Elastic Cache

  • Key-value store
  • In memory database
  • Sub millisecond performance
  • 2 types
  • Memcached
  • Redis
  • Support
  • Clustering (Redis)
  • Multi AZ
  • Read Replicas (sharding)
  • Have
  • Backup
  • Snapshot
  • Point in time recovery
  • Scheduled Maintenance
  • Monitoring through Cloudwatch
  • Redis has authentication feature Redis Auth
  • To secure the redis cluster access
  • Use redis auth in transit encryption, enabled for clusters
  • When Cluster Mode is enabled
  • All nodes should reside in the same region
  • Can not promote any more read replica

In most cases, it's better to use Redis. But should choice Memcached when,

  • Required the simplest model possible
  • Multi-thread or multi core supports

Redis is not primarily designed for using the multi-cpu.

Caching Strategies

  • Lazy Loading: Loads data only when it is required
  • Russian doll: Have nested records. Top level keys are the cahce keys for child resources.
  • Write Througth: Adds item to cache when a item is added or updated. may cause cachec churn ie. lots of cache is not being used or read.