Not sure how well the second gen supports appengine. With 1st gen you could ask the database to follow an appengine app so they are both in the same cell. I also don't see how to allow connection from appengine apps I only can select IP addresses. Are these unnecessary now?

Also curious about the on demand option. I had it in 1st gen but its gone now. I can only select Always on or Never. I had a large database that I only used for a few hours per month. I'd love to migrate to second gen but if its always in it might make it much more expensive.

At last I tried to perform an export from 1st gen into 2nd gen and I'm getting server errors will try again later.