This article was written by Darshan Jayarama .

It was a Friday, and I was quickly wrapping up my week, finishing the tasks that were assigned. Suddenly, the board became red — another S1. I was like, not now!!!

The application team started complaining about the API responses from the database, going from 600ms to 17 seconds. Booooom!!! That’s insane. No other choice — since it was production, I had to jump in. The war room was ready. The monitoring dashboard was nothing but a heart patient’s ECG — spikes, timeouts, and the main app was choking.

What's the Mystery?

From the dashboard, we identified a query that was asked by the VP to add a breakdown by region to the dashboard. It was just one more field. But it was ONE.MORE.FIELD.

Innocent query, which was harmless for years:

db . orders .…