From: | "Hicham G(dot) Elmongui" <elmongui(at)cs(dot)purdue(dot)edu> |
---|---|
To: | <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: enforcing a join type |
Date: | 2004-08-04 23:26:05 |
Message-ID: | 200408042326.i74NQ6Cm008563@newman.cs.purdue.edu |
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Lists: | pgsql-general pgsql-hackers |
I didn't mean about doing this from a front end. I want to disable
nested_loop and hash_join from the backend.
I tried to set the variables (enable_nestloop and enable_hashjoin) in
costsize.c, but this didn't do it.
Thanks,
--h
-----Original Message-----
From: Scott Marlowe [mailto:smarlowe(at)qwest(dot)net]
Sent: Wednesday, August 04, 2004 5:41 PM
To: Hicham G. Elmongui
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: [HACKERS] enforcing a join type
On Wed, 2004-08-04 at 14:53, Hicham G. Elmongui wrote:
> Hi,
> If I want the planner/optimizer to always choose merge join when it needs
to
> join relations. How can I do it ?
>From my past experience, I'd guess what you're really trying to do is
STOP the planner from choosing a nested_loop join, in which case it's
quite easy:
set enable_nestloop = off;
select * from ...
Of course, you could apply the same basic trick to all other join
methods, and postgresql would then favor using the merge join.
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