17. A computing system for processing a relational database query, comprising: a processor; a display coupled to the processor; a modeling subsystem configured to execute on the processor and further configured to generate a relational model of a multidimensional data source using one or more of a schema for the multidimensional data source and metadata for the multidimensional data source, wherein the relational model comprises: a relational-to-multidimensional mapping between the virtual relational table for a relational database application corresponding to the multidimensional data source and the multidimensional data source, and the schema and metadata accessed from the multidimensional data source for the virtual relational table; a graphical user interface subsystem configured to execute on the processor and further configured to form the relational database query from the relational database application against the relational model of the multidimensional data source, wherein the graphical user interface subsystem further displays a presentation layer representation of the virtual relational table for a relational database application corresponding to the multidimensional data source on the display, enables pointer-driven selection for query of one or more tables and columns of data stored in the multidimensional data source and represented by the displayed presentation layer representation, and enables selection of a detail filter to apply against the relational model; a query reception subsystem configured to execute on the processor and further configured to receive the relational database query, the received relational database query being drawn against the relational model of the multidimensional data source, wherein the relational database query specifies a detail filter against the relational model having selected predicates; a multidimensional query construction subsystem configured to execute on the processor and further configured to use the relational-to-multidimensional mapping to construct a multidimensional database query based on the received relational database query, wherein the constructed multidimensional query specifies, for each of the selected predicates that can be applied against the relational model of the multidimensional data source before a crossjoin operation is performed, applying the selected predicate against the relational model of the multidimensional data source before the cross join operation is performed; and a query submission subsystem configured to execute on the processor and further configured to submit the constructed multidimensional database query for execution against the modeled multidimensional data source, wherein the multidimensional data source comprises three or more dimensions.
17. A computing system for processing a relational database query, comprising: a processor; a display coupled to the processor; a modeling subsystem configured to execute on the processor and further configured to generate a relational model of a multidimensional data source using one or more of a schema for the multidimensional data source and metadata for the multidimensional data source, wherein the relational model comprises: a relational-to-multidimensional mapping between the virtual relational table for a relational database application corresponding to the multidimensional data source and the multidimensional data source, and the schema and metadata accessed from the multidimensional data source for the virtual relational table; a graphical user interface subsystem configured to execute on the processor and further configured to form the relational database query from the relational database application against the relational model of the multidimensional data source, wherein the graphical user interface subsystem further displays a presentation layer representation of the virtual relational table for a relational database application corresponding to the multidimensional data source on the display, enables pointer-driven selection for query of one or more tables and columns of data stored in the multidimensional data source and represented by the displayed presentation layer representation, and enables selection of a detail filter to apply against the relational model; a query reception subsystem configured to execute on the processor and further configured to receive the relational database query, the received relational database query being drawn against the relational model of the multidimensional data source, wherein the relational database query specifies a detail filter against the relational model having selected predicates; a multidimensional query construction subsystem configured to execute on the processor and further configured to use the relational-to-multidimensional mapping to construct a multidimensional database query based on the received relational database query, wherein the constructed multidimensional query specifies, for each of the selected predicates that can be applied against the relational model of the multidimensional data source before a crossjoin operation is performed, applying the selected predicate against the relational model of the multidimensional data source before the cross join operation is performed; and a query submission subsystem configured to execute on the processor and further configured to submit the constructed multidimensional database query for execution against the modeled multidimensional data source, wherein the multidimensional data source comprises three or more dimensions. 18. The computing system of claim 17 , further comprising: a query result reception subsystem that receives, in response to submitting the multidimensional database query, a multidimensional database query result; and a relational query result construction subsystem that uses a relational-to-multidimensional mapping to construct a relational database query result based on the received multidimensional database query result.