In a distributed system, such as a PBX (FIG. 1), which uses a database for its operation, a master copy (22) of the database having a first format is stored at a central node (10) and cache copies (32) of database portions (24) but having a different format are stored at peripheral nodes (11-12). A change...http://www.google.com/patents/US5136707?utm_source=gb-gplus-sharePatent US5136707 - Reliable database administration arrangement
