派生索引空间连接查询

空间连接查询是最耗时、最重要的空间查询。针对空间多路连接中一方有R树索引，另一方是连接或选择的中间结果，因而无索引的情况，提出派生索引连接方法。这一方法基于父母索引为中间结果建立派生索引，以用于随后的空间连接，分析其查询花费，用于多路连接的查询优化。最后用实验结果说明方法的有效性。

Derived Index Spatial Join Query

This paper proposed a novel algorithm--derived index spatial join (DISJ). Based on parent trees to construct index for intermediate result of another spatial operation, it efficiently computes the spatial join between two inputs, only one of which is indexed by an R-tree. Going one step further, DISJ and other spatial join algorithms can be implemented as operators in a database environment that joins more than two spatial data sets. Cost models and an optimization algorithm were proposed and evaluated through experimentation. The experiment reveals the flexibility of the method.