Question

我的MySQL查询代码如下所示，并且表中有大约数千条记录，现在SQL下执行大约5分钟甚至更多。我正在寻找优化它的方法，以便执行时间更短。谢谢！

SELECT `m`.`id`,
   `m`.`id`,
   `tr`.`name`,
   `m`.`m_date`,
   `t1`.`t_name` AS home,
   `t2`.`t_name` AS away,
   `m`.`score1`,
   `m`.`score2`,
   `cw1`.`tid` AS tid1,
   `cw2`.`tid` AS tid2,
   `o1`.`odds` AS odds1,
   `o2`.`odds` AS odds2,
   `m`.`m_time`
FROM `jos_bl_match` AS `m`
LEFT JOIN `jos_bl_matchday` AS `md` ON (`md`.`id` = `m`.`m_id`)
LEFT JOIN `jos_bl_seasons` AS `s` ON (`s`.`s_id` = `md`.`s_id`)
LEFT JOIN `jos_bl_tournament` AS `tr` ON (`tr`.`id` = `s`.`t_id`)
LEFT JOIN `jos_bl_teams` AS `t1` ON (`m`.`team1_id` = `t1`.`id`)
LEFT JOIN `jos_bl_teams` AS `t2` ON (`m`.`team2_id` = `t2`.`id`)
LEFT JOIN `jos_vuvuzelaodds_odds` AS `o1` ON (`o1`.`m_id` = `m`.`id`)
AND `o1`.`market_id` = 1
AND `o1`.`bookmaker_id` = 1
LEFT JOIN `jos_vuvuzelaodds_odds` AS `o2` ON (`o2`.`m_id` = `m`.`id`)
AND `o2`.`market_id` = 1
AND `o2`.`bookmaker_id` = 2
LEFT JOIN `jos_cwtags_tags` AS `cw1` ON (`cw1`.`item_id` = `o1`.`m_id`)
LEFT JOIN `jos_cwtags_tags` AS `cw2` ON (`cw2`.`item_id` = `o2`.`m_id`)
WHERE `m`.`published` = 1
AND `s`.`published` = '1'
AND `tr`.`published` = '1'
AND `s`.`s_id` = 869
AND `m`.`m_played` = '1'
AND `m`.`m_date` > 2013-01-01
AND `o1`.`odds` != ''
AND `o2`.`odds` != ''
AND `cw1`.`cat_id` = 19
AND `cw2`.`cat_id` = 21
ORDER BY `m`.`m_date`,
     `md`.`id`,
     `s`.`s_id`,
     `tr`.`id` DESC LIMIT 0, 15

Answer 1

“标准化，但不要过度标准化。”

您可能遗漏了一些复合索引......

jos_bl_match: INDEX(m_played, published, m_date)

列必须按此顺序排列。这将更快地开始过滤。

以下内容应加快他们的联接：

jos_vuvuzelaodds_odds: INDEX(market_id, bookmaker_id, m_id)
jos_cwtags_tags: INDEX(cat_id, item_id)

似乎最后两个索引可能（应该）是PRIMARY KEY。是吗？

LEFT JOINs中的一些（也许全部）也可能是INNER JOINs;你考虑过吗？

请提供EXPLAIN SELECT。

Answer 2

无法访问数据库，这有点难以辨别。这似乎是很多数据只能拉15条记录。您确定需要以这种方式提取数据吗？

可能是最好的路线：

如下所示优化您的数据库。
制作包含所需字段的所有游戏的平面数据库视图。静态表会快得多，但您需要使用触发器设置更新，这超出了本答案的范围，但过程类似
写入查询图。

您没有从您的选择中选择赛季表中的任何字段。我使用了jos_bl_matchday表中的字段。

这应该让你开始。您还可以在select语句中使用条件

(IF value = 1, table.field, null) as yadda

而不是一遍又一遍地连接一个表，但你必须进行实验。

CREATE VIEW allTheGames AS SELECT
`m`.`id` as id,
`md`.`s_id` as seasonId, 
  `tr`.`name` as name,
 `m`.`m_date` as m_date,
 `t1`.`t_name` AS home,
 `t2`.`t_name` AS away,
`m`.`score1` as score1,
 `m`.`score2` as score2,
 `cw1`.`tid` AS tid1,
 `cw2`.`tid` AS tid2,
 `o1`.`odds` AS odds1,
 `o2`.`odds` AS odds2,
 `m`.`m_time` as m_time 
          FROM `jos_bl_match` AS `m` 
          LEFT JOIN `jos_bl_matchday` AS `md` ON (`md`.`id` = `m`.`m_id`) 
          LEFT JOIN `jos_bl_tournament` AS `tr` ON (`tr`.`id` = `s`.`t_id`) 
          LEFT JOIN `jos_bl_teams` AS `t1` ON (`m`.`team1_id` = `t1`.`id`) 
          LEFT JOIN `jos_bl_teams` AS `t2` ON (`m`.`team2_id` = `t2`.`id`) 
          LEFT JOIN `jos_vuvuzelaodds_odds` AS `o1` ON (`o1`.`m_id` = `m`.`id`) AND `o1`.`market_id` = 1 AND `o1`.`bookmaker_id` = 1 
          LEFT JOIN `jos_vuvuzelaodds_odds` AS `o2` ON (`o2`.`m_id` = `m`.`id`) AND `o2`.`market_id` = 1 AND `o2`.`bookmaker_id` = 2 
          LEFT JOIN `jos_cwtags_tags` AS `cw1` ON (`cw1`.`item_id` = `o1`.`m_id`) 
          LEFT JOIN `jos_cwtags_tags` AS `cw2` ON (`cw2`.`item_id` = `o2`.`m_id`) 
          WHERE `m`.`published` = 1 AND `s`.`published` = '1' AND `tr`.`published` = '1' 
          AND `m`.`m_played` = '1' 
          AND `o1`.`odds1` != '' AND `o2`.`odds2` != ''

然后用以下方式查询：

select * from allTheGames 
  WHERE season_id = 869 AND m_date > 2013-01-01  AND tid1 = 19 AND tid2 = 21

优化步骤：

确切地了解您希望从此查询中获取哪些数据以及原因：这是一份自定义报告吗？一个网页？您是否需要同时拥有所有这些数据，或者让用户深入研究更有意义？查询运行的频率是多少？一分钟一次？一天一次？每张表中有多少条记录？您的观点应该反映这个＆＃34;游戏对象＆＃34;

您的数据库：

运行＆＃34;解释＆＃34;针对此查询http://dev.mysql.com/doc/refman/5.7/en/explain.html。
它将显示数据库正在执行的所有工作，查询执行计划以及它要查看的记录数。这通常很快发生：它实际上并不执行查询。
看看你是否可以将数据库放在SSD驱动器甚至RAM上

你的桌面结构：

确保您在搜索的所有字段上都有索引。有很多方法可以优化它。
使用＆＃34;解释＆＃34;确保MySQL能够使用索引。
如果jos_vuvuzelaodds_odds表中只有2个市场，请考虑制作2个字段。

祝你好运！

如何优化MySQL多表选择查询？

2 个答案: