Performance of certain query patterns is degradated

[D063520]

Part of the endpoint? (leave empty if you don't know)

• Backend (qendpoint-backend)
• Store (qendpoint-backend)
• Core (qendpoint-core)
• Frontend (qendpoint-frontend)
• Other

Description of the issue

My theory is that queries in WDBench that contain triple patterns with disjoint variables are timing out, example:

query 171,

SELECT * WHERE { 
?x3 <http://www.wikidata.org/prop/direct/P1082> ?x4 . 
?x6 <http://www.wikidata.org/prop/direct/P1448> ?x3 . 
?x1 <http://www.wikidata.org/prop/direct/P31> <http://www.wikidata.org/entity/Q6256> . 
?x1 <http://www.wikidata.org/prop/direct/P36> ?x7 . 
?x1 <http://www.wikidata.org/prop/direct/P1448> ?x5 . 
?x1 <http://www.wikidata.org/prop/direct/P1082> ?x2 . 
 } LIMIT 100000

query 183

SELECT * WHERE { ?x1 <http://www.wikidata.org/prop/direct/P115> ?x2 . ?x1 <http://www.wikidata.org/prop/direct/P31> <http://www.wikidata.org/entity/Q476028> . ?x3 <http://www.wikidata.org/prop/direct/P625> ?x3 . ?x2 <http://www.wikidata.org/prop/direct/P625> ?x4 . 
 } LIMIT 100000

query 209

SELECT * WHERE {
 ?x1 <http://www.wikidata.org/prop/direct/P131> <http://www.wikidata.org/entity/Q9899> . 
?x1 <http://www.wikidata.org/prop/direct/P31> <http://www.wikidata.org/entity/Q79007> . 
?x2 <http://www.wikidata.org/prop/direct/P625> ?x2 . 
 } LIMIT 100000

The disjoin part seams to resolve fast enough. This seams to affect many of the queries with timeout!

Excepted behavior

No response

Obtained behavior

No response

How to reproduce

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Endpoint version

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Do I want to contribute to fix it?

None

Something else?

No response