Re: row cache lock contention parallel insert

From: Kellyn Pedersen <kjped1313_at_yahoo.com>
Date: Thu, 24 Dec 2009 08:18:20 -0800 (PST)
Message-ID: <205653.69853.qm_at_web32007.mail.mud.yahoo.com>

"Kellyn raises hand for the monstrous number of partitions issue"  :)  As we are in a stabalize the environment mode here, since this company just migrated from a mainframe to Oracle this year, I did disable the automated job in our larger systems and request the other DBA's that if they wanted to run the segment advisor, execute it manually.

Kellyn Pedersen
Multi-Platform DBA
I-Behavior Inc.
http://www.linkedin.com/in/kellynpedersen  
"Go away before I replace you with a very small and efficient shell script..."

• On Tue, 12/22/09, Greg Rahn <greg_at_structureddata.org> wrote:

From: Greg Rahn <greg_at_structureddata.org> Subject: Re: row cache lock contention parallel insert To: "Kellyn Pedersen" <kjped1313_at_yahoo.com> Cc: exriscer_at_gmail.com, info_at_sqltools-plusplus.org, oracle-l_at_freelists.org Date: Tuesday, December 22, 2009, 8:35 AM

The space segment advisor auto job can consume significant resources (basically burn 1 CPU core) if the data dictionary has no stats or very stale stats and there are a large number of partitions in the database.  One of the dictionary queries ends up with an NLJ plan when it should have a HJ plan (because of large # of partitions/segments).

On Mon, Dec 21, 2009 at 5:53 PM, Kellyn Pedersen <kjped1313_at_yahoo.com> wrote:
>
> I'm a tired DBA tonight, but this query sure looks familiar and if I remember correctly, I found it when a job was impacting the large warehouse tablespaces/datafile, but is this the job from the space advisor?
>
> select * from dba_scheduler_jobs
> where program_name like 'AUTO_SPACE%';
> I'd check and see, if it's enabled and scheduled, see what kind of elapsed time it has, then check your AWR and ADDM reports to see if this is impacting performance...
>
> Greg, tell me if I'm off here, I know I need a nap this evening... :)

--
Regards,
Greg Rahn
http://structureddata.org
--
http://www.freelists.org/webpage/oracle-l





      
--
http://www.freelists.org/webpage/oracle-l

Received on Thu Dec 24 2009 - 10:18:20 CST