When you’re hiring a DBA, sysadmin, or developer, you’re not paying them to answer Trivial Pursuit questions all day long.
You’re hiring them to look at a screen, connect a few dots, and interpret what’s happening.
So for a position, I build a PowerPoint deck with a bunch of screenshots from the actual environment they’ll be working in. I start the deck by explaining that there’s no right or wrong answers – I just want to hear them think out loud about what they’re seeing.
For example, I’ll show a database administrator or developer this:
Typical reactions include things like:
- “Oh, that’s a fact table.” – What does that mean? Where have you seen a fact table before? How do you handle them differently than other kinds of tables?
- “It seems really wide.” – What does that mean? Are there strengths or challenges with wide tables? How many columns should a table have?
- “The fields are mostly nullable.” – Is that the default? How do fields end up that way? What would you recommend changing? How might it break things, and how would you check to see if they were going to break? Would end users notice the impact of your changes?
- “It isn’t normalized – it has both IDs and names.” – What kinds of tables might have that design pattern? What would be the performance impact of this design?
Whenever they say anything out loud, follow the thought. Don’t assume that they believe the same thing you do – ask open-ended questions to get them to explain what they know.
Let them talk until they’re silent for several seconds, and that’s their normal knowledge base. Resist the temptation to make suggestions like, “Did you notice how there doesn’t seem to be a clustered index?” If they don’t notice it, they don’t notice it – that’s your sign.
Another example – I’ll say, “Someone brought this query to you and complained that it’s slow. Where might you look for improvements?”
The query is abridged, but even just in that first screenshot, I want to hear their thought process around where they look, how they might run the query to check its effects, how to measure their work.
In your own interviewing, try to use real screenshots from your own environment. Show them the kinds of screens that they’re going to have to look at independently in their day-to-day work, and just let them brain dump about what they’re seeing.
Hearing their thought process is way more valuable than playing Trivial Pursuit.