SET allow_experimental_analyzer=1; SELECT 1 AS value, * FROM ( SELECT 1 AS key ) AS l LEFT JOIN ( SELECT 2 AS key, 1 AS value ) AS r USING (key) SETTINGS join_use_nulls = 1; SELECT 1 AS value, * FROM ( SELECT 2 AS key ) AS l LEFT JOIN ( SELECT 2 AS key, 1 AS value ) AS r USING (key) SETTINGS join_use_nulls = 1