uses for mongodb ObjectId creation time

Question

The ObjectId used as the default key in mongodb documents has embedded timestamp (calling objectid.generation_time returns a datetime object). So it is possible

Answer 1

Yes, you can use the generation_time of BSON ObjectId for the purposes you want. So,

db.collection.find().sort({ _id : -1 }).limit(10)

will return the last 10 created items. However, since the embedded timestamps have a one second precision, multiple items within any second are stored in the order of their creation.