6 Replies Latest reply on Apr 20, 2010 3:05 PM by 715399

false

766393 Apr 19, 2010 2:58 PM

Hi,
I am currently facing a surprising behaviour of listProperties.
While going through a ResultSet of a SPARQL query, all the Resources found show the same results :
- hasProperty(Property p) returns true when supposed to
- listProperties always returns an empty iterator (hasNext()=false)

I have only had this issue with this ModelOracleSem, never with in-memory Jena models.

Is there another way to iterate through all the statements which have a specified resource as a subject ?

Thanks,
Julien

1. Re: Jena: hasProperty(Property) -> true but listProperties().hasNext -> false

766393 Apr 19, 2010 3:37 PM (in response to 766393)

By the way, getProperty also works.
listProperties is the only one failing.
Like Show 0 Likes(0)

Actions
2. Re: Jena: hasProperty(Property) -> true but listProperties().hasNext -> false

715399 Apr 19, 2010 7:42 PM (in response to 766393)

Hi,

Have you tried Model.listStatements(s,p,o)? Using null for s,p, or o in the method will match anything.

Also, could you post a small code snippet that illustrates the listProperties issue?

Thanks,
Vladimir

Edited by: vkolovsk on Apr 19, 2010 12:41 PM
1 person found this helpful
Like Show 0 Likes(0)

Actions
3. Re: Jena: hasProperty(Property) -> true but listProperties().hasNext -> false

766393 Apr 20, 2010 8:58 AM (in response to 715399)

Hi,
Thanks for your help, but model.listStatements did not work either.
Here is part of my test code below.

QuerySolution soln = rs.nextSolution();
//....
RDFNode node = soln.get(n);
//...
if (node.isURIResource() && ((Resource)node).hasProperty(InfoAttrLongName)) {
Resource r = (Resource) node;

StmtIterator st = r.listProperties();
boolean test = st.hasNext(); //*false*

st = model.listStatements(r, null, (RDFNode)null);
test = st.hasNext(); //*false*

st = model.listStatements(r, null, (String)null);
test = st.hasNext(); //*false*

st = rs.getResourceModel().listStatements(r, null, (String)null);
test = st.hasNext(); //*false*

st = model.listStatements(r, InfoAttrLongName, (RDFNode)null);
test = st.hasNext(); //*true*

st = model.listStatements(); //*quite slow*
test = st.hasNext(); //*true* and iterates over all statements
}
Like Show 0 Likes(0)

Actions
4. Re: Jena: hasProperty(Property) -> true but listProperties().hasNext -> false

715399 Apr 20, 2010 2:36 PM (in response to 766393)

Hi,

Could you please try disabling one of the optimizations in GraphOracleSem? Just invoke graph.setSubjectOptFlag(false) on the GraphOracleSem you're running the tests against.

Regards,
Vladimir
1 person found this helpful
Like Show 0 Likes(0)

Actions
5. Re: Jena: hasProperty(Property) -> true but listProperties().hasNext -> false

766393 Apr 20, 2010 2:57 PM (in response to 715399)

Thanks !
It definitely made it work as expected.
So what is likely to be the issue here ?
Should I expect a significant loss in performance ?

Regards,
Julien
Like Show 0 Likes(0)

Actions
6. Re: Jena: hasProperty(Property) -> true but listProperties().hasNext -> false

715399 Apr 20, 2010 3:05 PM (in response to 766393)

Hi Julien,

The optimization that you disabled applies to cases where only the subject is bound.

Could you please send me a reproducible test case so we can fix this issue for the next Jena Adapter patch release? Send the code to vladimir dot kolovski at oracle dot com.

Thanks,
Vladimir
Like Show 0 Likes(0)

Actions

Go to original post

Join the world’s largest interactive community dedicated to Oracle technologies.