Memcached

Memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load. It is often used to cache data objects retrieved from a database or API calls, serving them from memory instead of repeatedly retrieving them from slower sources.

Memcached is designed to be simple yet powerful. It operates on a key-value pair basis, where data is stored with a unique key and retrieved using that same key. Keys are typically short strings. Values can be arbitrary data, such as HTML fragments, serialized objects, or query results.

The system is distributed, meaning that multiple Memcached servers can be deployed across a network. Clients use a client-side hashing algorithm to determine which server holds a particular key, distributing the load across available servers. If a server fails, the affected data may be lost, but the application can continue to function by retrieving the data from the original source and caching it in another available server.

Memcached is often characterized by its “least recently used” (LRU) eviction policy. When the memory allocated to Memcached is full, the least recently accessed items are automatically removed to make space for new data. This ensures that frequently accessed data remains in the cache.

Memcached is not persistent; data stored in the cache is lost when the server is restarted or when the cache is explicitly flushed. Therefore, it is typically used as a cache layer in front of a persistent data store.

Key features include:

• Distributed Caching: Data is spread across multiple servers, improving performance and scalability.
• In-Memory Storage: Data is stored in RAM for fast access.
• Key-Value Storage: Data is stored and retrieved using simple key-value pairs.
• LRU Eviction: Least recently used data is automatically removed to make room for new data.
• Simple API: Easy to integrate with various programming languages and applications.
• High Performance: Optimized for fast read and write operations.

Memcached is widely used in various web applications, social media platforms, and e-commerce sites to improve performance and reduce database load. Its simplicity, scalability, and speed make it a popular choice for caching dynamic data.