Cache Consistency: Strategies to Keep Data Fresh

This post details cache consistency strategies, explaining what it means, why caches drift (TTL timing, write ordering, instance races), and comparing classic patterns like cache-aside and write-through. It introduces event-driven synchronization using Redis Keyspace Notifications and Change Data Capture (CDC) as more robust methods to keep data fresh, especially for changes originating outside the application. The post highlights the engineering effort involved in managing ordering, deduplication, and replay logic for these event-driven approaches.