Re: - Slow Query
| От | Віталій Тимчишин |
|---|---|
| Тема | Re: - Slow Query |
| Дата | |
| Msg-id | 331e40660907030422p2375a09co827457c2dc7aff4c@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: - Slow Query (Mike Ivanov <mikei@activestate.com>) |
| Ответы |
Re: - Slow Query
|
| Список | pgsql-performance |
2009/7/1 Mike Ivanov <mikei@activestate.com>
This is not enough. You have to add this condition as well:
> LEFT outer JOIN ville ON ville.uid = bien.ref_ville
> LEFT outer JOIN freguesia_ville ON freguesia_ville.ref_ville =ville.uid
AND bien.ref_ville = freguesia_ville.ref_ville
In other words, when you link three tables by a common field, all three relationships should be explicitly expressed, otherwise you'll have this type of explosive row multiplication.
Why so? Is not changing "freguesia_ville.ref_ville =ville.uid" to "freguesia_ville.ref_ville =bien.uid" enough (to prevent cases when ville.uid is null as result of join)?
В списке pgsql-performance по дате отправления: