Why not use Rails? The book "Data Visualization Toolkit" [1] does exactly that: it uses Rails for AR's ease of use, not because they need a heavy server. If you need a UI instead of the CLI, you can use ActiveAdmin, or use Django which comes bundled with an admin interface. If neither of those fits your needs, if you can expand more on your requirements and why you want something light weight, I could have a few more suggestions, but they all mostly boil down to "use sqlite with an interactive UI".

1: https://www.amazon.com/Data-Visualization-Toolkit-Addison-We...