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https://issues.apache.org/jira/browse/JENA-199?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rob Vesse updated JENA-199:
---------------------------
Attachment: TDBEmptyOutput.java
Attached code which demonstrates the issue - allows you to run with the data as
a TDB dataset or as an ARQ in-memory dataset.
With TDB dataset I see a NPE in BindingBase.hashCode() whereas with ARQ I do
not - the implication is the QueryIterator that TDB returns can return
malformed Binding instances which have/return nulls for some variables OR whose
variables list is incorrect so BindingBase tries to access variables that don't
exist in the Binding
> 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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