Hannah_Bast added a comment.
Yes, QLever is developed in our group at the University of Freiburg. I presented it to the Wikidata team in March. You can try out a demo on the complete Wikidata on https://qlever.cs.uni-freiburg.de/wikidata . You can also select other interesting large knowledge graphs there, for example, the complete OpenStreetMap data. QLever's focus is on efficiency (also for hard queries) for large knowledge graphs on standard hardware, in particular, without the need for a cluster or an exorbitant amount of RAM. For example, the demo above runs on a standard PC with 128 GB of RAM and it can compute the complete result for the people-profession query from https://phabricator.wikimedia.org/T206560 (6.1 million rows, where one column contains the result of a GROUP_CONCAT) in five seconds: https://qlever.cs.uni-freiburg.de/wikidata/4oNHPq . Another non-trivial query involving many triples is this one (average height by occupation and gender): https://qlever.cs.uni-freiburg.de/wikidata/gVWJ4h . There are many more example queries, ranging from easy to hard, under the drop-down menu "Examples". The thing I personally love most about QLever is the interactive context-sensitive autocompletion feature. Constructing SPARQL queries is really hard and cumbersome, even if you are an expert. The autocompletion gives you suggestions at every point. They are context-sensitive in the sense that you only get completions that are a meaningful continuation of the query so far. This is important for large knowledge graphs, where you have millions of entities and guessing the right names is often impossible. Try it for yourself by first typing S for SELECT ... and then starting a query (with a variable or by typing the prefix of an entity name, as you like). QLever does not yet have full SPARQL 1.1 support, but we are approaching that and will be there soon. The basic features are all there and what's missing are mostly small things. The one bigger feature that is missing is SPARQL Update operations. We are also thinking about adding that, but that will probably not happen in the next few months. I think that for a read-only large knowledge graph, QLever is a very good option. Indexing is also fast: on a machine like the above, the complete Wikidata can be indexed in under a day. So having a daily fresh index would be no problem. TASK DETAIL https://phabricator.wikimedia.org/T290839 EMAIL PREFERENCES https://phabricator.wikimedia.org/settings/panel/emailpreferences/ To: Hannah_Bast Cc: Justin0x2004, Lucas_Werkmeister_WMDE, Bugreporter, Hannah_Bast, Aklapper, MPhamWMF, So9q, Invadibot, maantietaja, CBogen, Akuckartz, Nandana, Namenlos314, Lahi, Gq86, GoranSMilovanovic, QZanden, EBjune, merbst, LawExplorer, _jensen, rosalieper, Scott_WUaS, Jonas, Xmlizer, jkroll, Wikidata-bugs, Jdouglas, aude, Tobias1984, Manybubbles, Mbch331
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