Re: Question re System Statistics

Hi Brandon

I was wondering how much time do you gather system statistics, a couple of hours per day? Peak time perhaps?

Thanks

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LSC

On 6/15/07, Allen, Brandon <Brandon.Allen_at_oneneck.com> wrote:


>

> The point of system stats is to give the CBO the most accurate

> information about the CPU and I/O performance of your system so I'd say

> it's only necessary to gather new system stats whenever the performance

> of your system changes so, e.g. if you make any hardware changes,

> signficant code changes (e.g. add/remove/patch/upgrade an application),

> or load changes (e.g. add/remove a significant amount of users or

> transactions).

>

> I like to gather my stats over several "typical" business days and then

> average them and manually set my system stats to the average  values

> during a typical load.  Of course if you have wide variations in load,

> e.g. OLTP by day and batch/OLAP/DSS by night, then you might want to

> switch between two different sets of stats (set a job to do this

> automatically).

>

> Aside from gathering new system stats after significant changes to the

> system, I think a good approach is to periodically (maybe quarterly?)

> gather your system stats in a staging table, and then compare those to

> your system stats that are currently in effect and investigate any major

> differences and then update your real system stats if warranted by the

> results of your investigation.

>

> HTH,

> Brandon

>

> -----Original Message-----

> From: oracle-l-bounce_at_freelists.org

> [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of William Wagman

>

>

> I would be interested in folks thoughts about how frequently system

> statistics should be gathered

>

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