Monday, September 05, 2005

What do I need to know? Part I

I was asked to sit in on a 9i DBA course a couple of weeks ago.
The training was being given to some of the engineers from our support services provider (we outsource our network and infrastructure support).

I was asked along just to see how the training went, and to provide specifics about our systems if necessary.
I thought it would be a good idea also as the course was around 9i, which we are currently looking to upgrade to, so I might pick up a few tips!

It was a 3 day course, the first day of which concentrated on an introduction to SQL and using SQLPlus.
Out of the 4 delegates, only one had some database experience, using MS SQL Server, the others were complete Newbies.

On looking at creating tables, one delegate asked about the meaning of terms such as 'initial', 'next', and 'pctfree'.
They were told simply - 'you don't need to know that just yet'.

Similarly, on asking the difference between a database and an instance, the given answer was 'they are the same thing, you don't need to worry about it'.

I'm not disputing the trainers decision to not go into a lot of detail.
On a 3 day course it isn't always advisable, and too much detail can be overload for a Newbie!

So what does a Newbie need to worry about?

Newbies need to learn the basics to form a level of knowledge on which to build.

What has worked well for me the last few years, is to firstly try and gain a broad understanding of all areas of DBA work, without going into too much detail, and without trying to specialise.
I've also tended to learn on a 'need to know' basis.

Here's what I would recommend as a starting point:

1) Learn the structure of an Oracle database.
Know the different 'parts' that make up a database, and what each of them does.
You should be able to note the difference between datafiles, controlfiles and redo log files.

2) Learn how the different parts work together.
Know the different processes that exist and what they do.
You should be able to explain what the log writer or database writers do. At this stage, it is enough to know what is done, rather than how it is done!

3) Learn the concepts of backup and recovery.
Know the difference between archivelog mode and noarchivelog mode, and what that means to the recovery process.
Understand hot backups and cold backups and when you would use each one.

Once you have a good grounding in the above areas, you will be able to build on your knowledge.
Knowing how things are supposed to work will also make it easier to troubleshoot when things don't work.

In part II, I'll look at how to build on the basics and where to go next.


Blogger Niall said...

I wouldn't be so kind on the database=instance comment. Especially if you have SQL Server people in the class. Database != Instance as RAC so elegantly demonstrates, but even in single-instance environs, do you really want a new instance created when what you required was a new user with a dedicated default tablespace.

Monday, September 05, 2005 8:28:00 pm  
Blogger Rachel said...

As a newbie (oh so many years ago), the one thing I HATED to hear was "you don't need to know that". Perhaps I don't *need* to know it, but if I asked the question, it was because I WANTED to know.

I'd have preferred to hear "that's beyond the scope of what we are trying to do here, but see me after class and I'll give you some references to where you can learn this".

As I got more experience, and became the trainer, I made sure that I always answered the "what is this..." questions. My feeling was that the more the other people knew about how the database worked, the less likely they were to do something to mess it up

Tuesday, September 06, 2005 10:53:00 am  
Blogger Thomas Kyte said...

I agree with Niall, a quick explanation would have been in order for the instance/database thing.

And 30 seconds on what the pctfree/initial mean and where to find more information would be useful too.

I liked your 1,2,2 list (he-he, I might have used 1,2,3 myself), sounds very much like.....

The Concepts Guide

doesn't it :)

Tuesday, September 06, 2005 12:54:00 pm  
Blogger Paul Moore said...

You mentioned SQL server users - one other good thing to know is that not all databases work the same. I can easily understand a SQL server user getting confused over databases vs instances. Equally, I once had a conversation with an Ingres user and it took a long time for us to work out that neither of us understood what the other meant by "log files"...

Sometimes knowing about another type of database can be more confusing than helpful - be ready to go back to basics!

Tuesday, September 06, 2005 1:19:00 pm  
Blogger Lisa said...

Niall said....

I wouldn't be so kind on the database=instance comment.

After the class was finished, I had the other delegates ask if I would mind explaining things to them.

I used the analogy of a castle, moat and drawbridge for the database and instance explanation.

That's how I learned it, and still understand it!

Tuesday, September 06, 2005 3:17:00 pm  
Blogger Lisa said...

Thomas Kyte said...

I liked your 1,2,2 list

Thanks for the correction Tom, I guess that makes us even :-)

Tuesday, September 06, 2005 3:19:00 pm  
Blogger Lisa said...

Paul Moore said...

Sometimes knowing about another type of database can be more confusing than helpful

I found over the three days that it was the guy with the SQL Server experience that was having the most difficulty getting his head round some of the concepts.

He had big problems trying to differentiate between datafiles and tablespaces.

Tuesday, September 06, 2005 3:21:00 pm  
Blogger Daniel Fink said...

Simple rule - If it is included in the materials, you must explain it.

It is vital to what terms mean. Different systems use the same term to mean different things. Schema in Oracle is similar to database in Sybase.

I like the Castle analogy for database/instance, but what about us poor Yanks who never built castles? Must you be so anglo-centric?

...awaiting b-slap...

Tuesday, September 06, 2005 4:42:00 pm  
Blogger Niall said...

that pretty blonde with the princess leia thing going on with the hair :) said

I used the analogy of a castle, moat and drawbridge for the database and instance explanation.

Nope - entirely lost. Please stick it up as a post. It sounds like someone has thought carefully about the analogy - but I can't even begin to imagine what it might be.

I have a mnemomic for
Group by
Order by

though. Not a polite one, but memorable.

Tuesday, September 06, 2005 7:29:00 pm  
Blogger Lisa said...

Dan Fink said...

Must you be so anglo-centric?

...awaiting b-slap...

Oh Dan.

You were there. You were a witness. Yet you still try and antogonise me.

Will you ever learn?

Tuesday, September 06, 2005 8:28:00 pm  
Blogger Peter K said...

I am with niall.

Dying to hear the castle, moat and drawbridge analogy.

It's true that DBAs of other database systems tend to have a more difficult time getting their heads wrapped around the various terms/concepts used in Oracle. It's coz they are already biased (if that is the right term) with the other technology stuff plus it's harder to unlearn and relearn than to just learn ;)

Thursday, September 08, 2005 7:43:00 pm  
Anonymous Harry said...

I'm wondering what the engineers were supposed to go forth and do. Were they going to be DBAs of some sort? Or were they to be some variant of power users? If the former, dismissing pctfree etc. as things they didn't need to know was condescending. If the latter, why were they even exposed to the terms?

And I agree about the Anglo-centric thing. Maybe if you'd said "log cabin" and "split rail fence"???

Thursday, September 29, 2005 8:49:00 pm  
Anonymous Anonymous said...

is the castle the database, and the drawbridge each instance?


Monday, March 06, 2006 10:07:00 pm  
Blogger rich430 said...

I can see this blog as a very helpful place for someone like me.. well, I am new to the BI community .. I have a banking background as a business expert side .. but now am switching my career and working as an Oracle Financial Services Applications consultant .. I would like to ask you here as experts .. what would a Business Intelligence has to learn ?
thanks :)

Monday, December 11, 2006 9:14:00 am  
Blogger Jayanthi said...

hi experts,
iam new to this forum. i need ur advice. iam an MCA graduate and i know what is oracle,SQL,PL/SQL. iam trying to become a OracleDBA. is this Knowledge enough for that. i will take a DBA course for sure. is there much Diff. btw 9i,10g,11g versions(im not clear). in which shd i pursue my course. pls advice. waiting for the response

Sunday, December 30, 2007 1:55:00 pm  
Blogger Jayanthi said...

Hi experts,
Wishing you all very Happy New Year
with prayers

Sunday, December 30, 2007 2:22:00 pm  

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