* Cold start, connection is established.
* Code runs and returns.
* Lambda stops the process entirely but retains the container.
* DB detects the socket is closed and kills the connection.
* Warm start.
* Code runs and fails because the connection is invalid.
The issue is that actions taken by stateful clients can't always be retried.
You can detect these kinds of errors, but it's klugey because these drivers generally assume that sockets dying is relatively uncommon, and it's painful to test this behavior when FaaS doesn't give you direct control over it.
So you typically wind up either with a proxy, or you decorate any handlers to refresh the connection ahead of time to make sure you have a fresh object.