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0 pointsthomzi126y ago0 comments

Thanks for the feedback! The first section is intentionally about self-joins since they get asked about in interviews, but other people have brought up that window functions are more efficient, so I'll add in those solutions as well.

Sorry you feel that way! Thankfully my employer felt differently :)

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4 comments · 1 top-level

beckingz6y ago· 3 in thread

If it runs fast fast enough or the business can wait long enough, slow and ugly is acceptable.

deepsun6y ago

That's exactly what I look against on interviews. Slow SQL queries tend to work fine for some time, and as data grows, they start failing.

I'd want to hire a professional, who knows the perfect way of doing that, so for them it would be as easy to make it right, as to make it ugly.

thomzi12OP6y ago

Yes, in particular for data analysts using SQL to answer product/business questions in a one-off fashion

MaxBarraclough6y ago

Unless the dataset grows, poorly optimised queries slow down superlinearly, and things start falling over.

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