mysql long time query - php

Question

I have a query on my PHP script it takes too long time!
When I run the query, server load time increase and server goes down!
Note: these fields are index: t1.submits_id,t4.submit_id,t3.userid,t1.user_id,owner_id,invited_id,agreed,t2.users_id,,t1.sent_timestamp
SELECT
t1.submits_id,t1.user_id,is_html,shared_from,type,contents,url,sent_timestamp,show_type,album_cached_info,
t2.users_id,name,t2.active,page_url,
t3.time,
t4.like_time
FROM iv6_submits as t1 LEFT JOIN iv6_likes as t4 ON (t1.submits_id = t4.submit_id AND t4.user_id=1)
,iv6_users as t2 LEFT JOIN iv6_onlineusers as t3 ON (t2.users_id=t3.userid)
WHERE
t1.submits_id<19000 AND
(t1.user_id=1 OR t1.user_id in
(select IF(owner_id=1,invited_id,owner_id) as id
from iv6_add_lists
where ((owner_id=1 or invited_id=1) AND agreed=1) OR (owner_id=1 AND agreed=2)))
AND t2.users_id=t1.user_id
ORDER BY t1.sent_timestamp DESC LIMIT 10

Answer 1

I'd start by writing the query as:
SELECT t1.submits_id,
t1.user_id,
is_html, /* I'd append all table aliases here */
shared_from,
type,
contents,
url,
sent_timestamp,
show_type,
album_cached_info,
t2.users_id,
name,
t2.active,page_url,
t3.time,
t4.like_time
FROM iv6_submits as t1
JOIN iv6_users as t2
ON t2.users_id=t1.user_id
LEFT JOIN iv6_likes as t4
ON t4.submit_id = t1.submits_id
AND t4.user_id=1
LEFT JOIN iv6_onlineusers as t3
ON t3.userid = t2.users_id
WHERE t1.submits_id<19000
AND (
t1.user_id=1
OR t1.user_id IN (
SELECT IF(owner_id=1,invited_id, owner_id) as id
FROM iv6_add_lists
WHERE ((owner_id=1 OR invited_id=1) AND agreed=1)
OR (owner_id=1 AND agreed=2))
)
ORDER BY t1.sent_timestamp DESC
LIMIT 10
From this and your explain i'd guess that t1.submits_id< 19000 reduces your result set the most. So I'd then try:
...
FROM iv6_submits as t1 USE INDEX (submits_id)
...
Your subquery is also v. strange, i'd rewrite it as something like:
SELECT invited_id
FROM iv6_add_lists
WHERE owner_id = 1
AND agreed BETWEEN 1 AND 2
UNION ALL
SELECT owner_id
FROM iv6_add_lists
WHERE invited_id = 1
AND agreed = 1
AND owner_id != 1
And see if that helps as well, you can hint an index for each FROM. A composite index on (owner_id, agreed, invited_id) and (invited_id, agreed, owner_id) should cover both queries respectively.
You also could write this as
SELECT 1
UNION
SELECT DISTINCT invited_id
FROM iv6_add_lists
WHERE owner_id = 1
AND agreed BETWEEN 1 AND 2
UNION
SELECT DISTINCT owner_id
FROM iv6_add_lists
WHERE owner_id != 1
AND agreed = 1
AND invited_id = 1
And JOIN it to your t1 instead of the AND (t1.user_id=1 OR ...)
UPDATE
SELECT t1.submits_id,
t1.user_id,
is_html, /* I'd append all table aliases here */
shared_from,
type,
contents,
url,
sent_timestamp,
show_type,
album_cached_info,
t2.users_id,
name,
t2.active,page_url,
t3.time,
t4.like_time
FROM iv6_submits as t1
JOIN iv6_users as t2
ON t2.users_id=t1.user_id
JOIN (
SELECT 1 user_id
UNION
SELECT DISTINCT invited_id
FROM iv6_add_lists
WHERE owner_id = 1
AND agreed BETWEEN 1 AND 2
UNION
SELECT DISTINCT owner_id
FROM iv6_add_lists
WHERE owner_id != 1
AND agreed = 1
AND invited_id = 1
) t5
ON t1.user_id = t5.user_id
LEFT JOIN iv6_likes as t4
ON t4.submit_id = t1.submits_id
AND t4.user_id=1
LEFT JOIN iv6_onlineusers as t3
ON t3.userid = t2.users_id
WHERE t1.submits_id<19000
ORDER BY t1.sent_timestamp DESC
LIMIT 10

Answer 2

I suggest you split the query to see where the resources are being consumed.
Execute the subquery in the WHERE section and see if it runs fast
Remove the left joins and then add one by one to see where it all goes down.
Remove all the "WHERE" conditions and add one by one.
Try to run the query without the "ORDER BY" statement.
You did not referred t4.user_id as being indexed, it may be important.
Table iv6_add_lists also should have all the fields present in WHERE statement indexed.
Also suggest you to make an INNER JOIN between t1 and t2:
FROM (iv6_submits as t1
LEFT JOIN iv6_likes as t4 ON (t1.submits_id = t4.submit_id AND t4.user_id=1))
INNER JOIN
(iv6_users as t2
LEFT JOIN iv6_onlineusers as t3 ON (t2.users_id=t3.userid))
ON t2.users_id=t1.user_id
Then ou can remove
AND t2.users_id=t1.user_id
from the WHERE statement.

Answer 3

Try This.
SELECT
t1.submits_id,t1.user_id,is_html,shared_from,type,contents,url,sent_timestamp,show_type,album_cached_info,
t2.users_id,name,t2.active,page_url,
t3.time,
t4.like_time
FROM
iv6_submits as t1
LEFT JOIN iv6_users as t2 ON t2.users_id = t1.user_id
LEFT JOIN iv6_likes as t4 ON t1.submits_id = t4.submit_id AND t4.user_id = 1
LEFT JOIN iv6_onlineusers as t3 ON t2.users_id = t3.userid
WHERE
t1.submits_id < 19000
AND
(t1.user_id = 1 OR t1.user_id in
(
select IF(owner_id=1,invited_id,owner_id) as id from iv6_add_lists where (invited_id=1 AND agreed=1) OR ( owner_id=1 AND agreed IN (1,2) )
)
)
ORDER BY t1.sent_timestamp DESC LIMIT 1