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Re: partitioned table and ORDER BY indexed_fieldDESCLIMIT 1

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Luke Lonergan <LLonergan(at)greenplum(dot)com>
Cc: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, Anton <anton200(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: partitioned table and ORDER BY indexed_fieldDESCLIMIT 1
Date: 2007-10-28 09:13:53
Message-ID: 1193562833.4242.670.camel@ebony.site (view raw or flat)
Thread:
Lists: pgsql-performance
On Sat, 2007-10-27 at 17:48 -0400, Luke Lonergan wrote:
> Works great - plans no longer sort, but rather use indices as
> expected.  It's in use in Greenplum now.
> 
> It's a simple approach, should easily extend from gpdb to postgres.
> The patch is against gpdb so someone needs to 'port' it.

The part of the patch that didn't work for me was the nrels==1 bit. The
way it currently works there is only ever 0 or 2+ rels. The normal
Postgres code has to cater for the possibility of a non-empty parent
table, which seems to destroy the possibility of using this technique.

I agree its annoying and I have a way of doing this, but that's an 8.4
thing now.

Anybody think different?

-- 
  Simon Riggs
  2ndQuadrant  http://www.2ndQuadrant.com


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Subject: Append Cost in query planners
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Subject: Re: partitioned table and ORDER BY indexed_field DESC LIMIT 1

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