We recently added vector support to FeatureBase: https://cloud.featurebase.com/. What's interesting about using it with our existing b-tree storage layer is that I can now do set operations on the record's stringset fields before I do the similarity calculations on the vectors. I've been experimenting with laying out the vector space in a b-tree structure using this technique along with keyterm extraction, allowing for a type of semantic graph to be applied by the LLM to the vector space.