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我对MySQL相当陌生，并且一直在研究以下查询以从wordpress users/usermeta表中提取值列表。查询工作除了表现是可怕的，我不知道如何改进它。优化/ MySQL查询
查询需要12+秒才能完成，只有400个左右的用户，如果添加更多的话，这将成为一个巨大的问题。
我注意到MySQL报告没有唯一的列，但我不知道如何解决这个问题，因为用户ID已经是结果的一部分了。
这是默认查询，完整查询使用纬度/长度值添加额外计算来确定邮政编码搜索的距离，但这似乎不会增加太多额外时间。
我挣扎的主要部分是值被保存为meta_key和meta_value与关联的user_id作为外键的事实。
SELECT DISTINCT
wp_users.ID,
wp_users.user_email,
city_latitude.meta_value as cityLat,
city_longitude.meta_value as cityLong,
service_name.meta_value as service_name,
service_address.meta_value as service_address,
service_category.meta_value as service_category,
service_level.meta_value as service_level,
service_info.meta_value as service_info,
service_area.meta_value as service_area,
service_active.meta_value as service_active,
service_keyword.meta_value as service_keyword
FROM
wp_usermeta AS city_latitude
LEFT JOIN wp_usermeta as city_longitude ON city_latitude.user_id = city_longitude.user_id
LEFT JOIN wp_usermeta as service_name ON service_name.user_id = city_longitude.user_id
LEFT JOIN wp_usermeta as service_category ON service_category.user_id = city_longitude.user_id
LEFT JOIN wp_usermeta as service_address ON service_address.user_id = city_longitude.user_id
LEFT JOIN wp_usermeta as service_level ON service_level.user_id = city_longitude.user_id
LEFT JOIN wp_usermeta as service_info ON service_info.user_id = city_longitude.user_id
LEFT JOIN wp_usermeta as service_area ON service_area.user_id = city_longitude.user_id
LEFT JOIN wp_usermeta as service_active ON service_active.user_id = city_longitude.user_id
LEFT JOIN wp_usermeta as service_keyword ON service_keyword.user_id = city_longitude.user_id
INNER JOIN wp_users ON wp_users.ID = city_latitude.user_id
WHERE city_latitude.meta_key = 'service_lat'
AND city_longitude.meta_key = 'service_long'
AND (service_name.meta_key = 'service_name' AND service_name.meta_value != 'Anonymous')
AND (service_category.meta_key = 'service_category' ".$query_category.")
AND service_address.meta_key = 'service_address'
AND (service_level.meta_key = 'wp_user_level' AND service_level.meta_value = 0)
AND service_info.meta_key = 'service_additional'
AND service_area.meta_key = 'service_area'
AND service_keyword.meta_key = 'service_keywords'
AND (service_active.meta_key = 'active' AND service_active.meta_value = 1)
ORDER BY service_name ASC
我已经更新了查询，其中一些建议已经有了很大的改变。我仍然认为查询本身可以通过减少连接数量等来改善，如果有人有任何更多的想法我很乐意听到他们。
这是查询，其中包括用距离搜索的更改和附加部分。
SELECT DISTINCT
wp_users.ID,
wp_users.user_email,
city_latitude.meta_value as cityLat,
city_longitude.meta_value as cityLong,
service_name.meta_value as service_name,
service_address.meta_value as service_address,
service_category.meta_value as service_category,
service_level.meta_value as service_level,
service_info.meta_value as service_info,
service_area.meta_value as service_area,
service_active.meta_value as service_active,
service_keyword.meta_value as service_keyword,
((ACOS(SIN($userLat * PI()/180) * SIN(city_latitude.meta_value * PI()/180) + COS($userLat * PI()/180) * COS(city_latitude.meta_value * PI()/180) * COS(($userLng - city_longitude.meta_value) * PI()/180)) * 180/PI()) * 60 * 1.1515) AS distance
FROM
wp_usermeta AS usermeta
LEFT JOIN wp_usermeta as city_longitude ON city_longitude.user_id = usermeta.user_id AND city_longitude.meta_key = 'service_long'
LEFT JOIN wp_usermeta as city_latitude ON city_latitude.user_id = usermeta.user_id AND city_latitude.meta_key = 'service_lat'
LEFT JOIN wp_usermeta as service_name ON service_name.user_id = usermeta.user_id AND service_name.meta_key = 'service_name'
LEFT JOIN wp_usermeta as service_category ON service_category.user_id = usermeta.user_id AND service_category.meta_key = 'service_category'
LEFT JOIN wp_usermeta as service_address ON service_address.user_id = usermeta.user_id AND service_address.meta_key = 'service_address'
LEFT JOIN wp_usermeta as service_level ON service_level.user_id = usermeta.user_id AND service_level.meta_key = 'wp_user_level'
LEFT JOIN wp_usermeta as service_info ON service_info.user_id = usermeta.user_id AND service_info.meta_key = 'service_additional'
LEFT JOIN wp_usermeta as service_area ON service_area.user_id = usermeta.user_id AND service_area.meta_key = 'service_area'
LEFT JOIN wp_usermeta as service_active ON service_active.user_id = usermeta.user_id AND service_active.meta_key = 'active'
LEFT JOIN wp_usermeta as service_keyword ON service_keyword.user_id = usermeta.user_id AND service_keyword.meta_key = 'service_keywords'
INNER JOIN wp_users ON wp_users.ID = usermeta.user_id
WHERE (service_name.meta_value != '' AND service_name.meta_value != 'Anonymous') AND service_level.meta_value = 0 AND service_active.meta_value = 1
HAVING distance < $search_distance
ORDER BY distance ASC
删除这句话是什么EXPLAIN给？请告诉我们这个。有没有需要全表扫描的连接？而且您需要将WHERE条件添加到适当的ON部分！ – Seb
@P苍鹭 - 你可以从表格中创建一些样本日期。没有必要加入wp_usermeta超过1次。如果您通过http：// sqlfiddle发送一些数据，我会为您提供查询。com/ –
@Bernd Buffen - 那真是太好了，谢谢。我已经在[link]（http://sqlfiddle.com/#99/af672a）设置了一些数据，我以前从来没有使用过它，所以它很好。 –