This gets up to the 10 highest graded locations – same problem as the fruit. Setting temp table engine to memory makes it slightly faster still.

CREATE PROCEDURE getBestByCountry ()
BEGIN

DECLARE done INT DEFAULT FALSE;
DECLARE _country VARCHAR(40);
DECLARE cur1 CURSOR FOR SELECT DISTINCT country FROM Location;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

OPEN cur1;

DROP TABLE IF EXISTS best;

CREATE temporary TABLE best
( id INT UNSIGNED ) ;

read_loop: LOOP
FETCH cur1 INTO _country;
IF done THEN
LEAVE read_loop;
END IF;

INSERT INTO best (id)
SELECT id FROM Location WHERE country = _country
ORDER BY grade DESC
LIMIT 10;

END LOOP;

CLOSE cur1;

SELECT b.* — get rest of data
FROM best t,
listBest b
WHERE t.id = b.id
ORDER BY b.country, b.grade DESC, b.overallRating DESC
;

END;