0

I'm trying to do a very specific thing in WordPress: expire posts over 30 days old that have no "likes" (or negative "likes") based on someone else's plugin. That plugin stores individual likes/dislikes for each user/post in a separate table (+1/-1), which means that my selection criteria are complex, based on a SUM.

Doing the SELECT is easy, as it is a simple JOIN on post ID with a "HAVING" clause to detect the total likes value of more than zero. It looks like this (with all the table names simplified for readability):

SELECT posts.id, SUM( wti_like_post.value )
FROM posts
JOIN wti_like_post
ON posts.ID = wti_like_post.post_id
WHERE posts.post_date < DATE_SUB(NOW(), INTERVAL 30 DAY)
GROUP BY posts.ID
HAVING SUM( wti_like_post.value ) < 1

But I'm stuck on optimising the UPDATE query. The unoptimised version takes 2 minutes to run, which is unacceptable.

UPDATE posts
SET posts.post_status = 'trash'
WHERE posts.post_status = 'publish'
AND posts.post_type = 'post'
AND posts.post_date < DATE_SUB(NOW(), INTERVAL 30 DAY)
AND ID IN
(SELECT post_id FROM wti_like_posts
 GROUP BY post_id
 HAVING SUM( wti_like_post.value ) < 1 )

This is obviously because of my inability to create an UPDATE query with a join based on a SUM result - I simply don't know how to do that (believe me, I've tried!).

If anyone could optimise that UPDATE for me, I'd be terribly grateful. It'd also teach me how to do it properly, which would be neat!

Thanks in advance.

4

2 回答 2

0

好吧，这也取决于否。的帖子以及在子查询中，它将汇总被丢弃的帖子 ID 也应该在子查询中进行过滤，而不是您的更新查询试试这个

UPDATE posts
SET posts.post_status = 'trash'
WHERE ID IN
(
SELECT posts.id
FROM posts
INNER JOIN wti_like_post
ON (posts.ID = wti_like_post.post_id AND  posts.post_status = 'publish'
AND posts.post_type = 'post')
WHERE posts.post_date < DATE_SUB(NOW(), INTERVAL 30 DAY)
GROUP BY posts.ID
HAVING SUM( wti_like_post.value ) < 1    
 )
于 2013-08-03T14:53:41.573 回答
-1

好吧，也许听起来很愚蠢，但是您可以从选择中创建一个表，在其上放置一个索引，然后简单地使用标准 JOIN 来更新该新表。

我想即使你总是在运行中这样做，它应该比非索引版本更快。

编辑：这是代码，对不起，我没有检查它是否通过，但它至少应该让你知道我的意思。

CREATE TABLE joinHelper(
  id INT NOT NULL,
  PRIMARY KEY ( id )
);
INSERT INTO joinHelper(id)
SELECT post_id FROM wti_like_posts
GROUP BY post_id
HAVING SUM( wti_like_post.value ) < 1

UPDATE posts JOIN joinHelper ON (posts.ID = joinHelper.id)
SET posts.post_status = 'trash'
WHERE posts.post_status = 'publish'
AND posts.post_type = 'post'
AND posts.post_date < DATE_SUB(NOW(), INTERVAL 30 DAY)
于 2013-08-03T18:43:34.763 回答