pvanhoof@lenny:~$ tracker-sparql -qu 'insert { <b> a nie:InformationElement . <a> a nfo:Media ; extra:hasThing <b> }'
Done
pvanhoof@lenny:~$ tracker-sparql -q 'select ?a ?b { ?a extra:hasThing ?b }
> ^C
pvanhoof@lenny:~$ tracker-sparql -q 'select ?a ?b { ?a extra:hasThing ?b }"
> ^C
pvanhoof@lenny:~$ tracker-sparql -q 'select ?a ?b { ?a extra:hasThing ?b }'
Results:
  a, b

pvanhoof@lenny:~$ tracker-sparql -qu 'insert { <c> a nie:InformationElement . <a> a nfo:Media ; extra:hasThing <c> }'
Could not run update, GDBus.Error:org.freedesktop.Tracker1.SparqlError.Constraint: Unable to insert multiple values for subject `a' and single valued property `extra:hasThing' (old_value: '100001', new value: '100003')
pvanhoof@lenny:~$ tracker-sparql -q 'select ?a ?b { ?a extra:hasThing ?b }'Results:
  a, b

pvanhoof@lenny:~$ tracker-sparql -qu 'insert { <c> a nie:InformationElement . <a> a nfo:Media ; extra:hasThing <c> }'
Done
pvanhoof@lenny:~$ tracker-sparql -q 'select ?a ?b { ?a extra:hasThing ?b }'Results:
  a, b
  a, c

pvanhoof@lenny:~$ cat /opt/tracker/share/tracker/ontologies/94-extra.ontology
@prefix dc: <http://purl.org/dc/elements/1.1/> .
@prefix nco: <http://www.semanticdesktop.org/ontologies/2007/03/22/nco#> .
@prefix nfo: <http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#> .
@prefix nie: <http://www.semanticdesktop.org/ontologies/2007/01/19/nie#> .
@prefix nrl: <http://www.semanticdesktop.org/ontologies/2007/08/15/nrl#> .
@prefix nao: <http://www.semanticdesktop.org/ontologies/2007/08/15/nao#> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix tracker: <http://www.tracker-project.org/ontologies/tracker#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
@prefix nao: <http://www.semanticdesktop.org/ontologies/2007/08/15/nao#> .
@prefix extra: <http://www.tracker-project.org/ontologies/extra#> .


extra: a tracker:Namespace, tracker:Ontology ;
	tracker:prefix "extra" ;
	nao:lastModified "2014-08-28T14:15:01Z" .

extra:hasThing a rdf:Property ;
	rdfs:label "hasThing" ;
	rdfs:comment "Connects a media container with a single media stream contained within." ;
	rdfs:subPropertyOf nie:hasPart ;
	rdfs:domain nfo:Media ;
#    nrl:maxCardinality 1 ;
	rdfs:range nie:DataObject .

pvanhoof@lenny:~$ cat /opt/tracker/share/tracker/ontologies/94-extra.description
@prefix extra: <http://www.tracker-project.org/temp/extra#> .

<virtual-ontology-uri:93-extra.ontology> a dsc:Ontology ;
	dsc:title "extra-specific annotations Ontology" ;
	dsc:description "extra properties" ;

	dsc:author "Red Hat, Inc" ;
	dsc:editor "Red Hat, Inc" ;
	dsc:gitlog "http://git.gnome.org/cgit/tracker/log/data/ontologies/94-extra.ontology";

	dsc:localPrefix "extra" ;
	dsc:baseUrl "http://www.tracker-project.org/ontologies/extra#";
	dsc:relativePath "./94-extra.ontology" .
pvanhoof@lenny:~$