Re: Best course to understand why a bad plan is chosen by optimizer

Then we get I to the whole "what does COST even mean" when costing the same query but yet costs can't be compared.

I honestly think [sometimes? Often?] that Oracle has 'lost the plot' when it comes to the CBO.

Chris

On Mon, Sep 23, 2019, 7:08 PM Clay Jackson (cjackson) < Clay.Jackson_at_quest.com> wrote:

> As usual, Mark "hit the nail on the head!". If all Cost Accountants
> thought and acted as he proposes, I would wholeheartedly agree.
> Unfortunately, reality and human nature often intrude, and I think THAT's
> where the issues come in. Far too many times, I've seen decisions made on
> the basis of "least hard dollar cost", w/o considering the "hidden" or
> "soft" costs.
>
> One great example of that, WITHOUT starting a whole discussion on
> "outsourcing" was the decision a former employer of mine made to outsource
> "Account Provisioning" and "Security".
>
> They told the displaced employees, "You have six months to train your
> replacements REMOTELY" (i.e., they did NOT spend the money to bring the
> "new" employees from the "low cost location" (the specific location, other
> than the fact that it was 8 timezones away, is really irrelevant) to the
> location of the current employees or vice-versa). When they executed the
> switch, the time to provision a new account went from 6 hours to 3 days, as
> the new folks learned all of "tribal knowledge" "the hard way"'; and the
> error rate went from less than 1% rework to close to 75% rework.
>
> Clay Jackson
> Database Solutions Sales Engineer
> clay.jackson_at_quest.com
> office 949-754-1203 mobile 425-802-9603
>
>
> -----Original Message-----
> From: Mark W. Farnham <mwf_at_rsiz.com>
> Sent: Monday, September 23, 2019 2:35 PM
> To: 'Mladen Gogala' <gogala.mladen_at_gmail.com>; Clay Jackson (cjackson) <
> Clay.Jackson_at_quest.com>; oracle-l_at_freelists.org
> Subject: RE: Best course to understand why a bad plan is chosen by
> optimizer
>
> CAUTION: This email originated from outside of the organization. Do not
> follow guidance, click links, or open attachments unless you recognize the
> sender and know the content is safe.
>
>
> Blush (okay, I don't really do that, but, thanks.)
>
> Clay: Permission for re-use granted. I at least think that was original to
> me.
>
> Mladen, likewise, and further I suspect that *mostly* when we disagree
> we're looking at different pieces of the elephant.
>
> As for cost accounting the only thing I'm sure about is that it would be
> done better if we didn't tax corporations and have to legally mesh those
> views of the books.
> But I don't want to get into an argument about how corporate taxes are
> paid by customers on this technical forum, so I'll drop that without
> further wind.
>
> Of course meshing strategic provisioning with cost accounting as a check
> on predictions is a useful component of achieving the business goal of
> computer systems: 1) Reliable and quick enough most of the time to meet
> service delivery promises to customers, safe and recoverable enough to
> provide transaction integrity (which can be quite expensive to lose), and
> all done reasonably close to the minimum cost (where reasonably is where it
> would have cost more to plan better to reach a lower cost than the
> difference.)
>
> Experience guides toward erring a bit on the side of extra engineering to
> avoid expensively retooling too much too often. I think that newfangled
> method calls that "re-work." Experience also guides toward getting started
> sometime well before the last possible outcome is modelled and tested in a
> simulator (which is probably only justified rarely.)
>
> I'll take both of you as my allies if ever the opportunity crops up. And
> Lothar, too.
>
> mwf
>
> -----Original Message-----
> From: Mladen Gogala [mailto:gogala.mladen_at_gmail.com]
> Sent: Monday, September 23, 2019 2:45 PM
> To: Clay Jackson (cjackson); mwf_at_rsiz.com; oracle-l_at_freelists.org
> Subject: Re: Best course to understand why a bad plan is chosen by
> optimizer
>
> Hi Clay!
>
> Comments in line:
>
> On 9/23/19 1:19 PM, Clay Jackson (cjackson) wrote:
> > I've known Mark for a LONG time, and have ALWAYS been impressed with his
> elegant "turn of phrase"!
>
> I have never met Mark in my life and I am deeply sorry about it. I am
> following his contributions on various Oracle forums with a sort of
> fascination. I respect hist opinion deeply, even when I disagree with him.
>
>
> >
> >
> > I'm going to save this; and, with permission of course, may use it a
> few talks (I'm doing one in Dallas in a few weeks on "The Future of the DBA
> in a World of Autonomous Databases").
>
> Databases are extremely complex, even if autonomous. I don't envision
> being able to utilize a serious business database without having a DBA
> anytime soon. Also, databases are getting larger. Backup and recovery of
> 50+ TB database is not as simple as it may look. Look at the databases
> as modern airplanes. No robot can do what Sully Sullenberger has done.
> Auto-pilot is available for the long time but I would be very hesitant to
> fly an airplane which doesn't have a pilot on board.
>
> >
> > I think sometimes we forget the "Engineering" ; and I'm 100% certain my
> mother was correct, when, in 1970, she predicted "Cost Accounting will be
> the ruin of civilization".
>
> With all due respect, I disagree with your mother. Cost accounting is a
> necessary evil. You can call me crazy, but I prefer the money to be spent
> on my bonus over buying unnecessary software. My bonus is never unnecessary.
>
>
> >
> > Clay Jackson
> > Database Solutions Sales Engineer
> > clay.jackson_at_quest.com
> > office 949-754-1203 mobile 425-802-9603
>
>
>

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