【摘要】 建立了一个考虑更新代价的Web视图置换测度模型,并以此为基础,提出一种物化Web视图在线选择算法DCR.该算法在简单的缓存算法基础上引入了选择置换机制,通过监测提交的用户查询,决定是否将其结果予以保存,必要时依据置换测度值的大小进行置换,实现Web视图物化总量的控制,防止视图过分物化,以降低动态缓存管理、索引和检索的开销.同时可结合适当的维护方式,提高更新效率,避免频繁的更新对查询性能产生太大的影响,使整个算法更具适用性.实验表明,在查询集较大、数据源更新比较频繁的场合,DCR算法可以降低视图检索开销,并可通过机会更新有效减少了失效视图的数量,使算法在用户查询响应性能方面显示出较大的优势.更多还原

【Abstract】 Considering the cost of WebView maintenance,an improved replacement benefit model of dynamic cache is founded.Then an algorithm DCR(dynamic cache replacement) is proposed for online selection of materialized WebView,which is based on the new model and adopts the replacement mechanism to limit the sum of materialized view in cache.With its help,the cost of cache management,index and search can be reduced.In the meanwhile,DCR can combine any suitable update method to improve the efficiency of updating.It can also avoid degradation of the query response performance due to frequent updating and make the algorithm more applicable.Comparison experiments indicate that: when the user query set is large and the updating of data source is frequent,DCR is a more preferable and more efficient solution.更多还原