In my project (similar to mediafire and rapidshare), clients can upload files to the server. I am using DB2 database and IBM WAS web server and JSP as server side scripting. I am creating my own encryption algorithm, as it is the main aim of the project.
I need suggestion whether files themselves should be stored in the database or if only the location of the files should be stored. Which approach is best?
There are Pros and Cons for storing BLOBs in the database.
Advantages
- DBMS support for BLOBs is very good nowadays
- JDBC driver support for BLOBs is very good
- access to the "documents" can happen inside a transaction. No need to worry about manual cleanup or "housekeeping". If the row is deleted, so is the BLOB data
- Don't have to worry about filesystem limits. Filesystems are typically not very good at storing million of files in a single directory. You will have to distribute your files across several directories.
- Everything is backed up together. If you take a database backup you have everything, no need to worry about an additional filesystem backup (but see below)
- Easily accessible through SQL (no FTP or other tools necessary). That access is already there and under control.
- Same access controls as for the rest of the data. No need to set up OS user groups to limit access to the BLOB files.
Disadvantages
- Not accessible from the OS directly (problem if you need to manipulate the files using commandline tools)
- Cannot be served by e.g. a webserver directly (that could be performance problem)
- Database backup (and restore) is more complicated (because of size). Incremental backups are usually more efficient in the filesystem
- DBMS cache considerations
- Not suited for high-write scenarios
You need to judge for yourself which advantage and which disadvantage is more important for you.
I don't share the wide-spread assumption that storing BLOBs in a database is always a bad idea. It depends - as with many other decisions.