An application asynchronously flattens a graph in a relational store to provide fast access to node relationship queries. The application may implement an algorithm that retrieves forward paths of a start node. The algorithm may also retrieve reverse paths of end node. The application may cross-join the forward and reverse paths to determine link paths connecting the start and end nodes. The application may merge the link paths with existing paths. The application may increment path reference counts. The application may store the link paths as a link between the nodes to represent a relationship between the nodes.