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Memcached vs. Redis

Memcached and Redis are both open-source, in-memory data stores that can be used as a cache for speeding up web applications. Both of them have their unique use cases and strengths, but here are the main differences between them:

Data Types​

  • Redis supports a wide range of data structures such as strings, hashes, lists, sets, and sorted sets,
  • Memcached only supports simple key-value pairs.

Persistence:​

  • Redis offers persistence, which means that it can save its data to disk, so that even if the Redis process restarts or the server reboots, the data will still be there.
  • Memcached, on the other hand, is completely in-memory and has no persistence.
  • However, since Memcached doesn't persist data to disk, it doesn't need to read data from disk on start-up, which can be slower in Redis.

Atomic Operations​

  • Redis supports atomic operations, which means that it can execute operations like incrementing a value in a single step, without the need for locks.
  • Memcached does not have this capability.

Speed​

  • Both Memcached and Redis are very fast.
  • Memcached is faster than Redis for simple key-value operations.
  • Redis is faster for more complex data structures.

Scalability​

  • Redis has built-in support for distributed systems. It can be horizontally scaled across multiple machines
  • Memcached normally is used as a single interface.

Memory Management​

  • Redis has better memory management compared to Memcached.
  • Redis allows you to configure eviction policies for freeing up memory, and it also provides memory usage statistics.
  • Memcached, on the other hand, does not have these features, though Memcached might be a better choice as it will use less memory compared to Redis.

Lua Scripting:​

  • Redis supports Lua scripting, which means you can execute complex operations atomically using Lua scripts.
  • Memcached does not have this capability.

Transactions:​

  • Redis supports transactions, which allow you to execute multiple operations in a single step, either all of them or none.
  • Memcached does not support transactions.*

Replication:​

  • Redis has built-in support for master-slave replication, which allows you to have multiple read-only replicas of your data.
  • Memcached does not have this feature.

Monitoring:​

  • Redis provides a number of monitoring tools, such as the Redis command line interface and Redis Monitor, which allow you to monitor the performance of your Redis instances.
  • Memcached does not have these monitoring tools, and you need to write your own scripts or use third-party tools to monitor it

Simple Configuration​

  • Memcached has a simple configuration, and it doesn't have many configurable options compared to Redis.
  • If you don't need the advanced features provided by Redis, Memcached might be a better choice due to its simplicity.