Horton

Re: Aggregate ORDER BY patch

Greg Stark <gsstark@mit.edu>

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From: Greg Stark <gsstark@mit.edu>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: Andrew Gierth <andrew@tao11.riddles.org.uk>, pgsql-hackers@postgresql.org
Date: 2009-11-13T09:42:35Z
Lists: pgsql-hackers 
On Fri, Nov 13, 2009 at 7:54 AM, Heikki Linnakangas
<heikki.linnakangas@enterprisedb.com> wrote:
> Andrew Gierth wrote:
>> Herewith a patch to implement agg(foo ORDER BY bar) with or without
>> DISTINCT, etc.
>
> What does that mean? Aggregate functions are supposed to be commutative,
> right?

We certainly have non-commutative agggregates currently, notably array_agg()

I suspect it would be good to have a flag marking the commutative ones


-- 
greg