Concurrent View Maintenance Scheme for Soft Real-time Data Warehouse Systems

The data warehouse should be refreshed periodically or aperiodically in order to prevent OLAP transactions from reading extremely stale data. This refreshing process is referred to as view maintenance. There have been many researches on ways to preserve data consistency during the process of view maintenance. The simplest approach among them is to perform view maintenance in the nighttime while OLAP transactions are allowed to be active only in daytime. However, this approach cannot be applied to globalized corporations because no common idle time is available for such corporations. In this paper, we propose a new algorithm for performing view maintenance without blocking OLAP transactions. Our algorithm improves data freshness by allowing one or more maintenance transactions and OLAP transactions to be executed concurrently. We introduce the details of algorithm with some examples, present proofs of devised scheme, and then evaluate performance gains by means of simulation method.