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Re: sql tuning on X$ table

From: Tim Gorman <tim_at_evdbt.com>
Date: Wed, 29 Nov 2006 19:44:36 -0700
Message-ID: <456E4594.9070902@evdbt.com>


How much time is being spent in the "latch free" wait-event? If there is not a large amount of time spent waiting on this wait-event, then running this query is a waste of CPU.

Hope this helps...

Eagle Fan wrote:
> hi:
>
> We have a monitoring tool to monitor database performance.
>
> It run the following sql every few seconds and it cost a lot of CPU
> times. About 20% of total CPU time.
>
> select kslltnum latch#,sum(kslltwgt) gets,sum(kslltwff) misses,
> sum(kslltwsl) sleeps from x$ksllt group
> by kslltnum;
>
> The sql is used to collect latch statistics, latch#, gets, misses,
> sleeps and then get the top heavy latch contentions.
>
> I have no idea how to tune this sql. It's on x$ table.
>
> I have read kyle's presentation about direct SGA access and I think it
> may help the sql.
>
> Does anyone have experiences of using direct SGA access on production
> system?
>
> Any risks? How many performance gains?
>
> Thanks
>
> --
> Eagle Fan
>
> Oracle DBA

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Received on Wed Nov 29 2006 - 20:44:36 CST

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