: E.g. say I have a chain of book-stores, in different countries, and I'm aiming for the following: : - Each country has its own index file, on its own machine (e.g. books from Japan are indexed on machine "japan1") : - Most users search only within their own country (e.g. search only the "japan1" index) : - But sometimes, they might ask to search the entire chain (all countries), meaning some sort of "map/reduce" (=collect data from all countries).
what you're describing is one possible usecase of "Distributed Search" http://wiki.apache.org/solr/DistributedSearch as long as each of the individual "country" indexes have schemas that overlap (ie: share some common fields) and have the same uniqueKey field, with an id space that does *not* overlap between countries (ie: document "1" can only be in one index, not in any others) then you can do a distributed query that is distributed out to all of hte individual indexes, and then merged together to generate aggregate results. -Hoss
