1. A method for retrieving one or more data graphs from a collection of data graphs given a search data graph, said method comprising: generating, by a processing device, a graph lattice for the collection of data graphs, wherein the graph lattice is comprised of a graph of a related subgraphs mapping to the collection; determining, by a processing device, mappings of the graph lattice to the search data graph; using, by a processing device, the mappings to identify data graphs of the collection sharing subgraphs with the search data graph; ranking, by a processing device, the identified data graphs according to a number of subgraphs shared with the search data graph; selecting, by a processing device, a predetermined number of the most highly ranked data graphs from the collection.