I’m looking for suggestions for an in-memory database or other type of store that syncs to the file system (preferably as a single file) to store small, text-only documents (notes) and additional metadata.

It should preferably be made purely with Rust and have no dependencies to outside libraries like SQLite (without the dependency to the sqlite library in the system it would be my first choice). Also it shouldn’t depend on any server/service running in the system.

It should support relational data (but not necessarily relational as in SQL and relational databases) to allow fast and easy searching and retrieval of data.

So far I (from the crate descriptions only) I found RedDB. the rql crate looks promising, too, even though I’ll have to write the sync to the filesystem myself.

Are there more suggestions?