Caching Strategies

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What is Caching?

Caching is the practice of storing copies of frequently accessed data in a temporary, high-speed storage layer. It significantly reduces response time, minimizes database load, and improves the scalability of applications. Without caching, servers must repeatedly fetch or compute the same data, resulting in slower user experiences and higher infrastructure costs.

Caching is critical because it:

• Improves application performance and reduces latency
• Saves compute resources by avoiding repeated processing
• Lowers database and network load
• Enhances scalability during high traffic
• Helps deliver a smoother user experience

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Types of Caching Strategies

1. Cache-aside (Lazy Loading)

Description: Data is loaded into the cache only when requested. If the cache does not have the data (cache miss), the application loads it from the database and stores it in the cache.

Advantages:

• Efficient use of cache — only stores what’s needed
• Easy to implement
• Works well with read-heavy workloads

Challenges:

• First request is always slow (cache miss penalty)
• Risk of stale data if not paired with invalidation

Use Cases:

• Product catalog pages
• User profiles
• Any read-heavy application with predictable repeated reads

2. Write-through Cache

Description: Every write operation updates both the cache and the database simultaneously, ensuring the cache is always up to date.

Advantages:

• Strong consistency between cache and database
• Cache always contains the latest data

Challenges:

• Slower writes due to dual operations
• Unnecessary caching of data that may never be read

Use Cases:

• Systems requiring immediate consistency (e.g., financial data)
• Shopping carts

3. Write-back (Write-behind)

Description: Data is written to the cache first and persisted to the database asynchronously.

Advantages:

• Very fast write operations
• Reduces database load

Challenges:

• Risk of data loss if cache fails before DB update
• More complex implementation

Use Cases:

• High-write systems like logging or analytics events
• Real-time counters (views, likes)

4. Read-through Cache

Description: The application interacts only with the cache. On a miss, the cache itself fetches data from the database and stores it automatically.

Advantages:

• Simplifies application logic
• Ensures consistent cache-loading behavior

Challenges:

• Cache layer becomes a single point of failure
• Can increase latency on cache misses

Use Cases:

• Content management systems
• Article or blog platforms

5. TTL-based Caching

Description: Items stored in the cache automatically expire after a set time-to-live (TTL).

Advantages:

• Natural prevention of stale data
• Simple and widely supported

Challenges:

• Potential for synchronized cache misses if many keys expire at once (dogpile effect)
• Requires tuning TTL values

Use Cases:

• API responses (e.g., weather data)
• Promotional banners, UI content caches

6. CDN Caching

Description: Caches content at geographically distributed edge locations to reduce latency for global users.

Advantages:

• Drastically improves global performance
• Reduces load on the origin server

Challenges:

• Propagation delay for cache invalidation
• Limited to static or semi-static content

Use Cases:

• Images, videos, static assets
• Global websites and e-commerce platforms

7. Client-side Caching

Description: Browsers cache static files (HTML, CSS, JS, images) using headers like Cache-Control, ETag, and Last-Modified.

Advantages:

• Zero server cost for repeated loads
• Instant load times for cached assets

Challenges:

• Risk of outdated assets if caching rules are not configured correctly
• Requires versioning strategy (cache busting)

Use Cases:

• Web apps, PWAs
• Any frontend-heavy application

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Choosing the Right Strategy

The ideal caching strategy depends on your:

• Consistency requirements
• Read/write traffic patterns
• Data volatility
• Performance goals
• Infrastructure design

Often, multiple strategies are combined for optimal performance.

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Conclusion

Caching is one of the most powerful techniques for improving performance, reducing system load, and enhancing user experience. Understanding the strengths and weaknesses of each caching strategy allows developers to design systems that are both fast and reliable. With the right caching approach in place, applications scale more efficiently and deliver significantly better responsiveness.

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References

Medium: Cache Strategies

Dev: 9 Caching Strategies for System Design Interviews

ByteByteGo: Top Caching Strategies

Microsoft: Caching Guidance