Does a DB connection prevent AWS Aurora Serverless from pausing its compute capacity?

Question

I want to host an application that connects to a DB and makes queries to it. The application holds onto the connection indefinitely but only makes queries to the DB when the user interacts with the frontend.

I know that AWS Aurora Serverless has a "pause compute capacity" feature to only charge you for the DB's storage after a specified amount of time. If the application is still connected to the DB (even without making queries), does that prevent the DB from scaling down to 0 compute units and pausing its compute capacity?

Answer 1

I believe you are correct, a single long-running connection will prevent AWS Aurora Serverless from triggering the pause-and-resume feature.

Aurora Serverless v1 can also scale to zero capacity when there are no connections if you enable the pause-and-resume option for your DB cluster's capacity settings.

Source: How Aurora Serverless v1 works

Take this with a grain of salt, though, as I haven't tested this behaviour myself, and the docs aren't perfect. The same doc goes on to reference "no activity" without defining it:

You can choose to pause your Aurora Serverless v1 DB cluster after a given amount of time with no activity.

Which begs the question: "does an idle connection count as activity?"

I think the best hint that an idle connection counts as "activity" is that the moment a connection is needed, Aurora Serverless resumes:

If database connections are requested when an Aurora Serverless DB cluster is paused, the DB cluster automatically resumes and services the connection requests.