I Replaced a 2,000-Line Service with a SQL Query. It's Been Running for 3 Years.

I Replaced a 2,000-Line Service with a SQL Query. It's Been Running for 3 Years. Most developers are afraid of their database. I mean truly, deeply afraid. They'll spend weeks building elaborate application-layer solutions to problems that SQL could solve in fifteen minutes. I've watched brilliant engineers write thousands of lines of Python to do what a window function handles elegantly. Stop it. Three years ago, I inherited a service that was the poster child for this madness. A sprawling, 2,000-line Python monster that calculated user engagement scores by pulling data from six different tables, running complex transformations in memory, and somehow managing to be both slow and wrong. The original author had clearly never heard of a JOIN. The Problem Was Simple (The Solution Wasn't) We needed to calculate engagement scores for users based on their activity patterns. The score combined: Comment frequency over the past 90 days Post quality metrics (views, likes, shares) Session duratio