Have you tried to contact one of the developers? Or ask in the HDT forum [1]?
[1] http://www.rdfhdt.org/forum/rdf-hdt-support-group1/bugs-and-problems-forum2/ On 15.12.2017 03:57, Laura Morales wrote: > During one of my countless tests....... I've setup Fuseki with a HDT store. > In particular, the store is "wikidata.hdt". > > Then I've ran this query from Fuseki web UI: > > SELECT ?s > WHERE { ?s a <http://wikiba.se/ontology-beta#Item> } > LIMIT 10 > OFFSET 20000000 > > this query takes forever... so much forever in fact, that I killed it after > 15 minutes with no results. CPU 100% on *all* threads, Java VM using all the > allocated RAM (6G), no swap nor disk activity. > I don't know where the problem is, especially because I don't know the > dynamics among Fuseki/Jena and the HDT binding (hdt-java). > > However: > > - hdt-cpp has a small CLI tool that allows to match simple patterns like "? ? > ?" or "? a ?", so I searched for "? a <http://wikiba.se/ontology-beta#Item>" > and grepped all the output filtering out the first 20M triples. From when I > issued the command, to when I started to see the first results, it elapsed > about 1 minute (and a few seconds). *NOTE:* this time also takes into account > the time needed to setup the Java VM, map the HDT file into memory, and load > some HDT indices (in memory) > > - hdt-java (the Fuseki binding) instead, has a CLI tool called "hdtsparql" > that allows to run sparql queries directly against a HDT file, and AFAICT it > uses Jena ARQ. This tool also has some initialization time linked to the > loading of the HDT, anyway the query (above) was answered in 35 seconds (load > time + query) > > So as I said, I don't know what's going on between Fuseki and HDT-Java, but > this looks like a problem with Fuseki. Can somebody else confirm? Any idea? > Hint?
