空间查询优化是空间应用的突破点，由于现有的关系优化不能适应空间数据的查询，因此空间系统必须具有自己的代价模型和优化器，为此，给出了一个空间查询优化的系统方案FQPro，并在对空间查询优化的几个阶段做了一般性探讨后，将重点放在代价模型、谓词代价计算和优化方案的代价计算上，尤其对基于R－树的低代价模型给予了详细介绍，另外，参照关系优化器，FQPro还定义了一套谓词代价公式和谓词选择性公式，并在此基础上定义了查询方案代价计算公式和算法。文章最后指出，代价模型和可扩展的体系机构是空间查询优化系统的发展方向。

Spatial query optimization should be the focus of attention in spatial area. Since relational optimizer is unsuitable for dealing with spatial data, spatial systems should have their own cost model and optimizer. In this paper, a spatial query optimization system—FQPro was presented. After the overview of general phrases of spatial query optimization, we put the emphasis on cost model, calculation of predicate costs and plan costs. In particular, we give a detailed introduction of the cost model based on R-tree. Similar to relational systems, FQPro defines a set of formula for predicate costs and predicate selectivity respectively. They are used in G/SQL. On top of these formulas, the idea and algorithm for forming the optimum execution plan is defined. Concluding this paper are some issues that should be the concerns of research on spatial optimization, primarily the cost model and the extensible system architecture. Also, this paper summarizes the challenges and opportunites facing spatial query processing in the end.