US Patent 7174346 System and method for searching an extended database

Once a search query is received from a user, a standard index is searched based on the search query. The standard index forms part of a set of replicated standard indexes having multiple instances of the standard index. A signal is then determined based on the search of the standard index. When the received signal meets predefined criteria, an extended index is searched. The extended index forms part of a set of extended indexes having at least one instance of the extended index. There are fewer instances of the extended index than instances of the standard index. Extended search results are then obtained from the extended index and at least a portion of the extended search results is transmitted towards a user.