Abstract: An apparatus and method for processing an ontological query for data from any of a plurality of different databases on a network coupled to a computer that includes loading a ontological data model comprising a plurality of logical models based on data from the plurality of different databases, compiling the ontological query and optimizing 48 the compiled ontological query according to join and combination rules based on the logical models and describing meta-properties of the data and meta-relationships based on the meta-properties between the data from the plurality of different databases, and processing logical operations on the compiled ontological query.