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Re: Prioritised list of open issues (query, my bits)

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Tue, 09 Feb 2010 05:29:52 -0500
Message-ID: <4B713920.7010102@thefigtrees.net>
To: Steve Harris <steve.harris@garlik.com>
CC: Andy Seaborne <andy.seaborne@talis.com>, "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>
Steve Harris wrote:
> On 9 Feb 2010, at 09:00, Andy Seaborne wrote:
>> On 08/02/2010 10:23 AM, Steve Harris wrote:
>>> http://www.w3.org/2009/sparql/track/issues/35
>>> Can aggregate functions take DISTINCT as an argument a la SELECT
>>> COUNT(DISTINCT ?X)?
>>> - Seems consensus on yes.
>>
>> A URI should name the function, not a collection of related 
>> functionality.
>>
>> Example:
>>
>> COUNT(DISTINCT ?x) vs COUNT(?x)
>>
>> How do you name the difference if they are not different URIs?
> 
> In my view, DISTINCT does not change the function, it changes the 
> (multi)set that the function is applied to, c.f. 
> http://www.w3.org/2009/sparql/docs/query-1.1/rq25.xml#aggregateAlgebra
> 
> More concretely, you form a DISTINCT multiset of the bound values of ?x, 
> then apply the count function to the resulting set.

FWIW, this is exactly how Glitter treats the DISTINCT modifier for both 
built-in and custom aggregates. It modified the set of solutions passed 
to the aggregate function.

Lee

> 
>> In custom aggregates, what does my:agg name?
> 
> The aggregate function, defined as per the aggregate functions in 9.2.
> 
> - Steve
> 
Received on Tuesday, 9 February 2010 10:30:29 GMT

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