if you open the Sqlite source, the Vdbe engine, the engine that process the SQL queries to the backend, use a "simple" key value store, that is the on-disk btre

if you open the Sqlite source, the Vdbe engine, the engine that process the SQL queries to the backend, use a "simple" key value store, that is the on-disk btree backend of the sqlite.. so you can create a btree api-like using other key-value store as backend, and it would work the same.. This way you can give a full SQL engine to any key-value store out there.. Thats why the Sqlite4 are being designed to be more plugable.. with a shim key-value wrapper over the storage backend that can be changed, in compile time, or even in runtime given its use of C callbacks.. (but dont know any reason someone would want to to that.. to do a runtime switch anyway)