7. The method of claim 3 wherein performing the search includes: searching against searchable items that are within one bond of said particular searchable item; and if the number of documents, within the one bond of said particular searchable item, that match the search is less than a target number, then expanding the search to that are within two bonds of said particular searchable item; and repeatedly expanding the search to documents that are one further bond away from said particular searchable item until at least the target number of documents that match the search have been identified.
3. The method of claim 1 wherein performing the search includes determining the order in which searchable items are compared against search criteria of said search request based on the minimum number of bonds that have to be traversed from the searchable items to the particular searchable item.