CREATE TABLE `names` (`name` varchar(20));
假設names
表包含所有居住在加利福尼亞州的所有人的所有4000萬名(例如)。在大數據集中計算不同值(40M行):SELECT count(*)as count,name FROM names GROUP BY name ORDER BY name;
SELECT count(*) as count, name FROM names GROUP BY name ORDER BY name;
如何優化此查詢?
預期結果:
count | name
9999 | joe
9995 | mike
9990 | kate
.... | ....
2 | kal-el