1. A method for processing a relational database query, comprising: generating, using a processor coupled to a multidimensional data source, a relational model of the 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 a 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; forming the relational database query from the relational database application against the relational model of the multidimensional data source using a graphical user interface displayed on a display coupled to the processor, wherein the graphical user interface: displays a presentation layer representation of the virtual relational table for the relational database application corresponding to the multidimensional data source, 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; receiving 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; using the relational-to-multidimensional mapping together with relational/multidimensional equivalency logic to construct a multidimensional database query based on the received relational database query, wherein the relational/multidimensional equivalency logic comprises a general mapping between relational queries and structures and multidimensional queries and structures, 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 crossjoin operation is performed; submitting the constructed multidimensional database query for execution against the modeled multidimensional data source, wherein the multidimensional data source comprises three or more dimensions; and displaying, on the display, a result of the constructed multidimensional database query against the modeled multidimensional data source.