formula for OPTIMIZER_INDEX_COST_ADJ

From: Helma <helma.vinke_at_hotmail.com>
Date: Thu, 11 Dec 2008 07:12:48 -0800 (PST)
Message-ID: <b187f730-85e6-4335-b311-5ce558330cc2@s9g2000prm.googlegroups.com>


Hello *,

I am now looking at setting the optimizer_index_cost_adj. 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?

Thanks for any help Received on Thu Dec 11 2008 - 09:12:48 CST

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