Re: enforcing a join type

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@qwest.net] 
Sent: Wednesday, August 04, 2004 5:41 PM
To: Hicham G. Elmongui
Cc: pgsql-hackers@postgresql.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.