Re: The Cost Based Optimizer drives me crazy...

"Medscheme" <esmev_at_medscheme.co.za> wrote:

>Help me to explain this:
>
>We have a 7.3 database running on NT.
>
>This statement (an example) makes use of the index on column1:
>
> Select * from table A where column1='xxxx'
>
>This statement does NOT make use of the index on column1:
>
> Insert into table B (select * from table A where column1='xxxx')
>
>Why would this happen?
>
>Esmé Venter
>esmev_at_medscheme.co.za
>

Because the CBO is not real good yet. Try giving it a hint to force it to use the index.

insert into table b
(select /*index(a)*/ * from table a where column1 = 'xxxx');

--
Chuck Hamilton
Sr. DBA
Keystone Mercy Health Plan
chuckh_at_dvol.com

"So teach us to number our days that we may present to thee a heart of wisdom"
(Psalm 90:12 NASB)