Re: optimizer_index_cost_adj and optimizer_index_caching

From: Wolfgang Breitling <breitliw_at_centrexcc.com>
Date: Fri, 05 Mar 2004 08:04:38 -0700
Message-Id: <6.0.3.0.2.20040305080117.02b7f0b8@pop.centrexcc.com>

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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Received on Fri Mar 05 2004 - 09:40:03 CST