graph-databases

What is the difference between graph-based databases ( http://neo4j.org/ ) and object-oriented databases ( http://www.db4o.com/ )? I'd answer this differently: object and graph databases operate on two different levels of abstraction. An object database's main data elements are objects, the way we know them from an object-oriented programming language. A graph database's main data elements are nodes and edges. An object database does not have the notion of a (bidirectional) edge between two things with automatic referential integrity etc. A graph database does not have the notion of a pointer

I've been designing an application, based on .NET/Mono framework, which should make an heavy use of the shortest-path in a graph theories and I would like to use a native solution to traverse the nodes of the graph, instead of implementing surrogate solutions which would be hardly maintainable and would massively affect performances. I've found an application which would be perfect for my scope: neo4j . Unfortunately, this application is purely written in Java code and it's not portable to .NET, because of the massive differences between the two architectures. Is anyone out there knows if is

Consider instagram feed scenario. I want to get all the posts 'posted' by the people I follow. For each of these posts I want to know whether I have liked it or not and also know which of the other people I follow have liked it (if any). What is the best solution to get this in gremlin (possibly avoiding duplication)? Image for clarity The following just gives the posts 'posted' by USER 2. How to get other information in the same query? g.V().has('ID','USER 2').out('posted') When you ask questions about Gremlin, especially one of this complexity, it is always best to include a Gremlin script

I'm currently working on a project where I use natural language processing to extract emotions from text to correlate them with contextual information. Definition of contextual information: Every information that is relevant to describe an entity's situation in time an space. Description of the data structure I'm looking for: There is a arbitrary number of entities (an entity can either be a person or a group for example (twitter hash tags)) of which I want to track contextual information and their conversations with other entities. Conversations between entities are processed in order to

I was reading a paper published by Neo4J (a while ago): http://dist.neo4j.org/neo-technology-introduction.pdf and on the 2nd to last page the Drawbacks section states that Neo4J is not good for arbitrary queries. Say I had Nodes of users with the following properties: NAME, AGE, GENDER And the following relationships: LIKE (points to Sports, Technology, etc. NODE) and FRIEND (Points to another USER). Is Neo4J not very efficient in querying something similar to: Find FRIENDS (of given node) that LIKE Sports, Tech, & Reading that were OVER_THE_AGE 21. Therefore, you must first find the FRIEND

NoSQL refers to non-relational data stores that break with the history of relational databases and ACID guarantees. Popular open source NoSQL data stores include: Cassandra (tabular, written in Java, used by Cisco, WebEx, Digg, Facebook, IBM, Mahalo, Rackspace, Reddit and Twitter) CouchDB (document, written in Erlang, used by BBC and Engine Yard) Dynomite (key-value, written in Erlang, used by Powerset) HBase (key-value, written in Java, used by Bing) Hypertable (tabular, written in C++, used by Baidu) Kai (key-value, written in Erlang) MemcacheDB (key-value, written in C, used by Reddit)