От: Simon Riggs
Тема: Re: partition pruning
Дата: ,
Msg-id: 1268087950.10620.49.camel@ebony
(см: обсуждение, исходный текст)
Ответ на: Re: partition pruning  (Robert Haas)
Список: pgsql-performance

On Thu, 2010-03-04 at 17:40 -0500, Robert Haas wrote:
> On Mon, Mar 1, 2010 at 2:29 PM, Anj Adu <> 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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