Amazon Aurora

• Aurora is a proprietary technology from AWS (not open sourced)
• It provides support for both PostgreSQL and MySQL drivers in order to be able to connect to it
• Aurora is cloud optimized, it claims 5x performance over MySQL and over 3x performance over PostgreSQL
• Aurora storage automatically grows in increments from 10GB up to 64TB
• Aurora can have 15 replicas (while MySQL has only 5), replication process is faster
• Failover is Aurora is instantaneous
• Aurora costs more than classic RDS (around 20%)
• Aurora availability:
  • Stores 6 copies of the data across 3 AZs - only needs 4 copies for writes and 3 for reads
  • It has self healing properties with peer-to-peer replication
  • Storage is split across 100s of volumes
• In Aurora only one instance is used for writes (master instance)
• In case of master failure, the failover happens in less than 30 seconds
• Provides support for cross region replication

Aurora DB Cluster

• In Aurora we always have one writer endpoint
• We can have up to 15 read replicas
• Read replicas can be inside an auto scaling groups which provides the right read capacity all the time
• Read endpoint: basically does load balancing between read replicas
• Aurora endpoints: we can map each connection to the appropriate instance or group of instances based on an use case. For example, to perform DDL statements we can connect to whichever instance is the primary instance. To perform queries, we can connect to the reader endpoint, with Aurora automatically performing load-balancing among all the Aurora Replicas. For clusters with DB instances of different capacities or configurations, we can connect to custom endpoints associated with different subsets of DB instances
• Custom endpoints: provide load-balanced database connections based on criteria other than the read-only or read-write capability of the DB instances. For example, we might define a custom endpoint to connect to instances that use a particular AWS instance class or a particular DB parameter group. Then we might tell particular groups of users about this custom endpoint. For example, we might direct internal users to low-capacity instances for report generation or ad hoc (one-time) querying, and direct production traffic to high-capacity instances

Aurora Security

• It is similar to basic RDS security, because it is using the same engine under the hood
• Provides encryption at rest using KMS
• Provides automated backups, snapshots and replicas are also encrypted
• Encryption in flight is done using SSL
• Possibility to authenticate using IAM token
• The Aurora instance is protected with security groups (just like basic RDS)
• There is no way to SSH into an Aurora instance

Aurora Serverless

• Provides automated database instantiation and auto-scaling based on actual usage
• Recommended for infrequent, intermittent or unpredictable workloads
• No capacity planning is needed
• Users pay per seconds, can be cost-effective

Global Aurora

• There are two ways to have cross region replication:
  • Aurora Cross Region Read Replicas:
    • Useful for disaster recovery
    • Simple to put in place
  • Aurora Global Database (recommended):
    • We can specify one primary region for read/write
    • We can have up to 5 secondary regions (read-only)
    • Replication lag is bellow 1 second
    • We can have up to 16 read replicas per secondary region
    • In case we need to promote one region, the RTO (Recovery Time Objective) is bellow 1 minute