4. The method of claim 1 wherein the first-edit distance constraint corresponds to an upper limit on the number of components of the hash vector that are different between the root document and the target document.
4. The method of claim 1 wherein the first-edit distance constraint corresponds to an upper limit on the number of components of the hash vector that are different between the root document and the target document. 5. The method of claim 4 wherein the merging includes: for each of the initial clusters that has at least one child document, grouping the child documents into one or more maps, wherein all of the child documents that are grouped within a same map have hash vectors that differ from the root document of the cluster in the same one or more of the components; determining whether the number of maps for a first one of the initial clusters is at or below an upper bound; determining whether the number of maps for a second one of the initial clusters is at or below an upper bound; and in the event that the number of maps for the first initial cluster and the number of maps for the second initial cluster are at or below the upper bound: determining whether the maps for the first initial cluster correspond to differences from the root document in the same one or more of the plurality of components of the hash vector as the maps for the second initial cluster; and merging the first initial cluster and the second initial cluster in the event that the maps for the first cluster correspond to differences in the same one or more of the plurality of components of the hash vector as the maps for the second cluster.