Kriegel, Hans-PeterPfeifle, MartinPötke, MarcoSeidl, ThomasWeikum, GerhardSchöning, HaraldRahm, Erhard2019-11-142019-11-1420033-88579-355-5https://dl.gi.de/handle/20.500.12116/30060In order to achieve efficient execution plans for queries comprising userdefined data types and predicates, the database system has to be provided with appropriate index structures, query processing methods, and optimization rules. Although available extensible indexing frameworks provide a gateway to seamlessly integrate user-defined access methods into the standard process of query optimization and execution, they do not facilitate the actual implementation of the access method itself. An internal enhancement of the database kernel is usually not an option for database developers. The embedding of a custom block-oriented index structure into concurrency control, recovery services and buffer management would cause extensive implementation efforts and maintenance cost, at the risk of weakening the reliability of the entire system. The server stability can be preserved by delegating index operations to an external process, but this approach induces severe performance bottlenecks due to context switches and inter-process communication. Therefore, we present in this paper the paradigm of relational access methods that perfectly fits to the common relational data model and is highly compatible with the extensible indexing frameworks of existing object-relational database systems.enText/Conference Paper1617-5468