dcausse created this task. dcausse added projects: Wikidata, Wikidata-Query-Service. Restricted Application added a subscriber: Aklapper.
TASK DESCRIPTION The use of blank nodes makes an update process always a challenging operation (http://www.aidanhogan.com/docs/blank_nodes_jws.pdf). The use of blank nodes by wikibase is very limited and thus I propose to remove them to simplify the WDQS update strategy. In wikibase we use blank nodes for two purposes: - denote an //unknown value// (originally discussed in T95441 <https://phabricator.wikimedia.org/T95441>) - owl constraints of wdno property For the unknown value use-case we seem to only use the blank node as a way to //filter// such unknown value. For the OWL constraints it's unclear if it is actually used/useful. For unknown values I suggest: wd:Q3 a wikibase:Item wdunk:P2 . wds:Q3-45abf5ca-4ebf-eb52-ca26-811152eb067c a wikibase:Statement wdunk:P2; wikibase:rank wikibase:NormalRank . A query like SELECT ?human WHERE { ?human wdt:P106 ?o FILTER isBLANK(?o) . } Would become SELECT ?human WHERE { ?human a wdunk:P106 } And SELECT ?human WHERE { ?human wdt:P106 ?o } Would now mean: //All entities with a known occupation// As opposed to //All entities with a known or unkown occupation// which should be written as: SELECT ?human WHERE { {?human wdt:P106 ?o} union {?human a wdunk:P106} } For OWL constraints I simply suggest to remove them or materialize the blank node. wdno:P109 a owl:Class ; owl:complementOf wdowl:P109 . wdowl:P109 a owl:Restriction ; owl:onProperty wdt:P109 ; owl:someValuesFrom owl:Thing . This is a breaking change to https://www.mediawiki.org/w/index.php?title=Wikibase/Indexing/RDF_Dump_Format if this is accepted I suggest a transition period where blank nodes would be kept, the use of //isBlank// from the query service could start emitting a deprecation warning. TASK DETAIL https://phabricator.wikimedia.org/T244341 EMAIL PREFERENCES https://phabricator.wikimedia.org/settings/panel/emailpreferences/ To: dcausse Cc: Aklapper, dcausse, darthmon_wmde, 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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