The minimum incremental maintenance of materialized views in data warehouse

A large number of materialized views are stored in data warehouse to enable users to quickly get search results for OLAP analysis. But when the remote basic data source changes, the materialized views in data warehouse are also updated correspondingly in order to maintain the consistency with basic relations, which causes materialized views maintenance issues. There are two methods for materialized views maintenance. One way is to re-compute the views, which can lead to extra large storage and maintenance cost and is sometimes unachievable due to storage limitation. So incremental maintenance technique is more preferable in recent years. Its principle is that data source reports its changes to the integrator who then calculates the corresponding changes and inform the database with the results. Incremental maintenance technique is adopted in this paper. The amount of incremental data is different for the same view when adopting different methods, which result in different maintenance costs. The idea and strategy of minimum incremental maintenance is presented. The materialized view definitions and maintenance expressions, as well as algorithms are given. The experiment shows that the maintenance cost of materialized views is decreased and data warehouse processing efficiency is improved.