Looking for places to store my activitystuff tests for a little demo. It looks like my options are:

guile-dbi, very minimalist, just the basic SQL commands, nothing higher-level at all. Hasn't seen commits in 2 years and very few even then. Still, maybe simplicity here is a bonus: probably everything still works.
Do the above, and try to make a nice wrapper around jsonb which might be nice because activitystreams are json by default (more on jsonb)
Just do everything in-memory to start with, and for persistence, serialize everything to basic scheme structures with read/write functions. Upsides and downsides to this are obvious.
Minimalist key-value store with guile-gdbm (also hasn't seen commits in a while)
Could go totally crazy and try using slib's relational database system. Really interesting database manifestio behind it. Looks pretty interesting, but almost no users, given complexity.
Craziest option: use OpenCog's atomspace which has Guile bindings. (examples) Supposedly single-threaded, also all functions seem to operate on some global state.
Yak shaviest option: finally write"mollydb", a simple json-files with minimal index (xapian?)