The covering tiles can be quickly examined for any interaction between the layers. Database designers can specify the number of times a geometry should be subdivided to optimize the coverage with smaller and smaller uniformly sized tiles. Designers can also choose to use a preset number of tiles, allowing the geometry to subdivide into variable- sized tiles. Until now, database performance has largely been a factor of database size and index efficiency. But with an Oracle8 database using Oracle8 Spatial Cartridge, performance is a factor of the amount of data actually retrieved.
Performance is optimized through the use of a spatial index and a two-tiered query model.
This model significantly reduces load and query processing overhead and provides excellent scalability as the spatial data volume grows. The first tier, or primary filter, permits fast selection of a small number of candidate records to pass along to the secondary filter. The primary filter uses approximation to reduce computational complexity. The secondary filter applies exact computational geometry to the result set of the primary filter. These exact computations yield the final answer to a query.