如何加快MySQL查询的速度

有人能帮我解答这个问题吗？工作正常，但时间太长了。我确定问题在于

tbu活动中的语句太多。有没有人有什么想法可以让这个查询更快

SELECT tb_posts.*
FROM   tb_posts
WHERE  EXISTS (SELECT c_id
               FROM   tb_users
               WHERE  tb_posts.c_uid = tb_users.c_id
                      AND tb_users.c_tokens > 0)
       AND NOT EXISTS (SELECT c_id
                       FROM   tb_activities
                       WHERE  tb_posts.c_url = tb_activities.c_url
                              AND tb_activities.c_category = 'gplus'
                              AND ( tb_activities.c_uid LIKE '%,6x1,%'
                                     OR tb_activities.c_uid LIKE '%,6x1'
                                     OR tb_activities.c_uid LIKE '6x1,%'
                                     OR tb_activities.c_uid = '6x1' ))
       AND NOT EXISTS (SELECT c_id
                       FROM   tb_blacklist
                       WHERE  tb_posts.c_url LIKE Concat('%', tb_blacklist.c_url
                                                  , '%')
                              AND tb_blacklist.c_times > 2
                              AND tb_blacklist.c_category = 'gplus')
       AND tb_posts.c_category = 'classic'
       AND tb_posts.c_status = 'run'
       AND tb_posts.c_nogplus = 0
GROUP  BY tb_posts.c_url
ORDER  BY tb_posts.c_cost DESC,
          tb_posts.c_date DESC
LIMIT  30  

我在这里做的是重写第一个
存在的地方…
。为什么？这就是答案。另一本有趣的书是。因此，您可以考虑重新编写查询。不幸的是，我现在没有更多的时间了。但是，主要性能提升通过添加（复合）索引，您将得到。将索引放在
JOIN
s所基于的列或
WHERE
子句中常用的列上

SELECT tb_posts.*
FROM   tb_posts
INNER JOIN tb_users ON tb_posts.c_uid = tb_users.c_id
WHERE  tb_users.c_tokens > 0
       AND NOT EXISTS (SELECT c_id
                       FROM   tb_activities
                       WHERE  tb_posts.c_url = tb_activities.c_url
                              AND tb_activities.c_category = 'gplus'
                              AND ( tb_activities.c_uid LIKE '%,6x1,%'
                                     OR tb_activities.c_uid LIKE '%,6x1'
                                     OR tb_activities.c_uid LIKE '6x1,%'
                                     OR tb_activities.c_uid = '6x1' ))
       AND NOT EXISTS (SELECT c_id
                       FROM   tb_blacklist
                       WHERE  tb_posts.c_url LIKE Concat('%', tb_blacklist.c_url, '%')
                              AND tb_blacklist.c_times > 2
                              AND tb_blacklist.c_category = 'gplus')
       AND tb_posts.c_category = 'classic'
       AND tb_posts.c_status = 'run'
       AND tb_posts.c_nogplus = 0
GROUP  BY tb_posts.c_url
ORDER  BY tb_posts.c_cost DESC,
          tb_posts.c_date DESC
LIMIT  30

此外，您可能还想了解一下，以便知道使用了（或未使用）哪些索引

作为旁注，Peter Kiss关于更改
WHERE
子句的顺序的提示是毫无意义的。查询优化器仍会处理此问题。
索引。。。我所说的一切