Re: oracle can ignore hints

From: Kresimir Fabijanic <kfabijanic_at_optusnet.com.au>
Date: Fri, 05 Mar 2004 19:41:21 +1100
Message-ID: <40483D31.9060300@optusnet.com.au>

Hi Ryan

What version of Oracle and OS are you running? What hint did you try to use? How complex was query?

I have seen a case (OK it was 7.3.4.0 in 1999 on Sun's OS) where two databases - same version, same OS same Oracle and OS patches on both - hardware configuration was slightly different (not 100% sure but there were differences in RAM (1G vs 2G or 4G) and number of CPUs - (2 vs 4) and some disk layout differences) both databases running RULE (software vendor requested [Keystone - if you have ever heard of it]) - identical statement (cut and paste between two terminal sessions (and back)) generating very different execution plans.

I tried to verify few times and results were consistently different. Nothing would surprise me any more.

Kind regards

Kresimir Fabijanic

ryan.gaffuri_at_cox.net wrote:

>We had a discussion on here regarding hints. some of you stated that Oracle cannot ignore a proper hint. I have a TAR open and asked about this. Here is the response.
>
>
>
>"A hint simply adds weight to a cost estimation, it can still be overridden by the CBO if the values aren't seen as useful."
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Received on Fri Mar 05 2004 - 02:37:22 CST