RDS Features

Subnet groups

A subnet group is a collection of two or more subnets in a VPC where we want to launch an RDS database. These subnets should be in different AZs. Subnet groups are a must when deploying RDS.

RDS storage autoscaling

We can configure RDS storage autoscaling for existing and new (during launch) RDS databases. Storage autoscaling allows RDS to automatically scale its storage size as the database grows, with no downtime. It’s supported for all database engines in RDS.

Note: Storage autoscaling continuously monitors consumption and scales the storage automatically when it’s close to full.

RDS Proxy

When we create an RDS database for a real-world project, we usually create it in a private subnet. This means that any services within the VPC, like an application hosted on EC2, can access the RDS database, but it’s inaccessible over the internet. So if we have a default Lambda function, it’ll never be able to access the RDS database in a private subnet.

Note: By default, Lambda functions are created outside the VPC.

The following illustration shows use cases where a Lambda function can or can’t ...