From: Matteo Beccati <php@beccati.com>
To: Simon Riggs <simon@2ndquadrant.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: ORDER BY and LIMIT not propagated on inherited
Date: Fri, 02 Sep 2005 20:33:51 +0200
Message-ID: <43189B0F.2000904@beccati.com> (raw)
In-Reply-To: <1125683697.3956.310.camel@localhost.localdomain>
References: <43182789.4070307@beccati.com>
<1125683697.3956.310.camel@localhost.localdomain>
Simon Riggs wrote:
> Returning to Matteo's original query, what we are saying is that the new
> optimization for MIN/MAX queries doesn't work with inherited tables.
>
> It could do, by running optimize_minmax_aggregates() for each query that
> gets planned to see if a better plan exists for each child table.
>
> I think that's a TODO item.
Great. Of course I'm using ORDER BY ... LIMIT as a workaround to get the
index scan on pre-8.1, and because I'm used to it insted of the
previously not optimized MIN/MAX aggregates.
> Optimizing ORDER BY and LIMIT down looks like it would be harder to do
> in the general case, even if Matteo's simple transform looks good. I'm
> not sure it's a very common query type though...
If I can find some time, I'll try to write some hacks... I just need to
find out where to start ;)
Best regards
--
Matteo Beccati
http://phpadsnew.com/http://phppgads.com/
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To: pgsql-performance@postgresql.org
Cc: php@beccati.com, simon@2ndquadrant.com
Subject: Re: ORDER BY and LIMIT not propagated on inherited
In-Reply-To: <43189B0F.2000904@beccati.com>
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