ElastiCache is a web service that makes it easy to deploy and run Memcached or Redis protocol-compliant server nodes in the cloud.
The in-memory caching provided by ElastiCache can be used to significantly improve latency and throughput for many read-heavy application workloads or compute-intensive workloads.
Best for scenarios where the DB load is based on Online Analytics Processing (OLAP) transactions.
The following table describes a few typical use cases for ElastiCache:
| Use Case | Benefit |
|---|---|
| Web session store | In cases with load-balanced web servers, store web session information in Redis so if a server is lost, the session info is not lost, and another web server can pick it up |
| Database caching | Use Memcached in front of AWS RDS to cache popular queries to offload work from RDS and return results faster to users |
| Leaderboards | Use Redis to provide a live leaderboard for millions of users of your mobile app |
| Streaming data dashboards | Provide a landing spot for streaming sensor data on the factory floor, providing live real-time dashboard displays |
ElastiCache EC2 nodes cannot be accessed from the Internet, nor can they be accessed by EC2 instances in other VPCs.
Can be on-demand or reserved instances too (but not Spot instances).
ElastiCache can be used for storing session state.
There are two types of ElastiCache engine:
- Memcached – simplest model, can run large nodes with multiple cores/threads, can be scaled in and out, can cache objects such as DBs.
- Redis – complex model, supports encryption, master / slave replication, cross AZ (HA), automatic failover and backup/restore.