Methods and apparatus are provided for rewriting queries during a database query processing operation to include auxiliary attributes not included in the original query, thus improving processing efficiency. For example, in one aspect of the invention, a technique for rewriting a query in a query processing operation includes the following steps. First, the query is processed in accordance with at least a portion of a data set, producing query results. Second, data attributes from the query results are analyzed. Finally, at least one new predicate from at least one auxiliary data attribute is appended on the query.