Question

I’m trying to run the sql query below but I’m getting a 505 error after some long time wait. The wp_posts table holds much more than 50,000 rows…the purpose being to remove duplicates posts which are about 50,000 rows

DELETE bad_rows.*
FROM wp_posts AS bad_rows
INNER JOIN 
(
     SELECT post_title, MIN(id) as min_id
     FROM wp_posts
     GROUP BY post_title
     HAVING count(*) > 1
) AS good_rows 
ON good_rows.post_title = bad_rows.post_title
AND good_rows.min_id <> bad_rows.id;

Any idea on how to have this optmized and run ?

Answer 1

Don’t think you need to use a sub-query. This will select all pairs of posts with the same titles.

SELECT a.id, b.id
FROM wp_posts a
LEFT JOIN wp_posts b 
ON a.post_title = b.post_title
WHERE a.id > b.id

If you want to keep the oldest post, delete all posts with id a.id. If you want to keep the newest post, delete all posts with id b.id.

---

So, to keep the oldest post:

DELETE FROM wp_posts a
LEFT JOIN wp_posts b 
ON a.post_title = b.post_title
WHERE a.id > b.id

To keep the newest post:

DELETE FROM wp_posts a
LEFT JOIN wp_posts b 
ON a.post_title = b.post_title
WHERE a.id < b.id