MySQL Forums
Forum List  »  Performance

Re: Long execution time despite LIMIT 3
Posted by: Joachim Berger
Date: June 21, 2011 02:06AM

It somehow seems I might be getting there:


I could rewrite the SELECT as follows:

(SELECT m.*, m.flags + 0 flags
FROM messages_test m
WHERE (m.thread = 817549.001266066) AND (id_user_s = 817549) AND (del_s = 0))

UNION

(SELECT m.*, m.flags + 0 flags
FROM messages_test m
WHERE (m.thread = 817549.001266066) AND (id_user_r = 817549) AND (del_r = 0))

order by id desc
LIMIT 3;


and have indexes like:
test1 (thread,id_user_r,del_r)
test2 (thread,id_user_s,del_s)


What do you think?

Options: ReplyQuote


Subject
Views
Written By
Posted
Re: Long execution time despite LIMIT 3
757
June 21, 2011 02:06AM


Sorry, you can't reply to this topic. It has been closed.

Content reproduced on this site is the property of the respective copyright holders. It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.