RE: CBO parameters

Hi Gary,

I suggest that you leave the cost adjustment parameter alone (it should really be hidden along with the other fudge factor parameters). However, setting optimizer_index_caching is helpful in some cases where the optimizer is biased against index range scans with table access. Have a look at the cached_blocks.sql script on my web site for help with working out the actual degree of caching.

Regards,
Steve Adams

http://www.ixora.com.au/
http://www.oreilly.com/catalog/orinternals/
http://www.christianity.net.au/


-----Original Message-----
From:	Kirsh, Gary [SMTP:gary.kirsh_at_gs.com]
Sent:	Thursday, June 01, 2000 3:58 AM
To:	Multiple recipients of list ORACLE-L
Subject:	CBO parameters

Does anybody have any words of wisdom to share regarding tuning the CBO with
the init.ora parameters
OPTIMIZER_INDEX_COST_ADJ
OPTIMIZER_INDEX_CACHING
We're looking to come up with some good values to use for these across all our instances. I know that our mileage will vary, but has anybody seen any benefit by changing these from their default values?

TIA,
Gary

Gary Kirsh
Next Extent, Inc

--
Author: Kirsh, Gary
  INET: gary.kirsh_at_gs.com

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