I have spent a lot of time figuring out how to deal with a large graph a couple of years ago. My conclusion - there will never be such a thing as a "graph database". There are many efforts in this area, someone here already mentioned SPARQL and RDF, you can google for "triple stores", etc. There are also large-scale graph processing tools on top of Hadoop such as Giraph or Graphx for Spark.
For the particular project we ended up using Redis and storing the graph as an adjacency list in a machine with 128GB of RAM.
The reason I don't think there ever will be a "graph database" is because there are so many different ways you can store a graph, so many things you might want to do with one. It's trivial to build a "graph database" in a few lines of any programming language - graph traversal is (hopefully) taught in any decent CS course.
Also - the latest versions of PostgreSQL have all the features to support graph storage. It's ironic how PostgreSQL is becoming a SQL database that is gradually taking over the "NoSQL" problem space.
In my point of view, the fact that you can add an expert index very easily to a graph database written in a modern language (say no C/C++) makes it even easier to customize an existing graph database to suit your direct need. In turn, storage and runtime can be tunned more easily. Making so easy to have the performance you need. But at the end of the day not dealing with algreba is the best.
Years ago PostgreSQL already support recursive query, and in Oracle you have CONNECT BY. I have only used the recursive with once and it was just a quick demo, but my understanding is update is extremely expensive.
For the particular project we ended up using Redis and storing the graph as an adjacency list in a machine with 128GB of RAM.
The reason I don't think there ever will be a "graph database" is because there are so many different ways you can store a graph, so many things you might want to do with one. It's trivial to build a "graph database" in a few lines of any programming language - graph traversal is (hopefully) taught in any decent CS course.
Also - the latest versions of PostgreSQL have all the features to support graph storage. It's ironic how PostgreSQL is becoming a SQL database that is gradually taking over the "NoSQL" problem space.