Re: Why is outer Join way quicker?

From: Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com>
To: David Link <dlink(at)soundscan(dot)com>
Cc: "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org>
Subject: Re: Why is outer Join way quicker?
Date: 2002-04-23 16:57:07
Message-ID: 20020423095150.V14757-100000@megazone23.bigpanda.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: 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.

In response to

Responses

Browse pgsql-general by date

  From Date Subject
Next Message Neil Conway 2002-04-23 17:05:33 Re: Suggestions for Large DB Dump/Reload
Previous Message Ian Harding 2002-04-23 16:32:40 Re: Connections per second?