About: http://webisa.webdatacommons.org/66428306

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	update() documents that it is free of race-condition, select_for_update() is obviously free of race-condition on supported backends, it would not be too hard to assume that update_or_create() provides such guarantee as well.
http://www.w3.org/ns/prov#wasQuotedFrom	djangoproject.com