Re: row cache lock contention parallel insert

From: Kellyn Pedersen <>
Date: Thu, 24 Dec 2009 08:18:20 -0800 (PST)
Message-ID: <>

"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.  
"Go away before I replace you with a very small and efficient shell script..."

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

From: Greg Rahn <> Subject: Re: row cache lock contention parallel insert To: "Kellyn Pedersen" <> Cc:,, 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 <> 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... :)

Greg Rahn

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

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