1. A computer-implemented method, comprising: obtaining a plurality of Uniform Resource Locator (URL) strings, each URL string referring to a respective document, each respective document being associated with respective data, the respective data being derived from, at least, a count of times that the respective document was viewed for longer than a threshold period of time when the respective document was identified by search results responsive to queries; generating a plurality of respective groups of different strings from the plurality of URL strings according to a pattern extraction procedure; identifying a plurality of repeated strings, each repeated string occurring in two or more of the respective groups; for each repeated string, combining the respective data associated with different URL strings of the plurality of URL strings that contain the repeated string; generating a plurality of first strings from a first URL that references a document according to the pattern extraction procedure; and calculating respective data for the document based on the combined respective data for each repeated string that matches one of the first strings.