How To Implement A Database Oriented File System
for the majority of databases the data should be moved to the filesystem no the database.
I heartily disagree. Databases provide a quick and easy way of accessing data. Some data, such as photos, may be better of stored on a traditional filesystem, but you assertion that for the majority of databases is way off base, and indicates lack of experience within the industry. My entire job, and that of my colleagues, centers around programming applications to create, update, and maintain databases. The information we store could not be stored in the filesystem with any amount of security or safety. Most of the IT departments in neighboring corporations are much the same.
For Web-based corporations (Travelocity, Expedia, Amazon...), the same is pretty much true. A company with 20 to 30 32-CPU Irix machines is better off using a database backend for storing images and content. It makes more sense to utilize the indexing and storage capabilities of a database, both from a business perspective and from a safety/security/backup perspective. I know from personal experience it is much, much easier and quicker to restore a database than to restore a system (which is often necessary when a filesystem is corrupt).
Even for casual home use, a database-like system could provide benefits. It could make storage of such things as photos easier (for those without CD-Burners, e.g.) I definitely would recommend against using an RDBMS for file storage for the casual user. Most people here, I believe, are in it for the fun factor, though. Simply for the fun factor, using an RDBMS makes sense. For the practicality factor--not so much. However, in my experience, in the typical database useage scenario, what is in the database belongs in the database, and is best used in the database.