Abstract: Aggregation queries with group-by is now a fundamental issue of data warehouse in ROLAP.Materialized views can significantly improve the performance of query.The paper makes an extension to general rewriting query using materialized views considering the hierarchical relation of attributes of dimension tables and discusses the restrict condition of rewriting query using single materialized view，then presents a method of rewriting query.In the final a local optimal search algorithm is described to find an approximately optimal rewriting query when we consider multi-view to rewrite query.The experimental result shows the algorithm proposed is more efficient.

Key words: ROLAP, materialized view, rewriting query, query optimization

摘要： 分组聚集查询已成为数据仓库领域研究的核心问题之一，实视图是提高分组聚集查询性能的有效手段。利用维属性间的层次关系，对一般意义上的实视图重写查询进行了扩展，讨论了单一视图重写查询的限制条件，并给出重写方法，在此基础上，提出了一种利用多个实视图重写查询的优化选择算法，并通过实验表明，该算法进一步提高了分组聚集查询效率。

关键词: ROLAP, 实视图, 重写查询, 查询优化