Question

我的网站遇到的问题非常慢，如下所示。这是Joomla 2.5。

# Query_time: 19.797091  Lock_time: 0.000561 Rows_sent: 12  Rows_examined: 4127
SET timestamp=1385467501;
SELECT a.fulltext, a.id, a.title, a.alias, a.title_alias, a.introtext, a.state, a.catid, a.created, a.created_by, a.created_by_alias,a.images, a.modified, a.modified_by,a.publish_up, a.publish_down, a.attribs, a.metadata, a.metakey, a.metadesc, a.access, a.hits, a.featured, LENGTH(a.fulltext) AS readmore,a.fulltext, a.id, a.title, a.alias, a.title_alias, a.introtext, a.state, a.catid, a.created, a.created_by, a.created_by_alias,a.images, a.modified, a.modified_by,a.publish_up, a.publish_down, a.attribs, a.metadata, a.metakey, a.metadesc, a.access, a.hits, a.featured, LENGTH(a.fulltext) AS readmore,c.title AS category_title, c.path AS category_route, c.access AS category_access, c.alias AS category_alias,CASE WHEN a.created_by_alias > ' ' THEN a.created_by_alias ELSE ua.name END AS author,ua.email AS author_email,contact.id as contactid,parent.title as parent_title, parent.id as parent_id, parent.path as parent_route, parent.alias as parent_alias,ROUND(v.rating_sum / v.rating_count, 0) AS rating, v.rating_count as rating_count,c.published, CASE WHEN badcats.id is null THEN c.published ELSE 0 END AS parents_published
FROM j25_content AS a
LEFT JOIN j25_content_frontpage AS fp ON fp.content_id = a.id
LEFT JOIN j25_categories AS c ON c.id = a.catid
LEFT JOIN j25_users AS ua ON ua.id = a.created_by
LEFT JOIN j25_users AS uam ON uam.id = a.modified_by
LEFT JOIN (
SELECT contact.user_id, MAX(contact.id) AS id, contact.language
FROM j25_contact_details AS contact
WHERE contact.published = 1
GROUP BY contact.user_id, contact.language) AS contact ON contact.user_id = a.created_by
LEFT JOIN j25_categories as parent ON parent.id = c.parent_id
LEFT JOIN j25_content_rating AS v ON a.id = v.content_id
LEFT OUTER JOIN (SELECT cat.id as id FROM j25_categories AS cat JOIN j25_categories AS parent ON cat.lft BETWEEN parent.lft AND parent.rgt WHERE parent.extension = 'com_content' AND parent.published != 1 GROUP BY cat.id ) AS badcats ON badcats.id = c.id
WHERE a.access IN (1,1) AND c.access IN (1,1) AND CASE WHEN badcats.id is null THEN a.state ELSE 0 END = 1 AND a.featured = 0 AND a.catid IN (181,89,173,174,49,128,124,175,129,133,121,176,135,180,177,178,179,90) AND (a.publish_up = '0000-00-00 00:00:00' OR a.publish_up <= '2013-11-26 12:04:24') AND (a.publish_down = '0000-00-00 00:00:00' OR a.publish_down >= '2013-11-26 12:04:24')
GROUP BY a.id, a.title, a.alias, a.title_alias, a.introtext, a.checked_out, a.checked_out_time, a.catid, a.created, a.created_by, a.created_by_alias, a.created, a.modified, a.modified_by, uam.name, a.publish_up, a.attribs, a.metadata, a.metakey, a.metadesc, a.access, a.hits, a.xreference, a.featured, a.fulltext, a.state, a.publish_down, badcats.id, c.title, c.path, c.access, c.alias, uam.id, ua.name, ua.email, contact.id, parent.title, parent.id, parent.path, parent.alias, v.rating_sum, v.rating_count, c.published, c.lft, a.ordering, parent.lft, fp.ordering, c.id, a.images, a.urls
ORDER BY a.created DESC LIMIT 0, 12;

我该怎么做才能加快速度？索引其中一些表会有帮助吗？谢谢。

Answer 1

绝对索引帮助查询。我认为你的二级查找参考表（类别，用户，内容评级等）中的每一个都应该有一个MINIMUM的索引，表示你们之间的连接条件。

table                 index on
j25_content           ( access, featured, catid, publish_up, publish_down, state, id, created_by, modified_by )
j25_content_frontpage ( content_id )
j25_categories        ( id, parent_id )
ANOTHER index...
j25_categories        ( extension, published, lft, rgt, id )
j25_users             ( id )
j25_contact_details   ( published, user_id, language, id )
j25_content_rating    ( content_id )

我已将这些索引设置为“覆盖”索引...这意味着它们应该通过将所有字段作为索引的一部分来帮助优化查询，这样就不必转到原始数据页查看所有作品是否有资格返回记录

首先尝试......

我要尝试的下一件事是MySQL有一个特殊的关键字“STRAIGHT_JOIN”告诉了引擎按您所声明的顺序运行查询。你似乎有一个很好的基础表作为主要表，您的查找作为辅助表。引擎可能正在尝试为你思考并使用一个较小的表来运行查询。

select STRAIGHT_JOIN  (rest of your query exactly as it is)

非常慢的MySql查询Joomla 2.5

1 个答案: