Thread: need help optimizing query
Hi all,
The situation: there are users in one table, and their access statistics
in the other. Now I want to find users whose last access time was more
than one month ago. As I've only had to write quite simple queries
involving no sub-selects so far, I'd like to ask your opinion if this
one scales at all or not.
SELECT u.login,last_use_time
FROM users u
JOIN (SELECT user_id, MAX(stop_time) AS last_use_time
FROM stats
GROUP BY user_id) AS s ON (u.id=s.user_id)
WHERE status='3' AND next_plan_id IS NULL
AND last_use_time < now() - interval '1 month'
ORDER BY last_use_time;
It seems to do the job, but how good is it in the long run? Any way I
could tweak it?
Thanks.
Here's one without a subquery, so may be master:
select u.login, s.stop_time
from users as a
inner join stats as s
on s.user_id = u.user_id
where status = '3'
and next_plan_id is null
and stop_time < now() - interval '1 month'
group by u.user_id, u.login, s.stop_time
order by s.stop_time
--
Sincerely yours,
Olexandr Melnyk <><
http://omelnyk.net/
select u.login, s.stop_time
from users as a
inner join stats as s
on s.user_id = u.user_id
where status = '3'
and next_plan_id is null
and stop_time < now() - interval '1 month'
group by u.user_id, u.login, s.stop_time
order by s.stop_time
On 2/2/08, rihad <rihad@mail.ru> wrote:
Hi all,
The situation: there are users in one table, and their access statistics
in the other. Now I want to find users whose last access time was more
than one month ago. As I've only had to write quite simple queries
involving no sub-selects so far, I'd like to ask your opinion if this
one scales at all or not.
SELECT u.login,last_use_time
FROM users u
JOIN (SELECT user_id, MAX(stop_time) AS last_use_time
FROM stats
GROUP BY user_id) AS s ON (u.id=s.user_id)
WHERE status='3' AND next_plan_id IS NULL
AND last_use_time < now() - interval '1 month'
ORDER BY last_use_time;
It seems to do the job, but how good is it in the long run? Any way I
could tweak it?
Thanks.
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--
Sincerely yours,
Olexandr Melnyk <><
http://omelnyk.net/