1. 建表與插入數(shù)據(jù)
2. SQL對比

基本數(shù)據(jù)

• 創(chuàng)建表

  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1百萬條數(shù)據(jù)

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;
DELIMITER $$
CREATE FUNCTION rand_string(n INT) RETURNS VARCHAR(255)
BEGIN
  DECLARE chars_str VARCHAR(100) DEFAULT 'abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ';
  DECLARE return_str VARCHAR(255) DEFAULT '';
  DECLARE i INT DEFAULT 0;
  WHILE i < n DO
  SET return_str = CONCAT(return_str, SUBSTRING(chars_str, FLOOR(1 + RAND() * 52), 1));
  SET i = i + 1;
  END WHILE;
  RETURN return_str;
END $$;

DROP PROCEDURE IF EXISTS rand_num;
DELIMITER $$
CREATE FUNCTION rand_num()
  RETURNS INT(5)
BEGIN
  DECLARE i INT DEFAULT 0;
  SET i = FLOOR(100 + RAND() * 10);
  RETURN i;
END $$
;

call insert_Stu(1000000);

SQL對比

1. 常規(guī)分頁

   select s.* from student s limit 1000000,10;
   

2. 優(yōu)化分頁

   select s.*
   from student s
   WHERE s.id >= (SELECT s.id FROM student LIMIT 1000000, 1)
   LIMIT 10;
   

3. 最優(yōu)分頁

   SELECT s.* FROM student s WHERE s.id BETWEEN 1000000 AND 1000010;
   

4. 性能對比圖

   可以看到三種SQL的耗時(shí) ，為什么會有這么大的差距，這主要是MySQL的limit關(guān)鍵字會導(dǎo)致偏移量的原因

   image.png