Two example queries that require a lot of RAM (one uses wdt:P31/wdt:P279*)

[WolfgangFahl]

Examples for out of memory conditions:

• https://qlever.cs.uni-freiburg.de/wikidata/tnooBa

• https://qlever.cs.uni-freiburg.de/wikidata/Y5WES4

[hannahbast]

The problem with these queries is that the result without the GROUP BY is huge. For example, for the second query, it's over a billion triples. It's aggravated by the fact that the implementation for the predicate path is not very space-efficient.

I wonder if these queries work for any of the other engines around.

[hannahbast]

This was more an observation. Yes, some queries are very expensive, and QLever imposes a memory limit and there will be an error message when that limit is exceeded by a query.