Can binary file be used as database?

How to load a binary graph?
Will it load whole in RAM memory, or possible to load portion of it?

The approach I would like to simulate is:
- store graph topology on one file (graph.db)
- query one or more nodes > load a sub-graph from the graph.db
- decorate the nodes > pull data from a simple SQL or whatever db

I think it would enable a LOT of nice applications avoid use of graph databases and also to speed up responviness, for loading only sub-graphs at a time.

The issue asks whether a binary graph can be loaded partially rather than entirely into RAM, with topology in graph.db and node data in a separate database. No files, tests, or entry points are mentioned; clarify the intended loading API and completion criteria before starting.

Written by the indexing model from the issue text.