Beyond Cache-Control: max-age
Browser caching is just the first layer. In high-performance architecture, you need a multi-layer caching strategy. In this guide, we break down server-side caching vs client-side caching.
The Application Cache: Redis
Redis is more than a key-value store; it's a data structure server. You can cache entire HTML fragments, user session objects, or leaderboard sorted sets. Its in-memory nature allows for sub-millisecond response times, taking the load off your primary SQL database.
Stale-While-Revalidate (SWR)
This powerful HTTP directive allows a client to serve stale content immediately while fetching a fresh version in the background. It is the secret sauce behind the 'instant' feel of modern PWA (Progressive Web Apps). The user sees *something* instantly (even if it's 5 minutes old), and then the UI updates silently.
Cache Stampede Protection
What happens when a popular cache key expires and 1,000 requests hit your database simultaneously? This is a Cache Stampede. We discuss locking strategies (like the Redis Redlock algorithm) to ensure only one process regenerates the cache while others wait.