1. Create collection use students; db.grades.drop(); for (i = 0; i < 10000000; i++) { for (j = 0; j < 4; j++) { assess = ['exam', 'quiz', 'homework', 'homework'] ; record = {'student_id':i, 'type':assess[j], 'score':Math.random()*100} ; db.grades.insert(record); } } 2. Drop collection grades 3. show dbs command will show you that size of database was not changed 4. Removed collection is still on hard disk drive and takes place.