Affects Version/s: BLAZEGRAPH_2_1_4
Fix Version/s: None
Component/s: Wikidata Query Service
I try this query:
Which calculates top 20 items used with property P31, and it works just
fine, under 1 second. However, if I add a static projection to it:
it times out. Something is clearly wrong here.
The plans for the queries are very different:
I'm not sure why adding a constant into projection changes the plans so
Disabling the optimizer does not seem to help. Same problem happens if I
do something like this:
is slightly faster - 18 seconds - but way slower than original one,
under 1 sec. Converting ?x to BIND or VALUES and using various hints
don't seem to change anything (though VALUES seem to do it in 15s - a
bit faster, but still nowhere near proper performance).