Re: postgres 9 query performance

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: pgsql-performance(at)postgresql(dot)org, yazan suleiman <yazan(dot)suleiman(at)gmail(dot)com>
Subject: Re: postgres 9 query performance
Date: 2011-01-30 22:18:15
Message-ID: 21572.1296425895@sss.pgh.pa.us
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Andres Freund <andres(at)anarazel(dot)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=1df57f63f3f60c684aa8918910ac410e9c780713

regards, tom lane

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