On defining structured geometry types in PostgreSQL to implement a spatial database

PostgreSQL is a widely used open source object-relational database system, on which the PostGIS spatial database is built. By defining geometry types in PostgreSQL according to the OGC WKB standard, geographic features are usually defined as a base type which is stored as general binary data blocks without internal structures. But the unstructured representation of the structured geometry data model brings the problem of inefficient data access. In this paper, we propose a new approach that uses an array of structured composite types to replace the unstructured base types to store geometry types. Then PostgreSQL 8.3 is extended to support spatial data management in this proposed approach following the standard of OGC's Simple Feature Specification. A contrastive experiment proves the advantages and efficiency of this method.