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https://issues.apache.org/jira/browse/JENA-199?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13198994#comment-13198994
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Rob Vesse commented on JENA-199:
--------------------------------

Sorry for taking so long to reply on this, with an updated Fuseki/TDB snapshot 
and with a cleanly built database I can no longer reproduce this so I'll close 
as Not a Bug or similar
                
> BindingBase can hit a null pointer exception on certain queries against a TDB 
> dataset
> -------------------------------------------------------------------------------------
>
>                 Key: JENA-199
>                 URL: https://issues.apache.org/jira/browse/JENA-199
>             Project: Jena
>          Issue Type: Bug
>          Components: TDB
>            Reporter: Rob Vesse
>              Labels: csv, results, sparql, tdb, tsv
>         Attachments: 5b.txt, 8.txt, TDBEmptyOutput.java, sp2b10k.nt
>
>
> This is a strange bug which I have been unable to reduce to a more minimal 
> example than the files I will attach so I apologize for that.
> Essentially the problem manifests as follows, when using a TDB dataset with 
> Fuseki some queries will return blank output if the user requests Text, CSV 
> or TSV.  When using XML/JSON the output is fine.
> The test data used is SP2B 10k, two of the SP2B queries that exhibit this 
> issue are as follows:
> PREFIX rdf:   <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
> PREFIX foaf:  <http://xmlns.com/foaf/0.1/>
> PREFIX bench: <http://localhost/vocabulary/bench/>
> PREFIX dc:    <http://purl.org/dc/elements/1.1/>
> SELECT DISTINCT ?person ?name
> WHERE {
>   ?article rdf:type bench:Article .
>   ?article dc:creator ?person .
>   ?inproc rdf:type bench:Inproceedings .
>   ?inproc dc:creator ?person .
>   ?person foaf:name ?name
> }
> And:
> PREFIX xsd:  <http://www.w3.org/2001/XMLSchema#> 
> PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
> PREFIX foaf: <http://xmlns.com/foaf/0.1/>
> PREFIX dc:   <http://purl.org/dc/elements/1.1/>
> SELECT DISTINCT ?name
> WHERE {
>   ?erdoes rdf:type foaf:Person .
>   ?erdoes foaf:name "Paul Erdoes"^^xsd:string .
>   {
>     ?document dc:creator ?erdoes .
>     ?document dc:creator ?author .
>     ?document2 dc:creator ?author .
>     ?document2 dc:creator ?author2 .
>     ?author2 foaf:name ?name
>     FILTER (?author!=?erdoes &&
>             ?document2!=?document &&
>             ?author2!=?erdoes &&
>             ?author2!=?author)
>   } UNION {
>     ?document dc:creator ?erdoes.
>     ?document dc:creator ?author.
>     ?author foaf:name ?name
>     FILTER (?author!=?erdoes)
>   }
> }
> I will attach these as files as well for convenience.
> If you run Fuseki with a memory dataset using the --mem option, load this 
> data and run the same queries the Text, CSV and TSV output works fine.  This 
> implies that there is something in the TDB code related to its return of 
> results or iterators which somehow causes the Text, CSV and TSV formatters to 
> either error or to believe that they have no results to format.
> I'm completely unfamiliar with the TDB codebase so I haven't attempted to 
> discover what the cause of the issue is though I may poke around anyway

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