[dotNetRDF-bugs] Problems with SPARQL query

[<tom...@gm...>]

Hi Rob

I've been having some problems with a SPARQL query. Actually I extracted it from a larger one, where it is a subquery. As a subquery I get some inifinite loop and must terminate the process. On its own it times out. I get the same results in all version from 0.7.2 onwards.

prefix hydra: <http://www.w3.org/ns/hydra/core#> 
prefix dcterms: <http://purl.org/dc/terms/> 

select ?member ?title    
{     
  graph <http://localhost:17899/brochures>  
  {
    <http://localhost:17899/brochures> hydra:member ?member .
    ?member dcterms:title ?title      
  }    
}    
order by ?title
offset 0  
limit 10

I've played with this query to identify the problem and I've got some results. It works fine in either one case:

1. Remove order
2. Remove limit
3. Replace GRAPH <> with FROM <>
4. Remove the first triple pattern
5. Replace two triple patterns with property path (and ditch ?member)

Key observation however is a modification to 3. If I use FROM <> but wrap the triple pattern in a BGP I'm getting timeouts all the same.

My dataset can be downloaded from http://ge.tt/19Q3B582/v/0?c

As a bonus question, please tell me why is is not possible to use FROM (NAMED) in subqueries? SPARQL specification or library limitation?

Thanks,
Tom