Since the data is spatial, you need to specify the R-Tree accessmethod for this index.
由于涉及到空间数据，您需要为这个索引指定r - Tree访问方法。
2
Querying spatial dada is usually concerned with space position. Spatial dada need special multi-dimensional accessmethod.
空间数据的查询通常与空间位置有关，需要特殊的多维存取方法。
3
This paper describes the access control method for the specific relational-object data structure on the base of the self-developed spatial database, VISTA.