Notes on AllegroGraph's SPARQL implementation

Introduction

Release 4.5 of AllegroGraph provides numerous enhancements and bug fixes for the SPARQL 1.1 query engine. In particular, it now passes all of the DAWG property path and sub-query tests. It also supports the DISTINCT keyword in the aggregation functions.

Aside from the following caveats, AllegroGraph's sparql-1.1 engine supports all of the functions in the specification.

• we do not yet support the timezone or tz datetime functions

• we do not yet support the SHA384 hash function

• the BNODE function only works correctly in the no argument case

• we do not support ORDER BY clauses with aggregation.

• we do not yet support aggregate expressions in a HAVING clause. A work-around for this is to define an auxiliary variable to use in the HAVING clause. For example, instead of:
  

  PREFIX : <http://books.example/>  
  SELECT (SUM(?lprice) AS ?totalPrice)  
  WHERE {  
    ?org :affiliates ?auth .  
    ?auth :writesBook ?book .  
    ?book :price ?lprice .  
  }  
  GROUP BY ?org  
  HAVING (SUM(?lprice) > 10) 

use ?totalPrice directly:

PREFIX : <http://books.example/>  
SELECT (SUM(?lprice) AS ?totalPrice)  
WHERE {  
  ?org :affiliates ?auth .  
  ?auth :writesBook ?book .  
  ?book :price ?lprice .  
}  
GROUP BY ?org  
HAVING (?totalPrice > 10) 

• There are still some known issues with property path queries using arbitrary path lengths. In particular, AllegroGraph will return too few results.

If you find any other problems (with conformance or performance) please let us know by e-mailing support.