A tabular set provider is provided for processing a data agnostic business intelligence query with relational set operations, herein called a relational query against a multidimensional datasource. The tabular set provider comprises a query interceptor, a query decomposer, an OLAP query provider interface, and an operation module. The query interceptor is provided for detecting and intercepting a data agnostic Business intelligence query that has relational set operations that is issued against one or more multidimensional data sources. The query decomposer is provided for decomposing the operands of the set operation in the input query into one or more sub-queries. The OLAP query provider interface is provided for sending the OLAP supported sub-queries to an OLAP query provider and receiving results. The operation module is provided for using set operation functionality provided by a relational query provider that performs the set operations locally on the results of the OLAP data extraction.