Maintaining Remote Decision Support Databases

Abstract:This research describes and analyzes schemes for managing decision support databases that are extracted from a central database and “downloaded” to personal workstations. Unlike a (true) distributed database system, where updates are propagated to maintain consistency, these remote “snapshots” are updated only periodically (“refreshed”) upon command of the remote workstation user. This approach to data management has many of the same advantages of a distributed database over a centralized database (e.g., reduced communication costs, improved response time for retrievals, and reduction in contention), but it avoids the high overhead for concurrency control associated with updating in a distributed database. The added cost is in reduced data consistency.The schemes analyzed include full regeneration, the scheme used by System R*, and two new schemes. One new scheme—called modified regeneration—is a variation on simple full regeneration of the snapshot, but transmits only relevant changes to the sna...