Re: AWR Sample Report

From: Charles Hooper <>
Date: Fri, 21 Nov 2008 04:19:14 -0800 (PST)
Message-ID: <>

On Nov 18, 1:38 am, raja <> wrote:
> Hi,
> I have another AWR Report generated with 1hr interval.
> I dont know how to approach this. Please help on this...
> AWR Report :
>             Snap Id Snap Time          Sessions Cursors/Session
> Begin Snap: 10739   13-Nov-08 09:00:45 105      58.2
> End Snap:   10763   13-Nov-08 15:00:12 91       75.2
> Elapsed:   359.46 (mins)
> DB Time:   1,723.72 (mins)


One of my previous comments in this thread to you: "I would suggest collecting an AWR report for 10 to 15 minutes, unless the performance problem is only present in this 31 second time period." The first AWR report was of such a short duration that it is possible to obtain false positives (misleading information) about what is happening in the system - it is quite possible that some event started in that short time interval and ended just after the AWR snap ended, and it is also possible that an event started long before the AWR snap started and ended during the 31.2 second time interval. Some of the statistics reported in the AWR report are updated in the database immediately as they happen, and others are only updated in the database at the end of the event (the completion of a SQL statement, for instance). This inconsistency in the statistics may be very misleading, and that is why I recommended running an AWR report for 10-15 minutes, as the longer duration allows a greater percentage of events to start and end in the time interval. The latest version of your AWR report goes to the other extreme, with a six hour duration. The database server may have had severe performance problems for 30 minutes, yet when the statistics are averaged over six hours, the system might appear to be only 10% busy _on average_ (0.5 hours / 6 hours = 8.3%), which is likely an acceptable value, and the severe performance problem would be completely missed. That is what is meant by the phrase "if your head is on fire and your feet are are in a bucket of ice water, on average you should be pretty comfortable."

I will spend a couple minutes looking at the latest AWR report that you posted, but I still suggest collecting an AWR report for 10 to 15 minutes (and only 10 to 15 minutes).

Charles Hooper
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc. Received on Fri Nov 21 2008 - 06:19:14 CST

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