I want to retrieve all distinct object properties of instances with the same type (class), starting with two initial seeds (wd:Q963 and wd:Q42320). First, I ask for the type (and maybe subtype) of such seeds. Second, all instances of the same class of the seeds are retrieved. Third, properties of the instances are retrieved. Finally, I want to retrieve descriptions of such properties and if possible alternative labels. My query is as follows:
select distinct ?property ?description ?label where{
{
wd:Q963 wdt:P31 ?typesSubject .
?instancesS (wdt:P31|wdt:P279) ?typesSubject .
?instancesS ?property ?unknown .
}
UNION
{
wd:Q42320 wdt:P31 ?typesObject .
?instancesO (wdt:P31|wdt:P279) ?typesObject .
?unknown ?property ?instancesO .
}
?claimPredicate wikibase:directClaim ?property .
?claimPredicate schema:description ?description .
?claimPredicate rdfs:label ?label .
FILTER(strstarts(str(?property),str(wdt:)))
FILTER(strstarts(str(?unknown),str(wd:)))
FILTER(LANG(?description) = "en").
FILTER(LANG(?label) = "en").
}
The problem is that my actual query takes a lot of time and it fails in the public Wikidata endpoint. Does anyone can provide me some hints to optimize such a query?
To be honest, I can't understand the aim of your query. I suppose you are interested in semantic similarity or something like.
Basically, you could reduce the number of joins, retrieving only unique wdt-predicates with nested SELECT DITINCT
.
SELECT ?property ?claimPredicateLabel ?claimPredicateDescription
WHERE {
hint:Query hint:optimizer "None" .
{
SELECT DISTINCT ?property {
VALUES (?s) {(wd:Q963) (wd:Q42320)}
?s wdt:P31/^(wdt:P31|wdt:P279) ?instances .
?instances ?property ?unknown .
}
}
?claimPredicate wikibase:directClaim ?property .
SERVICE wikibase:label { bd:serviceParam wikibase:language "en" . }
}
This is fast enough (~ 3s) even with SERVICE wikibase:label
.
Also, you don't need FILTER(strstarts(str(?property),str(wdt:)))
after ?claimPredicate wikibase:directClaim ?property
.
As for hint:Query hint:optimizer "None"
, this hint forces Blazegraph to follow standard bottom-up evaluation order. In this particular query, hint:Query hint:optimizer "Runtime"
or hint:SubQuery hint:runOnce true
should also work.