Re: Why is outer Join way quicker?

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От Stephan Szabo
Тема Re: Why is outer Join way quicker?
Дата
Msg-id 20020423095150.V14757-100000@megazone23.bigpanda.com
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Ответ на Why is outer Join way quicker?  (David Link <dlink@soundscan.com>)
Список pgsql-general
On Tue, 23 Apr 2002, David Link wrote:

> Hi.
>
> We have found that by using an Outer Join it speeds up this query
> considerably.
>
> Why is that?
>
> According to the explain plan the hold up has to do with a single nexted
> loop and a "Materilize"?  This makes no sense to me.  Can some one
> explain.
>
> Thanks. -David
>
> The difference between these two queries is the first uses an outer join
> between u and t, while the second (the slower) uses a straight forward
> join).

See:
http://www.postgresql.org/idocs/index.php?explicit-joins.html

You can probably use an inner join as well, you just need to use
the explicit join syntax.


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