[vkazanov]

Huh? Offended?!

Filesystems present a durable way to store hierarchical binary/textual data. They normally have a very well-defined api used to provide a primitive query language. Sounds a lot like a database, no?

Even internally they are very similar: journalling, paging, tree indexes are normally present in typical popular implementations.

In some classic OS-s there is no separation at all between the concepts of a database and a filesystem.

In a way, a generic durable database can be though of as a special kind of a filesystem. And vice versa.