how do you determine how often to gather system stats?
>
> From: "Niall Litchfield" <n-litchfield_at_audit-commission.gov.uk>
> Date: 2004/03/05 Fri AM 10:55:11 EST
> To: <oracle-l_at_freelists.org>
> Subject: RE: optimizer_index_cost_adj and optimizer_index_caching
>
> Hi wolfgang
>
> I actually asked dan fink about this at UKOUG, because I haven't seen any investigations into system stats anywhere, do you have some evidence, links etc looking into the use of system stats anywhere? It instinctively sounds a good idea to me, but one that has the capability of blowing up in ones face. I don;'t like explosions much - I do like trying to do things the right way.
>
> Niall Litchfield
> Oracle DBA
> Audit Commission
> +44 117 975 7805
>
> > -----Original Message-----
> > From: breitliw_at_centrexcc.com
> > Sent: 05 March 2004 15:04
> > To: breitliw_at_centrexcc.com; oracle-l_at_freelists.org
> > Subject: Re: optimizer_index_cost_adj and optimizer_index_caching
> >
> >
> > If you are using Oracle 9, forget about O_I_C_A and O_I_C
> > (i.e. leave them
> > at their default) and use dbms_stats.gather_system_stats
> >
> > My 0.014938 cents (Canadian currency)
> >
> > At 07:30 AM 3/5/2004, you wrote:
> > >Oracle support(without knowing anything about my system) is
> > telling me to
> > >use the following settings:
> > >
> > >OPTIMIZER_INDEX_CACHING = 50
> > >OPTIMIZER_INDEX_COST_ADJ = 5
> > >
> > >Tom Kyte's book effective Oracle by Design recommends starting
> > >optimizer_index_caching at my cache/hit ratio and adjusting
> > as needed.
> > >
> > >Tim Gorman's paper 'Search for Intelligent Life in the Cost-Based
> > >Optimizer' states that OPTIMIZER_INDEX_COST_ADJ should be
> > set between 10
> > >and 50 for most OLTPs.
> > >
> > >This is a hybrid system, but I only have the OLTP parts to
> > stress test(the
> > >other parts are still in early phase development). Does
> > anyone have any
> > >opinions on this?
> >
> > Wolfgang Breitling
> > Oracle7, 8, 8i, 9i OCP DBA
> > Centrex Consulting Corporation
> > http://www.centrexcc.com
> >
> >
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>
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Received on Fri Mar 05 2004 - 11:20:23 CST
