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What are good questions for a DBA?

P: n/a
After 3 years of using DB2 on Linux, I'm leaving my current employers
to go work for a SQL Server shop instead. In order to find my
replacement, they're trying to put together a set of questions to get
both some understanding of how wide candidates knowledge is, and how
much DB2 specifics they know. Of the questions below, how many do you
think are useful in determining if you've got somebody capable of
keeping a DB2 instance up, developing new structures as new business
problems arrive, and writing useful/performant SQL? (these therefore
range from the inane to quite specific - how many do people feel are
actually unfair? or should I just get some questions from Celko?)
[I'm not trawling for a job or for other recruitment purposes here,
honest...]

1. I've got a bookings table with 20 million rows, broken down by
product, region, date and customer number. It's not loading new data
or querying very quickly. What should I do?
2. Do you like stored procedures?
3. What's an inline view?
4. How do you do a running sum when GROUP BY just gives you a total
per row?
5. Do you prefer star schemas or snowflake schemas? Why?
6. I have a table with three columns: date (date), country
(varchar(10)), bookings (int).
Write me a query that gives me a total by country of bookings made
in the last 2 weeks, AND that displays the total number of bookings
made in the last 2 weeks too.
7. Do you know what an MQT is?
8. If all my customers have been given x-y coordinates that describe
the position of their house (ie every line in customer has x_coordinate
(int) and y_coordinate (int), and Birmingham is at (35000, 55000), and
Manchester is at (25000, 65000) and York is at (33000, 70000), then,
assuming Euclidean geometry, give me a WHERE clause against the
customer table to return only customers who live north of Birmingham
and south of a line that passes through both York and Manchester.
9. I have two sets of customers with the same 15 columns. What's the
best way to return only those customers that are in both sets, for whom
the data is the same in both sets?
10. Give me a way to get the database to check on a daily basis if
something surprising is happening to sales when compared with last year
at the same time.
11. DB2 UDB LUW 8.1.4. For the next six months, ten new tables need
to be created every day and automated routines set up to load them
every day after they're created. You are the only person in the company
responsible for administering the database. Do you use a DMS or SMS
tablespace? Why?
12. Your manager has written some code that 'should take 5 minutes to
run'. It takes 4 hours. What do you do?
13. Cube Views?
14. What SQL that you've written are you most proud of?
15. What are the disadvantages of HADR vis a vis RAC?
16. SQL Server federation vs DB2 Information Integrator - any
thoughts?
Thanks

JCSJF

Sep 4 '06 #1
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P: n/a
"James Conrad StJohn Foreman" <ja**********************@gmail.comwrote in
message news:11*********************@m73g2000cwd.googlegro ups.com...
After 3 years of using DB2 on Linux, I'm leaving my current employers
to go work for a SQL Server shop instead. In order to find my
replacement, they're trying to put together a set of questions to get
both some understanding of how wide candidates knowledge is, and how
much DB2 specifics they know. Of the questions below, how many do you
think are useful in determining if you've got somebody capable of
keeping a DB2 instance up, developing new structures as new business
problems arrive, and writing useful/performant SQL? (these therefore
range from the inane to quite specific - how many do people feel are
actually unfair? or should I just get some questions from Celko?)
[I'm not trawling for a job or for other recruitment purposes here,
honest...]

1. I've got a bookings table with 20 million rows, broken down by
product, region, date and customer number. It's not loading new data
or querying very quickly. What should I do?
2. Do you like stored procedures?
3. What's an inline view?
4. How do you do a running sum when GROUP BY just gives you a total
per row?
5. Do you prefer star schemas or snowflake schemas? Why?
6. I have a table with three columns: date (date), country
(varchar(10)), bookings (int).
Write me a query that gives me a total by country of bookings made
in the last 2 weeks, AND that displays the total number of bookings
made in the last 2 weeks too.
7. Do you know what an MQT is?
8. If all my customers have been given x-y coordinates that describe
the position of their house (ie every line in customer has x_coordinate
(int) and y_coordinate (int), and Birmingham is at (35000, 55000), and
Manchester is at (25000, 65000) and York is at (33000, 70000), then,
assuming Euclidean geometry, give me a WHERE clause against the
customer table to return only customers who live north of Birmingham
and south of a line that passes through both York and Manchester.
9. I have two sets of customers with the same 15 columns. What's the
best way to return only those customers that are in both sets, for whom
the data is the same in both sets?
10. Give me a way to get the database to check on a daily basis if
something surprising is happening to sales when compared with last year
at the same time.
11. DB2 UDB LUW 8.1.4. For the next six months, ten new tables need
to be created every day and automated routines set up to load them
every day after they're created. You are the only person in the company
responsible for administering the database. Do you use a DMS or SMS
tablespace? Why?
12. Your manager has written some code that 'should take 5 minutes to
run'. It takes 4 hours. What do you do?
13. Cube Views?
14. What SQL that you've written are you most proud of?
15. What are the disadvantages of HADR vis a vis RAC?
16. SQL Server federation vs DB2 Information Integrator - any
thoughts?

Thanks

JCSJF
Most of the questions are very open-ended and highly subjective, and I doubt
that the person reading the answers from an answer sheet will be able to
understand equally valid answers that don't agree with the answer sheet.

The questions seem highly skewed toward decision support databases, but
maybe you are looking for someone with those skills. But if you are, I don't
see any questions about intra or inter partition parallelism which is much
more important than most of the questions you asked..

Seem to be a lot of questions about complex SQL. Are you looking for a DBA
or an SQL person?

If you are looking for a DB2 DBA, whey do they need to know about Oracle
RAC?

BTW, what is an inline view in DB2?
Sep 4 '06 #2

P: n/a

"James Conrad StJohn Foreman" <ja**********************@gmail.comwrote in
message news:11*********************@m73g2000cwd.googlegro ups.com...
After 3 years of using DB2 on Linux, I'm leaving my current employers
to go work for a SQL Server shop instead. In order to find my
replacement, they're trying to put together a set of questions to get
both some understanding of how wide candidates knowledge is, and how
much DB2 specifics they know. Of the questions below, how many do you
think are useful in determining if you've got somebody capable of
keeping a DB2 instance up, developing new structures as new business
problems arrive, and writing useful/performant SQL? (these therefore
range from the inane to quite specific - how many do people feel are
actually unfair? or should I just get some questions from Celko?)
[I'm not trawling for a job or for other recruitment purposes here,
honest...]

1. I've got a bookings table with 20 million rows, broken down by
product, region, date and customer number. It's not loading new data
or querying very quickly. What should I do?
2. Do you like stored procedures?
3. What's an inline view?
4. How do you do a running sum when GROUP BY just gives you a total
per row?
5. Do you prefer star schemas or snowflake schemas? Why?
6. I have a table with three columns: date (date), country
(varchar(10)), bookings (int).
Write me a query that gives me a total by country of bookings made
in the last 2 weeks, AND that displays the total number of bookings
made in the last 2 weeks too.
7. Do you know what an MQT is?
8. If all my customers have been given x-y coordinates that describe
the position of their house (ie every line in customer has x_coordinate
(int) and y_coordinate (int), and Birmingham is at (35000, 55000), and
Manchester is at (25000, 65000) and York is at (33000, 70000), then,
assuming Euclidean geometry, give me a WHERE clause against the
customer table to return only customers who live north of Birmingham
and south of a line that passes through both York and Manchester.
9. I have two sets of customers with the same 15 columns. What's the
best way to return only those customers that are in both sets, for whom
the data is the same in both sets?
10. Give me a way to get the database to check on a daily basis if
something surprising is happening to sales when compared with last year
at the same time.
11. DB2 UDB LUW 8.1.4. For the next six months, ten new tables need
to be created every day and automated routines set up to load them
every day after they're created. You are the only person in the company
responsible for administering the database. Do you use a DMS or SMS
tablespace? Why?
12. Your manager has written some code that 'should take 5 minutes to
run'. It takes 4 hours. What do you do?
13. Cube Views?
14. What SQL that you've written are you most proud of?
15. What are the disadvantages of HADR vis a vis RAC?
16. SQL Server federation vs DB2 Information Integrator - any
thoughts?
If you think these questions are going to be enough, good luck. I have a
certified DBA who can't do squat in front of a keyboard.
Sep 4 '06 #3

P: n/a
"Bob Jones" <em***@me.notwrote in message
news:LD*****************@newssvr29.news.prodigy.ne t...
>
If you think these questions are going to be enough, good luck. I have a
certified DBA who can't do squat in front of a keyboard.
Hmm. None of the questions the OP listed is anything like those on the IBM
DB2 DBA Certification test.

If your DBA can't do squat in front of keyboard, is that because they don't
Linux/UNIX, vi, etc, or some other reason.
Sep 4 '06 #4

P: n/a
James Conrad StJohn Foreman wrote:
15. What are the disadvantages of HADR vis a vis RAC?
This doesn't seem to be a valid question. I'm not sure of it's relevance
to the interview process, but assuming it has some, then it should be
HADR vs Oracle Data Guard. RAC is not a DR solution.
Sep 4 '06 #5

P: n/a

"Mark A" <no****@nowhere.comwrote in message
news:aZ******************************@comcast.com. ..
"Bob Jones" <em***@me.notwrote in message
news:LD*****************@newssvr29.news.prodigy.ne t...
>>
If you think these questions are going to be enough, good luck. I have a
certified DBA who can't do squat in front of a keyboard.

Hmm. None of the questions the OP listed is anything like those on the IBM
DB2 DBA Certification test.
Those questions are not enough regardless.
If your DBA can't do squat in front of keyboard, is that because they
don't Linux/UNIX, vi, etc, or some other reason.
Not just UNIX, but basic DBA stuff like configurating CLI, moving
containers, upgrading, and most of all using the right tool for the job.

Certifications may look good on paper, but they are no replacement for real
experience.
Sep 5 '06 #6

P: n/a
James Conrad StJohn Foreman wrote:
After 3 years of using DB2 on Linux, I'm leaving my current employers
to go work for a SQL Server shop instead. In order to find my
replacement, they're trying to put together a set of questions to get
both some understanding of how wide candidates knowledge is, and how
much DB2 specifics they know. Of the questions below, how many do you
think are useful in determining if you've got somebody capable of
keeping a DB2 instance up, developing new structures as new business
problems arrive, and writing useful/performant SQL? (these therefore
range from the inane to quite specific - how many do people feel are
actually unfair? or should I just get some questions from Celko?)
[I'm not trawling for a job or for other recruitment purposes here,
honest...]

1. I've got a bookings table with 20 million rows, broken down by
product, region, date and customer number. It's not loading new data
or querying very quickly. What should I do?
2. Do you like stored procedures?
3. What's an inline view?
4. How do you do a running sum when GROUP BY just gives you a total
per row?
5. Do you prefer star schemas or snowflake schemas? Why?
6. I have a table with three columns: date (date), country
(varchar(10)), bookings (int).
Write me a query that gives me a total by country of bookings made
in the last 2 weeks, AND that displays the total number of bookings
made in the last 2 weeks too.
7. Do you know what an MQT is?
8. If all my customers have been given x-y coordinates that describe
the position of their house (ie every line in customer has x_coordinate
(int) and y_coordinate (int), and Birmingham is at (35000, 55000), and
Manchester is at (25000, 65000) and York is at (33000, 70000), then,
assuming Euclidean geometry, give me a WHERE clause against the
customer table to return only customers who live north of Birmingham
and south of a line that passes through both York and Manchester.
9. I have two sets of customers with the same 15 columns. What's the
best way to return only those customers that are in both sets, for whom
the data is the same in both sets?
10. Give me a way to get the database to check on a daily basis if
something surprising is happening to sales when compared with last year
at the same time.
11. DB2 UDB LUW 8.1.4. For the next six months, ten new tables need
to be created every day and automated routines set up to load them
every day after they're created. You are the only person in the company
responsible for administering the database. Do you use a DMS or SMS
tablespace? Why?
12. Your manager has written some code that 'should take 5 minutes to
run'. It takes 4 hours. What do you do?
13. Cube Views?
14. What SQL that you've written are you most proud of?
15. What are the disadvantages of HADR vis a vis RAC?
16. SQL Server federation vs DB2 Information Integrator - any
thoughts?
Thanks

JCSJF
Assuming your DBA is intended to perform DBA duties how about?

1. What are the things that can go wrong that may require recovery
and/or restoration. What are the various strategies that you would
recommend to mitigate the dangers thing that can go wrong and for each
contrast the strengths and weaknesses.

2. Describe the architecture of DB2 and the basic concepts for locking
and the transaction model.

3. What is the most oldest version of DB2 on which you have worked? The
newest? Contrast them in terms of capabilities and features.

4. What is the worst situation you have ever faced as a DBA and what
did you personally do to solve it?

5. What is the largest database on which you have worked in terms of the
number of objects and the amount of data? Describe the challenges faced.

6. What is the single biggest mistake you see when you look at DB2
databases and what do you recommend to rectify it.

Also open ended. But pointedly intended to ferret out the poser.

And as Mark Townsend said ... DB2 has no technology equivalent to RAC so
bringing up an Oracle product serves no obvious purpose.
--
Daniel Morgan
University of Washington
Sep 5 '06 #7

P: n/a
"Bob Jones" <em***@me.notwrote in message
news:X5****************@newssvr21.news.prodigy.com ...
Certifications may look good on paper, but they are no replacement for
real experience.
No one is suggesting that there is any substitute for experience, but it is
useful in an interview to ask the applicant technical questions as one part
of the qualification process.

In my "experience" the questions on the DB2 DBA certification exam are
specifically designed so they are difficult to answer if one has not had
experience with the product. But obviously, there are no perfect questions.
Sep 5 '06 #8

P: n/a
Thanks Mark,
>
Most of the questions are very open-ended and highly subjective, and I doubt
that the person reading the answers from an answer sheet will be able to
understand equally valid answers that don't agree with the answer sheet.
Indeed. These are questions intended to be asked at interview, rather
than on paper. I tend to like open ended questions because there's
more opportunity for the candidate to get themselves in/out of trouble
than where there's one obvious right answer.
The questions seem highly skewed toward decision support databases, but
maybe you are looking for someone with those skills. But if you are, I don't
see any questions about intra or inter partition parallelism which is much
more important than most of the questions you asked..
Thanks. I'll follow up on that.
>
Seem to be a lot of questions about complex SQL. Are you looking for a DBA
or an SQL person?
Very good point, and my current employer has a certain level of
ambiguity about this. I guess I would have doubts about any DBA that
wasn't highly competent with SQL, but maybe that's an unfair
constraint.
>
If you are looking for a DB2 DBA, whey do they need to know about Oracle
RAC?
Some advice we hear is that a DBA is a DBA (or sometimes, a SQL
Server/Oracle DBA might be closer to what we want than a DB2 on z/OS
DBA) - trying to ferret out experience of clustering, federation, or
any other high availability or partitioned solution (yes, I know
there's a lot of concepts packed up in there that could be successfully
taken apart...)

BTW, what is an inline view in DB2?
OK:
SELECT max(bookings)
FROM (SELECT booking_date, count(bookings)
FROM generic.booking_table
GROUP BY booking_date) as a;
This gives me the most bookings I've had in one day. What's being
referred to as a is an inline view.

Or at least, that's what we've been told to call it in the past.

Sep 5 '06 #9

P: n/a

DA Morgan wrote:
>
And as Mark Townsend said ... DB2 has no technology equivalent to RAC so
bringing up an Oracle product serves no obvious purpose.
--
Daniel Morgan
University of Washington
Thanks Daniel. 4 & 6 are particularly nice questions. As to the RAC
question, as I think I said in my reply to Mark, it's more a general
question to get an idea of what they've touched in that general space.
Plus when you have salespeople telling you that HADR is the same as
RAC, and you have your own misgivings about believing this, it's always
interesting to canvas a few other opinions.

Sep 5 '06 #10

P: n/a
>BTW, what is an inline view in DB2?
>
"James Conrad StJohn Foreman" <ja**********************@gmail.comwrote in
message

OK:
SELECT max(bookings)
FROM (SELECT booking_date, count(bookings)
FROM generic.booking_table
GROUP BY booking_date) as a;
This gives me the most bookings I've had in one day. What's being
referred to as a is an inline view.

Or at least, that's what we've been told to call it in the past.
It is called a "nested table expression" in DB2. Other databases may call it
an inline view.

As I said earlier, a lot of question and answer lists have the wrong
answers, so that even those who give the right answer in the interview may
not get hired.
Sep 5 '06 #11

P: n/a
"James Conrad StJohn Foreman" <ja**********************@gmail.comwrote in
message news:11**********************@i42g2000cwa.googlegr oups.com...
>
Thanks Daniel. 4 & 6 are particularly nice questions. As to the RAC
question, as I think I said in my reply to Mark, it's more a general
question to get an idea of what they've touched in that general space.
Plus when you have salespeople telling you that HADR is the same as
RAC, and you have your own misgivings about believing this, it's always
interesting to canvas a few other opinions.
As previously mentioned, HADR is most similar to Oracle Data Guard, which
both provide more protection than RAC (since they have completely redundant
nodes and redundant data for the primary and standby databases). RAC
provides redundancy at the hardware node level, but since it uses shared
disk it does not protect you in the case of a disk system failure. But RAC
has other advantages such a scalability (but not linear scalability) that
are not directly related to High Availability.

Again, if the questioner does not know the correct answers to the questions,
then applicant may be punished even if they provide the correct answer. I
suppose it is nice to canvas other opinions at an interview, but how do you
which opinions are correct?
Sep 5 '06 #12

P: n/a
Mark A wrote:
It is called a "nested table expression" in DB2. Other databases may call it
an inline view.

As I said earlier, a lot of question and answer lists have the wrong
answers, so that even those who give the right answer in the interview may
not get hired.
In Oracle an 'in-line view'. In SQL Server a 'derived table'.
--
Puget Sound Oracle Users Group
Sep 5 '06 #13

P: n/a
Mark A wrote:
RAC
provides redundancy at the hardware node level, but since it uses shared
disk it does not protect you in the case of a disk system failure.
RAC is intended to eliminate the server as a single point of failure. If
you want disk protection use RAID. Just as if you want network
protection protection use NIC bonding (teaming) and redundant switches.
--
Daniel Morgan
University of Washington
Sep 5 '06 #14

P: n/a
"DA Morgan" <da******@psoug.orgwrote in message
news:11***************@bubbleator.drizzle.com...
RAC is intended to eliminate the server as a single point of failure. If
you want disk protection use RAID. Just as if you want network
protection protection use NIC bonding (teaming) and redundant switches.
--
Daniel Morgan
University of Washington
I have seen an entire disk subsystem go down (both NAS and SAN), and the
entire local network go down (bad switch flooded the network with garbage
messages).

HADR and Data Guard provide complete redundancy that can be located far
enough apart to eliminate all (or almost all) single points of failure.
Sep 5 '06 #15

P: n/a
Mark A wrote:
"DA Morgan" <da******@psoug.orgwrote in message
news:11***************@bubbleator.drizzle.com...
>RAC is intended to eliminate the server as a single point of failure. If
you want disk protection use RAID. Just as if you want network
protection protection use NIC bonding (teaming) and redundant switches.
--
Daniel Morgan
University of Washington

I have seen an entire disk subsystem go down (both NAS and SAN), and the
entire local network go down (bad switch flooded the network with garbage
messages).

HADR and Data Guard provide complete redundancy that can be located far
enough apart to eliminate all (or almost all) single points of failure.
Why don't we stick to the topic. Unless we _want_ to start a flame war
through none of Mark T. and Daniel's fault who have shown noteworthy
restraint.

Cheers
Serge

--
Serge Rielau
DB2 Solutions Development
IBM Toronto Lab

IOD Conference
http://www.ibm.com/software/data/ond...ness/conf2006/
Sep 5 '06 #16

P: n/a
"Serge Rielau" <sr*****@ca.ibm.comwrote in message
news:4m************@individual.net...
Why don't we stick to the topic. Unless we _want_ to start a flame war
through none of Mark T. and Daniel's fault who have shown noteworthy
restraint.

Cheers
Serge
Sorry, but I don't see a flame war coming. I agree that RAC and HADR are not
directly comparable, and that Data Guard and HADR are much closer in
functionality. Certainly, RAC does provide for a fair amount of redundancy,
but not as much as Data Guard.

I am sticking to the topic, which is figuring out the correct answer to the
DBA quiz. That would be helpful if one wants to evaluate the DBA applicant's
responses correctly.
Sep 5 '06 #17

P: n/a

Mark A wrote:
>
Sorry, but I don't see a flame war coming. I agree that RAC and HADR are not
directly comparable, and that Data Guard and HADR are much closer in
functionality. Certainly, RAC does provide for a fair amount of redundancy,
but not as much as Data Guard.

I am sticking to the topic, which is figuring out the correct answer to the
DBA quiz. That would be helpful if one wants to evaluate the DBA applicant's
responses correctly.
Thanks. I was a bit worried that something might kick off. The
implicit problem I have that provokes that question is that our
e-commerce director's belief is that you could have a solution where
you just bash another server into a cluster every time the load gets a
bit much, and not worry about partitioning the data across machines
(like DPF?). But not being an expert in these things, I'm not sure
that RAC or HADR or any other technology is an adequate means to
sidestep issues like thinking about where to situate your data, how to
form a disaster recovery plan, etc etc.

Sep 5 '06 #18

P: n/a
"James Conrad StJohn Foreman" <ja**********************@gmail.comwrote in
message news:11*********************@i3g2000cwc.googlegrou ps.com...
Thanks. I was a bit worried that something might kick off. The
implicit problem I have that provokes that question is that our
e-commerce director's belief is that you could have a solution where
you just bash another server into a cluster every time the load gets a
bit much, and not worry about partitioning the data across machines
(like DPF?). But not being an expert in these things, I'm not sure
that RAC or HADR or any other technology is an adequate means to
sidestep issues like thinking about where to situate your data, how to
form a disaster recovery plan, etc etc.
RAC provides scalability (although not 100% linear) and some redundancy.
HADR and Data Guard (alone) provide almost complete redundancy but not
scalability.

Scalability and disaster recovery (or redundancy) are two different things.

It just seems to me that if you want these questions answered, an interview
of an applicant is not the proper forum to find out the answers.
Sep 5 '06 #19

P: n/a
Mark A wrote:
"DA Morgan" <da******@psoug.orgwrote in message
news:11***************@bubbleator.drizzle.com...
>RAC is intended to eliminate the server as a single point of failure. If
you want disk protection use RAID. Just as if you want network
protection protection use NIC bonding (teaming) and redundant switches.
--
Daniel Morgan
University of Washington

I have seen an entire disk subsystem go down (both NAS and SAN), and the
entire local network go down (bad switch flooded the network with garbage
messages).

HADR and Data Guard provide complete redundancy that can be located far
enough apart to eliminate all (or almost all) single points of failure.
I didn't mean to imply that there isn't value in other parts of the
HA stack. But if my sole concern was loss of a disk subsystem I would
mirror between disk arrays. I too primarily see Data Guard as creating
redundant remotely located data centers.

But within any single data center there is also a need for minimizing
single points of failure.
--
Daniel Morgan
University of Washington
Sep 5 '06 #20

P: n/a
Mark A wrote:
"Serge Rielau" <sr*****@ca.ibm.comwrote in message
news:4m************@individual.net...
>Why don't we stick to the topic. Unless we _want_ to start a flame war
through none of Mark T. and Daniel's fault who have shown noteworthy
restraint.

Cheers
Serge

Sorry, but I don't see a flame war coming.
I don't.
--
Puget Sound Oracle Users Group
Sep 5 '06 #21

P: n/a
Mark A wrote:
RAC provides scalability (although not 100% linear) and some redundancy.
Documented at approximately 84% in 9i and somewhat improved above that
in 10g.
--
Puget Sound Oracle Users Group
Sep 5 '06 #22

P: n/a
ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ

DA Morgan wrote:
Mark A wrote:
RAC provides scalability (although not 100% linear) and some redundancy.

Documented at approximately 84% in 9i and somewhat improved above that
in 10g.
--
Puget Sound Oracle Users Group
Sep 6 '06 #23

P: n/a

"Mark A" <no****@nowhere.comwrote in message
news:yP******************************@comcast.com. ..
"Bob Jones" <em***@me.notwrote in message
news:X5****************@newssvr21.news.prodigy.com ...
>Certifications may look good on paper, but they are no replacement for
real experience.

No one is suggesting that there is any substitute for experience, but it
is useful in an interview to ask the applicant technical questions as one
part of the qualification process.
I did not say you suggested that. All I am saying is that OP's questions are
insufficient.
In my "experience" the questions on the DB2 DBA certification exam are
specifically designed so they are difficult to answer if one has not had
experience with the product. But obviously, there are no perfect
questions.
A competent DBA could fail the test without preparation. I know a guy with
no DBA experience actually passed the test. All he did was studying the
materials.
Sep 6 '06 #24

P: n/a
"Bob Jones" <em***@me.notwrote in message
news:Km*******************@newssvr11.news.prodigy. com...
>
I did not say you suggested that. All I am saying is that OP's questions
are insufficient.
I agree, the OP interview questions were insufficient, and if the
interviewer doesn't know the correct answers, they are probably worse than
insufficient.
>
A competent DBA could fail the test without preparation. I know a guy with
no DBA experience actually passed the test. All he did was studying the
materials.
Yes that can happen. But how do measure someone's technical knowledge if you
don't ask them questions (in an interview or an exam)? I have known many
DBA's with many years of experience doing the same very limited scope of
activities every day, but were incompetent when doing any other DBA tasks.

Any when it comes to more subjective activities, like configuring
bufferpools in an optimal manner or designing a database, there is almost
zero correlation with experience and the ability to do it well.
Sep 7 '06 #25

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Mark A wrote:
Any when it comes to more subjective activities, like designing a database,
there is almost zero correlation with experience and the ability to do it well.
That has not been my experience. In fact I would say an expert opinion
of one RDBMS doesn't translate into competence in another. It may ease
the transition but it is unlikely to result in best practices just
because it exists.

An interview must separate book knowledge from actual experience.
Someone can read the docs and memorize a lot of material. But that
doesn't mean I can diagnose a problem I have never seen.
--
Daniel Morgan
University of Washington
Sep 7 '06 #26

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"Mark A" <no****@nowhere.comwrote in message
news:TJ******************************@comcast.com. ..
"Bob Jones" <em***@me.notwrote in message
news:Km*******************@newssvr11.news.prodigy. com...
>>
I did not say you suggested that. All I am saying is that OP's questions
are insufficient.

I agree, the OP interview questions were insufficient, and if the
interviewer doesn't know the correct answers, they are probably worse than
insufficient.
>>
A competent DBA could fail the test without preparation. I know a guy
with no DBA experience actually passed the test. All he did was studying
the materials.

Yes that can happen. But how do measure someone's technical knowledge if
you don't ask them questions (in an interview or an exam)? I have known
many DBA's with many years of experience doing the same very limited scope
of activities every day, but were incompetent when doing any other DBA
tasks.
Of course questions have to be asked, but just not the same set of questions
for everyone. I prefer to ask more general questions than some trivial
details, questions that are more relevant to the person's experience. I look
for talents and skills, not a long list of facts.
Any when it comes to more subjective activities, like configuring
bufferpools in an optimal manner or designing a database, there is almost
zero correlation with experience and the ability to do it well.
Actually, you do learn those from experience, but they cannot be tested in
the exams because there is no absolute answer.
Sep 8 '06 #27

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Bob Jones wrote:
>Any when it comes to more subjective activities, like configuring
bufferpools in an optimal manner or designing a database, there is almost
zero correlation with experience and the ability to do it well.

Actually, you do learn those from experience, but they cannot be tested in
the exams because there is no absolute answer.
That doesn't matter. What matters is determining (A) how the person
approaches a problem, (B) how they think, and (C) if they think.

I often interview with questions where the appropriate answer is either
* You can't do that
* I read the documentation
* I don't know

If someone is not willing to say "I don't know" then I really don't
want them on a project.
--
Daniel Morgan
University of Washington
Sep 8 '06 #28

P: n/a

"DA Morgan" <da******@psoug.orgwrote in message
news:11***************@bubbleator.drizzle.com...
Bob Jones wrote:
>>Any when it comes to more subjective activities, like configuring
bufferpools in an optimal manner or designing a database, there is
almost zero correlation with experience and the ability to do it well.

Actually, you do learn those from experience, but they cannot be tested
in the exams because there is no absolute answer.

That doesn't matter. What matters is determining (A) how the person
approaches a problem, (B) how they think, and (C) if they think.

I often interview with questions where the appropriate answer is either
* You can't do that
* I read the documentation
* I don't know
If those are all the answers, I will immediately say "Next".
Sep 8 '06 #29

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Bob Jones wrote:
"DA Morgan" <da******@psoug.orgwrote in message
news:11***************@bubbleator.drizzle.com...
>Bob Jones wrote:
>>>Any when it comes to more subjective activities, like configuring
bufferpools in an optimal manner or designing a database, there is
almost zero correlation with experience and the ability to do it well.
Actually, you do learn those from experience, but they cannot be tested
in the exams because there is no absolute answer.
That doesn't matter. What matters is determining (A) how the person
approaches a problem, (B) how they think, and (C) if they think.

I often interview with questions where the appropriate answer is either
* You can't do that
* I read the documentation
* I don't know

If those are all the answers, I will immediately say "Next".
Not all but there are questions where they are the only correct answer.
For example:

You are given a copy of <new version of product herethat you've never
installed before and you are asked to put it on a server. What are the
first things you would do?

If the answer doesn't include "read the documentation" you have a
potential problem.
--
Daniel Morgan
University of Washington
Sep 8 '06 #30

P: n/a
>
If the answer doesn't include "read the documentation" you have a
potential problem.
Yes. Although in my own experience, DBAs willing to read the
documentation first have been few and far between. Then again, this
may be less symptomatic of the general population and more to do with
those that we've sampled.

Sep 11 '06 #31

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