Re: Clarification of the meaning of "unaggregated variable"

Yes this text seems to be in tension with 11.4
http://www.w3.org/TR/2013/REC-sparql11-query-20130321/#aggregateRestrictions <http://www.w3.org/TR/2013/REC-sparql11-query-20130321/#aggregateRestrictions>
In a query level which uses aggregates, only expressions consisting of aggregates and constants may be projected

I guess it may be talking about the exception, the variables in the GROUP BY itself, which would be treated correctly by replacing with a SAMPLE() aggregation, since in each group the values of the group by variable are always the same, and SAMPLE of the multiset of values is just the value itself.

Jeremy


> On Jul 2, 2015, at 9:12 AM, Matthew Horridge <matthew.horridge@stanford.edu> wrote:
> 
> Hi,
> 
> I’ve been reading through the definition of SPARQL in the SPARQL 1.1. Query Language Document.  In particular, section 18.2.4, which describes how to convert aggregate queries into the SPARQL algebra.  
> 
> The algorithm listed in 18.2.4.1, which I’ve pasted in below talks about “unaggregated variables”.  However, there isn’t a definition for “unaggregated variable” in the spec, and it isn’t totally clear to me what an “unaggregated variable” is.  If anyone could provide me with a precise definition for what an “unaggregated variable” is, and thus clarify this part of the spec, I would really appreciate it.
> 
> Thanks a lot,
> 
> Matthew
> 
> 
> 
> 
> 
> For each (X AS Var) in SELECT, each HAVING(X), and each ORDER BY X in Q
>   For each unaggregated variable V in X
>       Replace V with Sample(V)
>       End
>   For each aggregate R(args ; scalarvals) now in X
>       # note scalarvals may be omitted, then it's equivalent to the empty set
>       Ai := Aggregation(args, R, scalarvals, G)
>       Replace R(...) with aggi in Q
>       i := i + 1
>       End
>   End
>