In one aspect, in general, a method is described for managing an archive. The archive is used for determining approximate matches associated with strings occurring in records. The method includes processing records to determine a set of string representations that correspond to strings occurring in the records. The method also includes generating, for each of at least some of the string representations in the set, a plurality of close representations that are each generated from at least some of the same characters in the string. The method also includes storing entries in the archive. Each stored entry represents a potential approximate match between at least two strings based on their respective close representations.