Ivan Peikov
Fri, 27 Aug 2010 04:58:07 -0700
Hi Buddy! Directly on your questions:
1) What do you mean by "not yet built"? Are querying the repository while statements are being inserted? If there is an ongoing process of statement loading into repository this definitely will slow down all queries. 2) This is normal behavior. After the first several queries lots of data will be cached into memory which allows for faster access. When we assess the query performance we usually make several runs to warm-up the repository and then do the actual measuring. I consider this type of measurement closest to the real life usage. 3) When using the SKOS vocabulary it is not uncommon to generate a huge amount of broaderTransitive/narrowerTransitive relations which then make queries harder. This is because the linear growth of the explicit broader relations generates quadratic number of broaderTransitive ones. You can check what is the case with you but my guess is that a big part of those 10M statements are actually broaderTransitives (which might be a reason for query performance degradation). Cheers, Ivan On Friday 27 August 2010 11:54:49 Buddy Rich wrote: > Hi, I am assessing the performance of SwiftOWLIM and I have three > questions: > > 1) It seems to me that the query time when the repository is not yet > "built" is slower than when the repository is ready. Is it an accident? > > 2) It seems to me that if I repeat the same kind of query for very similar > nodes during the same execution, the performances improve a lot (e.g. from > 400 ms to 100 ms). In other words, How should I carry out the assessment? > One query at a time or I can execute more queries at the same time? > > 3) I have a query like this: > > prefix skos: <http://www.w3.org/2004/02/skos/core#> > > SELECT Distinct ?IdRelDoc > WHERE > { > ?IdDescendant skos:broaderTransitive <http://www.ex.it/concept#207>. > ?idDescendant skos:related ?IdRelConcept. > ?IdRelDoc skos:subject ?IdRelConcept. > } > > Is it plausible that from an ontology with ~4M statements to one with ~10M, > the performances increase from 234 ms (for 10k results) to 70k ms (for 26k > results)? > > Thank you in advance! > > > > > _______________________________________________ > OWLIM-discussion mailing list > OWLIM-discussion@ontotext.com > http://ontotext.com/mailman/listinfo/owlim-discussion > _______________________________________________ OWLIM-discussion mailing list OWLIM-discussion@ontotext.com http://ontotext.com/mailman/listinfo/owlim-discussion