From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Manuel Sugawara <masm(at)fciencias(dot)unam(dot)mx> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: left join query does not perform well |
Date: | 2002-08-25 15:12:23 |
Message-ID: | 5882.1030288343@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-sql |
Manuel Sugawara <masm(at)fciencias(dot)unam(dot)mx> writes:
> Ouch, 3117.48 msec vs. 1.15 msec is a huge difference. I need
> something else? or may be postgres optimizer can't cope with
> left/right joins?
I think the problem is you're constraining the join order into a very
inefficient one. See
http://www.ca.postgresql.org/users-lounge/docs/7.2/postgres/explicit-joins.html
But it's difficult to be sure, when you are showing us EXPLAIN output
that manifestly doesn't correspond to what you say the queries are.
For instance the nearest match to "epr_vord_grupo AS grupo" in the
explain output is "epr_ord_grupo g" ... I'm also wondering if any of
the tables used in the queries are really views, and if so what the
view definitions are.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2002-08-25 15:20:42 | Re: weird situation, BUG or I'm not doing it right |
Previous Message | Michael Paesold | 2002-08-25 12:49:21 | Re: weird situation, BUG or I'm not doing it right |