[mmsmatt]

> Once you know window functions, you risk putting them all over the place

Agreed.

A few years of writing expressive, powerful, performant SQL in big blocks will really change your mental model of data across _all_ languages.

I highly recommend a deep dive into the relational world, and I feel super grateful for the SQL-focused job I held previously. Brought those lessons back with me to both FP and OO.

[nickpeterson]

They are extremely useful, although they seem to vary in performance quite a bit (SQL Server experience here, so YMMV). I'm always a bit shocked how little SQL most software developers know, especially because it's often the bottleneck if used poorly.