数据仓库中实视图聚集函数的增量更新

Incremental updates of aggregate functions of materialized view in the data warehouse

提出在视图表达式树中以由下到上的方式计算中间结点的变化 ,将计算出的中间结果作为辅助视图保存在数据仓库中 ,利用这些辅助视图或子视图计算出来的聚集函数的变化 ,来计算本视图聚集函数值的更新 ,实现视图的增量维护 ,从而缩短数据仓库更新维护时间 ,提高OLAP查询效率 .同时 ,介绍了实视图中聚集函数的增量更新算法 。

This paper proposes a method to compute the changes of each intermediate node in a bottom up fashion in the view expression tree and store the data as auxiliary view in the data warehouse. By computing the updates of the aggregate functions with these auxiliary view or child view, we can compute the updates to the aggregate function of the view and implement the view incremental maintenance.Thus the maintainable time of updating the data warehouse can be reduced and the efficiency of the OLAP queries improved. The authors also propose a maintainable and incremental update algorithm to make aggregate functions on materialized views maintained.