Re: correlated exists with join is slow.

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: <tivv00(at)gmail(dot)com>,"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: correlated exists with join is slow.
Date: 2012-06-18 14:58:24
Message-ID: 4FDEFBC002000025000485EB@gw.wicourts.gov
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Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> 9.2 will make this all better. These are exactly the type of case
> where you need the "parameterized path" stuff.

Yeah, with HEAD on my workstation all of these queries run in less
than 0.1 ms. On older versions, I'm seeing times like 100 ms to 150
ms for the slow cases. So in this case, parameterized paths allow
an improvement of more than three orders of magnitude. :-)

-Kevin

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