It would be extremely handy to have a document store / graph database which had row polymorphism. I started writing a prototype, but unfortunately never got there. I wonder if any such things already exist?
> Datomic Cloud is slow, expensive, resource intensive, designed in the baroque style of massively over-complicated CloudFormation astronautics. Hard to diagnose performance issues. Impossible to backup.
You should give TerminusDB a go (https://terminusdb.com/), it's really OSS, the cloud version is cheap, fast, there are not tons of baroque settings, and it's easy to backup using clone.
TermiusDB is a graph database with a git-like model with push/pull/clone semantics as well as a datalog.