Abstract: A method and apparatus is disclosed for accurately estimating the cost of a database query, including the total computer resources used and estimated elapsed time for the production of a first row and last row of an operator involved in the query and/or the total resources used and elapsed time for returning the overall response to a database query. The method and apparatus accurately accounts for resources used and elapsed time associated with blocking operators, such as sorts and hash joins, which cannot produce a first row until they have completed their operations.