Posts Tagged DBA interview
Screening and Interview Questions for DBAs
Posted by Jay Caviness in general on August 7th, 2008
I mentioned in a previous post (Are You Certifiable?) that when I interview DBA’s I want to see if they know why things work, not just how they work. I want to see an underlying systemic understanding of not only the database but how other parts of a system affect and are affected by the database. However, to get to that point there is typically a pre-screening phone interview to weed out applicants, and I do need to know core knowledge. Depending on the level of DBA I am looking for come a few questions, I will ask some of the lower level questions to senior level people because I have seen many-a-DBA lock up on remembering the parts of the SGA.
- What is the SGA? What are its components?
- Name several methods to back up an Oracle database. What are their advantages/disadvantages?
- What are the four states a database instance can be in?
- What are undo segments for?
- What is the temporary tablespace?
- What is the cost based optimizer? What are statistics, histograms, etc?
- What happens during a crash recovery?
- How do you recover from a lost: datafile, tablespace, undo tablespace, control file?
- Is a full table scan ever better than an index scan? If so, how and why?
- What is an ORA-1555, how can it be avoided?
- What is your philosophy on datafile placement on SAN, NAS or local storage?
- When is it appropriate to set tracing on SQL*Net?
- When is RAC/Dataguard/streams appropriate to use for high availability?
- List methods to prevent, detect and repair corruption in a database
- Finally, my database is slow, ask me five questions to determine a cause.
This is a starting point. You may have noticed that the questions get more open ended as the level increases. Generally the more complex a problem the more solutions can present themselves, and I would want to hear several ideas. Later I will focus this list for RAC/ASM specifically. Feel free to post your own screening/interview questions, I good base of questions will help both interviews and candidates. Cheers!