I'am sorting messages in my program according to the ObjectId and than trying to fetch messages from MongoDB with ID bigger than the one I have, but than I'm getting messages I already have.
After some tests and reading the documentation it looks like the Java ObjectId / compareTo is wrong.
My test:
@Test
public void compareMongoToMongo2()

{ final String MONGO_ID_1 = "4b5d4825f5f32ad607e4c7c7"; final String MONGO_ID_2 = "4b5d4825f5f32ad6eae3c7c7"; ObjectId id1 = new ObjectId(MONGO_ID_1); ObjectId id2 = new ObjectId(MONGO_ID_2); System.out.println(id1.compareTo(id2)); }

output: 29
Meaning MONGO_ID_1 > MONGO_ID_2

But when running the following query on MongoDB:
> db.messages.find({"_id": {$gt: ObjectId("4b5d4825f5f32ad607e4c7c7")}} ,

{"_id":1}

)

{ "_id" : ObjectId("4b5d4825f5f32ad6eae3c7c7") }

Meaning MONGO_ID_2 > MONGO_ID_1