Implementing geospatial operations in an object-relational database system

Over the last decade the need to implement functions into a DBMS that are application-specific has increased. For this reason today most object-relational DBMS (ORDBMS) provide features that allow the user to include application-specific functions into the DBMS for their execution within database queries. This paper reports on an implementation effort to include spatial operations into an ORDBMS as a basis to support geographic information systems (GIS). Based on the technique of multi-step query processing using z-values we show how to transform "straight forward" queries into more sophisticated ones that use the existing ORDBMS as is. That is, existing index methods and existing optimization techniques are sufficient to execute the rewritten queries efficiently. For this purpose we introduce several user-defined functions and types that provide the necessary basis for an efficient implementation. To validate our implementation we used a subset of queries as defined in the SEQUOIA2000 benchmark. Our measurements show that the performance improvements between the original queries and the rewritten ones are dramatic.