document: Counting beyond a Yottabyte , or how SPARQL 1.1 property paths will prevent adoption of the standard SPARQL - the standard query language for querying RDF - provides only limited navigational functionalities , although these features are of fundamental importance for graph data formats such as RDF . This has led the W3C to include the property path feature in the upcoming version of the standard , SPARQL 1.1 . We tested several implementations of SPARQL 1.1 handling property path queries , and we observed that their evaluation methods for this class of queries have a poor performance even in some very simple scenarios . To formally explain this fact , we conduct a theoretical study of the computational complexity of property paths evaluation . Our results imply that the poor performance of the tested implementations is not a problem of these particular systems , but of the specification itself . In fact , we show that any implementation that adheres to the SPARQL 1.1 specification ( as of November 2011 ) is doomed to show the same behavior , the key issue being the need for counting solutions imposed by the current specification . We provide several intractability results , that together with our empirical results , provide strong evidence against the current semantics of SPARQL 1.1 property paths . Finally , we put our results in perspective , and propose a natural alternative semantics with tractable evaluation , that we think may lead to a wide adoption of the language by practitioners , developers and theoreticians .
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