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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-performance@postgresql.org, yazan suleiman <yazan.suleiman@gmail.com>
Subject: Re: postgres 9 query performance
Date: Sun, 30 Jan 2011 17:18:15 -0500
Message-ID: <21572.1296425895@sss.pgh.pa.us> (raw)
In-Reply-To: <201101282219.29777.andres@anarazel.de>
References: <AANLkTi=2peg+cbGLb1Tn2Bf+-rnq3YfOO_8JaOrJCP0X@mail.gmail.com>
	<201101282219.29777.andres@anarazel.de>

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.  Fixed now:
http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=1df57f63f3f60c684aa8918910ac410e9c7...

			regards, tom lane

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