Re: formula for OPTIMIZER_INDEX_COST_ADJ

On Thu, 11 Dec 2008 07:12:48 -0800, Helma wrote:

> I am now looking at setting the optimizer_index_cost_adj.

What problem are you trying to solve? What version of Oracle RDBMS do you work on? What platform?

> I read that a
> nice starting point would be to look at the ratio of the dbfile
> sequential read vs the scattered read (see
> http://www.evdbt.com/SearchIntelligenceCBO.doc for details.) However,
>
> EVENT TOTAL_WAITS
> AVERAGE_WAIT
> ----------------------------------------------------------------
> ----------- ------------
> db file sequential read
> 1704269587 0
> db file scattered read
> 238876588 0
>
>
> this would be a 0/0 division. I don't think these numbers are correct.
> Timed statistics is TRUE:
>
>
> SQL> show parameter timed
>
> NAME TYPE VALUE
> ------------------------------------ --------------------------------
> ------------------------------
> timed_os_statistics integer 0
> timed_statistics boolean TRUE
>
> Startup time is 3 weeks. So how is it possible that the average wait is
> always zero?

How did you get those numbers? Which version of the DB? Please give the group the necessary information, when asking questions. My ESP abilities are a little bit rusty these days.

-- 
Mladen Gogala
http://mgogala.freehostia.com