Re: downgrades in v$sql_monitor
- From: Randolf Geist <info@xxxxxxxxxxxxxxxxxxxxxxxxx>
- To: Josh Collier <Josh.Collier@xxxxxxxxxxxx>
- Date: Wed, 10 Jul 2013 15:31:08 +0200
Hi Josh,
regarding the video tutorial: I completely forgot but at
AllThingsOracle.com I did an introduction into the topic of Parallel
Execution Challenges / Troubleshooting and skew in particular in form of
a webinar.
You can watch the recording here:
http://allthingsoracle.com/analyzing-and-troubleshooting-oracle-parallel-execution/
It doesn't cover what I'll show in the video tutorial but is
nevertheless helpful and shows among other things how skew can be
identified in a SQL Monitoring report (only possible when using the
"active" (the flash based thing) version from 11.2 on).
Randolf
Am 10.07.2013 13:25, schrieb Randolf Geist:
> Hi Josh,
>
> it might depend on how your other queries work so that they indicate a
> downgrade.
>
> Remember that you might see a lower *activity* than expected in case
> of Parallel Execution skew where only a part of the assigned Parallel
> Execution Servers actually do the work (data distribution skew), or
> only a limited number of them is active concurrently (temporal skew).
>
> Depending on what you try to measure this *might* look like a
> downgrade but actually is a skew problem.
>
> If I ever find the time to put together the planned video tutorial on
> that topic I could simply point you to that - but it's not available
> yet unfortunately.
>
> Randolf
>
> Am 09.07.2013 18:07, schrieb Josh Collier:
>> Hi,
>>
>> I set up a job to capture the contents of v$sql_monitor once a minute
>> during my ETL run last night. I am having a hard time writing a query to
>> find evidence of queries downgraded to serial. My other queries indicate
>> that there were operations downgraded, but I cannot find them in my
>> version of V$sql_monitor. All the px_servers_requested contents have the
>> same value in px_server_allocated.
>>
>> Thanks for your time,
>>
>> Josh C.
>>
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