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Re: Anywy to accurately predict time for long running queries?

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Tue, 10 Feb 2004 20:08:26 -0000
Message-ID: <005801c3f011$a6d800f0$6702a8c0@Primary>

The "silly-season" answer to your question is to run the query through explain plan, then multiple by the calculated cost by the manufacturer's quoted average I/O time.

The calculated cost of a query is the CBO's estimate of time to completion in units of single block reads, so any other method is trying to second guess the optimizer.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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People here want me to accurately predict how long it will take long running SQL to execute. I'm reading carrie milsap's book now, and I believe he has some methods that give good estimates on overall performance(I have not gotten to that part yet).

any known methods to accurately predict sql? BTW, I dont have specs on the hardware, its a customer site... and yes I know you really need that.

I dont think this is doable, but im wondering if anyone has put together any papers on the subject.



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Received on Tue Feb 10 2004 - 14:08:26 CST

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