>
>
>
>
>
>
> On Thu, 14 Apr 2022 at 16:41, Goti <aryan.goti_at_gmail.com> wrote:
>
>> Hi,
>>
>> ENV: Oracle 12.1.0.2 on RHEL 7.
>>
>> There is one single pconventional insert which slows down occasionally.
>> The wait event during the slow down is "latch: cache buffer chains". Using
>> Tanel Poder's latchprofx.sql , it was identified that the wait event was
>> mainly for the LOB segment with 1 level bmb as the block class. Details are
>> there in the gists below. Is there any way to identify what is causing this
>> and how the issue can be fixed?
>>
>> https://gist.github.com/aryangoti/06bcd2ead5efbea910afa4e7e5af5e4a
>>
>> https://gist.github.com/aryangoti/7d462225877c648f8a88b669b4b68b08
>>
>>
>> Thanks,
>>
>> Goti
>>
> --
Thanks,

Goti

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