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Comment by toomuchtodo | Hacker News Reader

I hire people based on their ability to learn, not what they know.

If you're asking interview questions that can be googled in 20-30 seconds, you're wasting your time and theirs.

You have a pretty low opinion of our field if you think everything that you need to know about our field can be googled in 20-30 seconds. I'm not arguing about minutia questions, but if you can't be bothered to understand how and why to optimize a database or the difference between TCP and UDP (really?) and that's what the job requires, then I don't want to hire you.

My argument is don't play puzzles, don't ask stupid questions about "What does this command do with these flags?".

An interview should be the same as a discussion about concepts you'd have with a colleague. Does the person know the concepts? That's all that matters.

Basic computer science knowledge (and yes, B-Trees qualifies) cannot be learned in 20 seconds. Most of this knowledge is actually a prerequisite to being able to search Google properly.

Fair point. I was unfamiliar with B-Trees because most of my time is spent as DevOps/Networking/Sysadmin. It took me 15 minutes to learn and understand what they are and how they work.

http://slady.net/java/bt/view.php?w=800&h=600 http://en.wikipedia.org/wiki/B-tree http://en.wikipedia.org/wiki/B%2B_tree http://guide.couchdb.org/draft/btree.html

Now if you make understanding B-trees a prerequisite for the job, I can at least learn it ahead of time for the position.

how often does a normal software developer find himself in a situation where he has to know about B-Trees in depth?

Basic computer science problems creep up often enough (about once a month) at my mostly normal job. We had to implement a prefix trie (specifically a modified radix trie with extra caching) to solve an interesting problem.

If you don't know about these data structures or algorithms, you won't even know where to look.

When he works for the company that this whole conversation is stemming from.

Database indexes are very frequently btrees; understanding how a btree works can inform how you structure and query data, resulting in substantially better software. They're also a generalization of the binary search pattern, which every programmer should be able to describe and utilize.

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