From: Scott Carey <scott@richrelevance.com>
To: David Kerr <dmk@mr-paradox.net>
To: Chris <dmagick@gmail.com>
Cc: Craig Ringer <craig@postnewspapers.com.au>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Optimizer + bind variables
Date: Wed, 4 Nov 2009 21:47:01 -0800
Message-ID: <C717A6D5.15F03%scott@richrelevance.com> (raw)
In-Reply-To: <20091104001825.GA79191@mr-paradox.net>
On 11/3/09 4:18 PM, "David Kerr" <dmk@mr-paradox.net> wrote:
> On Wed, Nov 04, 2009 at 11:02:22AM +1100, Chris wrote:
> - David Kerr wrote:
> - >On Wed, Nov 04, 2009 at 07:43:16AM +0800, Craig Ringer wrote:
> - >- David Kerr wrote:
> - No.
> -
> - This is explained in the notes here:
> -
> - http://www.postgresql.org/docs/current/static/sql-prepare.html
>
> <sigh> and i've read that before too.
>
> On the upside, then it behaves like I would expect it to, which is
> good.
>
> Thanks
>
> Dave
Note that the query plan can often be the same for the example here.
It depends on whether the knowledge of the exact value makes a difference.
The most common case is an identifier column.
If the column is unique and indexed, and the parameter is an exact = match
in the where clause to that column, the plans won't differ.
>
> --
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To: pgsql-performance@postgresql.org
Cc: scott@richrelevance.com, dmk@mr-paradox.net, dmagick@gmail.com, craig@postnewspapers.com.au
Subject: Re: Optimizer + bind variables
In-Reply-To: <C717A6D5.15F03%scott@richrelevance.com>
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