RE: DBA Interview Questions
- From: "Freeman, Donald" <dofreeman@xxxxxxxxxxx>
- To: "Hollis, Les" <Les.Hollis@xxxxxx>, "Oracle-L (E-mail)" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 24 Nov 2004 15:51:24 -0500
Although I've collected a raft of good info here on histograms and =
system stats we haven't implemented them. I don't feel a strong need to =
do that because everything is running fine and everybody is happy. So, =
I don't have a lot of things in mind that really need to be done but am =
still a bit tweaked about some of the Oracle technology that I think may =
be beneficial.
Todays applicant is a 9i guy but just hasn't used RAC. Since we are =
planning to install this year I'd like to find a candidate that has at =
least one skill or qualification that matches 1 requirement<g>. I've =
kind of gone with: certified? warehouse? hands-on or architect? RAC? =
Dataguard? Windows 2000, backup and recovery? tuning? Cognos?=20
Very good post by the way. I have a notebook although I don't think I =
would have brought it to the interview.
-----Original Message-----
From: Hollis, Les [mailto:Les.Hollis@xxxxxx]
Sent: Wednesday, November 24, 2004 3:36 PM
To: Post, Ethan; dofreeman@xxxxxxxxxxx; Oracle-L (E-mail)
Subject: 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@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Post, Ethan
Sent: Wednesday, November 24, 2004 1:57 PM
To: dofreeman@xxxxxxxxxxx; 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@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] 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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