A very concise argument for graph databases and why they can be an even better fit than document databases for a set of specific problems (those having a schema-less data model and featuring graph-like relationships:
Then I found CouchDB and MongoDB. Both are document databases, it address problem 1 by schema free design. Problem 2 it cannot take care naturally, thus I have to write the code to handle the graph structures. […]
Just today, I found there are graph databases. Like neo4j. neo4j store everything as graphs. The relations are mapped out as graph in the database. It is also schema free.
It addressed both problem 1 and 2. Awesome.
Note: Neo4j is getting closer to its 1.0 release. You can download the latest RCs from ☞ here