1. A method of processing documents, comprising: at a computer system comprising 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: grouping a set of documents into a plurality of clusters, wherein each cluster includes one or more documents of the set of documents and a respective cluster of the plurality of clusters includes a plurality of documents including a first document and a second document; compressing the plurality of documents in the respective cluster to generate compressed cluster data, wherein compressing the plurality of documents includes: determining that the second document includes duplicate data that is duplicative of corresponding data in the first document; eliding the duplicate data from compressed cluster data; and storing document data from which the first document and the second document can be reconstructed, the document data including document reconstruction data; and generating an index of the compressed cluster data.