dcausse created this task. dcausse added projects: Wikidata, Wikidata-Query-Service. Restricted Application added a subscriber: Aklapper.
TASK DESCRIPTION Due to their nature such blank nodes are hard to keep in sync with the triple store. We already know that some are duplicated in the triple store (T231515 <https://phabricator.wikimedia.org/T231515>). This ticket is about tracking how blank nodes are used in the rdf output from wikibase and make sure that we do not duplicate them during the update process. Blank used to denote "unknown value" in wikidata ------------------------------------------------ and never used as subject. Blank node only used as an object of statement qualifier: s:Q233-a9844587-4029-33bc-7b34-13b0d3c10ed3 a wikibase:Statement, wikibase:BestRank ; wikibase:rank wikibase:NormalRank ; ps:P138 wd:Q10987 ; pq:P407 _:genid1 . from: https://www.wikidata.org/wiki/Special:EntityData/Q233.ttl (does not seem to be duplicated currently <https://query.wikidata.org/#SELECT%20%2a%20WHERE%20%7B%0A%20%20wd%3AQ233%20p%3AP138%20%3Fs%20.%0A%20%20%3Fs%20pq%3AP407%20%3Fo%0A%7D>) As statement values: s:Q17619314-5cd290f5-4659-e699-74b9-52714a955c62 a wikibase:Statement, wikibase:BestRank ; wikibase:rank wikibase:NormalRank ; ps:P268 _:genid4 ; pq:P813 "2016-03-14T00:00:00Z"^^xsd:dateTime ; pqv:P813 v:bcddb148b45928cdcf857b69eeb88df9 . from: https://www.wikidata.org/wiki/Special:EntityData/Q17619314.ttl ([[https://query.wikidata.org/#SELECT%20%2a%20WHERE%20%7B%0A%20%20wd%3AQ17619314%20p%3AP268%20%3Fs%20.%0A%20%20%3Fs%20ps%3AP268%20%3Fo%0A%7D | does not seem to be duplicated currently). But they don't seem to link to same anonymous bnode when used as `ps` and `wdt` objects (T239397 <https://phabricator.wikimedia.org/T239397>). But in general, are these triples interesting in wdqs? Since they're never used as subject there are no way to use them directly, it seems the only thing that we can do is to display them (T173248 <https://phabricator.wikimedia.org/T173248>). Blank nodes used to indicate owl constraints on properties ---------------------------------------------------------- wdno:P3418 a owl:Class ; owl:complementOf _:genid1 . _:genid1 a owl:Restriction ; owl:onProperty wdt:P3418 ; owl:someValuesFrom owl:Thing . from https://www.wikidata.org/wiki/Special:EntityData/P3418.ttl The ones are not properly synced and are duplicated (T231515 <https://phabricator.wikimedia.org/T231515>). But again, are they really useful on the triple stores, these constraints seem to be always the same and since we do not use any inference engine nor constraint checks do we really need to sync them? Fin others ---------- We shout investigate other uses of blank nodes by extracting all of them from the triple store using this query: select ?p (count(*)as ?cnt) { ?s ?p ?o . filter ((!isLiteral(?o))&&(!isUri(?o))) } group by ?p TASK DETAIL https://phabricator.wikimedia.org/T239414 EMAIL PREFERENCES https://phabricator.wikimedia.org/settings/panel/emailpreferences/ To: dcausse Cc: dcausse, Aklapper, darthmon_wmde, DannyS712, Nandana, Lahi, Gq86, Lucas_Werkmeister_WMDE, GoranSMilovanovic, QZanden, EBjune, merbst, LawExplorer, _jensen, rosalieper, Scott_WUaS, Jonas, Xmlizer, jkroll, Smalyshev, Wikidata-bugs, Jdouglas, aude, Tobias1984, Manybubbles, Mbch331
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