From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org, yazan suleiman <yazan.suleiman@gmail.com>
Subject: Re: postgres 9 query performance
Date: Sun, 30 Jan 2011 23:35:03 +0100
Message-ID: <201101302335.03863.andres@anarazel.de> (raw)
In-Reply-To: <21572.1296425895@sss.pgh.pa.us>
References: <AANLkTi=2peg+cbGLb1Tn2Bf+-rnq3YfOO_8JaOrJCP0X@mail.gmail.com>
<201101282219.29777.andres@anarazel.de>
<21572.1296425895@sss.pgh.pa.us>
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
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To: pgsql-performance@postgresql.org
Cc: andres@anarazel.de, tgl@sss.pgh.pa.us, yazan.suleiman@gmail.com
Subject: Re: postgres 9 query performance
In-Reply-To: <201101302335.03863.andres@anarazel.de>
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