Images in database vs file system

Question

We have a project coming up where we will be building a whole backend CMS system that will power our entire extranet and intranet with one package. The question I have been

Answer 1

There are valid concerns on either side of the debate, so always give your requirements. How much data, how many images, how large?

Inline / BLOB storage

Upside: simplifies architecture and implementation, simplifies backup and recovery or migration of the system; just do a dump, backup, export (whatever the term for your flavor of DB) and move it to the new database. Version control / consistency is handled by the DB, so allows for point-in-time recovery. Security / access control is also cleaner, since access to an image BLOB is intrinsic to access to the overall row. Moving the image outside the DB and letting the HTTP server fetch it up, while better for concurrency and scalability, can have problems with ensuring people cannot hack URLs and request images they don't own. If you do house them outside the DB, make sure either your security policy covers access control of images between users. Either your HTTP server authentication has to integrate with the overall system's authentication, or your HTTP server program that serves up the images uses some sort of session mechanism to ensure the HTTP request is valid. This is a very big concern in multi-tenant databases. Less of a concern in single purpose, single-tenant systems, with simple authentication.

Downside: For really REALLY large databases, the backup and recovery gets frustrating, or even problematic and costly, because where you may have a small core dataset otherwise, you may have many GB or TB of image data. Treating it all as one consistent database is both good from integrity point of view, but bad for backups unless you use DBMSes with enterprise quality, data warehouse tuned backup and recovery (example is Oracle RMAN and rolling backups).

Always consider time to recovery in any system. If your storage requirements are < a few gigabytes, say 50-100GB even, and you have plenty of backup space planned, inline storage is cleaner. Above that, separation of concerns and letting the filesystem do its job becomes a key advantage. Nothing is worse than trying to restore, recover and open a huge database for the sake of a small data error. Recovery time would be my biggest concern.