Groww's engineering team tackled a high-traffic problem where the Holdings page received up to 1M requests per minute at market open. Analysis revealed 90% of users didn't trade on a given day, yet every request triggered full data fetches from Portfolio and Positions services. The solution shifted from optimizing retrieval speed to avoiding unnecessary retrieval entirely. A dedicated Holdings Service was built using CQRS, ingesting data via CDC pipelines. HTTP ETags stored in Redis enabled lightweight cache validation before any expensive downstream calls — returning 304 Not Modified when holdings hadn't changed. The result: 66% of requests never reached the retrieval path, downstream services were scaled down, and infrastructure costs dropped significantly. The service was built on CockroachDB to support future cell-based architecture.
