"_" character + optional clause in SPARQL gives SQL error

Question

Hello
I run the following query through Jena Adaptor (11.1.0.7) (note the "_(E00-E90)" part of the URI) :
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT ?predicate ?object ?objectLabel
WHERE {
<http://www.chu-rouen.fr/stms#CIM10_(E00-E90)> ?predicate ?object .
OPTIONAL {?object rdfs:label ?objectLabel.}
LIMIT 5
I have the following exception in the Jena adaptor (note the corresponding "(E00-E90)" in the last SQL query) :
15:07:15,191 INFO [OracleSPARQLDOMEndPoint] Query: PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX rdf:
<http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT DISTINCT ?predicate ?object ?objectLabel WHERE { <http://w
ww.chu-rouen.fr/stms#CIM10_(E00-E90)> ?predicate ?object . OPTIONAL { ?object  rdfs:label  ?
objectLabel .} } LIMIT 5
15:07:15,191 INFO [OracleSemQueryPlan] Final clause = SELECT object$RDFVTYP, object$RDFLTYP, object$RDFLANG, object$RDF
CLOB, decode(object$RDFVTYP, 'BLN', ('_:'||substr(object,instr(object,'m',4)+1)), object) object, predicate$RDFVTYP, de
code(predicate$RDFVTYP, 'BLN', ('_:'||substr(predicate,instr(predicate,'m',4)+1)), predicate) predicate FROM table(sdo_
rdf_match('(<http://www.chu-rouen.fr/stms#CIM10_(E00-E90)> ?predicate ?object) ', sdo_rdf_models('RDF_MODEL'), sdo_rdf_r
ulebases('OWLPRIME'), null, null, null))
15:07:15,191 INFO [OracleSemQueryPlan] Final clause = SELECT objectLabel$RDFVTYP, objectLabel$RDFLTYP, objectLabel$RDFL
ANG, objectLabel$RDFCLOB, decode(objectLabel$RDFVTYP, 'BLN', ('_:'||substr(objectLabel,instr(objectLabel,'m',4)+1)), obj
ectLabel) objectLabel FROM table(sdo_rdf_match('(<http://www.chu-rouen.fr/stms#CIM10Chapitre> <http://www.w3.org/2000/0
1/rdf-schema#label> ?objectLabel) ', sdo_rdf_models('RDF_MODEL'), sdo_rdf_rulebases('OWLPRIME'), null, null, null))
15:07:15,207 INFO [OracleSemQueryPlan] Final clause = SELECT objectLabel$RDFVTYP, objectLabel$RDFLTYP, objectLabel$RDFL
ANG, objectLabel$RDFCLOB, decode(objectLabel$RDFVTYP, 'BLN', ('_:'||substr(objectLabel,instr(objectLabel,'m',4)+1)), obj
ectLabel) objectLabel FROM table(sdo_rdf_match('("(E00-E90)" <http://www.w3.org/2000/01/rdf-schema#label> ?objectLabel)
', sdo_rdf_models('RDF_MODEL'), sdo_rdf_rulebases('OWLPRIME'), null, null, null))
15:07:15,254 WARN [QueryIteratorCheck] Open iterator: QueryIterBlockTriplesQH$StagePattern/322
15:07:15,254 ERROR [STDERR] oracle.spatial.rdf.client.jena.NoEntailmentException: executeBindings: ORA-29532: appel Java
arrÛtÚ par une exception Java non interceptÚe : oracle.spatial.rdf.server.ParseException: Encountered "\"(E00-E90)\"" a
t line 1, column 2.
Was expecting one of:
<URI> ...
<QNAME> ...
<VAR> ...
ORA-06512: Ó "MDSYS.RDF_MATCH_IMPL_T", ligne 181
ORA-06512: Ó "MDSYS.RDF_MATCH_IMPL_T", ligne 67
ORA-06512: Ó ligne 4
15:07:15,254 ERROR [STDERR] at oracle.spatial.rdf.client.jena.OracleSemQueryPlan.executeBindings(OracleSemQueryPlan.java:334)
15:07:15,254 ERROR [STDERR] at com.hp.hpl.jena.sparql.engine.iterator.QueryIterBlockTriplesQH$StagePattern.<init>(QueryIterBlockTriplesQH.java:89)
15:07:15,254 ERROR [STDERR] at com.hp.hpl.jena.sparql.engine.iterator.QueryIterBlockTriplesQH.nextStage(QueryIterBlockTriplesQH.java:55)
15:07:15,254 ERROR [STDERR] at com.hp.hpl.jena.sparql.engine.iterator.QueryIterRepeatApply.makeNextStage(QueryIterRepeatApply.java:92)
15:07:15,254 ERROR [STDERR] at com.hp.hpl.jena.sparql.engine.iterator.QueryIterRepeatApply.hasNextBinding(QueryIterRepeatApply.java:54)
etc.
However :
If I remove the OPTIONAL clause, the error disapear.
If I simply remove the "_" character from the URI, the error disappear.
If I do a query where the URI is in the "object" part of the triple, the error disappear. ie :
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT ?predicate ?subject ?subjectLabel
WHERE {
?subject ?predicate <http://www.chu-rouen.fr/stms#CIM10_(E00-E90)> .
OPTIONAL {?subject rdfs:label ?subjectLabel.}
Is that a bug ?
Thanks
Thomas
Edited by: thomas francart on 4 nov. 2009 15:14

Answer 1

Hi,
I assume you are using Jena Adaptor v2. It is a v2 bug. This problem does not have much to do with "_" actually. Rather, it is because ARQ is breaking this query into a nested loop and ?object is bound to a literal and that literal is in turn passed to the OPTIONAL part as a binding. SEM_MATCH complains because it receives a literal subject which is illegal.
The latest Jena Adaptor should be free of this problem. And it is a lot faster dealing with OPTIONALs, UNIONs, Filters in general.
Please check
http://www.oracle.com/technology/software/tech/semantic_technologies/index.html
If you want to continue using Jena Adaptor v2, can you please try the following workaround? A FILTER is added to the OPTIONAL clause.
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT ?predicate ?object ?objectLabel
WHERE {
<http://www.chu-rouen.fr/stms#CIM10_(E00-E90)> ?predicate ?object .
OPTIONAL {?object rdfs:label ?objectLabel  *FILTER isURI(?object)*}
LIMIT 5
Thanks,
Zhe Wu