I’m not sure if I would call SQLite’s needs incommon — in a perfect world, every app should have SQLite’s properties like preserving user data on power loss, etc… It’s just that other apps just don’t care enough about these issues as much as SQLite.

For example, I’m pretty sure I would like every app to automatically handle cases where the underlying file gets renamed or removed. (AFAIK apps that use the Cocoa API automatically does these.) However there really isn’t any POSIX API that allows handling these kind of situations — and to do these now you need to do all of these nitty-gritty things that SQLite does.

In fact, I think that the reason why SQLite needs all of these nitty-gritty details that does everything is because of an insufficient abstraction. If the file APIs were better and didn’t require everyone to consider whether you have to call fsync or not, SQLite wouldn’t have needed any of these. But well POSIX have flied and here we are.