Jac Mar Jac Mar - 3 months ago 10
SQL Question

Why does this MYSQL UPDATE query take 2 minutes to run?

This query takes almost 2 minutes to execute (changing 9 records):

UPDATE table1 t1
SET t1.code_id = null, t1.code_group = null
WHERE t1.another_id IN (SELECT t2.another_id
FROM table2 t2
WHERE ((t2.id_parent = 2658 AND t2.year = 2016)
OR (t2.id = 2658 AND t2.year = 2016)))


Executing this query alone takes 0.0030s:

SELECT t2.another_id
FROM table2 t2
WHERE ((t2.id_parent = 2658 AND t2.year = 2016)
OR (t2.id = 2658 AND t2.year = 2016))


and returns 3 rows in form of a integer.

Here is info about both tables:

CREATE TABLE IF NOT EXISTS `table1`
(
`another_id` int(11) NOT NULL,
`table1_id` int(11) NOT NULL,
`code_group` varchar(1) DEFAULT NULL,
`code_id` int(10) DEFAULT NULL,
PRIMARY KEY (`another_id`,`table1_id`),
KEY `another_id` (`another_id`),
KEY `code_group` (`code_group`,`code_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

CREATE TABLE IF NOT EXISTS `table2`
(
`id_year` int(11) NOT NULL,
`id` int(11) NOT NULL,
`id_parent` int(11) DEFAULT NULL,
`another_id` int(11) NOT NULL,
`code_group` varchar(1) DEFAULT NULL,
`code_id` int(10) DEFAULT NULL,
PRIMARY KEY (`id_year`,`id`),
KEY `id_parent` (`id_year`,`id_parent`)
KEY `another_id` (`another_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_polish_ci;


Is there anyone, who can tell my why it needs 2 minutes to execute this query?

Answer

You can use INNER JOIN to update as following:t2.year is also not exist

UPDATE table1 t1
INNER JOIN table2 t2 ON t2.another_id = t1.another_id
    AND ((t2.id_parent= 2658 AND t2.year= 2016) OR (t2.id= 2658 AND t2.year= 2016))
SET t1.code_id = NULL, t1.code_group = NULL