W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > January to March 2011

Re: Aggregation Set Functions

From: Matthew Perry <matthew.perry@oracle.com>
Date: Fri, 11 Feb 2011 09:00:25 -0500
Message-ID: <4D5540F9.2070407@oracle.com>
To: Steve Harris <steve.harris@garlik.com>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>
Hi Steve,

Lets say M = (1, 2, 3, "a", "b")

Does this change COUNT(xsd:int(?x)) from 3 to 5?

- Matt

On 2/11/2011 7:03 AM, Steve Harris wrote:
> I've spoken with Andy on IRC, and he also agrees that it's probably better without it, so the current draft of rq25 doesn't have the error count argument.
>
> Following some discussion on IRC last night, I've also clarified the return types of the set functions.
>
> - Steve
>
> On 2011-02-11, at 10:55, Steve Harris wrote:
>
>> Hi all,
>>
>> Currently the Set Functions in Aggregates (ie. the underlying functions) are defined like:
>>
>> Func(M, errors, scalars)
>>
>> where M a multiset of the values from the group, e.g. if you have SUM(?x) and ?x is 1,2,3 in the group, then M = (1,2,3). But M is defined used ListEvalE(), so all the results which are errors are removed from the multiset.
>>
>> errors is a count of the errors (which where removed from M).
>>
>> I think it would be much simpler if instead M included the errors, and the error count argument was dropped, then it would be:
>>
>>    M = ListEval(exprlist, range(g))
>>
>>    func(M, scalarvals), for non-DISTINCT
>>    func(Distinct(M), scalarvals), for DISTINCT
>>
>> Dave B also complained about the error count argument saying it was redundant in his comment.
>>
>> I don't quite remember why it was included? I think Andy S might have suggested it, something about future extensibility? But I don't see what function it performs.
>>
>> So, my question is, can anyone think of a good reason to keep it?
>>
>> - Steve
>>
>> -- 
>> Steve Harris, CTO, Garlik Limited
>> 1-3 Halford Road, Richmond, TW10 6AW, UK
>> +44 20 8439 8203  http://www.garlik.com/
>> Registered in England and Wales 535 7233 VAT # 849 0517 11
>> Registered office: Thames House, Portsmouth Road, Esher, Surrey, KT10 9AD
>>
>>
Received on Friday, 11 February 2011 14:02:06 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:45 GMT