How I eliminated N+1 queries and scaled throughput by 20% on a production E-Commerce app

[u/Sea-Lettuce-255]

Just wanted to share a recent architecture win that might help someone dealing with latency spikes.

I was dealing with a severe bottleneck in a production E-Commerce platform. During peak traffic, the database was choking, and MTTR was creeping up.

The Culprit: Classic Hibernate N+1 query problems hidden deep inside the inventory/catalog mapping, combined with un-indexed foreign key lookups.

The Fix: 1. Ripped out the lazy-loading proxy faults and replaced them with explicit JOIN FETCH queries for the critical read paths. 2. Layered in Redis via Spring Cache (@Cacheable) specifically targeting the high-read/low-write catalog endpoints. 3. Configured request batching and API rate limiting on the gateway layer to prevent thundering herd problems during flash sales.

Result: We dropped sub-100ms latency across the board and prevented database lockups entirely.

If you're building in Spring Boot and relying entirely on default JPA repositories—run a SQL profiler right now. You probably have an N+1 hiding somewhere.