Not long ago, weeding through DBA applicants with a tech interview was a straightforward process. You'd ask candidates 200 or so technical questions. If they got 100 correct answers, you knew they'd been around block; 150 or more and you knew you were on to superior talent. But once Oracle Certification Program (OCP) became popular in late 90s, traditional tech interview lost its effectiveness. These days, candidates can answer 180 questions correctly and you still won't know whether they're talking from experience or simply regurgitating what they memorized at OCP a few weeks earlier. Although it has become increasingly difficult to determine whether you've found a seasoned, highly qualified DBA or a newly minted OCP Graduate, there are ways.
First, start by throwing out questions. Any candidate who has been through OCP knows answers—all of them. That list that helped you find superstar employees in past is unfortunately useless now. Second, if you are a manager without solid database experience, enlist help of an experienced DBA to help you prepare that critical interview. IT Managers have varied backgrounds and here it's important to pull from right background, be it yours or someone else's.
You also need to analyze your needs. If you're looking to hire a junior person and mentor them, OCP program ensures that candidate has been exposed to most areas of Oracle RDBMS. You can assume you'll have an employee who knows commands and has a general concept of how a database works. But if you select an inexperienced OCP candidate thinking you're getting a skilled veteran, you'll be in for countless unpleasant surprises. Typical horror stories sound like: A DBA restores backup for first time in a real-life situation, finds out backup strategy was flawed and loses whole database. S/he probably also forgot to make a backup of database before attempting recovery, therefore rendering Oracle support intervention nearly impossible.
A DBA recommends technical implementation decisions based on limited experience with a single user database that has 10 tables of 100 rows each. Of course, system hangs a few hours after launch—as soon as 10,000 users start pounding on a 500GB database.
The most damaging aspect of newer DBAs is that they don't know when they are in over their heads, or how to plan properly. Senior IT professionals, no matter their field of expertise, have a gut feeling when it's happening. They know they have to step away, talk things over with a peer, roll everything back, and try another day. Inexperienced IT professionals are fearless and can therefore be dangerous, especially if they're expected to run show.