| From: | Alexander Staubo <alex(at)purefiction(dot)net> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | PgSQL General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Slow left outer join |
| Date: | 2006-11-27 09:34:21 |
| Message-ID: | E42CBF48-B44F-48C4-8746-1BD10F359E39@purefiction.net |
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| Thread: | |
| Lists: | pgsql-general |
On Nov 27, 2006, at 02:45 , Tom Lane wrote:
> Alexander Staubo <alex(at)purefiction(dot)net> writes:
>> select comments.*, users.*
>> from comments
>> left outer join users on
>> users.id = comments.creator_id
>> inner join events_comments on
>> comments.id = events_comments.comment_id
>> and events_comments.event_id = 9244
>
>> The outer join seems unnecessarily slow.
>
> Try flipping the order of the two joins. PG 8.2 will be smart
> enough to
> do that for itself, but no existing release understands when it's safe
> to rearrange outer-join order.
That fixes it. Thanks.
Alexander.
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