Re: poor clob performance with very high CPU

From: Greg Rahn <>
Date: Mon, 2 Nov 2009 12:37:57 -0700
Message-ID: <>

With any performance issue you need to analyze the performance data. What do the ASH/ADDM/AWR reports show?

On Mon, Nov 2, 2009 at 12:30 PM, Josh Collier <> wrote:
> I have a CTAS that involves a CLOB. The expected duration of this process is
> 180 minutes. Recently it started taking > 5 hours. The data and rowcounts
> are very similar, the trace shows only CPU consumption and very little else.
> I am wondering if you guys have any insight into how to diagnose a clob
> performance issue where the only information I have is excessive CPU
> consumption.
> The execution paths have not changed. These are staging tables and they
> never have statistics as we always want full tablescans. The tablespaces
> underlying the tables/clobs have not changed.  They are local  ASSM with
> uniform extent sizes of 128k.

Greg Rahn
Received on Mon Nov 02 2009 - 13:37:57 CST

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