1. A non-transitory computer-readable medium storing instructions that, when executed by a computer, cause the computer to perform a method for uniquely identifying returning client computing devices, the method comprising: performing a first query with less than all available input Locality Sensitive Hash (LSH) values, the first query performed against a data store comprising a plurality of stored LSH values associated with a plurality of stored device fingerprints each fingerprint comprising a set of features identifying a particular computing device, wherein each input LSH value comprises a segment of an input fingerprint comprising a plurality of features obtained from a request from a client computing device, and wherein performing a first query comprises identifying in the data store a plurality of candidate LSH values, the candidate LSH values associated with candidate device fingerprints, at least including one candidate LSH value matching at least one of the less than all input LSH values; performing a second query with at least one of the input LSH values not queried in the first query, the second query performed against the candidate LSH values, wherein the performing the second query comprises identifying the candidate LSH values matching at least one of the input LSH values not queried in the first query; and based on responses to the first query and the second query, identifying a most closely matching device fingerprint.