Much ado about job interview questions
Posted on
January 12, 2015
Don't expect to ace a job interview with canned answers to tech questions.

On various public forums about Oracle (and I suspect for other IT careers as well), one of the more common posts is from people who request to be supplied lists of interview questions. A number of these lists can be located easily on the Web. In addition, Amazon is filled with books that claim to have lists of the most commonly asked Oracle interview questions.

Requests for these lists are almost as prolific as requests for brain dumps. Of course, unlike brain dumps, interview Q&A lists are not cheating per se. Despite that, there is an inherent problem with using question lists of this type when preparing for an interview. Almost without exception, the candidates who are most inclined to use these lists do not really know enough about Oracle to be applying for the position. If they were confident of their Oracle knowledge, then there would be no need to make use of such a list.

The types of questions that are normally included in these are generally obscure facts or definitions that someone who has administered an Oracle database, written code as an Oracle developer, or worked with a specific Oracle application would have encountered in their daily activities. Presumably the act of memorizing these questions and answers is intended to demonstrate that someone has experience with a given element of Oracle. Since most of the people who request these lists do so specifically because they have no experience, in many ways it is pointless to memorize the facts.

That may seem counter-intuitive, so let me give an example. I recently conducted interviews to fill a position for someone to act as an Oracle developer. Since it was an entry-level position, none of the candidates had experience with the Oracle database. For that reason, I asked the candidates zero questions that required Oracle knowledge. Perhaps some of the candidates memorized one or more of the aforementioned lists. I neither know nor care. Since these questions are used to check for Oracle experience, the only way someone without that experience should expect to be asked them is if the candidate intends to lie on their resume by inventing prior work experience.

It is certainly possible for someone to memorize a bunch of question-answer combinations from an interview list. In doing so, they could theoretically develop a surface veneer of Oracle knowledge. To say that this veneer would be paper-thin is a vast understatement. Even if an interviewer happened to ask one of the questions from the list, almost any follow-on question would shatter any illusion of competence. Take for example one of the questions from a list available on a site popular with Oracle professionals:

Q: What background process refreshes materialized views?

A: Job Queue Process (CJQ)

This particular factoid falls into the “very nearly useless” category of information. Essentially, it is nothing more than trivia. An Oracle Database Administrator should know the Oracle architecture. Part of that knowledge is understanding what the various background processes are and the functions they serve. An administrator should certainly know which of the processes are the big players, and what they do: PMON, SMON, DBWR, and ARCH for example.

That said, memorizing the names and functions of all the bit players is definitely secondary information. If I were interviewing candidates for a position where the interviewees were expected to have Oracle knowledge, I might ask the above question. If the candidate were able to answer it, however, I would continue with one or more follow-up questions like:

  • What is the difference between a view and a materialized view?
  • What is a fast refresh?
  • What are the tradeoffs involved in using materialized views?

Understanding the answers to these three questions is much more useful for a database administrator than the name of the process performing refreshes. If an interview candidate were able to answer the first question, but not the follow-up ones, it would strongly indicate to me that they were making use of one or more lists to project a façade of Oracle knowledge.

I am a huge proponent of helping people to learn about the Oracle database. My articles, website, blog, books and more are all dedicated to making advice and information available to the broadest possible audience. Brain dumps and interview question lists are both simply crutches used by people who want to appear knowledgeable without taking the time and effort to become knowledgeable.

These lists can be used by interviewers as per my above example to look for posers. Interviewers who would prefer not to use them at all can easily create questions that would never appear on such a list. When I have been part of a team interviewing DBAs, I often picked a recent problem encountered on our databases to use as a scenario question. I would describe the problem to the candidate in detail and then ask how they would have diagnosed (or resolved) the issue.

I have been working with the Oracle database for 19 years. Even after almost two decades I would never claim to know everything about it. There are certainly questions that someone could ask in an interview that I would be unable to answer off the top of my head. This is not, however, something that would concern me prior to an interview.

I am confident of my ability to demonstrate my knowledge of the portions of Oracle that fall into the areas I highlight on my resume. Only people who try to claim knowledge that they do not truly have need to be worried about being caught out by a question in an interview. At that, it is better to be honestly caught out than to be ambushed by something like my example above.

As noted above, the internet contains huge numbers of these interview lists and books on the subject are a dime a dozen. Be aware, however, that if you prepare for an interview using Oracle Interview Answers for Dummies, then you had better hope that the person running the interview is working directly from their copy of The Complete Idiot's Guide to Interviewing Oracle Professionals.

About the Author

Matthew Morris is an experienced DBA and developer. He holds Oracle DBA Certifications for every Oracle release from 7 through 12c; Expert certifications for SQL, SQL Tuning, and Application Express; and is an Oracle PL/SQL Developer Certified Professional. He is the author of more than 20 study guides for Oracle certification exams, as well as a suite of Oracle practice tests that are available at

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