I have the following query which joins 5 related tables to get the desired result set of 10 rows, I did my best to solve the issue by adding indexes and re-writing the query in many different ways but I ended up either unexpected result or a very slow query.
HERE IS THE QUERY
SELECT
a.*,
c.id as category_id,
c.title as catname,
CONCAT(u.fname, ' ', u.lname) as username,
DATE_FORMAT(a.created, '%W %M %d, %Y - %T') as long_date,
DATE_FORMAT(a.created, '%d/%m/%Y - %T') as short_date,
(SELECT
COUNT(article_id)
FROM
comment
WHERE
article_id = a.id) as totalcomments,
YEAR(a.created) as year,
MONTH(a.created) as month,
DAY(a.created) as day
FROM
article as a
INNER JOIN
article_related_categories rc ON a.id = rc.article_id
LEFT JOIN
category as c ON c.id = rc.category_id
LEFT JOIN
user as u ON u.id = a.user_id
WHERE
rc.category_id = 1
AND a.created <= NOW()
AND (a.expire = '0000-00-00 00:00:00'
OR a.expire >= NOW())
AND a.published IS NOT NULL
ORDER BY a.created DESC
LIMIT 0 , 10
Click Here to see the explain screenshot
Currently there are over 13,000 rows in the article table and a rapid growth is expected.
The trouble is, this query can take a significant amount of time to execute and it takes about 3-4 seconds. I suspect that the INNER JION causes most of the issue, but I thought I would ask here if anyone had any ideas for improving the performance of this query.