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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