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. @Sirius started a rust port of it, but then switched to Nostr.

Here is a good tutorial https://youtu.be/68svY76thiQ

And part 2 covers namespaces and encryption https://youtu.be/FauETOkRtEk