Re: Sorted group by - Mailing list pgsql-performance

From Thom Brown
Subject Re: Sorted group by
Date
Msg-id AANLkTikaYYY0xftv=1nqPQZWbqiqyOgaSLz69cV_OcMo@mail.gmail.com
Whole thread Raw
In response to Re: Sorted group by  (Matthew Wakeling <matthew@flymine.org>)
Responses Re: Sorted group by
List pgsql-performance
On 10 August 2010 17:03, Matthew Wakeling <matthew@flymine.org> wrote:
> On Tue, 10 Aug 2010, Thomas Kellerer wrote:
>>
>> No. It's built in (8.4) and it's called Windowing functions:
>> http://www.postgresql.org/docs/8.4/static/tutorial-window.html
>> http://www.postgresql.org/docs/8.4/static/functions-window.html
>>
>> SELECT group, last_value(value) over(ORDER BY number)
>> FROM table
>
> I may be mistaken, but as I understand it, a windowing function doesn't
> reduce the number of rows in the results?
>

I think you are mistaken.  The last_value function is a window
function aggregate.  Give it a try.

--
Thom Brown
Registered Linux user: #516935

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