Date: Wed, 22 Jan 2003 16:52:29 -0800 (PST)
From: Stephan Szabo <sszabo@megazone23.bigpanda.com>
To: Tomasz Myrta <jasiek@klaster.net>
Cc: <pgsql-sql@postgresql.org>
Subject: Re: To use a VIEW or not to use a View.....
In-Reply-To: <3E2F130B.4030002@klaster.net>
Message-ID: <20030122164520.O4204-100000@megazone23.bigpanda.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Wed, 22 Jan 2003, Tomasz Myrta wrote:

> Stephan Szabo wrote:
>
> >That's not the same join for optimization purposes
> >since postgresql treats explicit join syntax as a
> >constraint on the ordering of joins.
> >
> >The same join would be something like:
> >
> >przystanki p1 join miasta m1 using (id_miasta)
> >join (przystanki p2 join miasta m2 using (id_miasta))
> > using (id_przystanku)
> >
> >minus the fact I think you'd need some explicit naming in
> >there.
>
> You are right.
>
> The result of your query is:
> explain select * from
> przystanki p1 join miasta m1 using (id_miasta)
> join (przystanki p2 join miasta m2 using (id_miasta))
>  using (id_przystanku)
> where id_przystanku=1230
>
> Hash Join  (cost=13.00..30.10 rows=1 width=128)
>   ->  Hash Join  (cost=6.74..21.02 rows=374 width=64)
>         ->  Seq Scan on przystanki p2  (cost=0.00..7.74 rows=374 width=41)
>         ->  Hash  (cost=5.99..5.99 rows=299 width=23)
>               ->  Seq Scan on miasta m2  (cost=0.00..5.99 rows=299 width=23)
>   ->  Hash  (cost=6.26..6.26 rows=1 width=64)
>         ->  Nested Loop  (cost=0.00..6.26 rows=1 width=64)
>               ->  Index Scan using przystanki_pkey on przystanki p1  (cost=0.00..3.14 rows=1 width=41)
>               ->  Index Scan using miasta_pkey on miasta m1  (cost=0.00..3.10 rows=1 width=23)
>
> Anyway - is it possible to expose table "przystanki alias p2" to get valid result?

I think it's possible that the work Tom mentioned in current CVS may
make these cases work the way you want.  I don't have access to my
test machine to try it right now however.

> Stephan - I have some problems with mail relay to you.
> Does my mail server have any open-relay problem, or something like this (213.25.37.66) ?

Doesn't seem to be a simple open relay (but I didn't try anything
complicated).  It acted a little wierd about email addresses in
reacting to my telnet, but I think it was acting correctly as far as
standards are concerned.