I am using this query:
SELECT district, id
FROM adverts ls
GROUP BY district, id
HAVING (
SELECT count( * )
FROM adverts
WHERE district = ls.district
AND id > ls.id
) <5
ORDER BY district, id DESC ;
LIMIT 0 , 30
It tooks about 35 seconds. Here is the explanation:
id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY ls range NULL i_id 5 NULL 16166 Using index for group-by; Using temporary; Using f...
2 DEPENDENT SUBQUERY ilan_genel ref PRIMARY,i_id,i_ozellik_id,i_tip_fiyat,i_tip_id,i_d... i_durum_id 2 func 25 Using where; Using index
Is there a way to make it faster ?
try this:
SELECT district, id, COUNT(b.district)
FROM adverts a INNER JOIN adverts b
ON a.district = b.district
WHERE b.id > a.id
GROUP BY district, id
HAVING COUNT(b.district) < 5
ORDER BY district, id DESC
by definition, Joins
are faster than subqueries
.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.