From: | Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com> |
---|---|
To: | David Olbersen <dave(at)slickness(dot)org> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: Optimization via explicit JOINs |
Date: | 2001-03-10 02:18:47 |
Message-ID: | Pine.BSF.4.21.0103091817560.82859-100000@megazone23.bigpanda.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-sql |
Actually, just thought of something else. If you remove
the probably redundant p.song_id=s.song_id from the second
query (since the join ... using should do that) does it
change the explain output?
On Fri, 9 Mar 2001, David Olbersen wrote:
> On Fri, 9 Mar 2001, Stephan Szabo wrote:
>
> ->As a question, how many rows does
> ->select * from playlist p join songs s using (song_id) where
> ->p.waiting=TRUE;
> ->actually result in?
>
> Well it depends. Most of the time that playlist table is "empty" (no rows where
> waiting = TRUE), however users can (in a round about way) insert into that
> table, so that there could be anywhere from 10, to 2,342, to more.
>
> Why do you ask?
>
> (The reason those plans chose 14 was because, at the time, there were 14 rows in
> playlist)
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2001-03-10 03:03:10 | Re: Optimization via explicit JOINs |
Previous Message | Stephan Szabo | 2001-03-10 02:17:35 | Re: Optimization via explicit JOINs |