存储过程加上事务能够提高插入效率：

CREATE DEFINER=`root`@`%` PROCEDURE `autoinsert`(IN NUM INT)
BEGIN
  DECLARE INIT_NUM INT DEFAULT 0 ;
    START TRANSACTION;
    WHILE(INIT_NUM < NUM)
    DO
        insert into `user`(`name`,`city_id`) values(rand_str(10),rand_int(2));
        SET INIT_NUM = INIT_NUM+1;
    END WHILE;
    COMMIT;
    END

CREATE TABLE `test` (
  `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `forum_id` bigint(20) unsigned NOT NULL,
  `created` datetime NOT NULL,
  PRIMARY KEY (`id`),
  KEY `test_forum_id_IDX` (`forum_id`) USING BTREE
) ENGINE=InnoDB AUTO_INCREMENT=750136 DEFAULT CHARSET=utf8mb4

DROP PROCEDURE IF EXISTS test.BatchInsertTest;
delimiter //
CREATE PROCEDURE BatchInsertTest(IN loop_time INT)
  BEGIN
      DECLARE Var INT;
      SET Var = 0;
      START TRANSACTION;
      WHILE Var < loop_time DO
          INSERT INTO `test` ( `forum_id`, `created`) select  FLOOR(1 + (RAND() * 1000)),FROM_UNIXTIME(UNIX_TIMESTAMP()-(RAND() * 30 * 86400));
          SET Var = Var + 1;
      END WHILE;
     COMMIT;
  END;
  //
delimiter ;

CALL BatchInsertTest(10000);

select count(*) from test;

mysql生成固定位数随机字母以及数字

随机数字

CREATE DEFINER=`root`@`%` FUNCTION `rand_int`(counts INTEGER) RETURNS varchar(20) CHARSET utf8
BEGIN
       DECLARE sTemp VARCHAR(20);
    DECLARE sTempCounts INTEGER;
       SET sTemp = CONCAT( ROUND(ROUND(RAND(),counts)*(POW(10,counts))),'');

    IF(CHAR_LENGTH(sTemp)<counts) THEN

      SET sTempCounts = counts - CHAR_LENGTH(sTemp);
      SET sTemp = CONCAT(sTemp, RIGHT(CONCAT(POW(10,sTempCounts),''),sTempCounts));
    END IF;
      RETURN sTemp;
END

随机字母：

CREATE DEFINER=`root`@`%` FUNCTION `rand_str`(  
    f_num INT UNSIGNED
    ) RETURNS varchar(200) CHARSET latin1
BEGIN
      DECLARE i INT UNSIGNED DEFAULT 0;   
      DECLARE v_result VARCHAR(200) DEFAULT '';   
      DECLARE v_dict VARCHAR(200) DEFAULT '';  
      SET v_dict = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';  
      SET v_dict = LPAD(v_dict,200,v_dict);  
      WHILE i < f_num   
      DO   
        SET v_result = CONCAT(v_result,SUBSTR(v_dict,CEIL(RAND()*200),1));  
        SET i = i + 1;   
      END WHILE;    
      RETURN v_result;   
END

MYSQL在使用Online DDL之后，主从复制或多或少还存在问题，可以考虑使用pt-online-schema-change

• mysql在线修改表结构大数据表的风险与解决办法归纳
• pt-online-schema-change 在线更改MySQL表结构