user: Question: What was the lenGTh for GT class at Portland International Raceway?
Columns: ['Race', 'Length', 'Class', 'Circuit', 'Date']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Rolex 24 at Daytona', '24 Hours', 'All', 'Daytona International Speedway', 'February 5 February 6']
SQL:

assistant: SELECT "Length" FROM "Table" WHERE "Class" = 'GT' AND "Circuit" = 'Portland International Raceway';