The present invention relates to a system (10) for generating and maintaining virtual and physical metadata layers in a MetaBase metadata repository (110b) in order to simplify and optimize the retrieval of data from a plurality of disparate information sources (130a-130c). The system stores in a physical metadata layer of a MetaBase metadata repository a plurality of physical metadata elements, wherein each one of the physical metadata elements corresponds to the metadata elements in the plurality of information sources. Logical metadata elements are stored in the virtual metadata layer and are linked to the physical metadata elements in order to maintain the relationships therebetween. By maintaining the relationships between the physical metadata elements, users can initiate a data query request for data corresponding to a logical metadata element, and the system is configurated to retrieve the desired data from the relevant information sources, even in the event that relevant information sources maintain the data in fields having different data field names, that the information sources employ incompatible data formats, and that the relevant information sources employ different query languages.