For people here experienced with graph databases, do you typically use the graph db as your primary data store or do you use it in combination with something like postgresql? If you're using both, can you talk about how that works and if it's been successful for you?<p>I'm curious because I've had a couple situations where I thought using neo4j (or some graph db) would be a natural fit for something I wanted to do, but otherwise I thought most of my other data fit into postgresql just fine. My instinct is that if I'm doing this in a web app then querying from two different databases is going to slow down my responses a lot.