RE: oracle can ignore hints
- From: "Khedr, Waleed" <Waleed.Khedr@xxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Fri, 5 Mar 2004 00:19:34 -0500
This would be nice if it causes Oracle itself to ignore its own hints
specified in the kernel that take care of execution plans, PQ, etc :)
Waleed
-----Original Message-----
From: K Gopalakrishnan [mailto:kaygopal@xxxxxxxxx]
Sent: Thu 3/4/2004 11:41 PM
To: oracle-l@xxxxxxxxxxxxx
Cc:
Subject: Re: oracle can ignore hints
Jonathan:
It is version dependent. I am sure you like that.
BTW starting from 10g you can ask oracle to ignore the hints by setting an
underscore parameter.
Regards,
Gopal
----- Original Message -----
From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Friday, March 05, 2004 3:09 AM
Subject: Re: oracle can ignore hints
>
> No.
>
> The intent is that they should be absolute directives;
> but there are conditions that put hints out of context,
> which means they become irrelevant.
>
> If it can happen at all, it can be hinted.
>
> Regards
>
> Jonathan Lewis
> http://www.jlcomp.demon.co.uk
<https://access0.fidelity.com/,DanaInfo=www.jlcomp.demon.co.uk+>
>
> The Co-operative Oracle Users' FAQ
> http://www.jlcomp.demon.co.uk/faq/ind_faq.html
<https://access0.fidelity.com/faq/ind_faq.html,DanaInfo=www.jlcomp.demon.co.
uk+>
>
> March 2004 Hotsos Symposium - The Burden of Proof
> Dynamic Sampling - an investigation
> March 2004 Charlotte OUG (www.cltoug.org) CBO Tutorial
> April 2004 Iceland
> June 2004 UK - Optimising Oracle Seminar
>
>
> ----- Original Message -----
> From: "April Wells" <AWells@xxxxxxxxxx>
> To: <oracle-l@xxxxxxxxxxxxx>
> Sent: Thursday, March 04, 2004 7:44 PM
> Subject: RE: oracle can ignore hints
>
>
> :
> : Yep, they are 'friendly suggestions' that the CBO can simply choose to
> : ignore if it thinks it knows better than you.
> :
> : We have one query that we have hinted, we have computed statistics, we
> have
> : built histograms, we have jumped through hoops... the only way to force
it
> : to use an index is to Never analyze that index and to hope, then, that
the
> : CBO makes the right assumptions.
> :
>
>
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