mongo copy from one collection to another (on the same db)

Question

I have got mongo db called test and in this db two collections collection1 and collection1_backup. How to replace content of col

Answer 1

Using Java Driver

Try below one:

public void copyTo(String db,String sourceCollection,String destinationCollection,int limit) throws        
UnknownHostException {

    MongoClient mongo = new MongoClient("localhost", 27017);
    DB database = mongo.getDB(db);
    DBCollection collection = database.getCollection(sourceCollection);
    DBCursor dbCursor = collection.find().limit(limit);
    List list =  dbCursor.toArray();
    DBCollection destination =  database.getCollection(destinationCollection);
    destination.insert(list, WriteConcern.NORMAL); //WRITE CONCERN is based on your requirment.

}