Re: Top 10 things a DBA should know

It all depends on what you consider a DBA to be. There are different types of jobs that can use that title. For example, there is a database system administrator who is concerned with keeping a system up and tuning it for performance to the extent he can without touching the database design. Then there are development DBAs who work closely with analysts and programmers. The exact skill set required to do the job acceptably might be very different for these two jobs.

Now, with that said ... I interview a lot of candidates for DBA and developer positions. I prefer a well rounded DBA, or at least someone I can turn into one without starting from scratch. I am with you in that any candidate ought to know about normalization at least through third normal form, preferably fifth (most developers certainly do not know this). It would help if they also understand denormalization because it is one of the tools to get acceptable performance from a system. They should have experience as a developer and be excellent SQL programmers with experience writing stored procedures and triggers. They also should have some modelling experience. They should have some experience doing database administration on one of the major RDBMSs (not necessarily the ones I have). All these are pretty basic skills and experience. If a candidate has these and reasonable aptitute, I can turn him into the DBA I want. So far I have been talking about an entry level DBA position. I am not likely to hire someone into a position like this. I would rather develop someone from within the company.

If I am looking for an experienced DBA, I want more. He should have significant experience installing, configuring, monitoring, backing up, recovering, and tuning, both the RDBMS and the underlying operating system. Depth of experience is more important than experience with the specific products I am supporting. So, I might not care if the candidate knew the difference between pessimistic and optimistic locking if he came from an environment where it was not an issue. If the candidate has the right general skills and experience, I can send him to the appropriate product training and be pretty sure I have made a good investment. Of course, I would prefer someone with a skill set that matches the products I have to support.

If I am looking for a senior DBA, I want experience supporting a 24x7 operation and solving difficult issues under pressure. I also want experience with the specific products I have to support. The more the better. This guy is going to have to train and mentor more junior DBAs and developers.

In general, I try to ascertain the candidate's level of knowledge and experience without requiring correct answers to any specific set of questions. I have about 50 pages of questions in various subject areas at hand to use based on the candidate's background. I initially ask questions that will verify the statements on the candidate's resume and give me some idea of his level of knowledge and experience and then tailor the following questions to nail it down. Because so many DBA candidates are really DBA wannabes, I do phone interviews before inviting a candidate for an on-site interview. Will someone who doesn't know at least 3rd normal form be invited? Probably not.

The on-site interviews zero in some more, and clear up any remaining questions about the candidate's knowledge or experience. But most important is determing how well the candidate will fit in with the existing database team and the company in general. All the team members are involved in this process. Managers and members of other groups may also be involved.

If you get the feeling that there are a lot of unqualified people seeking DBA positions you are right. There are well qualified candiates out there, but it is a seller's market. Headhunters frequently aren't a good source. They will feed you lots of marginally qualified or unqualified candidates just on the hope that you will bite one out of a hundred times. But sometimes you luck out. Recently the headhunters fed us the resumes of some database (not DBA) candidates who were looking for new opportunities because they were concerned about recent changes in the company they were working for. We hired two of them, and now we are getting interest from their DBA friends at the same company.

So, don't lower your standards unless you have to.

Sorry for the long response. Hope its useful. Received on Thu May 14 1998 - 00:00:00 CDT