Re: optimizer not using function based indexes

I take it back... the query was correct as originally written. Just tried similar queries on my database and the FBI was used for:

   upper(ename)=upper('abc98')
   upper(ename)='ABC98'

It's been a LONG week...

Rachel_Carmichael_at_Sonymusic.com wrote:
>
> and stats have to have been collected on the index and base table as well
>
> just checked the 9i docs... I was wrong you do need the upper on the column, my
> bad.. but you need the stats, the compatibility set (as Beth says)
>
> |--------+-------------------------->
> | | |
> | | |
> | | Beth.Seefelt_at_tet|
> | | leyusa.com |
> | | |
> | | 05/09/2002 05:24|
> | | PM |
> | | Please respond |
> | | to ORACLE-L |
> | | |
> |--------+-------------------------->
> >----------------------------------------------------|
> | |
> | To: ORACLE-L_at_fatcity.com |
> | cc: (bcc: Rachel Carmichael) |
> | Subject: RE: optimizer not using function|
> | based indexes |
> >----------------------------------------------------|
>
> Another requirement is that your compatibility init.ora parameter must
> be set to 8.1.7 or higher, I believe, but check the doco.
>
> If that doesn't fix it, then trying using a hint to force the use of
> that index. If it doesn't work with the hint, then you know you have an
> environment problem that is preventing the use of function-based
> indexes. If it does work with the hint, then you know that function
> based is working but you have to figure out why the optimizer is not
> choosing it.
>
> HTH,
>
> Beth
>
> -----Original Message-----
> Sent: Thursday, May 09, 2002 4:19 PM
> To: Multiple recipients of list ORACLE-L
>
> 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
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> Author: Harvinder Singh
> INET: Harvinder.Singh_at_MetraTech.com
>
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> Author: Seefelt, Beth
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> Author:
> INET: Rachel_Carmichael_at_Sonymusic.com
>
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