Depends on what your information is and what your access patterns and scale are. Two of the biggest benefits of a relational databases are:
Caching. Unless you're very clever, you can't write a cache as good as that of a DB server
Optimizer.
However, for certain specialized applications, neither of these 2 benefits manifest itself compared to files+folders data store - therefore the answer is a resounding "depends".
As for files/folders, the tricks are:
- Cache the contents of frequently requested files
- Have small directories (files in deeply nested small directories are much faster to access than in a flatter structure, due to the time it takes to read the contents of a big directory).
- There are other, more advanced optimizations (slice across disks, placement on different places in a disk or different partition, etc..) - but if you have need of THAT level, you are better off with a database in the first place.
