Indexing: The Force Awakens in My Rate Limiter Quest (opens in new tab)

The Quest Begins (The "Why") Ever had one of those days where your API feels like it’s stuck in quicksand? I was building a simple rate‑limiter for a microservice that throttles requests per IP address. The idea was straightforward: every incoming hit checks a counter stored in Postgres, increments it, and if the counter exceeds the limit we return 429. At first it worked like a charm on my laptop. Then we pushed to staging and… boom. Latency spiked from 2 ms to 200 ms under a modest load of ...