mysql secondary index query differs much, innodb vs myisam

Question

1.table des

innodb_test

CREATE TABLE `innodb_test` (
  `id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `city` varchar(255) DEFAULT NULL,
  `status` mediumint(9) DEFAULT NULL,
  `date` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `name_city_satus` (`name`,`city`,`status`)
) ENGINE=InnoDB AUTO_INCREMENT=1;
myisam_test** is just the same as innodb_test but with MyISAM engine.

2.I run the fllowing sql getting 57 rows:

1):

SELECT SQL_NO_CACHE * FROM innodb_test WHERE `name` LIKE 'H%' AND city LIKE 'O%' LIMIT 0, 10000;

2):

 SELECT SQL_NO_CACHE * FROM myisam_test WHERE `name` LIKE 'H%' AND city LIKE 'O%' LIMIT 0, 10000;

By show profilings, the first sql takes 0.029s, while the other takes 0.0069.

Why they have so big difference?

Answer 1

Try add Fixed row format to your table .

44% improvement in speed for Fixed row format over Dynamic.

The disadvantage to Fixed row formats is the space required to store columns. Changing to a Fixed row format will pad any variable length columns with spaces. However, any time your trade-off for performance comes at a cost of disk space, performance wins.

ALTER TABLE  `innodb_test` ROW_FORMAT = FIXED

more info here