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Re: FW: Re: Tuning approach question

From: Orlando L <>
Date: Wed, 28 Sep 2005 03:07:01 -0400
Message-ID: <>

Thanks for the responses.

 On 9/26/05, Joel Garry <> wrote:
> Mladen wrote:
> > Oracle instances seldomly complain, users do that instead.
> The first thing one should do is look at the alert log, since that is
> where Oracle complains, and the problem has already stated that many
> users are affected. We all ought to know that most performance problems
> lay in the sql, but when you have a production instance you need to
> check the obvious production issues first, even before any complaints
> are made - and shouldn't the assumption be that the sql was tuned in
> development? Then, when a problem is given, you must narrow it down -
> what has changed? So I think the second step is what the OP said, use
> tools to see if anything is out of the ordinary (including waits). At
> that point you may see something obvious - for example, excessive
> scattered reads, maybe an index got lost? You can use the GUI's (or try
> to be impressive by giving CLI scripts off the top of your head :-) to
> look at the SQL in question, and perhaps get a clue where to look next -
> statistics messed up, plan stability lost... Then you can get into such
> things as, are they running statspack, various tracing options, etc. as
> in the OP.
> It's difficult to know in an interview situation what the correct answer
> they are seeking is, so you must also query the interviewer to get an
> idea . You never know when they think hit ratio tuning is a good idea
> (after all, don't the advisors use ratios?), and must be able to divine
> from them where to go. Hopefully, the best interviewers will be more
> interested in your methods for getting to an answer than whether you
> know how to twiddle a particular knob or parrot a party line, but I
> don't know that many interviewers are "best." Most just seem to have a
> checklist of keywords. Some are impressed if you happen to mention a
> tuning controversy making the rounds online. Some are unimpressive if
> they have no clue about such things.
> YMMV, I may have a minority viewpoint about these things.
> Joel Garry
> --

Received on Wed Sep 28 2005 - 02:09:54 CDT

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