- From: Andy Seaborne <andy@apache.org>
- Date: Fri, 10 Mar 2017 14:05:11 +0000
- To: public-sparql-exists@w3.org
On 09/03/17 11:49, Peter F. Patel-Schneider wrote:
> I thought that I had already reported this problem with proposal B, but
> maybe not.
I don't think you have.
> The translation to the SPARQL algebra may not produce any place for values
> insertion to take place. This is due to the simplification step in
> 18.2.2.8.
>
> For example, the graph pattern
> { VALUES ?x ( ex:b ) }
> is translated into an SPARQL algebra expression containing only a multiset,
> something like
> {{ (x,ex:b) }}
> This results in counterintuitive behaviour on queries like
>
> SELECT ?x WHERE {
> BIND ( ex:a AS ?x )
> FILTER EXISTS { VALUES ?x ( ex:b ) }
> }
This query is illegal because it attempts to reassign a variable already
a bound in the current row.
If it were a different name, ?z say, then its just fixed data
independent of the current row.
As soon as the query adds anything that can influenced by the current
row, the current row variables will be available.
Andy
>
> peter
>
Received on Friday, 10 March 2017 14:05:45 UTC