Re: How to change query planner configuration paramerters - Mailing list pgsql-admin

From Craig Ringer
Subject Re: How to change query planner configuration paramerters
Date
Msg-id 4E75CB6D.9000302@ringerc.id.au
Whole thread Raw
In response to Re: How to change query planner configuration paramerters  (Melaka Gunasekara <donmelaka@gmail.com>)
Responses Re: How to change query planner configuration paramerters  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-admin
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

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