Message-ID: <4E75CB6D.9000302@ringerc.id.au>
Date: Sun, 18 Sep 2011 18:43:57 +0800
From: Craig Ringer <ringerc@ringerc.id.au>
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To: Melaka Gunasekara <donmelaka@gmail.com>
CC: Raghavendra <raghavendra.rao@enterprisedb.com>, pgsql-admin@postgresql.org
Subject: Re: How to change query planner configuration paramerters
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On 18/09/2011 5:51 PM, Melaka Gunasekara wrote:
> Merge Full Join (cost=10000000074.40..10000000093.69 rows=1159 width=286)

> Can you suggest why the merge join is being suggested when I have 
> turned it off ?
>

AFAIK SETting a join type to "off" really just increases the cost 
estimate so high that the planner will avoid using it where it has any 
alternative. In this case, it doesn't seem to think it has any other way 
to execute the query, or it thinks that any other way will be so 
incredibly, insanely slow that the merge join is still better.

--
Craig Ringer