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--- sjx238 (8/23/2010)
看到很多job deion 都有这样的要求:
n+ years experience working with large (3+TB, 3+B obs) databases
-- Yes, this is true.
-- When you see they requiring you know how to manage large size database, it usually means data warehouses.
-- For OLTP system, usually the size is not that kind of big.
-- I have managed many high transaction OLTP databases with more then 10TB in size, therefore,OLTP database can also grow big if you have a large customer base.

这都包括哪些skill set呢,

-- When I interview DBA candidates, I like to ask following questions:

1) How do you set up a database server? (If you are hired as a DBA, I send you join a meeting for a new project, this project need set up a new database. You are the only DBA in that meeting. Unix/Linux SA asks you in the meeting: What kind of server should we buy for this project? How do you answer? (this is a very practical question, because you will do it in the work.)

2) How do you do monitor your database system? (you need this in your work)

2) How do you do if people complain the database system is slow?

Case 1: A system running well for many years, there is nothing changed, however, this morning, people come to you, say why the Purchase Labor system is so slow this morning? What will you do? (This is very common on work.)
Case 2: Company released a new version of application to production system last night. This morning, NOC reported that that application is a piece of junk, developers don't know how to scale up the application, so it stuck when multi-million people starting connecting on the production. What will you do as a production DBA for this system? (This is a problem you will face in the work.)

3) How do you back up and recover your database? (you will do this on your work)

4) If you have a production issue, you don't know how to solve (and 老土不接你的丝盖披 at that moment), what will you do? (You will face this on production.)

5) Let's test some basic stuff, just want to see how good you are when you reading a book:
What is check point?
When a checkpoint happen?
What is the reason a check point takes very long time?
We all know large memory is good for the performance of the database, right? How about I have a machine with unlimited memory, I run a database on it. What is the problem fir this database?
( I interviewed a candidate, he said he used teaching at Oracle University in the last ten years. He did well for all above 4 questions, but he failed this one. He said: Sorry, I can't remember all these fundamental stuff. I didn't hire him.)
-- You can see all the above questions are open end. There is NO fixed answers.
-- As long as you can answer all the above questions well, you can pass my interview. Many people told me: Are you only asking so simple question? I aid Yes.
-- By the way, do you know what is the golden rule as a DBA? "Don't touch the production system as long as it is running well." Because 90% of the problem is human made error.

-- Yes, theoretically everything is self-learnable.
-- However, it will take a long time to pickup DBA skills by reading books yourself. N years ago, I want to learn DBA skill by reading DBA handbook becasue I thought I was smart, so I borrowed a book from our DBA. I gave up after three days, because I didn't understand what is extent, segment, etc.
-- The best way is find a good teacher who has the skill and who is willing to give the tool from him toolbox to you,and who is willing to pass his experience to you so you will be a handy girl/man in a short time.

-- All the company will NOT give their important Database System to a newcomer unless that manager does not care the data.
-- However, there are openings for Jr. DBAs in a large team.
-- Start from Database Analyst, get familiar with the smell of the Data, learn how to setup a small database for your Reporting system to run your report if you manager said they need a database for them self but the IT DBA doesn't have time to help them or don't want to help them. You tell your manager that your teacher already told you how to do it (and you did it with your home PC many many times already, so you sure you can do it without bother the IT DBA. (By the way, now you know how to answer my first interview question above.)
-- Then step by step, start from manage the baby database you setup for your project, you will learn the skills....
-- By the way, try to get answer for the questions I asked above, or, talk these questions, chat these questions use your own language during your interview (即: 从您的口中讲出老土的话), you will make a big difference and you will get a DBA job eventually...
-- I wish I had people told me these kind of experience and stories when I trying to be a DBA...
-- I wish I am as young as you so I can avoid lots of mistakes I made ...
-- 咱参与,咱丰献,咱健康,咱高兴!
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