- 建表與插入資料
- SQL對比
1. 基本資料
- 建立表
CREATE TABLE student
(
id int(10) NOT NULL AUTO_INCREMENT,
name varchar(25) DEFAULT NULL,
age tinyint(2) DEFAULT NULL,
live varchar(255) DEFAULT NULL,
PRIMARY KEY (id)
) ;
- 批量插入1百萬條資料
DROP PROCEDURE IF EXISTS insert_Stu;
DELIMITER $$
CREATE PROCEDURE insert_Stu(IN max_num INT(10))
BEGIN
DECLARE i INT DEFAULT 0;
REPEAT
SET i = i + 1;
INSERT INTO student (name, age, live) VALUES (rand_string(3), rand_num(), rand_string(6));
UNTIL i = max_num
END REPEAT;
COMMIT;
END $$
DROP PROCEDURE IF EXISTS rand_string;
CREATE FUNCTION rand_string(n INT) RETURNS VARCHAR(255)
DECLARE chars_str VARCHAR(100) DEFAULT 'abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ';
DECLARE return_str VARCHAR(255) DEFAULT '';
WHILE i < n DO
SET return_str = CONCAT(return_str, SUBSTRING(chars_str, FLOOR(1 + RAND() * 52), 1));
SET i = i + 1;
END WHILE;
RETURN return_str;
END $$;
DROP PROCEDURE IF EXISTS rand_num;
CREATE FUNCTION rand_num()
RETURNS INT(5)
SET i = FLOOR(100 + RAND() * 10);
RETURN i;
;
call insert_Stu(1000000);
2. SQL對比
- 正常分頁
select s.* from student s limit 1000000,10;
- 優化分頁
select s.*
from student s
WHERE s.id >= (SELECT s.id FROM student LIMIT 1000000, 1)
LIMIT 10;
- 最優分頁
SELECT s.* FROM student s WHERE s.id BETWEEN 1000000 AND 1000010;
性能對比圖
可以看到三種SQL的耗時 ,為什麼會有這麼大的差距,這主要是MySQL的limit關鍵字會導緻偏移量的原因