Memcached vs RocksDB: What are the differences?

Key differences between Memcached and RocksDB

Memcached and RocksDB are both popular in-memory data storage systems used in web applications. However, they have several key differences that make them suitable for different purposes.

1. Implementation and data storage:

   • Memcached is an in-memory key-value store that stores data in a hashtable in RAM. It is simple and lightweight, designed for fast data access and caching.
   • RocksDB, on the other hand, is a persistent embedded key-value store that stores data on disk. It is optimized for durable storage and can handle large datasets.

2. Durability and persistence:

   • Memcached does not provide durability or persistence out of the box. If the system crashes or restarts, all the cached data is lost. It is typically used for caching transient and non-critical data.
   • RocksDB, being a disk-based storage system, provides durability and persistence. It flushes data to disk periodically and can recover data in case of system failures.

3. Performance and scalability:

   • Memcached is known for its exceptional performance in terms of storing and retrieving data from memory quickly. It is highly scalable and can handle a large number of concurrent requests.
   • RocksDB, while not as fast as Memcached for in-memory operations, offers better performance for disk-based storage. It can handle large datasets efficiently and is designed for high read and write throughput.

4. Data consistency and atomicity:

   • Memcached does not provide built-in support for data consistency or atomic operations. It is eventually consistent and relies on the application layer for maintaining data integrity.
   • RocksDB supports atomic and consistent operations on a single key-value pair. It ensures that read and write operations on a single key are ACID-compliant.

5. Data size and storage capacity:

   • Memcached is limited by the amount of memory available in the system. It is not suitable for storing large datasets that exceed the available memory.
   • RocksDB can handle large datasets that can exceed the available RAM. It efficiently manages data on disk and allows applications to handle larger workloads.

6. Usability and ease of deployment:

   • Memcached is extremely easy to deploy and configure. It has a simple and straightforward API, making it suitable for lightweight caching and session storage use cases.
   • RocksDB requires more setup and configuration as it needs to be integrated into the application. It provides a more granular level of control and flexibility for data storage and retrieval.

In summary, Memcached is a lightweight, in-memory caching system optimized for performance and scalability, while RocksDB is a durable disk-based storage system designed for managing large datasets efficiently.