Caching strategy

Definition

A caching strategy is a planned approach to storing copies of data or content temporarily so that future requests can be served faster. Instead of retrieving information from the original source every time, caching allows data to be delivered from a closer or more efficient location, improving speed and reducing server load.

Caching is used across web applications, APIs, and content delivery systems to enhance performance, scalability, and user experience. Different strategies determine how long data should be cached, when it should be refreshed, and how to handle invalid or expired content.

Advanced

At an advanced level, caching strategies are implemented at multiple layers, such as browser cache, server cache, reverse proxy cache, and content delivery networks (CDNs). Techniques include time-to-live (TTL), cache invalidation, lazy loading, and cache busting with versioning.

Developers often choose between cache-first, network-first, stale-while-revalidate, or hybrid strategies depending on the balance of performance and data freshness. Monitoring cache hit ratios, eviction policies, and memory limits is key to optimising system efficiency.

Why it matters

• Improves performance by reducing load times.
• Decreases server strain and infrastructure costs.
• Provides scalability for high-traffic applications.
• Enhances user experience with faster responses.

Use cases

• Delivering static assets like images, scripts, and stylesheets via CDNs.
• Storing API responses to reduce database queries.
• Caching search results or product listings in e-commerce platforms.
• Speeding up mobile apps with offline caching strategies.

Metrics

• Cache hit ratio compared to total requests.
• Latency reduction in response times.
• Server load and bandwidth savings.
• Frequency of cache invalidation events.

Issues

• Stale data if caches are not refreshed correctly.
• Cache misses leading to inconsistent performance.
• Overuse of caching may hide underlying performance issues.
• Complex invalidation rules can cause errors in dynamic applications.

Example

A news website implements a stale-while-revalidate strategy for article content. Visitors receive cached versions instantly, while the cache is refreshed in the background. This reduces load times during peak traffic while ensuring content remains up to date.