db.jason.find().sort({"rank":1})
{ "_id" : ObjectId("51ae517372779b7eeeb81342"), "name" : "jason" }
{ "_id" : ObjectId("51ae517372779b7eeeb81343"), "name" : "jason" }
{ "_id" : ObjectId("51ae513772779b7eeeb8133a"), "name" : "jason", "rank" : 0 }
{ "_id" : ObjectId("51ae513772779b7eeeb8133b"), "name" : "jason", "rank" : 1 }
{ "_id" : ObjectId("51ae513772779b7eeeb8133c"), "name" : "jason", "rank" : 2 }
我希望文档未排序,而不是按开始时间排序...但同时保持有排序的项目按升序排列。这是否可行,或者我需要使用字符串或高数值(如99999)来默认空值?