关系数据库中基于区域聚类的多区域查询优化

针对关系数据库及其应用中多个区域查询的并发处理,提出了一种区域聚类的方法,其基本思路是将多个查询中相近的区域分成若干组,每组构成较大的区域,从较大的区域中检索元组.这种方法避免了多个区域中相同部分的多次访问,减少了数据库I/O操作的次数.对于低维和高维数据,此方法与一一查询的朴素方法相比,其性能都有明显提高.

Region Clustering Based Multiple Range Query Optimization in Relational Databases

In relational databases and their applications,it is one of important issues to evaluate multiple range queries concurrently.For this issue,the authors propose a new method,which is called Region Clustering Method.The basic idea of this method is region clustering that groups the search regions of individual range queries into larger regions and retrieves the tuples from larger regions.This method avoids having the same region accessed multiple times and reduces the number of random I/O accesses to the underlying databases. Meanwhile,it does not suffer much feared"dimensionality curse"as this method remains effective for high- dimensional data.Extensive experiments are carried out to measure the performance of this new strategy and the results indicate that it is significantly better than the naive method of evaluating these queries one by one for both low-dimensional and high-dimensional data.