Tom Lane wrote:
I think the problem was that he had
select ... from a, b full join c on ... where ...
where table b is big and you only need a few rows from it, so it really
needs to be joined last, but the above forced doing it first. It wasn't
clear to me why he wanted the full join
I see. I think I'm going to restructure my logic so I won't have to use
the outer join after all, but thanks for the pointers anyway.
Tom Lane wrote:
Ben <[EMAIL PROTECTED]> writes:
Hrm, as I understand that page, there's not much that can be done about
the join order for outer joins. At l
On Tue, 2005-09-13 at 13:28, Ben wrote:
> Hrm, as I understand that page, there's not much that can be done about
> the join order for outer joins. At least, not when there's on 3 tables
> and 1 outer join involved. Am I missing something?
You might be able to do some kind of thing like:
select
Scott Marlowe <[EMAIL PROTECTED]> writes:
> Tom, would that help the planner make better choices for this kind of
> query?
I think the problem was that he had
select ... from a, b full join c on ... where ...
where table b is big and you only need a few rows from it, so it really
needs t
Ben <[EMAIL PROTECTED]> writes:
> Hrm, as I understand that page, there's not much that can be done about
> the join order for outer joins. At least, not when there's on 3 tables
> and 1 outer join involved. Am I missing something?
Without knowing what you want the query to do, it's difficult to
Hrm, as I understand that page, there's not much that can be done about
the join order for outer joins. At least, not when there's on 3 tables
and 1 outer join involved. Am I missing something?
Tom Lane wrote:
Ben <[EMAIL PROTECTED]> writes:
Are full outer joins expected to perform much wo
Ben <[EMAIL PROTECTED]> writes:
> Are full outer joins expected to perform much worse than inner joins?
You're getting burnt by the outer join forcing a bad join order.
There's some related discussion here:
http://www.postgresql.org/docs/8.0/static/explicit-joins.html
reg
Are full outer joins expected to perform much worse than inner joins?
I'm seeing 2 orders of magnitude difference for an almost identical
query. (Well, as "identical" as you can get, comparing a query with an
outer join to one without.) This is on 8.0.3, recently analyzed. Here
are the explain
