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 at least one processing device, a graph lattice from the collection of data graphs, wherein the graph lattice is comprised of a graph of related subgraphs mapping to the collection; determining, by the at least one processing device, mappings of the graph lattice to the search data graph; using, by the at least one processing device, the mappings of the data graphs and the search data graph to identify data graphs of the collection sharing subgraphs with the search data graph, the identified data graphs mapping to those nodes of the graph lattice to which the search data graph maps; ranking, by the at least one processing device, the identified data graphs according to a number of subgraphs shared with the search data graph; selecting, by the at least one processing device, a predetermined number of the most highly ranked data graphs from the collection.