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Date: Mon, 06 Jan 2003 17:59:54 +0100
From: Tomasz Myrta <jasiek@klaster.net>
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To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Richard Huxton <dev@archonet.com>, pgsql-sql@postgresql.org
Subject: Re: order by and aggregate
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Tom Lane wrote:

> Tomasz Myrta  writes:
>
> >Standard Postgresql aggregate functions don't need sorted data, but my
> >function needs. Look at the data:
> >
> >3	  3
> >-2        1
> >6         7 *** max_sum=7
> >-3        4
> >2         6
>
>
> But if the input data is sorted into increasing order, then the largest
> running sum value is always at the end.  Therefore max(sum()) is
> equivalent to sum(); therefore you do not need the special aggregate,
> nor the ordering.
>
> 			regards, tom lane

Sorting data by "value" was only an example,
In my case data is sorted by another key and has mixed positive and 
negative values.
Tomasz Myrta