Re: [SQL] order by and aggregate

[Tomasz Myrta]

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



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