1. David Ostrovsky | Couchbase
Who’s afraid of graphs?
David Ostrovsky | Couchbase

2. The Seven Bridges of Konigsberg Problem
Leonard Euler
The Seven Bridges of Konigsberg Problem
Devise a route through the city that only crosses each bridge once. Paper published in 1736 – regarded as the first paper on Graph Theory.
Konigsberg, Prussia – which is Kaliningrad, Russia today.

3. Graph Databases Use Nodes, Edges and Properties to store data.
Important to note that a graph database has:
Native graph storage – the engine is built to handle graph data
Native graph processing capability, including index-free adjacency to facilitate traversals

4. Use Cases For Graph Databases Social – of course
Recommendation systems (a logical extension from the social graph, or stand-alone – find all customers who bought a book that X customers liked., then find all books similar to that one, etc.)
Managing interconnected datasets:
Networks, Organization Hierarchies, ACL, in-game economy, etc.
Geo-location and routing (think Waze or network routing.)
Use-cases for migrating from RDBMS:
Problems with JOIN performance
Continually evolving dataset or open-ended business requirements
The domain is naturally designed for graph representation

5. Meet the Players
For comparison – MongoDB has a score of , Cassandra

6. Databases vs Frameworks
Real-time queries
Smaller datasets
Standard NoSQL features (scaling, HA, etc.)
Offline/batch
Larger datasets
Relies on big data platform (usually Hadoop)
Frameworks:
Giraph – apache project, used by Facebook to power it’s graph search and process trillions of connections.
GraphX – Integrated with Apache Spark, has a library of build in algorithms and ETL functionality. Doesn’t perform as well as Giraph.
Franus (from the same team as Titan)
GraphLab – open source graph toolkit.

7. Querying
and Traversal

8. (a) –[:FRIEND]-> (b)
Cypher (Neo4j) a b
FRIEND
(a) –[:FRIEND]-> (b)

9. SQL-Derivatives (OrientDB)

10. g.v(1).outE('friend').inV.name // Starting with vertex 1
// find outgoing edges ‘friend’,
// follow to the next vertex,
// and return the property ‘name’.
Gremlin is the graph traversal language of Apache TinkerPop, which in turn a graph computing framework for both graph databases (OLTP) and graph analytic systems (OLAP).

11. Scaling Graphs
is Hard
Most graph partitioning algorithms fall into the N—Hard category, which is a set of problems that are at least as hard as the hardest problem in NP. Some specialized graph partitioning algorithms have NP-Complete complexity. So unless P=NP, graph partitioning solutions will continue to rely on approximations and various statistical approaches.

12. Clustering Architecture
Neo4J
Clustering Architecture

13. Polyglot Persistence
To the Rescue