Databases

RDS

  • Read Replicas are for performance
  • Multi-AZ is for DR
  • SQL, MySQL, PostgreSQL, Oracle, Aurora, MariaDB
  • Runs on VM’s but you do not have OS level access to them
  • Patched by Amazon
  • Not serverless (except for Aurora Serverless)
  • Encryption at rest is supported
  • SQL Server and Oracle can have a maximum of 2 databases per instance
  • Aurora
    • 2 copies of the data is stored in each AZ at a minimum of 3 AZ’s
    • Snapshots can be shared across accounts
    • Automated backups turned on by default

DynamoDB

  • No SQL
  • Uses SSDs
  • Spread accross 3 geographically distinct data centers
  • Eventual consistent reads by default but strongly consistent reads can be enabled (for a cost).
  • Name and value combined cannot exceed 400kb

Elasticache

  • Memcached (caching)
  • Redis (caching + pub/sub)

Redshift

  • For Business Inelligence or Data Warehousing
  • Only available in 1 AZ
  • Can restore snapshots to new AZs if there is an outage
  • Can retain backups for a maximum of 35 days