[jira] [Commented] (JENA-1487) Incorrect SPARQL query result set when applying ORDER BY after an empty GROUP BY

["Andy Seaborne (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-1487?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16397043#comment-16397043 ] 

Andy Seaborne commented on JENA-1487:
-------------------------------------

See JENA-1507.

> 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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