21. The computer storage medium as recited in claim 15 , further comprising code for parsing the selected database query to determine whether the database query includes at least one subquery joined by at least one of a NOT EXISTS, a NOT IN and an ALL clause.
21. The computer storage medium as recited in claim 15 , further comprising code for parsing the selected database query to determine whether the database query includes at least one subquery joined by at least one of a NOT EXISTS, a NOT IN and an ALL clause. 22. The computer storage medium as recited in claim 21 , further comprising code for prompting a user to select preferences to be used during tuning based on whether the database query includes at least one of a NOT EXISTS, a NOT IN and an ALL clause.