From: Tom Lane <tgl@sss.pgh.pa.us>
To: Dave Dutcher <dave@tridecap.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Left Join Performance vs Inner Join Performance
Date: Tue, 10 Jan 2006 23:38:20 -0500
Message-ID: <8321.1136954300@sss.pgh.pa.us> (raw)
In-Reply-To: <011f01c61653$96c509f0$8300a8c0@tridecap.com>
References: <011f01c61653$96c509f0$8300a8c0@tridecap.com>
"Dave Dutcher" <dave@tridecap.com> writes:
> I have an inner join query that runs fast, but I when I change to a left
> join the query runs 96 times slower.
This looks like an issue that is fixed in the latest set of releases,
namely that OUTER JOIN ON conditions that reference only the inner
side of the join weren't getting pushed down into indexquals. See
thread here:
http://archives.postgresql.org/pgsql-performance/2005-12/msg00134.php
and patches in this and the following messages:
http://archives.postgresql.org/pgsql-committers/2005-12/msg00105.php
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, dave@tridecap.com
Subject: Re: Left Join Performance vs Inner Join Performance
In-Reply-To: <8321.1136954300@sss.pgh.pa.us>
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