Re: Competition for OraPerf

From: joel garry <joel-garry_at_home.com>
Date: 8 Nov 2006 13:54:10 -0800
Message-ID: <1163022850.524924.236570@m73g2000cwd.googlegroups.com>

hpuxrac wrote:
> joel garry wrote:
> > > >
> > > >> I'm a consultant and I'm not the slightest bit worried. That's because I
> > > >> don't rely on reports that recommend throwing hardware at problems that
> > > >> don't exist and solve problems that really do exist by determining what's
> > > >> actually wrong ...
> > > >
> > > > Richard, such a statement would hold water if the world was clearly cut
> > > > into right and wrong things but, alas, it is not. I thought it was us
> > > > Americans who tend to over-simplify things, but I see that Aussies are not
> > > > immune to that, either.
> > >
> > > Hi Mladen
> > >
> > > Ummmm, such a statement holds all the water I need in this desert called
> > > Oracle consulting because it's exactly what I do.
> > >
> > > It's not a simplification, it's a fact. Perhaps a rather simple fact but a
> > > statement of fact nonetheless ...
> > >
> >
> > Perhaps you guys are talking at cross-purposes here because of the
> > different ways one can determine a problem statement. It is certainly
> > near-trivial to come up with realistic examples of how a dumb profiler
> > can spit out inanity - the example on the web site is ironically one of
> > those, as Richard demonstrated. And I think Mladen's example is a good
> > one - it demonstrates that short-circuiting a proper tuning methodology
> > by someone who knows what he is doing can be more cost-effective to a
> > business. Will it always be? Of course not, but that is only a
> > problem when it is always used by the business, which removes the
> > "knows what he is doing" from the solution. Will it _never_ be?
> > Also, of course not, there is implicit value to experience, the problem
> > domain allows intuition to extrapolate correctly from past experience.
> > Will it be the optimal solution to the problem? Most likely not - but
> > then, when you insert business valuation into the process, optimal no
> > longer necessarily equals best. Or maybe the other way round.
> >
> > I often see people (yes, including myself) making extrapolations that
> > are ridiculously wrong. When it blows up in some huge project, that
> > can be both educational and entertaining. On the other hand, many
> > incorrect assumptions may be innocuous or lead to correct results
> > through fallacies. With the limited resources we all have, it has to
> > be a judgement call about many things. The important thing is that we
> > make an effort to make things more rational, while accepting that some
> > things will be difficult to change. Doing nothing invites
> > irrationality. Limiting the solution domain too severely can also be
> > destructive. The trick is to know how and when to use observation to
> > feedback control to go in the right direction.
> >
> > Sometimes it's good to throw the hardware at it first, because that
> > doesn't rule out tuning it properly later, whereas if you got it going
> > good enough, you suffer when you do need the capacity and can't get it
> > due to arcane capital expenditure rules. So fight BS with BS :-)
> >

> Cary Millsap's book is currently the state of the art in regards to how
> to approach this area.

I agree, and yet, even it has some shortcomings. Sometimes ordering everything by business priority misses technical problems (for example, rating the 15th most important problem as identified by the methodology, when in actuality it should be a topper), and there are perhaps some unspoken assumptions in the methodology. Unless I am mistaken (quite possible, as I haven't looked at it too closely), one assumption is that there are a few issues that cause most of the problems. This is often true, but not always, especially in newbie systems and systems that have many different apps. So any testimonials would be suspect.

> I have a feeling that he wouldn't exactly agree with the proposition of
> throwing hardware first into any of the scenarios that this thread is
> discussing.

But would that be for a technical reason, or a not invented here reason?

> "Doing nothing invites irrationality" ... sorry I can't buy that
> statement at all.

> Often doing nothing is the best decision that can be made in many
> situations. It all centers around whether you will provide a tangible
> benefit to a business function that yields a better rate of return than
> doing nothing, as well as the cost of the resources and hardware ( if
> any ) needed to implement some kind of change.

Ah, sorry, I wasn't clear that I was referring in general to trying to make things better, as the sort of scientific inquiry Richard and others champion, not in evaluating a specific situation. Absolutely, doing nothing is often correct in the latter. I should have made a new paragraph at "The important thing..." and explained the transition.

> Eliminating workload that's un-necessary and fixing needed SQL so that
> it uses less resources ... that's what should be driving any competent
> DBA.
Agreed. But that needs to exist within the greater business context, where overall business considerations can be at odds with tuning specific workloads.

What do you think Cary would say about tuning an arbitrary SQL that is one of 10000 bad SQL's? Of course his methodology orders the badness so you may never get there. The "wrong" throwing of hardware works when it solves a more global problem (including the cost of hardware v. cost of people, and postponing proper fixes until they can be made). They are not necessarily mutually exclusive, there's only a problem when people say they are mutually exclusive, or use one when the other is appropriate. Throwing hardware at an untuned newbie system would be inappropriate - I've seen some pretty old systems that could be described that way (maybe every Oracle system put together by people who think it is another db, too...), and I think the Competition for OraPerf would be particularly egregious for those.

--
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Received on Wed Nov 08 2006 - 15:54:10 CST