Below are some questions you might want to ask a potential DBA you are considering hiring. Rampant Press has a very good book with technical questions on this subject,
but these aren’t nearly so technical. These questions are designed to find out how the DBA thinks, and how well he will fit in with the others in your organization. There are no 100% correct answers to this, but there incorrect answers.
1. Describe your work experience.
2. Describe your activities during a typical day in your current job?
3. What do you do when priorities change quickly? Please give an example.
If she answers ‘finish my current task’ before looking at the requirements of the new one, she has given a wrong answer.
4. It is 2:22 am Monday. A database has crashed and you are the on call DBA what steps will you follow to bring the database back on line?
An incorrect answer would be turn over and go back to sleep. Correct answers might be log onto the server box and read the alert log. Check for activity on the server, etc.
5. What is the biggest error in judgement you have made in your current job? Why did you make it? How did you correct it? What did you learn from it?
If he says he has never made a big error in judgment, he is lying.
6. When given a special project to work on (patch all the dbs with a critical patch for example), how do you approach the project.
A reverse planning method would be appropriate.
7. As an on-call DBA what are the most common issues you have had?
A full archive log destination is pretty common. Failed backup scripts also.
8. Describe a time when you came up with a creative solution to a database performance problem.
9. A developer comes to you with a complex query that does not perform well. What steps do you take to help her optimize this query.
Get an explain plan, look at the indexes and use of wildcards. There are a lot of good answers for this.
10. An application in production that has always performed well in the past has suddenly started timing out. During your research, you discover that a query that has performed well in the past has suddenly started running slowly. What steps do you take to resolve this problem?
See if the explain plan has changed. See if stats are good on the table. Check for invalid indexes.
11. You are observing the database, and discover that there are several ad-hoc queries being run through sql-navigator in the production database. There is no rule against this, but you suspect that the number and size of the queries is slowing down the response time in production. What do you do?
This is really a trick question. The answer you are looking for is talk to the people who are running the queries, or their supervisors, explain the problem, and see if they can reduce or eliminate the activity. Diplomatically.