Re: Performance inside and outside view ( WAS Re: Select the max on a field )

"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote in message
news:7350(dot)1031842223(at)sss(dot)pgh(dot)pa(dot)us(dot)(dot)(dot)
> "Gaetano Mendola" <mendola(at)bigfoot(dot)com> writes:
> > Yes that's right it's help me,
> > but here the optimizer have some problems:
>
> What's the datatype of id_user, and why are you quoting the compared
> constant in some cases but not others? I don't think the difference
> has anything to do with the view here ...

id_user is an INTEGER type.

Well what about this two selects:

a) SELECT DISTINCT ON (id_user) *
FROM user_logs
WHERE id_user = 5430
ORDER BY id_user, id_user_log DESC;

b) CREATE VIEW last_user_logs AS
SELECT DISTINCT ON (id_user) *
FROM user_logs
ORDER BY id_user, id_user_log DESC;

SELECT *
FROM last_user_logs
WHERE id_user = 5430

I think that in the second case the filter is not pushed inside the view.

Ciao
Gaetano