Elasticache

• Elasticache is a web service that makes it easy to deploy, operate, and scale an in-memory cache in the cloud. The service improves the performance of web applications by allowing you to retrieve information from fast, managed, in-memory caches, instead of relying entirely on slower disk-based databases.

• Caching improves application performance by storing critical pieces of data in memory for low-latency access. Cached information may include the results of I/O-intensive database queries or the results of computationally-intensive calculations.

Types of Elasticache

• Memcached
  • A widely adopted memory object caching system. Elasticache is protocol compliant with Memcached, so popular tools that you use today with existing Memcached environments will work seamlessly with the service.
• Redis
  • A popular open-source in-memory key-value store that supports data structures such as sorted sets and lists. Elasticache supports Master / Slave replication and Multi-AZ which can be used to achieve cross AZ redundancy.

Elasticache Exam Tips

• Typically you will be given a scenario where a particular database is under a lot of stress/load. You may be asked which service you should use to alleviate this.

• Elasticache is a good choice if your database is particularly read heavy and not prone to frequent changing.

• Redshift is a good answer if the reason your database is feeling stress is because management keep running OLAP transactions on it, etc.