Evaluating performance impact of removing Redis-cache from a Scylla-backed service

This post details the investigation and removal of a Redis cache from a Scylla-backed counter service. The primary motivation was to eliminate performance spikes and latency issues caused by the cache's 15-minute truncation strategy and 5-minute TTL, which led to cache hit misses and increased Scylla QPS at the end of every 15-minute block. By removing the Redis cache and relying on Scylla's native caching, the service achieved more balanced load distribution and reduced latency, demonstrating a trade-off between external caching complexity and leveraging the underlying database's capabilities.