A method is disclosed for modeling application-level objects in terms of join graphs defined over tables containing structured data residing in a relational database. In accordance with the disclosed metamodel, each object is modeled logically as a join graph. A query received from an application that requests the return of objects meeting certain conditions is reformulated to refer to the metamodel. The metamodel includes an index structure having a plurality of indexes and a set of join conditions that specify relationships between the indexes. Some series of join conditions form join paths, such that each join path originates on an anchor table and ends on a table corresponding to one of the plurality of indexes. The metamodel further includes at least one view representing a subgraph of the join graph having at least one anchor table as a key.