1. A method comprising the computer-implemented steps of: receiving, at a relational database server, a relational database statement that specifies one or more relational operations to perform on a data subset of one or more n-dimensional data objects that are stored according to a multidimensional schema; passing, from said relational database server to a multidimensional database server, a) a function that identifies the data subset based on information that is contained in said relational database statement and, b) separate from the function, one or more value-filtering criteria involved in the one or more relational operations; identifying, by the multidimensional database server and based on said function, the data subset of said n-dimensional data objects; generating, by said multidimensional database server, a filtered set of one or more values from the data subset based on the one or more value-filtering criteria; passing, from said multidimensional database server to said relational database server, said filtered set of one or more values; performing, at the relational database server, the one or more specified relational operations on the filtered set of one or more values returned to the relational database server; and producing and returning, by said relational database server and in response to said relational database statement, results of the one or more relational operations; wherein the method is performed by one or more computing devices.