Question

我写了一个可以正常工作的查询。但是执行需要更多时间。我无法理解如何优化当前查询。

这里将有数千或数百万的数据。喜欢不喜欢每个用户每个喜欢/不喜欢插入一个新行。

我的查询：

  select i.id,i.category,i.url,i.upload_by,i.upload_date,
(select count(*) from `like_dislike` where `ulike`='1' and `imageid`=i.id) AS 'allLike',
(select count(*) from `like_dislike` where `ulike`='1' and `imageid`=i.id and i.category !='4' and FROM_UNIXTIME(performdate)>= NOW() - INTERVAL '1' DAY) AS 'daytotalLike',

(select count(*) from `like_dislike` where `ulike`='1' and `imageid`=i.id and i.category !='4'  and FROM_UNIXTIME(performdate)>= NOW() - INTERVAL '7' DAY) AS '7daytotalLike',
(select count(*) from `like_dislike` where `ulike`='1' and `imageid`=i.id and i.category !='4'  and FROM_UNIXTIME(performdate)>= NOW() - INTERVAL '30' DAY) AS '30daytotalLike',
(select count(*) from `like_dislike` where `ulike`='1' and `imageid`=i.id and i.category !='4'  and FROM_UNIXTIME(performdate)>= NOW() - INTERVAL '90' DAY) AS '90daytotalLike',
i.status from `image` as i, `like_dislike` as  likeDislike
WHERE i.status='approved' and i.id=likeDislike.imageid and FROM_UNIXTIME(likeDislike.performdate)>= NOW() - INTERVAL '90' DAY
    GROUP BY i.id ORDER BY '90daytotalLike' DESC Limit 50

sqlfiddle Demo

Answer 1

答案很简单：你试图在一个查询中做太多。据我所知，你想知道所有用户，哪50个用户在许多变量上得分最高。是的，对不起，有点不清楚你在这里想要实现的目标。

因此，摆脱所有子查询，并留下一个主要查询。类似的东西：

SELECT 
  count(*) as 90daytotalLike,
  image.id,
  image.category,
  image.url,
  image.upload_by,
  image.upload_date,
  image.status 
FROM 
  image, 
  like_dislike
WHERE 
  like_dislike.ulike = 1 AND
  image.category != 4  AND
  image.status = 'approved' AND 
  image.id = like_dislike.imageid AND 
  FROM_UNIXTIME(like_dislike.performdate) >= NOW() - INTERVAL '90' DAY
GROUP BY image.id 
ORDER BY '90daytotalLike' DESC Limit 50

如果您需要知道任何其他时期的数据，请运行单独的查询。

降低数据库负载的另一种方法是将您喜欢的总喜好存储在数据库中。它只是一个简单的计数器，没有任何花哨的东西，但是你总是可以安全地总结这些喜欢的东西。

您也可以使用期间计数器，只需在投票到期时更新每个计数器。

如何优化我当前的Mysql查询

1 个答案: