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As someone who has had bad data science interviews before getting my current data science job, the process is highly variable. I've had interviews where the interviewer is looking for a specific right answer, with the answer being a binary you-know-it-or-you-don't thing that can't be talked through or worked out in a dialogue with the interviewer.

An example was a whiteboard problem requiring the BETWEEN syntax for SQL window functions, which is very uncommon. After I asked for a hint, the interviewer replied "You don't know the BETWEEN syntax for window functions? Everyone knows that."



My favorite iteration of this is also when the interviewer has a suboptimal answer to this question, and expects you to parrot the wrong thing back to them.

I could tell I annoyed my interviewer when they told me I was wrong and I demurred, and politely asked them to look it up since there was some question about the facts. They did not look it up.


I had that from a Microsoft interviewer. Thought my code was O(n^2) because he was a C guy...whereas I was writing it in Java (something I had checked would be okay with both the recruiter and the interviewer). Querying the length of a string is an O(1) operation, not O(n), so while you could make the case it's suboptimal (since a function call per loop instead of just a variable lookup), it's not quadratic in behavior. And when he asked what I would do if a number overflowed and I said "...let the exception bubble up because based on the function you asked me to write there is nothing I can do cleanly within it" it was pretty clear the interview was over.

Good times.


TIL even sqlite has window functions.


MySQL and sqlite only got window functions very recently, years after the aforementioned interview.

On a take-home test around that time, the question specifically said to use PostgreSQL just because the answer required a window function.




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