I have used GunDB a lot in the past. It’s awesome and I miss it. The graph database aspect in particular was genius. It just wasn’t very stable. nostr:npub1g53mukxnjkcmr94fhryzkqutdz2ukq4ks0gvy5af25rgmwsl4ngq43drvk started a rust port of it, but then switched to Nostr. Here is a good tutorial ...

Iris used to be built on it. I fiddled with it some, it was sort of flaky. The guy who wrote it is interesting.