Different SPARQL execution order with recent Jena update (JENA-1813?)

[Holger Knublauch]

Hi,

on a branch of our product we have upgraded to jena 3.14 (due to the 
Thrift issue). Since then various SPARQL queries have stopped working. 
Of particular concern appears to be the evaluation of GRAPH ?graph 
clauses where ?graph is determined by a BIND. I am still trying to 
narrow down what has changed but suspect it's due to

https://issues.apache.org/jira/browse/JENA-1813

Here is an example query - a simplified version derived from a query in 
the product:

SELECT *
WHERE {
    BIND(<http://topbraid.org/teamwork#teamGraph>($this) AS ?teamGraph)
    GRAPH ?teamGraph {
        BIND (42 AS ?dummy)
    }
}

which is executed with $this prebound to a graph resource (e.g. 
<urn:x-evn-master:geo>). In 3.14 this seems to produce the following 
algebra:

(join
  (extend ((?teamGraph (<http://topbraid.org/teamwork#teamGraph> ?this)))
    (table unit))
  (graph ?teamGraph
    (extend ((?dummy 42))
      (table unit))))

while in 3.13.1 it produces

(sequence
  (extend ((?teamGraph (teamwork:teamGraph ?this)))
    (table unit))
  (graph ?teamGraph
    (extend ((?dummy 42))
      (table unit))))

As a result, the new version enters the GRAPH ?teamGraph with unbound 
?teamGraph and thus iterates over all graphs which is not working for 
our platform:

If my observations so far are correct then this change to Jena would 
have quite deep consequences and break not just our own queries but also 
those written by customers. We will likely have to roll back to a 
previous Jena version for the upcoming release of our product.

Question: was this change intentional and is this behavior going to stay 
in Jena? If it does stay, how can I switch it off?

Thanks
Holger