A distributed cache is a system that stores data across multiple servers to improve access speed and reduce load on a database. Unlike a traditional cache, which typically exists on a single server, a distributed cache allows data to be distributed across a network of machines. This setup enhances performance and scalability, especially in distributed databases where multiple nodes may need quick access to frequently requested data. When an application needs data, it first checks the distributed cache; if the data is present, it can be retrieved quickly without querying the main database, thereby reducing latency.
In distributed databases, a distributed cache plays a critical role in optimizing read operations. For example, consider an e-commerce application that frequently accesses product details. Instead of hitting the main database every time a user requests this information, the application can store these details in a distributed cache. If multiple users are accessing the same product simultaneously, the cache can efficiently serve the data without burdening the primary database. Tools like Redis and Memcached are commonly used for this purpose, providing mechanisms for storing, retrieving, and invalidating cached data effectively.
Additionally, distributed caches support fault tolerance and load balancing in distributed systems. If one node in the cache fails, the data can still be accessed from other nodes, providing resilience. Moreover, as the load on the system increases, new cache nodes can be added to share the load, ensuring that response times remain fast. Using a distributed cache not only speeds up data retrieval but also enhances the overall efficiency and reliability of distributed database systems, making it a fundamental component in the architecture of modern applications.