面向原生XML数据库的自适应路径索引

Adaptive Path Index for Native XML Databases

路径索引是改善原生XML数据库(NXD)性能的一项重要技术.然而现有NXD中的路径索引缺乏动态性、自适应性,妨碍了NXD的查询性能改善.本文根据Chung C等提出的面向XML数据的自适应路径索引(APEX)[1],结合NXD的特点,提出面向NXD的自适应路径索引(NXD-APEX).NXD-APEX继承了APEX自适应性,并通过加入时间特征到APEX的常用路径挖掘算法中,使NXD-APEX能有效处理具有时间局部性的查询.同时针对NXD-APEX可能导致的大空间开销问题,提出一种基于收益的索引筛选算法.试验表明:NXD-APEX能以合理的空间开销有效地改善NXD的查询性能.

For native XML databases （ NXD）, path index is one important way to improve query performance. However, main stream native XML databases just index paths in static ways, which lacks the adaptive feature to go against the speed improvement of dynamic queries. In this paper, based on APEX and the common features of NXD, an adaptive path index for NXD （NXD-APEX） is proposed. Unlike APEX, NXD-APEX can speed up the queries of temporal locality by integrating temporal feature into frequently-used paths extracting algorithm. Meanwhile, NXD-APEX can greatly reduce its space cost under slight performance degradation, using a novel gain-based filtering algorithm. Experiments show that NXD-APEX can effectively improve the query performance of NXD at a reasonable space cost.