AWS Elasticache vs AWS RDS Read Replicas (some very high level comparisons.) AWS Elasticache If the same read query is performed over and over again. AWS RDS Read Replica if the read query changes dynamically or has dynamic elements such as NOW(). AWS Elasticache is speed is required, since data is stored in RAM. AWS Read Replicas is there is a low tolerance for stale data. AWS Read Replica if the data returned by a read query is huge since RAM is not unlimited.
The concept behind in crisp and clear
By Pallav Bora
( Click for Linkedin Profile )