Re: order by and aggregate

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