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0 pointsatomicnumber310mo ago0 comments

If I was your interviewer, I would: respect your answers a lot, not be able to check off anything on my rubric, try to explain this in the debrief, get told we have to stick to the rubric to counter bias, and then watch while they pass on you for someone who decided to play architecture jenga instead. I would potentially even consider emailing you to apologize later, then not do it because I'd probably get in trouble for exposing us to liability or something because apologizing can be construed as admission of guilt.

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7 comments · 3 top-level

yojo10mo ago· 4 in thread

If a candidate doesn’t ask clarifying questions that lead them to an understanding of QPS, storage requirements, and throughput considerations, that’s a mark against.

At that point, if you want to see them design a distributed system with all the bells and whistles, you should stop them, tell them the kind of traffic they need to handle, then let them go again.

If they persist in designing a system that cannot handle the specified load, they have probably failed the interview.

ndriscoll10mo ago

The problem with this is people seem to have mismatched understandings of what a single system can handle. e.g. my 8 year old quad core i5 desktop with a bit of batching optimization can handle 5 digit requests per second with 15 ms p99 with some nontrivial application logic doing several joins. I don't think I've tried that same benchmark on a modern minipc, but I expect it should be similar. That's well above what most companies will ever need to handle. Visa advertises they can process ~70k tps worldwide.

Last time I interviewed I was asked about designing a system to handle 10s of thousands of events per minute, and if you thought about the problem a little you'd realize most of them didn't require real work to be done. I answered something along the lines of "you don't need to do anything special. Just normal postgres/mysql usage can handle more than that on a laptop". After I got hired I learned the rubric had some expected answers about queues (e.g. Kafka) in it. No idea why still.

sgarland10mo ago

Because web devs are so used to terrible design, poorly-optimized DB schemas, and networked storage latency that they have no idea what a single server (or indeed, a humdrum desktop) is capable of.

Like when I inform teams complaining of “slow queries” that the DB is executing them in sub-msec time. No idea what the rest of your stack is doing, but good luck with figuring that out - it ain’t me.

jiggawatts10mo ago

“Prove that you can apply solutions to yesterday’s problems today.” is a good strategy except in industries where today is exponentially different to yesterday.

gopher_space10mo ago

I’m also going to need a dollar value on your data and a list of consequences. We will spend our allotted time together in Excel.

willio5810mo ago

I’ve interviewed dozens of people and while I rarely do system design questions and our process isn’t nearly as check-all-the-boxes, it’s funny how accurate your comment still is. Near the later stages especially, politics starts coming in.

belinder10mo ago

Exactly, it would only work if you have enough sway with your boss and the willingness to take responsibility for the hire

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