Wednesday, January 27, 2010

Experts are Sharp

You know I was thinking just this morning about the last round of interviewing I did to find a new DBA at work.  And that of course got me thinking about some of the interviews I’ve done in the past.  There are a few that really stick out.  The ones that are sticking out right away are the ones who didn’t know anything and claimed that they had so much experience and were so good that they didn’t have to be bothered with memorizing every little thing anymore.

This astounds me because all the experts I know are really sharp and on top of their game.  So what these guys are telling me is that they’re so good they don’t have to demonstrate even the most basic knowledge of SQL because they’ve transcended above that?  If that’s the case then my mother’s 100x the DBA any of us will ever be because she doesn’t know the first thing about it.

I remember this one guy especially.  He claimed both on his resume and in person to be an expert in query tuning.  He said, I’ve never found anyone who’s my equal at tuning queries.  So armed with that bit of knowledge I set about quizzing him with the basics.  I mean after all, you have to just get the basics out of the way, right?  I asked him if he had ever worked with exec plans.  He said of course, you don’t tune queries without them.  I said, that’s what I think, but i just wanted to make sure we were on the same page.  And I then asked him how expert his knowledge was of exec plans.  He said he was a very deep expert and didn’t know anyone with his knowledge.  Wow, now I’m getting a little nervous, right?

So I started with the basics.  What’s the difference between an index scan and an index seek?  Well, I’m not sure the exact difference, but I know you want to get rid of one of them.  OK, which one?  I can’t remember.  Um, ok.

So what’s a bookmark lookup (this was back when SQL2K was stull ubiquitous)?  I’ve seen it before, but I’m not sure what it does.

We went back and forth like that a couple more times and I finally broke down and told him that there was no evidence that he had ever tuned a query because he didn’t even have basic knowledge of exec plans.  I asked him what he was basing his claim of being an expert on.  That’s when he let me have it.  Look, I’m an enterprise DBA and I don’t have to know every piddling definition you dig up out of BOL.  Maybe someday when you’re at the level I am you’ll understand.

Um… ok, I’d say we’re done, huh? 

So like I said, I was thinking about that this morning and while I can’t keep up with everything, and nobody can, I like to think that I’ve got a lot of the basics covered.  And the real experts certainly know their stuff.  Go ahead and see how many people would follow her if you asked Kalen how big a SQL page is and she couldn’t answer.  And how many people do you think would follow Paul Tripp if he couldn’t tell you what DBCC CheckDB() was for? 

It just doesn’t hold water.  So for those of you out there thinking you’re all the Pooh, go test yourself and see how much knowledge you really have.  You may find out you’re not as hot as you thought.


Peter Schott said...

I think he was extremely honest, though. There was nobody his equal at query tuning. Beyond that, I'd say it's just a good idea to not put something on your resume unless you're prepared to talk about it.

Anonymous said...

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Brent Ozar said...

"And how many people do you think would follow Paul Tripp if he couldn’t tell you what DBCC CheckDB() was for?"

Wait - did you mean Paul Randal? Or is that an inside joke for the combination of Paul & Kimberly?

Anonymous said...

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I am a Contributing Editor for InfoWorld Magazine, and a frequent contributor to as well as I live with my wife and 3 kids, and have practiced and taught Kenpo for 22yrs now.
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