Optimize queries by inverting the property path

[nicolas-raoul]

https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/query_optimization#Inverse_property_paths

Another technique for subverting the optimizer into delivering results is to invert the property path used in the query; possibly particularly useful when dealing with timeouts of reports having wdt:P31/wdt:P279* constructions. Consider the following examples - the first times out, the second works speedily:

# Museums in Northern Ireland - TIMES OUT
SELECT distinct ?museum ?museumLabel WHERE {
  ?museum wdt:P131* wd:Q26 .
  ?museum wdt:P31/wdt:P279* wd:Q33506 .
  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
}

# Museums in Northern Ireland - SUCCEEDS
SELECT distinct ?museum ?museumLabel WHERE {
  ?museum wdt:P131* wd:Q26 .
  wd:Q33506 ^wdt:P279*/^wdt:P31 ?museum .
  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en". }
}

It is worth a try.