Good morning to all, I'm having some trouble using apache Jena TDB API,
in particular when I have to add a lot of statement to my model.
I need to save the result which I get from the dbpedia endpoint for
about two thousand entities. For each entity I get about ten properties
that I need for my task. So, when I execute the query, I loop through
all the result set and do multiple add operations for each statement in
the result set.
This is the code that I use in order to save the properties for a single
subject:
|public void saveResourceProperties(String resourceURI, Collection<String>
specificProp, PropertiesManager propManager) throws Exception {
String proprVariable = "?prop",
valueVariable = "?value",
fixedURI = "<" + resourceURI + ">",
queryProp = "select " + proprVariable + " " + valueVariable + " where
{\n" +
fixedURI + " " + proprVariable + " " + valueVariable +
" values " + proprVariable + "{" + formatPropertiesList(specificProp)
+ "} \n" +
"}";
Query query = QueryFactory.create(queryProp);
QueryExecution qexec = null;
try {
qexec = QueryExecutionFactory.sparqlService(endpoint, query);
ResultSet resultSet = qexec.execSelect();
QuerySolution currSolution;
// invokes dataset.begin(ReadWrite.Write);
propManager.start(true);
while (resultSet.hasNext()) {
currSolution = resultSet.nextSolution();
writer.write(resourceURI + "\t" +
currSolution.getResource(proprVariable).toString() +
"\t" + currSolution.get(valueVariable).toString() + "\n");
// prepare the statement using the resource URI and the current
solution
// and adds it using add() method
propManager.addSolution(currSolution, resourceURI);
}
// I commit the results calling dataset.commit()
propManager.commitChanges();
}
finally {
if (qexec != null)
qexec.close();
// calls dataset.end() in order to end the current transaction
propManager.closeManager();
}
}
|
Everything goes ok, but at the end of the process I receive this
exception (it happens each time that I call this method): Inconsistency:
base.allocOffset() = 1982292 : allocOffset = 0 After that, no file are
stored and for this reason I'm not able to read nothing.
I've tried to execute all the commit in a single, huge transaction, but
I receive the same error and the program is not able to store TDB index
files.
How can I manage this kind of situation? Can you suggest to me an
efficient way to do that? I'm getting mad...
Thank you in advance.
Alessandro Suglia
