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ad-freiburg / qlever

Very fast SPARQL Engine, which can handle very large knowledge graphs like the complete Wikidata, offers context-sensitive autocompletion for SPARQL queries, and allows combination with text search. It's faster than engines like Blazegraph or Virtuoso, especially for queries involving large result sets.
Apache License 2.0
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Timing support for GRAPH and FROM NAMED clauses in qlever #1501

Open Stiksels opened 6 days ago

Stiksels commented 6 days ago

@joka921 with PR #1444 merged, there is now a NQuad parser and it seems to work. However, the sparql server doesn't support the GRAPH and FROM NAMED clauses yet, so the named graphs are still queried as if they are all part from one large graph. Do you have a timeline for when these clauses are supported?

Originally posted by @Stiksels in https://github.com/ad-freiburg/qlever/discussions/1334#discussioncomment-10556642

hannahbast commented 6 days ago

@Stiksels You can already try out #1445 . If that is hard for you, we can build a docker image for you to test it. We have some deadline stress this week. We hope to have this in the master next week.

Stiksels commented 5 days ago

hi @hannahbast , thanks for the reply. I would be happy to test this with a custom docker image, but this would also be somewhere next week

sennierer commented 3 days ago

Tested the PR with a nq file with 3m triples. Parsing worked, but it seems to not yet take the NGs into account. Putting one of the NGs in FROM <NG> showed the same number of triples as the query against the default graph. FROM NAMED or using a variable for the graph claims to be not implemented yet. For testing I just checked out #1445 (server log shows: "QLever Server, compiled on Fri Sep 20 09:55:28 UTC 2024 using git hash ef5743"), created a docker image from it and used that with current main qlever-control repo. Might have missed something. Also recognized that while my nq file has little over 3m triples and the statistics shows the same number, counting the triples in the SPARQL query brings little less than 3m triples. However, thanks for the hard work and the great (open-source) piece of software. I am very happy that NG support is going to land in qlever, thats the last feature we need for using it in one of our new projects. Obviously I am happy to test new versions of this with our data and/or retry if I did something wrong.

sennierer commented 3 days ago

For queries not only counting all triples, but filtering, I get the following error:

Error processing query

Assertion `numBlocksTotal == details.numBlocksRead_ || !limitOffset.isUnconstrained()` failed. Please report this to the developers. In file "/app/src/index/CompressedRelation.cpp " at line 254