Several local databases may be linked together to form a large database. Each database may share a common type definition, but may contain only a portion of the large database. When a local database queries information from another database, the result may be stored locally using the type system. Across the entire database, items may be identified as their local or home database along with an identifier provided by that database. Cached information may be stored locally and may refer to the source for that information through the identifier. Once the cached information is present, queries that reference the record may be satisfied by the cached information. The cached information may be refreshed from the source database or may expire to avoid stale or changed data in the cache.