Re: blocking enq-ss wait events

From: Bhavani Dhulipalla <bhavanidba6_at_gmail.com>
Date: Wed, 5 May 2021 22:44:59 -0600
Message-ID: <CAC=-2+x_xsJMio2oFi_qsQdkPr9q4b5UwNCUMj=8y6TnKkz-aA_at_mail.gmail.com>



We did run into this on Exadata and oracle support had told us it was some bug - we had to create the separate temp tablespace for the user to avoid contention on sort segment

On Wed, May 5, 2021 at 10:43 PM Chris Taylor < christopherdtaylor1994_at_gmail.com> wrote:

> I had to look up ENQ-SS on Oracle support. That's a sort segment
> contention, usually encountered when SMON is really busy cleaning up a dead
> / killed transaction.
>
> Oracle support has a few notes on this but the most applicable seem to
> stop at 11.1 .
>
> There is one note that says to try to increase PGA_AGGREGATE_TARGET
> SS Sort Segment Enqueue: 'enq: SS - contention' (Doc ID 2601825.1)
>
>
> Chris
>
> On Wed, May 5, 2021 at 11:56 PM Lok P <loknath.73_at_gmail.com> wrote:
>
>> Hi All, Need some help, we had killed one of the long running sessions
>> which was running since ~8hrs+ , but after we kill that we see a lot of
>> "wait for a undo record" wait events but we ignored that thinking that will
>> run for sometime as because it will do rollback. But suddenly now we are
>> seeing "enq-SS contention" wait event in addition to "wait for a undo
>> record" and that is blocking all other application queries. So wondering
>> how we should mitigate this issue?
>>
>> The version is 11.2.0.4 of Exadata.
>>
>> Regards
>> Lok
>>
>

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Received on Thu May 06 2021 - 06:44:59 CEST

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