Question

我找到了info on how to optimize MySQL queries，但大多数提示似乎建议避免MySQL不是为了构建（例如，计算，验证等）而我的查询是非常直接但是加入了很多桌子。

是否有一种方法可以加快许多INNER JOINS的简单查询？我如何修复下面的查询？

SELECT t_one.id FROM table_one t_one 
INNER JOIN entr_to_state st 
INNER JOIN entr_to_country ct 
INNER JOIN entr_to_domain dm 
INNER JOIN entr_timing t 
INNER JOIN entr_to_weather a2w 
INNER JOIN entr_to_imp_num a2i 
INNER JOIN entr_collection c 
WHERE t_one.type='normal' 
AND t_one.campaign_id = c.id 
AND t_one.status='running' 
AND c.status='running' 
AND (c.opt_schedule = 'continuous' OR (c.opt_schedule = 'schedulebydate' 
AND (c.start_date <= '2011-03-06 14:25:52' AND c.end_date >= '2011-03-06 14:25:52'))) 
AND t.entr_id = t_one.id AND ct.entr_id = t_one.id 
AND st.entr_id = t_one.id AND a2w.entr_id = t_one.id 
AND (t_one.targeted_gender = 'male' OR t_one.targeted_gender = 'both') 
AND t_one.targeted_min_age <= 23.1 AND t_one.targeted_max_age > 23.1 
AND (ct.abbreviation = 'US' OR ct.abbreviation = 'any') 
AND (st.abbreviation = 'CO' OR st.abbreviation = 'any') 
AND t.sun = 1 AND t.hour_14 = 1 
AND (a2w.weather_category_id = 1 OR a2w.weather_category_id = 0) 
AND t_one.targeted_min_temp <= 46 
AND t_one.targeted_max_temp > 46 GROUP BY t_one.id

Answer 1

索引所有相关字段，当然，我相信你已经

然后通过运行EXPLAIN SELECT...

找到哪些联接是最昂贵的联接

考虑将它们拆分为单独的查询，即缩小您要查找的记录，然后对那些记录而不是所有记录执行连接

即。

SELECT c.*, ....
FROM (SELECT x, y, z .... ) AS c

Answer 2

您需要EXPLAIN SELECT查询，检查查询的哪些部分未在索引中使用，然后尝试索引这些部分。如果可能，请将查询分解为更小的部分。

如果您真的无法以任何方式优化基础数据库或查询，则可以使用具有快速访问所需数据的平面表。然后，只需连接主查询，即可根据需要更新平面表。

如何使用大量INNER JOINS优化简单的MySQL查询

2 个答案: