Keys for graphs uses the topology and value constraints needed to uniquely
identify entities in a graph database. They have been studied to support object
identification, knowledge fusion, data deduplication, and social network
reconciliation. In this paper, we present our algorithm to mine keys over
graphs. Our algorithm discovers keys in a graph via frequent subgraph
expansion. We present two properties that define a meaningful key, including
minimality and support. Lastly, using real-world graphs, we experimentally
verify the efficiency of our algorithm on real world graphs.