1. A method performed by a computing system, the method comprising: creating a graph, wherein nodes of the graph represent data objects of a data storage cluster, wherein edges of the graph represent joins between data objects represented by both nodes of respective edges, wherein node values of the nodes and weights of the edges are based on statistics related to use of the data objects; assigning a first subset of the data objects to a relational database storage node within the data storage cluster, the first subset of data objects being represented by nodes within a cluster of the graph; assigning a second subset of the data objects to a non-relational database storage node within the data storage cluster, the second subset of data objects being represented by stand-alone nodes within the graph.