Caching Strategies for Web Applications

Caching is one of the most effective ways to improve application performance.

Cache Layers

1. Browser Cache - Client-side
2. CDN Cache - Edge network
3. Application Cache - Redis/Memcached
4. Database Cache - Query cache

Common Strategies

Cache-Aside (Lazy Loading)

async function getData(key: string) {
  let data = await cache.get(key);
  if (!data) {
    data = await db.query(key);
    await cache.set(key, data, { ttl: 3600 });
  }
  return data;
}

Write-Through

async function saveData(key: string, data: any) {
  await db.save(key, data);
  await cache.set(key, data);
}

Write-Behind (Write-Back)

• Queue writes to cache
• Async flush to database

Invalidation Strategies

1. TTL (Time To Live) - Expire after time
2. Event-based - Invalidate on write
3. LRU (Least Recently Used) - Evict old entries

Key Decisions

• What to cache?
• How long to cache?
• When to invalidate?

Cache wisely - it's not just about speed, it's about consistency!