/*ф-я randstr(N) возвратит строку из N символов АНГЛ алфавита*/
CREATE FUNCTION randstr(lenstr INT)
  RETURNS varchar(255)
BEGIN
  SET @randstr := "";
  SET @engstr="abcdefghjklmnopqrstuvwxyz";
  WHILE lenstr > 0 DO
    SET @randstr = CONCAT(@randstr,SUBSTR(@engstr,ROUND(RAND()*CHAR_LENGTH(@engstr)),1)); 
    SET lenstr = lenstr - 1;
  END WHILE;

RETURN @randstr;
END

/*таблица */
CREATE TABLE popotable (
  id int(11) NOT NULL AUTO_INCREMENT,
  pole varchar(50) DEFAULT NULL,
  PRIMARY KEY (id),
  INDEX IDX_popo (pole)
)
ENGINE = INNODB;
/* ЗАПРОС для заполнения*/
 /* 5*5*4*5*5*4*5*4 =200тыс  */
/*выполнить 5 раз для 1млн.*/
INSERT INTO popotable (popopole) 
SELECT randstr(50) FROM 
  (select 1 as a union select 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) AS t1,
  (select 1 as a union select 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) AS t2,
  (select 1 as a union select 2 UNION SELECT 3 UNION SELECT 4 ) AS t3,
  (select 1 as a union select 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) AS t4,
  (select 1 as a union select 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) AS t5,
  (select 1 as a union select 2 UNION SELECT 3 UNION SELECT 4 ) AS t6,
  (select 1 as a union select 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) AS t7,
/*  (select 1 as a union select 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5) AS t8,*/
  (select 1 as a union select 2 UNION SELECT 3 UNION SELECT 4 ) AS t9;