8. The method of claim 7 , wherein a first vantage point of the plurality of vantage points is selected from a random node in a cluster, and wherein a second vantage point of the plurality of vantage points is selected from a node in the cluster that is the farthest from the random node.
7. The method of claim 6 , wherein constructing the multi-vantage point tree comprises, for each of the plurality of nodes, partitioning the plurality of document vectors in the node into clusters based on a distance of each of the plurality of document vector from the plurality of vantage points.