Knowledge Graphs have been sprouting in the past decade driving a wedge between the traditional relational database and IR based indices. The fundamental change is modelling data as a graph, with first class relationships between entities, where edges separate them from relational databases tables and nodes strong identities separate them from word based IR indices. We present a survey of the known knowledge graphs and the application classes that they enable, including the LinkedIn Economic Graph. We discuss how graph databases differ from relational ones and IR indices and where the graph databases would benefit from IR techniques. We conclude with a set of challenges we see in our experience in scaling Knowledge graphs and graph databases in low latency on-line applications.

Bogdan Arsintescu has worked with graphs and semantic data throughout his whole career, most recently at Google Knowledge Graph leading the graph query language team, in Google Research working on semantic trajectories using location data and at LinkedIn as a manager in the graph database team. He received his Ph.D.