Faire face à des tables temporaires quand j'ai un contrôle sur db les variables

Question

Je ne contrôle pas sur des choses comme tmp_table_size et max_heap_table_size, et ainsi que nos tables se développent le temps pris par les requêtes nécessitant des tables temporaires est de plus en plus géométriquement.

Je me demande s'il y a un moyen d'éviter d'utiliser MySQL tables temporaires pour ces requêtes? Quelle serait la meilleure approche dans cette situation:

Voici un exemple du plus grand délinquant:

SELECT `skills`.`id`
FROM (`jobs_skills`)
JOIN `jobs` ON (`jobs`.`id` = `jobs_skills`.`job_id`)
JOIN `skills` ON (`skills`.`id` = `jobs_skills`.`skill_id`)
WHERE `jobs`.`job_visibility_id` = 1
AND `jobs`.`active` = 1
AND `skills`.`valid` = 1
AND `jobs_skills`.`skill_id` IN (96,101,103,108,121,2610,99,119,2607,102,104,112,113,122,1032,1488,2608,109,126,1438,2310,2318,2622,118,1046,1387,2609,100,116,123,2611,2612,2616,2618,114,127,1562,1587,1608,2276,2615,125,1070,1071,1161,1658,2613,2614,2617,105,110,111,120,1394,1435)
GROUP BY `jobs_skills`.`job_id`

pour lequel copying to temp table a pris 107 secondes, 99% du temps total de la requête.

en dépit des craintes de tl; dr syndrome, je propose. . .

PLUS DE DÉTAILS

Voici la déclaration de EXPLAIN pour la requête:

+----+-------------+-------------+--------+----------------------+--------------+---------+----------------------------------+--------+----------------------------------------------+
| id | select_type | table       | type   | possible_keys        | key          | key_len | ref                              | rows   | Extra                                        |
+----+-------------+-------------+--------+----------------------+--------------+---------+----------------------------------+--------+----------------------------------------------+
|  1 | SIMPLE      | jobs        | ref    | PRIMARY,active_index | active_index | 1       | const                            | 468958 | Using where; Using temporary; Using filesort |
|  1 | SIMPLE      | jobs_skills | ref    | PRIMARY              | PRIMARY      | 4       | 557574_prod.jobs.id              |      1 | Using where; Using index                     |
|  1 | SIMPLE      | skills      | eq_ref | PRIMARY              | PRIMARY      | 4       | 557574_prod.jobs_skills.skill_id |      1 | Using where                                  |
+----+-------------+-------------+--------+----------------------+--------------+---------+----------------------------------+--------+----------------------------------------------+

et voici les déclarations de CREATE TABLE pour les tableaux correspondants:

| jobs  | CREATE TABLE `jobs` (
  `id` int(10) unsigned NOT NULL auto_increment,
  `user_id` int(10) unsigned NOT NULL,
  `title` varchar(40) NOT NULL,
  `description` text NOT NULL,
  `address_id` int(10) unsigned NOT NULL,
  `proximity` smallint(3) unsigned NOT NULL default '15',
  `job_payrate_id` tinyint(1) unsigned NOT NULL default '1',
  `payrate` int(10) unsigned NOT NULL,
  `start_date` int(10) unsigned NOT NULL,
  `job_start_id` tinyint(1) unsigned NOT NULL default '1',
  `duration` tinyint(1) unsigned NOT NULL COMMENT 'Full-time, Part-time, Flexible',
  `posting_date` int(10) unsigned NOT NULL,
  `revision_date` int(10) unsigned NOT NULL,
  `expiration` int(10) unsigned NOT NULL,
  `active` tinyint(1) unsigned NOT NULL default '1',
  `team_size` tinyint(2) unsigned NOT NULL default '1',
  `job_type_id` tinyint(1) unsigned NOT NULL default '1',
  `job_shift_id` tinyint(1) unsigned NOT NULL default '1',
  `job_visibility_id` tinyint(1) unsigned NOT NULL default '1',
  `position_count` smallint(5) unsigned NOT NULL default '1',
  `impressions` int(10) unsigned NOT NULL default '0',
  `clicks` int(10) unsigned NOT NULL default '0',
  `employer_email` varchar(100) NOT NULL default '',
  `job_source_id` smallint(6) unsigned NOT NULL default '0',
  `job_password` varchar(50) NOT NULL default '',
  PRIMARY KEY  (`id`),
  KEY `active_index` (`active`),
  KEY `user_id_index` (`user_id`),
  KEY `address_id_index` (`address_id`),
  KEY `posting_date_index` USING BTREE (`posting_date`)
) ENGINE=InnoDB AUTO_INCREMENT=875013 DEFAULT CHARSET=utf8

-

| jobs_skills | CREATE TABLE `jobs_skills` (
  `job_id` int(10) unsigned NOT NULL,
  `skill_id` int(10) unsigned NOT NULL,
  `required` tinyint(1) unsigned NOT NULL,
  PRIMARY KEY  (`job_id`,`skill_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |

-

| skills | CREATE TABLE `skills` (
  `id` int(10) unsigned NOT NULL auto_increment,
  `parent_id` int(10) unsigned NOT NULL,
  `name` varchar(35) NOT NULL default '',
  `description` varchar(250) NOT NULL,
  `valid` tinyint(1) unsigned NOT NULL default '0',
  `is_category` tinyint(1) unsigned NOT NULL default '0',
  `last_edited` int(10) unsigned NOT NULL default '0',
  `impressions` int(10) unsigned NOT NULL default '0',
  `clicks` int(10) unsigned NOT NULL default '0',
  `jobs` int(10) unsigned NOT NULL default '0',
  PRIMARY KEY  (`id`),
  KEY `name` (`name`),
  KEY `parent` (`parent_id`)
) ENGINE=InnoDB AUTO_INCREMENT=2657 DEFAULT CHARSET=utf8 |

Comme je l'ai dit, ce n'est pas la seule question à ce problème, de sorte que tout conseil général serait très utile, bien que je ne baissera pas tout spécifique de conseil à cette requête.

Answer 1

Votre sous-requête originale:

SELECT `skills`.`id`
FROM (`jobs_skills`)
JOIN `jobs` ON (`jobs`.`id` = `jobs_skills`.`job_id`)
JOIN `skills` ON (`skills`.`id` = `jobs_skills`.`skill_id`)
WHERE `jobs`.`job_visibility_id` = 1
AND `jobs`.`active` = 1
AND `skills`.`valid` = 1
AND `jobs_skills`.`skill_id` IN (96,101,103,108,121,2610,99,119,2607,102,104,112,113,122,1032,1488,2608,109,126,1438,2310,2318,2622,118,1046,1387,2609,100,116,123,2611,2612,2616,2618,114,127,1562,1587,1608,2276,2615,125,1070,1071,1161,1658,2613,2614,2617,105,110,111,120,1394,1435)
GROUP BY `jobs_skills`.`job_id`

Vous devez rafactor la requête dans une telle manière que vous contrôlez et microgérer les tables temporaires en cours de création et de leur taille. En se basant uniquement sur la REJOIGNEZ, où et les clauses GROUP BY, vous devez mettre en œuvre les modifications suivantes:

emplois doit être indexé sur job_visibility_id, actif, id

nécessaire des sous-requêtes

(SELECT id job_id FROM jobs WHERE job_visibility_id=1 AND active=1 ORDER BY id)

compétences doit être indexé sur valide, id

nécessaire des sous-requêtes

(SELECT id skill_id FROM skills WHERE valid=1 ORDER BY id)

jobs_skills doit être indexé sur skill_id, job_id

nécessaire des sous-requêtes

(SELECT job_id FROM jobs_skills WHERE skill_id IN (96,101,103,108,121,2610,99,119,2607,102,104,112,113,122,1032,1488,2608,109,126,1438,2310,2318,2622,118,1046,1387,2609,100,116,123,2611,2612,2616,2618,114,127,1562,1587,1608,2276,2615,125,1070,1071,1161,1658,2613,2614,2617,105,110,111,120,1394,1435) ORDER BY skill_id,job_id)

SQL pour créer des index nécessaires

ALTER TABLE jobs ADD INDEX (job_visibility_id,active,id);
ALTER TABLE skills ADD INDEX (valid,id);
ALTER TABLE jobs_skills ADD INDEX (skill_id,job_id);

Maintenant combiner les sous-requêtes pour former VOLTRON

SELECT skill_id
FROM (SELECT JS.*
FROM (SELECT skill_id,job_id FROM jobs_skills WHERE skill_id IN (96,101,103,108,121,2610,99,119,2607,102,104,112,113,122,1032,1488,2608,109,126,1438,2310,2318,2622,118,1046,1387,2609,100,116,123,2611,2612,2616,2618,114,127,1562,1587,1608,2276,2615,125,1070,1071,1161,1658,2613,2614,2617,105,110,111,120,1394,1435) ORDER BY skill_id,job_id) JS
INNER JOIN
(SELECT id job_id FROM jobs WHERE job_visibility_id=1 AND active=1 ORDER BY id) J
USING (job_id) INNER JOIN
(SELECT id skill_id FROM skills WHERE valid=1 ORDER BY id) S USING (skill_id)
) A
GROUP BY job_id;

Lui donner un essai !!!

BTW si la syntaxe est incorrecte, je vais essayer de le régler !!!