selected_related只做一次鏈表查詢,會將鏈表數據全部取出
prefetch_related做兩次查詢,第二次爲鏈表查詢
如果鏈表很多,prefetch_related效率高於selected_related,同時prefetch_related支持m2m,而selected_related只支持fk和one2one
selected_related只做一次鏈表查詢,會將鏈表數據全部取出
prefetch_related做兩次查詢,第二次爲鏈表查詢
如果鏈表很多,prefetch_related效率高於selected_related,同時prefetch_related支持m2m,而selected_related只支持fk和one2one