Aurora Serverless

Since Aurora Serverless became available from early this month, I started to use it for this blog’s database.

Impression

Though it took several seconds to connect to an Aurora instance for the first time after its launch, it’s quite natural since then. It responds quickly. It appears to me this is already practicable enough as long as I use it simply.

There’re many limitations such as only a few supported cluster parameters, no support for cross region replicas, etc. So it may be still early to use it for complicated scenarios.

Price

As for storage and I/O, it’s same to provisioned Aurora. But computing capacity which is called “Aurora Capacity Unit (ACU)” is kind of confusing. AWS website states “Pay only for the database resources you consume, on a per-second basis”, but it also states “$0.06 per ACU Hour” in a pricing page. I was not sure it will be billed per second or hour.

FAQ page states in detail.

You pay a flat rate per second of ACU usage, with a minimum of 5 minutes of usage each time the database is activated.

That says AWS bills by accumulated seconds per month, but there’s an hidden factor. When will database be deactivated after last request? This minimum of 5 minutes of usage won’t affect much if a database has constant requests, but I’m still interested in this internal behavior.