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Re: initial set of aggregates test cases plus ACTION-210

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Mon, 23 Aug 2010 12:02:13 +0100
Message-ID: <4C725535.7010204@epimorphics.com>
To: Axel Polleres <axel.polleres@deri.org>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>


On 23/08/10 11:51, Axel Polleres wrote:
>> >  But: observation: agg06.rq
>> >
>> >  ------------------------------------------
>> >  PREFIX :<http://www.example.org>
>> >
>> >  SELECT ?P (COUNT(*) AS ?C)
>> >  WHERE { ?S ?P ?O }
>> >  HAVING (COUNT(*)>  0 )
>> >  ------------------------------------------
>> >  uses non-group key variable ?P in the SELECT line.
>> >
> thanks, that wad wrong, should've been without the ?P in the select.
>
>> >  In ARQ, this results in, effectively, a new ?P (it's a different scope -
>> >  the use in the group is hidden because only variable from the group key
>> >  are in-scope and the mention of ?P in the SELECT line is a new,
>> >  different ?P and is hence unbound).
> Wouldn't we rather want this to be a syntax error (don't remember in detail, but I think we discussed this, need to check)


Could be (IIRC we'd suggested this as a warning if an impl chooses) - in 
ARQ ?P can be resued (e.g. select expression:

SELECT (SAMPLE(?P) as ?P) (COUNT(*) AS ?C)
{...}

If we wish to make it an error, then we really ought to specify the 
condition to check (e.g. give an algorithm).

Leaving it as-is is fine as well.

	Andy
Received on Monday, 23 August 2010 11:02:50 GMT

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