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Re: How hints affect the CBO?

From: Niall Litchfield <n-litchfield_at_audit-commission.gov.uk>
Date: Thu, 27 Jun 2002 14:33:54 +0100
Message-ID: <3d1b1442$0$230$ed9e5944@reading.news.pipex.net>


I was thinking some more about this, and this makes sense. The purpose of hints is to enable the optimiser to choose a *different* path to the one that it calculates as best. The behaviour that you originally postulated would probably make people swear at the optimiser even more than they currently do.

--
Niall Litchfield
Oracle DBA
Audit Commission UK
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"Vladimir M. Zakharychev" <bob_at_dpsp-yes.com> wrote in message
news:aff0kg$s6h$1_at_babylon.agtel.net...

> Ok, MetaLink note 69992.1 explicitly states that
> "Correctly defined hints are DIRECTIVES to the optimizer to use a
particular
> access method or access type. They should not be ignored and should be
> obeyed at all times by the optimizer."
>
> So my assumptions about CBO were incorrect after all.
>
> --
> Vladimir Zakharychev (bob_at_dpsp-yes.com)
http://www.dpsp-yes.com
> Dynamic PSP(tm) - the first true RAD toolkit for Oracle-based internet
applications.
> All opinions are mine and do not necessarily go in line with those of my
employer.
>
>
Received on Thu Jun 27 2002 - 08:33:54 CDT

Original text of this message

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