Re: Order by optimisations? - Mailing list pgsql-hackers

From Hannu Krosing
Subject Re: Order by optimisations?
Date
Msg-id 1121285578.5551.0.camel@fuji.krosing.net
Whole thread Raw
In response to Order by optimisations?  (Christopher Kings-Lynne <chriskl@familyhealth.com.au>)
Responses Re: Order by optimisations?  (Christopher Kings-Lynne <chriskl@familyhealth.com.au>)
Re: Order by optimisations?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On K, 2005-07-13 at 16:08 +0800, Christopher Kings-Lynne wrote:
> Hi,
> 
> Does PostgreSQL do the following optimisation:
> 
> SELECT * FROM diary WHERE date = '2005-05-01' ORDER BY date;
> 
> or in fact even better (for my situation)
> 
> SELECT * FROM diary WHERE date BETWEEN '2005-05-01' AND '2005-05-01' 
> ORDER BY date;
> 
> Does it know that the input to the sort routine is already sorted and 
> hence is a no-op?

Yes

try EXPLAIN ;)

-- 
Hannu Krosing <hannu@skype.net>



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