help optimizing query - Mailing list pgsql-general

From rihad
Subject help optimizing query
Date
Msg-id 47A43395.1000805@mail.ru
Whole thread Raw
Responses Re: help optimizing query
List pgsql-general
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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