how feasible is the development of a db application on the app engine

[phista]

I want to transfer a web application which currently runs on a local machine to the cloud. I have searched various APIs like Cloud SQL but i would like some more information about how easy it is to do this transfer.The application is written in Java, and connects via JDBC to a PostgreSQL. The content is generated in HTML and the user can query the database, update the content etc.