Question: Is ElastiCache a relational database?

Answer

No, ElastiCache is not a relational database. It is a fully managed in-memory caching service that provides high-performance, scalable, and cost-effective caching solution for web applications.

ElastiCache supports two popular open-source in-memory caching engines: Memcached and Redis. Both of these caching engines store data in-memory, which makes them faster than disk-based databases. However, they differ in their functionality and use cases.

Memcached is a simple key-value store that can be used to store small amounts of data, such as session data or frequently accessed data. It has limited data manipulation features and does not support persistence, multi-AZ replication, or backup and restore options.

Redis, on the other hand, is a more advanced data structure server that supports rich data types such as strings, hashes, lists, sets, and sorted sets. Redis also provides advanced features such as persistence, pub/sub messaging, transactions, Lua scripting, and cluster mode.

Both Memcached and Redis are non-relational databases and are optimized for fast read and write operations. ElastiCache uses these caching engines to improve application performance by reducing the load on backend databases and improving response times.

Here's an example of how to create an ElastiCache Redis cluster using the AWS Command Line Interface (CLI):

aws elasticache create-cache-cluster \
    --cache-cluster-id my-redis-cluster \
    --engine redis \
    --cache-node-type cache.t2.micro \
    --num-cache-nodes 1 \
    --preferred-availability-zone us-west-2a

This command creates a single-node Redis cluster with a cache node type of cache.t2.micro in the us-west-2a availability zone. You can customize the configuration according to your requirements.