RE: Why are my indexes being ignored?

Correct me if I'm wrong , if you have a index of field and your total of row is 83000 , you index uniqueness is about 73/83000 only ,if will not have any much performance if compare with 50% diffrences in values.

-----Original Message-----
Sent: Saturday, June 30, 2001 12:51 AM
To: Multiple recipients of list ORACLE-L

You table doesn't have a degree > 1 does it?. I've seen examples where this caused a lot of indexes to be ignored.

-----Original Message-----
Sent: 29 June 2001 16:53
To: Multiple recipients of list ORACLE-L

I'm returning 117 rows.

Bill Carle
AT&T
Database Administrator
816-995-3922
wcarle_at_att.com

 -----Original Message-----
Sent: Friday, June 29, 2001 9:50 AM

To:     ORACLE-L_at_fatcity.com; Carle, William T (Bill), NLCIO
Subject:        Re: Why are my indexes being ignored?

"Carle, William T (Bill), NLCIO" wrote:
>
> Hi,
>
> I created an index on a table. The table has about 83,000 rows. The
> index is a simple index on one field, 35 different values of the index. I
> analyzed the table and I analyzed the index, trying it both with a
histogram
> and without a histogram. No matter how I do it, it does a full table scan.
> Any ideas why? I know I can use a hint, but it seems to me that it ought
to
> use the index.

how many rows are you returning? if i remember right, and if i don't i'm sure i'll be reminded;-), if you return more than a certain % of the table it does a full table scan even if there are indexes.

--
Bill "Shrek" Thater   Certifiable ORACLE DBA
Telergy, Inc.            thaterw_at_telergy.net
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You gotta program like you don't need the money,
You gotta compile like you'll never get hurt,
You gotta run like there's nobody watching,
It's gotta come from the heart if you want it to work.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"It's not a bug. It's an undocumented feature"
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-- 
Author: Carle, William T (Bill), NLCIO
  INET: wcarle_at_att.com

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