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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: postgres 9 query performance
Date: Sun, 30 Jan 2011 23:35:03 +0100
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Cc: pgsql-performance@postgresql.org,
 yazan suleiman <yazan.suleiman@gmail.com>
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On Sunday 30 January 2011 23:18:15 Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > What happens if you change the
> > 
> >     left join event.origin on event.id = origin.eventid
> > 
> > into
> > 
> >     join event.origin on event.id = origin.eventid
> > 
> > ?
> > 
> > The EXISTS() requires that origin is not null anyway. (Not sure why the
> > planner doesn't recognize that though).
> 
> Sloppy thinking in reduce_outer_joins() is why. 
Wow. Nice one, thanks.

Andres