I've taken a stab at this and made quite a bit of progress. However, the idea was to use the sqlite fuse layer as a stacked layer over the underlying filesyste

I've taken a stab at this and made quite a bit of progress. However, the idea was to use the sqlite fuse layer as a stacked layer over the underlying filesystem rather than a full scale file-system (which for example, is what libsqlfs provides). The motivation was not to improve filesystem performance but improving the speed of querying (ie: lightning fast stat of the entire deeply nested directory tree) at the expense of slower writes. Additionally I could (in theory, never got around to it) store rich metadata about the files, build all sorts of indexes, apply a richer access-control mechanism etc. Unfortunately, it remains in pre-alpha state, because life.