Re: Pushing LIMIT into sub-queries of a UNION ALL?

From: Robert Klemme <shortcutter(at)googlemail(dot)com>
To: Dave Johansen <davejohansen(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Pushing LIMIT into sub-queries of a UNION ALL?
Date: 2011-05-22 17:34:23
Message-ID: BANLkTi=-dhJuyMLQU6SyS1YEa0co_3Bjxw@mail.gmail.com
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Dave,

how often do you want to repeat that posting? What about instead
replying to the answers you got so far?

Cheers

robert

On Tue, May 17, 2011 at 5:31 PM, Dave Johansen <davejohansen(at)gmail(dot)com> wrote:
> I am using Postgres 8.3 and I have an issue very closely related to the one
> described here:
> http://archives.postgresql.org/pgsql-general/2005-06/msg00488.php
>
> Basically, I have a VIEW which is a UNION ALL of two tables but when I do a
> select on the view using a LIMIT, it scans the entire tables and takes
> significantly longer than writing out the query with the LIMITs in the
> sub-queries themselves. Is there a solution to get the view to perform like
> the sub-query version?
>
> Thanks,
> Dave

--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/

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