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

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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