RE: how to set optimizer_index_cost_adj and cache parameters?
- From: "Khedr, Waleed" <Waleed.Khedr@xxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 26 Mar 2004 12:55:10 -0500
Hi Jonathan,
This is from the article:
"Essentially, this formula tells Oracle the number of block visits (see side
bar) that a process will have to make to collect all the data from the table.
If the selectivity (fraction of the table's data) is X, then it seems
reasonable that the number of index leaf blocks to visit will be X% of the
clustering_factor; and the number of table block visits will also be X%. Add on
the fact that you have to walk from the root to the leaf level just once, and
you have the formula."
I believe it's the other way around:
the number of index leaf blocks = X% of leaf blocks
the number of table block visits = X% of clustering_factor
Regards,
Waleed
-----Original Message-----
From: Jonathan Lewis [mailto:jonathan@xxxxxxxxxxxxxxxxxx]
Sent: Thursday, March 25, 2004 11:51 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Re: how to set optimizer_index_cost_adj and cache parameters?
Just in case you haven't come across it, the following
article of mine has just been published on DBAZine:
www.dbazine.com/jlewis18.shtml
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