1. A method for determining documents that are nearest to a query, the method comprising: constructing, by a computer processor, a vantage point tree based on a plurality of document vectors; searching, by a computer processor, the vantage point tree to determine a plurality of nearest neighbor document vectors to a query vector by removing a portion of the plurality of document vectors from the vantage point tree based on one or more vantage points for each of a plurality of nodes in the vantage point tree and a specified search radius centered about the query vector; removing any of the plurality of document vectors belonging to document clusters that do not intersect a hypersphere of the specified search radius centered about the query vector; removing any of the plurality of document vectors that do not satisfy a triangle inequality condition for the specified search radius between one of the one or more vantage points, the document vector, and the query vector; and adjusting the specified search radius such that only a specified number of nearest neighbor document vectors are remaining after document vectors that are outside the hypersphere of the specified search radius for the query vector and document vectors that do not satisfy the triangle inequality condition have been removed.