Lucas_Werkmeister_WMDE created this task.
Lucas_Werkmeister_WMDE added projects: Wikidata, Wikidata-Query-Service.

TASK DESCRIPTION
  In T244341: Wikibase RDF dump: stop using blank nodes for encoding SomeValue 
and OWL constraints <https://phabricator.wikimedia.org/T244341>, the question 
arose whether we should use “some value” or “unknown value” terminology. The UI 
and the data model primer 
<https://www.mediawiki.org/wiki/Wikibase/DataModel/Primer#Statements> use 
“unknown value”, but the full data model 
<https://www.mediawiki.org/wiki/Wikibase/DataModel#PropertySomeValueSnak> uses 
“some value”, and @Jheald has argued that this matches the current use of that 
snak type in Wikidata better (see T244341#5862287 
<https://phabricator.wikimedia.org/T244341#5862287>). We’d like to get some 
number on this, but it doesn’t seem to be possible on the public query service 
– even for a single property, a query like the following times out:
  
    SELECT ?property (COUNT(*) AS ?count) WHERE {
      ?statement ps:P20 ?unknown.
      FILTER(ISBLANK(?unknown))
      ?statement ?pq ?qualifier.
      ?property wikibase:qualifier ?pq.
    }
    GROUP BY ?property
    ORDER BY DESC(?count)
  
  More generally, we would be interested in the number of qualifiers of 
statements with “unknown value” in the main snak, aggregated by main statement 
and qualifier property. In SPARQL, that would be more or less:
  
    SELECT ?mainProperty ?qualifierProperty (COUNT(*) AS ?count) WHERE {
      ?mainProperty wikibase:claim ?p;
                    wikibase:statementProperty ?ps.
      ?qualifierProperty wikibase:qualifier ?pq.
      ?subject ?p ?statement.
      ?statement ?ps ?unknown. FILTER(isBlank(?unknown))
      ?statement ?pq ?qualifier.
    }
    GROUP BY ?mainProperty ?qualifierProperty
  
  (This doesn’t count statements without any qualifiers, but we could probably 
get those numbers separately for the top properties we’re interested in.) This 
may be more efficient to query with a different technology, though (Hadoop?).

TASK DETAIL
  https://phabricator.wikimedia.org/T246238

EMAIL PREFERENCES
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To: Lucas_Werkmeister_WMDE
Cc: Gehel, Aklapper, dcausse, Igorkim78, Lucas_Werkmeister_WMDE, Jheald, 
darthmon_wmde, Nandana, Lahi, Gq86, GoranSMilovanovic, QZanden, EBjune, merbst, 
LawExplorer, _jensen, rosalieper, Scott_WUaS, Jonas, Xmlizer, jkroll, 
Smalyshev, Wikidata-bugs, Jdouglas, aude, Tobias1984, Manybubbles, Mbch331
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