... generation of object-relational database applications, including multime-dia and web-based applications, often make extensive use of user-defined func-tions(UDFs) within the database. Incorporating ... different sizes. In our experiments, for thesake of simplicity, we place the first tile at the beginning of a track. The disk parametersare: The transfer time is 0.05ms, the access time is5ms, ... Using the Memory-Limited Quadtree515Fig. 1. Query feedback-driven UDF cost modeling.spatial database environment for the indexing and retrieval of spatial objects [12,13], in the on-line...