Anyway to have multiple databases on a neo4j instance?

Question

Coming from a relational database mindset, it seems odd that one only one one graph db per instance of neo4j. Is the idea that we do multiple subgraphs starting from root ?

Answer 1

The concept of "root" node is going away. There are many problems with this, most of which revolve around node density.

I believe the heart of your question is around database design, and whether it is smarter to have several graph database instances, or one instance with several subgraphs.

Really it's up to you, but I would go with the subgraph idea as it allows some of your data to be shared in the same connection, and Neo4j doesn't really any performance penalties if you do this, provided you keep them separated, then the only problem you'll eventually run into is the max size of nodes/relationship, but this is an artificial limit that will be bumped up later.