good morning; > On 2017-10-10, at 23:32, George News <george.n...@gmx.net> wrote: > > > On 2017-10-10 11:25, Rob Vesse wrote: >> Personally I am certain that Jena is correct in its interpretation of >> specification and that the specification is the appropriate. >> >> The key point here is that any aggregation requires at least one group to >> operate over, in the absence of a GROUP BY then there is an implicit group >> of all Solutions. In the case where there are zero solutions you have an >> implicit empty group. As has been pointed it out we can still meaningfully >> aggregate over an empty group e.g. COUNT is zero > > I'm not an expert and have already expressed my concerns. I'm just using > common sense. I have also discussed it internally with some of my > colleagues and they somehow agree with my view.
while both common sense and consensus among developers may help to frame a discussion about sparql conformance, in the end, there is no way to avoid coming to terms with the recommendation. thus the citation in an earlier message: >> >> On 09/10/17 15:27, George News wrote: >>> On 2017-10-09 12:31, james anderson wrote: >>>> good afternoon; >>>>> On 2017-10-09, at 12:03, George News <george.n...@gmx.net> wrote: >>>>> >>>>>> […] >>>>> >>>>> I understood it, but I don't agree with this behaviour. Is this in the >>>>> standard or is it just Jena behaviour? >>>> >>>> the recommendation describes the intended behaviour here : >>>> >>>> https://www.w3.org/TR/sparql11-query/#aggregateAlgebra this passage describes how a form which involves a “group by” clause it to be interpreted. the process involves constructing a set of labeled solution sequences and reducing those sets by applying aggregation “set functions" to them. it says nothing about special treatment for an intermediate state in which the set of labeled sequences is empty. one reading of the recommendation is that it stipulates that the result of a query of the sort under discussion is empty, rather than a unit table. if this interpretation stands, then the reported result is non-conformant in this regard. best regards, from berlin,
