As far as SQLite is concerned, a Raspberry Pi is a very powerful machine. There's no reason why you sholdn't be able to enjoy all the benefits of flat file

As far as SQLite is concerned, a Raspberry Pi is a very powerful machine. There's no reason why you sholdn't be able to enjoy all the benefits of flat files together with all the benefits of a relational database. Yes. There are reasons to avoid databases, but saving resources usually isn't one of them. Definitely not on a RaspberryPi where you have 256MB or 512MB of memory which is plenty for a lightweight database like SQLite. By the time you're done reinventing all the things a storage engine like SQLite or one of the NoSQL storage engines would give you, you'd be hard-pressed to do it more efficiently than they do.