Re: Vagaries of the CBO: Out-of-Range Predicates
- From: Wolfgang Breitling <breitliw@xxxxxxxxxxxxx>
- To: panandrao@xxxxxxxxx
- Date: Mon, 18 Dec 2006 05:34:55 -0700
At 12:11 AM 12/18/2006, Anand Rao wrote:
adding one more question,
3) How does CBO calculate the density in cases of bind variables
when the value is out of range?
or is this a RTFM / RTFB ... ??
density is a "property" of the column and is roughly related to the
probability of finding a particular value in the rows of the table.
It is calculated when statistics are collected, not at parse time.
density is in no way dependent on bind variables - or literals for
that matter. You may be mistaking density with selectivity.
Regards
Wolfgang Breitling
Centrex Consulting Corporation
www.centrexcc.com
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