Graph database that supports efficient sorting and/or range retrieval

Question

Using Twitter's data model as an example:

User A follows N other users, each of whom posted N different posts. Posts are timestamped.

Is there a data store or graph database that supports efficiently reading the latest N posts from users that User A is following?

It seems best that posts are stored in sort order (like a Cassandra ColumnFamily or a Redis ZSET).

Also, the ability to shard the data across different machines is critical.

Answer 1

Have a look at Neo4J, it should fit your needs perfectly. One recommendation though, use its REST interface since it gives you the freedom to chose your weapon uhm programming language and abstracts a lot of the complexity of working with the Java bindings directly