Unknown namespace prefix Error - when using custom Aliases with RDF aliases

Question

I am getting unknown namespace prefix error when I use custome SEM_ALIAS with rdf SEM_ALIAS. It seems once you specify custom SEM_ALIAS, the default rdf alias is not recognized. Following are the details of queries
I have a sem_Model "test" which has "event" as a class and "Merger" as a sub-class of event, with "acquiringorg" as a property having the domain "org". "Org" is also defined as a class with the literal attribute "hasname". I have added one instance of "merger" class with appropriate values for "acquiringorg" property. There is one instance or "Org" as well for reference in the instance above.
the following query(return all objects having property "acquiringorg" and its .e. "hasName" attribute for the object) runs fine and returns appropriate resultset
select x event,z acquiringorg ,l acquireeorg from table(SEM_MATCH(
'(?x Evnt:AcquiringOrg ?y)(?k orgn:hasName ?l)',
SEM_MODELS('test'),
null,
SEM_ALIASES(SEM_ALIAS('Evnt','http://www.abc.com/Event/Merger/'),
SEM_ALIAS('orgn','http://www.abc.com/Org/')),
null));
However when I want to add another criteria i.e. show me events of type merger(?x rdf:type :Merger) , the query fails with the "unknown namespace prefix error" as above
select x event,z acquiringorg ,l acquireeorg from table(SEM_MATCH(
'(?x rdf:type :Merger)(?x Evnt:AcquiringOrg ?y)(?k orgn:hasName ?l)',
SEM_MODELS('test'),
null,
SEM_ALIASES(SEM_ALIAS('Evnt','http://www.abc.com/Event/Merger/'),
SEM_ALIAS('orgn','http://www.abc.com/Org/')),
null));
specifying "rdf" ALIAS explicitly also does not work
select x event,z acquiringorg ,l acquireeorg from table(SEM_MATCH(
'(?x rdf:type :Merger)(?x Evnt:AcquiringOrg ?y)(?k orgn:hasName ?l)',
SEM_MODELS('test'),
null,
SEM_ALIASES(_SEM_ALIAS('rdf', 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'),_
SEM_ALIAS('Evnt','http://www.abc.com/Event/Merger/'),
SEM_ALIAS('orgn','http://www.abc.com/Org/')),
null));
I am unable to figure out why default namespace i.e. rdf is returning this error
Stuck at this point badly!!Any pointers would be useful!!

Answer 1

Full error details are as below
ORA-29532: Java call terminated by uncaught Java exception: oracle.spatial.rdf.server.ParseException: Unknown namespace prefix ''
ORA-06512: at "MDSYS.RDF_MATCH_IMPL_T", line 153
ORA-06512: at "MDSYS.RDF_MATCH_IMPL_T", line 842
ORA-06512: at "MDSYS.RDF_MATCH_IMPL_T", line 235
ORA-06512: at line 1
29532. 00000 - "Java call terminated by uncaught Java exception: %s"
*Cause:    A Java exception or error was signaled and could not be
resolved by the Java code.
*Action:   Modify Java code, if this behavior is not intended.