A database system that provides independence between the query and physical structure of the database tables by captioning each database table with a partial query reflecting the contents of that table. In particular, the partial query is a query that if applied to a larger database of a standard configuration would produce the data of the table. Relevant tables for a particular query may be identified by piecing together the partial queries until the user query is obtained. The database system may be integrated with an optimizer by comparing each of the identified tables against the others for the amount of overlap their sub-queries have with the user query and the cost of accessing the table and then repeating this process as the tables are joined in various combinations.