- Relational Database Service
- Database in cloud managed by AWS
- Postgres
- MySQL
- MariaDB
- Oracle
- MS SQL Server
- IBM DB2
- Aurora (AWS Proprietary)
- Managed service: automate backups, dashboards, disaster recovery, scaling capability.
- Cannot SSH into instances
Storage Auto Scaling
- Increase storage dynamically
- Set Maximum Storage Threshold
Read Replicas
- Upto 15 replicas
- Within AZ, Cross AZ or Cross Region
- It costs if the replica is in another region.
- Replicas is Async, eventually consistent
- Application must update connection string to leverage read replicas.
Use Cases
- Read replica for running analytics to that the main database is unaffected.
Disaster Recovery (Multi AZ)
- No manual intervention
- Not for scaling
- Read replicas can be setup as Multi AZ for disaster recovery.

Single AZ to Multi AZ

RDS Custom
- Oracle and MS SQL Server with OS and DB customization.
RDS Backup
Automated Backup
- Daily backup; Transaction logs are backed up every 5 mins.
- 1 to 35 days of retention; can be disabled.
Manual DB Snapshots
- Manual trigger
- Retention as long as you want.
- Trick: Stopped RDS costs more for storage. If you plan to stop for long time, you should snapshot and restore it.
Amazon RDS Proxy
- Allows apps to pool or share DB connections.
- Improve DB efficiency by reducing stress on database resources and minimize open connections.
- Reduce RDS and Aurora failover time by 66%.
- Enforce IAM authentication for DB and securely store credentials in AWS Secrets Manager.
- Proxy is not accessible publically, only from VPC.