8. The computer readable storage medium of claim 1 wherein the dimension usage is based on references to dimension members in query expressions.
1. A non-transitory computer readable storage medium, comprising executable instructions to: receive an abstract query specifying a set of objects, wherein at least a portion of the set of objects is stored in a first semantic domain associated with an Online Analytical Processing (OLAP) data source and at least a portion of the set of objects is stored in a second semantic domain associated with a relational data source, the set of objects is defined by a combined semantic abstraction having at least one level of combined semantic abstraction data with relational data and at least one nested level of semantic abstraction data with OLAP base data; analyze the abstract query to determine member and level dependencies for any calculations within the abstract query and to determine values that are required by the abstract query; generate query analysis results based on the analysis of the abstract query, the query analysis results comprising a summary of requirements and dependencies of the abstract query; construct, using the combined semantic abstraction, at least one first query of the OLAP data source based on the query analysis results by mapping required dimension members and measures from the query analysis results into the first semantic domain, building a query for the first semantic domain to retrieve its contributing values, and converting dimension member sets and measure references to corresponding dimension member sets and measure references in the first semantic domain; add required base measures to the at least one first query, wherein the base measures are grouped into compatible measure groups based on dimensionality and query-compatibility such that queries are built for each compatible measure group and a sequence for executing the queries is built, wherein each applicable dimension for the corresponding compatible measure group contributes columns corresponding to its data bindings to the corresponding query, wherein dimension usage adds filters to limit columns and rows returned; construct a member set expression for each dimension required by the at least one first query based on dimension usage information specified in the query analysis results; section any dimensions that do not have a corresponding member set expression to a default dimension in the at least one first query; add content to the at least one first query to push at least a portion of processing of a calculated dimension or calculated measure specified by the at least one first query to the OLAP data source; pass the at least one first query to the OLAP data source for execution; construct, using the combined semantic abstraction, at least one second query of the relational data source based on the abstract query; pass the at least one second query to the relational data source for execution; and receive and store results from the execution of the at least one first query and the at least one second query.