processing .rdf files for specific property types only

[Gunaratna, Dalkandura Arachchige Kalpa Shashika Silva]

Hi,
   I have a simple requirement and that is to read 
<http://www.w3.org/2002/07/owl#sameAs> object values (sameAs link value) in a 
rdf file. For that I create an ontology model and read the whole file. 
Following is a code sample I sue for that.

model=ModelFactory.createOntologyModel(OntModelSpec.RDFS_MEM);
                SysRIOT.wireIntoJena() ;
                model.read(url);
                StmtIterator stmtItr=model.listStatements();

This way of processing has a huge processing overhead for my program since for 
every rdf file I just need to read the whole file to get sameAs links. Is there 
any other way of doing this kind of work or only possible way is to read the 
whole file to get the specific property type we want?

And also, what happens if we do not call model.close() at the end? Will it be a 
problem which will cause heap out of space problem?

Thank you,
Kalpa