In an approach, memory usage within a database management system is optimized by designating an application root which stores data and metadata for database objects that are common across pluggable databases which support the same application. In addition, the application root can be used to manage access to the pluggable databases by defining common users which are created at the application root, but can be used to access any of the member pluggable databases. Furthermore, different versions of the same application can be supported concurrently by maintaining separate application roots for each version. For instance, when an upgrade is applied to the application root, a clone can be created and the update can be applied to the clone. Then, the member pluggable databases which are to be upgraded can be synchronized to the clone, while leaving other pluggable databases servicing the previous version of the application.