In most of the cases, the application will be updated to reflect latest changes in version 12, but this could also turn into a complete mess. For example, it's possible that the new version implements new features and working algorithms that the database can't handle, therefore corrupting its structure. It's always recommended backing up the data and only then then performing the upgrade and when the process is over importing the data. I advise you to do it this way: backup, install, import.
