From: Simon Riggs <simon@2ndQuadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Anj Adu <fotographs@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: partition pruning
Date: Mon, 08 Mar 2010 22:39:10 +0000
Message-ID: <1268087950.10620.49.camel@ebony> (raw)
In-Reply-To: <603c8f071003041440r2ec69a9dw91153f35ab2b3d53@mail.gmail.com>
References: <f2fd819a1003011129h2222281fqa67bc45e051c6dd8@mail.gmail.com>
<603c8f071003041440r2ec69a9dw91153f35ab2b3d53@mail.gmail.com>
On Thu, 2010-03-04 at 17:40 -0500, Robert Haas wrote:
> On Mon, Mar 1, 2010 at 2:29 PM, Anj Adu <fotographs@gmail.com> wrote:
> > When I use intervals in my query e.g col1 between current_timestamp -
> > interval '10 days' and current_timestamp...the optimizer checks ALL
> > partitions whereas if I use col1 between 2 hardcoded dates..only
> > the applicable partitions are scanned.
>
> Yep. This is one example of a more general principle:
> constant-folding happens before planning, but anything more complex
> has to wait until execution time. So the plan can't take into account
> the value of current_timestamp in forming the plan.
It could, but it doesn't yet. Partition removal can take place in the
executor and this is currently targeted for 9.1.
--
Simon Riggs www.2ndQuadrant.com
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To: pgsql-performance@postgresql.org
Cc: simon@2ndQuadrant.com, robertmhaas@gmail.com, fotographs@gmail.com
Subject: Re: partition pruning
In-Reply-To: <1268087950.10620.49.camel@ebony>
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