Re: Is Sr. DBAs afraid of not be able to pass cert exam ??

> 20. You try to do a select count on a table, but get an error that there
> is a bad data block, yet selecting data by specifying the field names
> returns all of the data fine. How would you go about fixing the problem?
> Archivelog is turned off.

One could answer this very detailed

- depending on the Oracle version (7, 8.0, 8i)
- setting instance variable or use built in package to skip corrupted blocks
- export table or create tables as where rowid (exclude corrupted blocks)
- extract corrupted data out of indexes
- etc .......

but did anyone have the guts to answer with : - yeah well - I would go ahead and use BBED (block editor) and edit the flippin' block
or
- heck - I would use my favorite hex editor and check the 2byte checksum at offset 0x16, verify
the row directory, length bytes in the row header, check the 4 byte block tail ...

coz that would be really cool :-)

"Alan" <alanshein_at_erols.com> wrote in message news:a39jih$16hsai$1_at_ID-114862.news.dfncis.de...
> Here is a list of questions we came up with to ask interviewees. They go
> from easy to hard, mostly. Note that for some of the answers, we expected
"I
> don't know", which was an acceptable answer, so long as they could
describe
> where they would go to find the answer. Unacceptable answers to the tough
> ones were guesses based on thin air. And yes, some OCPs (with little or no
> experience) could NOT ANSWER question #1!!! I put the question in there as
> an easy one to start with to make the interviewees feel comfortable (same
> with #2). I was shocked when the first interviewee couldn't answer it
(#1).
> On #3, these OCPs would always answer with, "I would MONITOR...", whereas
> experienced interviewees answered with "I would DO thus and such..." When
> quizzed further about how they would actually go about SOLVING the
problem,
> the OCPs answered, "I would monitor..." again.
>
> Note that the questions are heavily based on skills and knowledge
acquired
> during experience, rather than from a book. BTW, can anyone here answer
#20?
> (It actually happened to me, but we never expected a real answer, just an
> "I'm not sure, but I would..."). Yes, there may be one or more trick
> questions (with an answer like, "You can't do that")
>
> Also, only experienced interviewees even came close on #13. Book OCPs had
no
> idea at all. So, for your enjoyment...
>
> 1. How would you go about obtaining the system date in a select
> statement?
>
>
>
> 2. What is the difference between SYS and INTERNAL?
>
>
>
> 3. A query is taking a long time to execute. Describe what you would
> look at to determine the causes.
>
>
>
> 4. What kinds of things need to be considered when calculating the
> sizes of the tablespaces for a new production system?
>
>
>
> 5. Describe an outer join, why it would be used, and how it would be
> implemented.
>
>
>
> 6. Describe a Cartesian product and what would cause this to happen.
>
>
>
> 7. How would you go about ensuring that certain rollback segments
are
> on line at startup if the database instance needs to be shut down?
>
>
>
> 8. How would you ensure that very large update statements had enough
> rollback space?
>
>
>
> 9. Describe the SGA and what it is used for.
>
>
>
> 10. How many types of triggers are there? How many times can one type of
> trigger be used on any one table?
>
>
>
> 11. What are some of the inefficiencies of using views?
>
>
>
> 12. Tell me about a situation in which you had to deal with a difficult
> user, and how you resolved it.
>
>
>
> 13. Two new applications are being developed that use different
databases
> (schemas). Some data sharing is needed, but mostly they are separate. A
new
> database server is being ordered to handle the two new systems. It will
have
> 5 hard drives. How would you configure the drives (mirror or not, etc).
How
> would you configure the tablespaces? What recommendations would you make
to
> improve the situation? What if you had 7 drives? What do you feel is the
> minimum number of drives needed in this situation and why?
>
>
>
> 14. What does a control file do in SQL-LOADER?
>
>
>
> 15. What does this report tell you (show disk I/O report)?
>
>
>
> 16. How would you go about issuing a truncate statement from a stored
> procedure?
>
>
>
> 17. What are some of the problems when migrating data from (dBase,
FoxPro,
> Access, etc.) to Oracle via ODBC?
>
>
>
> 18. What is a mutating table?
>
>
>
> 19. Describe a difficult technical problem that you have solved, and the
> solution you came up with.
>
>
>
> 20. You try to do a select count on a table, but get an error that there
> is a bad data block, yet selecting data by specifying the field names
> returns all of the data fine. How would you go about fixing the problem?
> Archivelog is turned off.
>
>
>
> 21. A user initiates an update. It is taking a lot longer than expected.
> Is there a way to determine if the update is in process or if a rollback
is
> occurring? What is involved?
>
>
>
> 22. How do you use a sequence in an update statement?
>
>
>
> 23. Considering that we are not a 7/24 shop, how would you implement a
> backup strategy?
>
>
>
>
>
>
> "Keith Boulton" <kboulton_at_ntlworld.com> wrote in message
> news:zFX58.2140$zB.607331_at_news2-win.server.ntlworld.com...
> > Tom Dyess <tdyess_at_dyessindustries.com> wrote in message
> > news:pfW58.167682$_w.25696938_at_typhoon.tampabay.rr.com...
> > > Keith,
> > >
> > > You didn't get much out of your first year of DBA work, did you?
You
> > > remind me of the poeple who claim to know 'everything' there is to
know
> > > about computers. I ususally run away when I hear that.
> >
> > I didn't claim that you would know everything after a year, but I do
claim
> > you should know everything you need to know. By the end of a year, you
> will
> > have encountered almost all the problematic situations that are likely
to
> > arise in that environment, you should have a good understanding of how
the
> > database works and you should be able to resolve new problems. This is
why
> I
> > said "in a single job."
> >
> > This is different from the level of knowledge that might be preferred
> > (although rarely found) in a troubleshooting consultant who might be
> > expected to have both a broader and more detailed knowledge than is
> required
> > for most permanent DBA jobs.
> >
> > In my opinion, it is not knowledge that is important to be good at a job
> in
> > this industry, but rather the ability to adapt to new tools, software
> > releases, development methods, hardware platforms and user requirements.
> >
> > To take an example, I've never used advanced queueing. I know advanced
> > queuing exists and I've read the manuals about it. I'm confident
(possibly
> > incorrectly) that it would take me a very short time to get up to
speed -
> > I've used other message queueing software. The most important thing I've
> > learnt from experience however is that you can never trust something to
> work
> > as expected. You have to devise usage and load scenarios and test them
> > before committing to a production architecture - even if you've used the
> > particular tool before it may have changed between releases or your
> previous
> > usage may have been been in a sufficiently different environment so as
not
> > to be comparable. If AQ didn't fit my particular needs, I'm quite happy
to
> > use another queueing mechanism or write my own. I believe this attitude
to
> > be more desirable than particular knowledge of AQ. I have often worked
> with
> > people who are knowledgeable but don't test their approaches before
> > committing to a design. I've also often worked with people who force the
> > requirement to fit their knowledge - ie if all you have is a hammer,
every
> > problem looks like a nail. What I'm saying is that attitude and aptitude
> is
> > mostly more important than detailed technical skill for recruitment to a
> > permanent (or even long-term contract). Obviously for a 2 day
consultation
> > contract, the criteria must be different.
> >
> >
> >
> >
> >
>
>
Received on Wed Jan 30 2002 - 14:35:12 CST