Redis and Memcached are two of the most popular in-memory caching solutions available. They are both powerful tools for storing and retrieving data quickly, but there are some key differences between them. In this article, we’ll look at how they compare to one another and discuss their advantages and disadvantages.
Comparing Redis and Memcached
Redis and Memcached are both open source, in-memory data stores. They are designed to provide fast access to cached data, making them ideal for high-performance applications. Both Redis and Memcached store data in key-value pairs, but the similarities stop there. Redis is a much more versatile solution, offering a range of data structures such as hashes, lists, and sets. Memcached, on the other hand, is limited to just strings. Redis also supports transactions, which Memcached does not.
Advantages of Redis over Memcached
Redis has several advantages over Memcached. For one, it is much more powerful and feature-rich. As previously mentioned, Redis supports a range of data structures, allowing developers to store and manipulate complex data. Additionally, Redis offers features such as transactions and replication, while Memcached does not. Finally, Redis can be configured to persist data to disk, which is not possible with Memcached.
Drawbacks of Memcached Compared to Redis
Despite its advantages, Redis does have some drawbacks compared to Memcached. For instance, Redis is more resource-intensive and requires more memory than Memcached. Additionally, Redis is more complex to set up, making it more difficult to use for inexperienced developers. Finally, Redis is not as widely used as Memcached, making it more difficult to find developers with experience in working with it.
In conclusion, Redis and Memcached are both useful tools for caching data. Redis is more powerful and feature-rich but also more resource-intensive and complex to set up. Memcached is simpler and less resource-intensive but also less versatile. Depending on your needs, one may be a better choice than the other.
Although both Memcached and Redis appear similar on the surface, in that they are both in-memory key stores, they are quite different in practice. Because of the replication and persistence features of Redis, ElastiCache manages Redis more as a relational database. Redis ElastiCache clusters are managed as stateful entities that include failover, similar to how Amazon RDS manages database failover.
Conversely, because Memcached is designed as a pure caching solution with no persistence, ElastiCache manages Memcached nodes as a pool that can grow and shrink, similar to an Amazon EC2 Auto Scaling group. Individual nodes are expendable, and ElastiCache provides additional capabilities here such as automatic node replacement and Auto Discovery.
When deciding between Memcached and Redis, here are a few questions to consider:
- Is object caching your primary goal, for example to offload your database? If so, use Memcached.
- Are you interested in as simple a caching model as possible? If so, use Memcached.
- Are you planning on running large cache nodes, and require multithreaded performance with utilization of multiple cores? If so, use Memcached.
- Do you want the ability to scale your cache horizontally as you grow? If so, use Memcached.
- Does your app need to atomically increment or decrement counters? If so, use either Redis or Memcached.
- Are you looking for more advanced data types, such as lists, hashes, bit arrays, HyperLogLogs, and sets? If so, use Redis.
- Does sorting and ranking datasets in memory help you, such as with leaderboards? If so, use Redis.
- Are publish and subscribe (pub/sub) capabilities of use to your application? If so, use Redis.
- Is persistence of your key store important? If so, use Redis.
- Do you want to run in multiple AWS Availability Zones (Multi-AZ) with failover? If so, use Redis.
- Is geospatial support important to your applications? If so, use Redis.
- Is encryption and compliance to standards, such as PCI DSS, HIPAA, and FedRAMP, required for your business? If so, use Redis.
Although it’s tempting to look at Redis as a more evolved Memcached due to its advanced data types and atomic operations, Memcached has a longer track record and the ability to leverage multiple CPU cores.
Because Memcached and Redis are so different in practice, we’re going to address them separately in most of this paper. We will focus on using Memcached as an in-memory cache pool, and using Redis for advanced datasets, such as game leaderboards and activity streams.
