Re: Oracle DBA Interview Questions

Joel Garry wrote:
>
> In article <31C63456.7F63_at_ni.net> ngreene_at_ni.net writes:
> >John Jones wrote:
> >>
> >TECHNICAL QUESTIONS
> >
> >Always ask the candiates the versions and releases they worked with in the database, tools and operating
> >systems. I usually find it a bad indication to find a candidate that doesn't know which version of the
> >operating system they were using, or the RDBMS or patch information.
> >
>
> I don't know which versions I have worked with off the top of my head. I
> think anyone who does know:
>
> A: Doesn't have enough experience, hasn't worked with very many versions.
>
> B: Is way too smart, should be doing something more suited to their talent.
>
> C: Worked at some place that doesn't keep up with the versions, a place
> that is very static.

Static or not, you should know what versions you are using.  

> Better to ask them to describe some problem they had ("say, did you
> ever get rollback segment problems?"), and how they dealt with it.

More good questions. Agreed.  

> No, a good DBA should be able to have this informations at his/her fingertips,
> when at the job. Why should the DBA be able to tell you this? Again, this is
> just showing the above lettered possibilities. This puts people with
> experience in modern monitoring tools or very complex environments at a
> disadvantage - to your detriment. As a manager, you should be looking for
> people to complement your groups skills, not replicate them (unless your
> group explicitly plan on leaving or are looking for a backup for a skill).

Again, the goal of these questions is not to find quantified answers. But, to determine what environments the DBA worked in and how they respond to the questions. Did he/she manage 1 database or 100? What size? A DBA knows how big a database is...you gotta back the thing up. You also know what tables are crtical to your applications. You now know the schema. But, you have no idea if there are 100 tables or 1,000. Doesn't make sense to me? You don't know if there are 100 triggers/procedures or 1,000. How do you manage performance as a DBA? Sounds like you lack the knowledge on how the application and database are running. How do you answer performance issues with no knowledge of the database design?  

> The candidate should be able to give examples of DBA information, and you
> need to know enough to tell if they are just parrotting training classes.
> Demonstration of methodology is more important than arbitrary trivia.
> Although, our local user group played an Oracle Trivia game at one meeting,
> and it was fun. If the person who is making the hiring decision doesn't
> know enough to tell, he needs to get someone who does.

Methodology is good. But, we are now going back to technical issues. I thought we were trying to stay away from the basic technical questions in an effort to find out more about the person. I think we can all come up with technical questions.  

> So what do you do if the candidate tells you they worked with developers, who
> were constantly changing and rearranging things? That person likely would
> have much better experience than someone who could be "aware," as you say,
> perhaps with a boring static system.

That is a valid answer. You gave me a respones that was specific to your environment. You now know what is going on. That is a lot better answer then saying, "Well, I am not sure...let me check my notes."  

> This assumes they were the ones making this decision. I have been at
> places where I would have to avoid this question!

Still a valid answer. Regardless, as DBA's we all come to a day when we have to upgrade an Oracle database. Are you saying you have no knowledge in this area? You have been a DBA since version 5, but you can't answer a question related to what you did in the past to upgrade a database. At no time sice version 5 have you been in an environment where revision control was required. (That is still a valid answer too)  

> This is a technical question, isn't it?

Technical questions are still valid.  

> On the other hand, some people think pessimism, even to the point of
> paranoia, is a desireable trait in an Oracle DBA. At least designing
> backups. If the database never screwed up, you'd be an Rdb DBA, eh?

What I mean by work with databases is "Be DBA for the sake of being DBA" ... control of information. Hire people that have desire to learn and move forward.  

Are you trying to say you don't know what version of the database or operating system you are using? I say if you don't know, then maybe you are the junior level DBA or maybe it just isn't your responsability. What is the first question Oracle asks you when you call for Oracle support? Or, are you such a good Oracle DBA that you never have to call Oracle support? They ask you the version of the database and they ask you which operating system you are using. Now, are you saying you don't know what versions you are using or that you still need to look at a notebook to decide.

Sure, you might be managing many versions. But, so do I, and I know which versions of the operating system they are running and I know which versions of the database they are running. And I know at which patch levels we have migrated to. Sure, you should document these answers and you should be able to refer to you documentation. During the interview, if I was to ask you "How many systems do you manage?" and you say "1" and if I was to ask you which version of the operating system were you using and you were to say, "Ohh well, I am not sure. It was either SunOS or Solaris. Maybe AIX?" What does that tell me about you. Sure, it might not be specific to you DBA skills, but it sure doesn't sound like you are too aware of what is going on or where things are. And in my opinion, those are some qualities I would look for in the people hired. Would you have to refer to your documentation to tell me if it was a 20GB database or a 200GB database? I hope not.

The reply sounds like what many people try to say when they get pulled over by the police for speeding. "Did you know how fast you were going?" "Well, not really, let me look at my speedometer." A good DBA is aware of the technical details of the database, the application, the network and the operating system.

-- 
Neil Greene				"Pinky, you make me worry.  You are too
Sr. Oracle DBA / Unix Administrator		close to being a poster child for 
SHL Systemhouse, Inc. - L.A.			cheese wiz," Brain
<URL:mailto:ngreene_at_laoc.SHL.com>