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From: Richard Huxton <dev@archonet.com>
Organization: Archonet Ltd
To: Tomasz Myrta <jasiek@klaster.net>, pgsql-sql@postgresql.org
Subject: Re: order by and aggregate
Date: Mon, 6 Jan 2003 13:41:32 +0000
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On Monday 06 Jan 2003 12:44 pm, Tomasz Myrta wrote:
> Hi
> I created my own aggregate function working as max(sum(value))
> It adds positive and negative values and finds maximum of this sum.
> To work properly this function needs data to be sorted.

I'm not sure that an aggregate function should require data to be sorted=20
before processing. Could you show details of your function - there may be a=
=20
way to rewrite it to handle unsorted data.

> select
>    maxsum(value)
> from some_table
>    order by some_field
>
> doesn't work:
> ERROR:  Attribute some_table.some_field must be GROUPed or used in an
> aggregate function

The "order by" isn't necessarily handled before calculating maxsum() anyway.

--=20
  Richard Huxton