cost of index range scan

From: <jernigam_at_kochind.com>
Date: 15 May 2006 07:02:09 -0700
Message-ID: <1147701729.083477.160210@j55g2000cwa.googlegroups.com>

I am trying to determine how the CBO is calculating the index selectivity of a range scan using bind variables. I have the query below.

select * from table_a
where acct_date >= :b1
and acct_date <= :b2

There is an index on acct_date plus two other fields.

According to most things I have read the selectivity should be .0025, because it defaults .05 for each. However instead the selectivity according to a 10053 trace is .0045

Any ideas?

This is a 9.2.0.7 instance running on Solaris. Received on Mon May 15 2006 - 09:02:09 CDT