A database includes a repository of data segments to be searched, called standard streams. But rather than searching all possible segments of each standard stream, the database includes a set of index files that reference a number of different segments in the repository. Each index file provides information about whether various data segments in the repository are likely to match a given test stream, although in the presence of noise there may be multiple possible matches. By consulting a number of the index files, a searching algorithm identifies a set of candidate data segments to test and thus reduces the number of streams that must be tested.