RE: optimizer not using function based indexes

I respectfully disagree. In order to use a function based index you do need the upper. If optimizer doesn't pick it up straigt away, he should give a hand with a hint (/*+ INDEX(alias,index) */)

> -----Original Message-----
> From: Rachel_Carmichael_at_Sonymusic.com
> [mailto:Rachel_Carmichael_at_Sonymusic.com]
> Sent: Thursday, May 09, 2002 4:49 PM
> To: Multiple recipients of list ORACLE-L
> Subject: Re: optimizer not using function based indexes
>
>
>
>
> you don't need the upper(ename) in your where clause... that
> forces oracle to
> NOT use an index
>
>
>
>
> |--------+----------------------------->
> | | |
> | | |
> | | Harvinder.Singh_at_met|
> | | ratech.com |
> | | |
> | | 05/09/2002 04:18 PM|
> | | Please respond to |
> | | ORACLE-L |
> | | |
> |--------+----------------------------->
> >----------------------------------------------------|
> | |
> | To: ORACLE-L_at_fatcity.com |
> | cc: (bcc: Rachel Carmichael) |
> | Subject: optimizer not using function |
> | based indexes |
> >----------------------------------------------------|
>
>
>
>
> Hi,
>
> We are trying to use function based indexes in our
> application but it looks like
>
> optimizer is not using them.
> So we created a sample table emp with 3 columns
> empno,ename,sal and populate
> this table with 100000 rows and created function based index
> on upper(ename).
> we try to run simple query like below and optimzer is not using index:
> select sal from emp
> where upper(ename)=upper('abc98');
>
> Even we use index hint optimizer is still not using index.....
>
> 1) table is analyzed as compute after creating index.
> 2) query rewrite is granted to user
> 3) query_rewrite_enabled=true.
> 4) optimzer mode is choose.
> 5) optimer should use index as there is no way full scan can
> be faster than
> index in this case as i tried to create simple
> index on ename and remove upper function from where clause of query..
>
>
> What can be the possible reason that optimzer is not using index??????
>
> Thanks
> --Harvinder
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Harvinder Singh
> INET: Harvinder.Singh_at_MetraTech.com
>
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> Author:
> INET: Rachel_Carmichael_at_Sonymusic.com
>
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