Neo4j open source nosql graph database » Claudio martella. Google Pregel's paper is finally out. But what is Pregel? It has been mentioned in many posts talking about NoSQL, GrabhDBs, Big Data, even the Facebook OpenGraph, so it looks like, apart of the hype fuzz, there's a little confusion about what it is, what it does, what it's good for and what it certainly is not. Let's start with the latter. Google Pregel is not a database (neither RDBMS nor NoSQL), no key-value store or any new means of storing data (big or small it might be). Putting it in the same lists with GraphDBs like Neo4j, HyperGraphDB or even Twitter's FlockDB is somehow like putting MapReduce in the NoSQL group. The Graph Traversal Programming Pattern. GraphPath Language.
GraphPath is a little-language for analysing graph-structured data, especially RDF.
The syntax of GraphPath is reminiscent of Xpath. It has a python implementation that can be teamed up with your favourite python RDF API (e.g. Redland, rdflib, or your own API).