RE: DBA Interview Questions

Hi Ethan....

I tend more towards trying to determine if the candidate has honest to goodness real world experience or is it all book knowledge and passed the OCP.

An OCP is good (don't get me wrong) but I'd almost rather consider someone that has actually "been there done that".

Did an interview for a contractor once. Some pretty tough questions. I noticed she kept glancing towards a spiral notebook she had carried in. I asked her if the answers I was looking for were in the book.

When she told me they were, I told her to find them and answer my question.

The fact that she had made a note of the problem and the 'fix' told me she had indeed run in that problem and thought enough about it to makes notes of the fix.

Told her to use her notes the remainder of the interview if she wanted.

I am a firm believer that you don't try to remember everything....you'll

never do it ...especially as you get a little further along in age. You just MIGHT remember it incorrectly and cause yourself more pain than gain.
Books exist for more than lining your shelves.

As far as the individual not knowing what RAC was/is.....maybe they haven't had the 'privilege' of working on 9i yet and their world is centered still in 8i or even V7. Did they know what OPS was/is?

How often do you REALLY get in to histograms on a daily basis? =20

I'd much rather a DBA know how to backup and be able to restore and recover a database than give me a stock/pat answer on what a histogram is and how it is used.

This goes to what Ethan Post said about personal knowledge " and questions are usually skewed to my own knowledge" or your own idea of what is relevant or important.

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Post, Ethan Sent: Wednesday, November 24, 2004 1:57 PM To: dofreeman_at_state.pa.us; Oracle-L (E-mail) Subject: RE: DBA Interview Questions

I would propose two common scenarios...

1. Most users complain at unpredictable times about performance, how do you find the problem?
2. Single users complain about a specific form/screen with performance issues and problem is re-creatable, how do you find the problem?

These questions lead in to many others about performance tuning. I am basically looking for this...

1. Does the candidate have a good methodology for tracking overall system performance, setting up some type of "alert/capture" to tell them when a problem is occurring, and then responding to the alert or interpreting the captured info to determine what the problem is/was.
2. What tools does the candidate use (OEM, scripts, 10046, statspack), I will ask follow-up q's to ensure they actually use these tools.
3. Do they understand the wait interface, can the describe common wait events, problems with checkpointing too frequently, sizing methodologies for memory, redo logs etc...
4. Do they look at the OS level, iostat, sar, top, etc....
5. What resources do they use to troubleshoot other than standard (metalink), if they say oracle-l it is always a big plus!

I rate the interview on how much the candidate knows without being prompted or helped. I understand people get nervous and forget things and questions are usually skewed to my own knowledge so if they handle most of this stuff with even semi-reasonable responses I will usually recommend them for an interview.

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Freeman, Donald Sent: Wednesday, November 24, 2004 1:29 PM To: Oracle-L (E-mail)
Subject: DBA Interview Questions

We have a position open suddenly and I'll be participating in =3D3D interviewing my contract co-dba next week for a Oracle 9i data warehouse
=3D3D

position. One of the resumes I read mentioned the applicant had =3D3D experience in performance tuning by 'tuning buffer cache hit ratios' and
=3D3D

that made me want to buckle down and ask a few appropriate questions.

I first plan to ask what a buffer cache hit ratio is and then what a =
=3D3D

10046 trace is: If they can explain how to use it and explain waits =
=3D
=3D3D

then I'll know I've got a winner. =3D3D20

Whats the quickest way to find out if somebody knows something about =
=3D3D

tuning? I'm just a novice myself and would like to be sure that the =
=3D
=3D3D

guy/gal we hire knows more than I do and can strengthen us in that area.
=3D3D

The guy we interviewed today didn't know what system stats and =3D3D histograms were and didn't know what RAC was. Hopefully we'll do =3D3D better next week when we resume. If anybody is interested in these =
=3D3D

kind of contract positions you have to get on the list with Deloitte and
=3D3D

Touche. They are our primary contractors.=3D3D20

Don Freeman
Database Administrator 1
Pennsylvania Dept of Health
Bureau of Information Technology

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