On 19/03/17 15:52, Manuel Enrique Puebla Martinez wrote:
I consider that I did not know how to explain correctly in my previous email, I repeat the two questions: 1) I read the page https://jena.apache.org/documentation/tdb/assembler.html, I do not think it is what I need. I work with large OWL2 ontologies from the OWLAPI framework, generated automatically. With thousands of individuals and more than 13 million property assertions (data and objects). As one may assume, one of the limitations I have is that OWLAPI itself can not manage these large ontologies, that is, because OWLAPI loads the whole owl file into RAM. Not to dream that some classical reasoner (Pellet, Hermit, etc.) can infer new knowledge about these great ontologies. Once explained the problem I have, comes the question: Does JENA solve this test ?, ie with JENA and TDB I can generate my great ontologies in OWL2 ?, With JENA and TDB I can use a reasoner to infer new implicit knowledge (unstated) on my big ontologies? I do not think JENA will be able to solve this problem, it would be a pleasant surprise for me. Unfortunately so far I had not read about TDB and the potentialities of JENA in external memory.
Indeed Jena does not offer fully scalable reasoning, all inference is done in memory.
That said 13 million assertions is not *that* enormous, the cost of inference depends on the complexity of the ontology as much its scale. So 13m triples with some simple domain/range inferences might work in memory.
TDB storage itself scales just fine and querying does not load all the data into memory. So if you don't actually need inference, or only need simple inference that can be usefully expressed as part of the SPARQL query then you are fine.
Dave
