Redis vs Memcached: Choosing the Right Engine
Compare Redis (persistence, replication, sorted sets, pub/sub) with Memcached (simplicity, multi-threading) and select based on use-case requirements.
What Is Amazon ElastiCache?
Amazon ElastiCache is a fully managed, in-memory caching service that makes it easy to deploy, manage, and scale popular open-source in-memory data stores in the cloud. It supports two engines: Redis and Memcached. By serving frequently requested data from memory rather than from a database, ElastiCache can reduce database load by orders of magnitude and cut response latency from milliseconds to microseconds. Choosing between Redis and Memcached is a common SAA-C03 exam question.
Memcached: Pure Simplicity
Memcached is a distributed, in-memory key-value store focused on simplicity and horizontal scalability. Key characteristics: multi-threaded (can use all CPU cores on a single node), simple key-value storage (strings only, no complex data structures), no persistence (data is lost when a node restarts), no replication (no standby or replicas), and horizontal sharding via client-side consistent hashing. Memcached is the right choice when you need a simple, large-scale cache and have no need for persistence, complex data types, or high availability.
# Create a Memcached cluster with 3 nodes
aws elasticache create-cache-cluster \
--cache-cluster-id my-memcached \
--engine memcached \
--cache-node-type cache.r7g.large \
--num-cache-nodes 3 \
--cache-subnet-group-name my-subnet-group
# Memcached auto-discovers nodes via the config endpoint
# Application connects to: my-memcached.cfg.use1.cache.amazonaws.com:11211All lessons in this course
- Redis vs Memcached: Choosing the Right Engine
- ElastiCache Redis Replication Groups and Cluster Mode
- Caching Strategies: Lazy Loading and Write-Through
- Session Storage and Leaderboard Patterns