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https://issues.apache.org/jira/browse/JENA-1487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16362205#comment-16362205
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Andy Seaborne commented on JENA-1487:
-------------------------------------

This was discussed on the users mailing list in the past few months.

https://lists.apache.org/thread.html/72c2045e639c589880619443beafec5be963733e0f9f0887e134d467@%3Cusers.jena.apache.org%3E

The current behaviour in Jena is intended but it not clear, to me at least, 
that is what the spec intended, or that the spec says. (The spec has some other 
problems so it is not itself consistent.)


> Incorrect SPARQL query result set when applying ORDER BY after an empty GROUP 
> BY
> --------------------------------------------------------------------------------
>
>                 Key: JENA-1487
>                 URL: https://issues.apache.org/jira/browse/JENA-1487
>             Project: Apache Jena
>          Issue Type: Bug
>          Components: ARQ
>    Affects Versions: Jena 3.6.0
>            Reporter: Claus Stadler
>            Priority: Major
>
> Ordering an empty result set must not introduce additional bindings, but this 
> happens with the following example (run on an arbitrary dataset - including 
> an empty one):
> {code:bash}
> ./fuseki-server --file=test.ttl /foobar
> {code}
> The Json below is obtained from the Fuski bundle; but I noted this issue 
> first using the ARQ API, where the incorrect result set contains a single 
> BindingProjectNamed instance.
> {code:sql}
> SELECT ?s
> WHERE {
>   ?s ?p ?o
>   FILTER(false)
> }
> GROUP BY ?s
> ORDER BY DESC(COUNT(?o))
> {code}
> {code:json}
> {
>   "head": {
>     "vars": [ "s" ]
>   } ,
>   "results": {
>     "bindings": [
>       {
> # NOTE THIS EMPTY BINDING HERE!        
>       }
>     ]
>   }
> }
> {code}
> The result set is correct without the ORDER BY:
> {code:sql}
> SELECT ?s
> WHERE {
>   ?s ?p ?o
>   FILTER(false)
> }
> GROUP BY ?s
> {code}
> {code:json}
> {
>   "head": {
>     "vars": [ "s" ]
>   } ,
>   "results": {
>     "bindings": [
> # CORRECT      
>     ]
>   }
> }
> {code}



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