30. A method of processing a query, comprising: at a computer system including one or more processors and memory storing one or more programs for execution by the one or more processors so as to perform the method, receiving a query, the query comprising one or more tokens; identifying, in a compressed sequence of tokens that includes a plurality of cluster subsequences, each cluster subsequence corresponding to a respective cluster of documents, one or more cluster subsequences that each include at least one of the query tokens, wherein the compressed sequence of tokens includes respective cluster subsequences from which duplicate sequences of tokens have been elided; for at least one respective cluster subsequence of the identified cluster subsequences, identifying one or more documents within the respective cluster subsequence that satisfy the query; and returning the identified documents as matches to the query.
30. A method of processing a query, comprising: at a computer system including one or more processors and memory storing one or more programs for execution by the one or more processors so as to perform the method, receiving a query, the query comprising one or more tokens; identifying, in a compressed sequence of tokens that includes a plurality of cluster subsequences, each cluster subsequence corresponding to a respective cluster of documents, one or more cluster subsequences that each include at least one of the query tokens, wherein the compressed sequence of tokens includes respective cluster subsequences from which duplicate sequences of tokens have been elided; for at least one respective cluster subsequence of the identified cluster subsequences, identifying one or more documents within the respective cluster subsequence that satisfy the query; and returning the identified documents as matches to the query. 33. The method of claim 30 , wherein the query comprises a Boolean expression that includes of two or more of the query tokens; and identifying cluster subsequences comprises identifying in the compressed sequence of tokens one or more cluster subsequences that satisfy the Boolean expression.