18. A system comprising: a training data generation module stored on one or more memories and executed by one or more processors, the training data generation module to determine training data based at least in part on user behavior data, the training data comprising at least one of similar or dissimilar query pairs; an n-gram mapping module stored on one or more memories and executed by one or more processors, the n-gram mapping module to: determine n-grams from own content of queries in the training data; and map the n-grams into vectors represented in an n-gram space, each unique one of the n-grams being represented as an orthogonal dimension of the n-gram space; a learning module stored on one or more memories and executed by one or more processors, the learning module to learn a similarity function using at least a subset of the training data by optimizing an objective function, the similarity function based at least in part on a similarity measurement in a transformed n-gram space having one or more of the unique n-grams being non-orthogonal with respect to one or more other of the unique n-grams, the objective function based at least in part on the similarity function; an indexing module to: determine a family of hash functions in the n-gram space that are based on the transformed n-gram space; and index queries from a collection of queries into sets of similar queries utilizing the family of hash functions; and a retrieval module to: receive a new query; calculate an index for the new query utilizing the family of hash functions; utilize the index for the new query to retrieve one or more queries similar to the new query; and provide at least one of the one or more queries similar to the new query or information associated with the one or more queries similar to the new query.
18. A system comprising: a training data generation module stored on one or more memories and executed by one or more processors, the training data generation module to determine training data based at least in part on user behavior data, the training data comprising at least one of similar or dissimilar query pairs; an n-gram mapping module stored on one or more memories and executed by one or more processors, the n-gram mapping module to: determine n-grams from own content of queries in the training data; and map the n-grams into vectors represented in an n-gram space, each unique one of the n-grams being represented as an orthogonal dimension of the n-gram space; a learning module stored on one or more memories and executed by one or more processors, the learning module to learn a similarity function using at least a subset of the training data by optimizing an objective function, the similarity function based at least in part on a similarity measurement in a transformed n-gram space having one or more of the unique n-grams being non-orthogonal with respect to one or more other of the unique n-grams, the objective function based at least in part on the similarity function; an indexing module to: determine a family of hash functions in the n-gram space that are based on the transformed n-gram space; and index queries from a collection of queries into sets of similar queries utilizing the family of hash functions; and a retrieval module to: receive a new query; calculate an index for the new query utilizing the family of hash functions; utilize the index for the new query to retrieve one or more queries similar to the new query; and provide at least one of the one or more queries similar to the new query or information associated with the one or more queries similar to the new query. 19. A system as recited in claim 18 , the system further comprising a ranking module to rank the one or more queries similar to the new query using the similarity function.