Homework: Homework 6.3
Which of the following statements are true about choosing and using a shard key? MongoDB can not enforce unique indexes on a sharded collection other than the shard key itself, or indexes prefixed by the shard key. There must be an index on the collection that starts with the shard key. You can change the shard key on a collection if you desire. Any update that does not contain the shard key will be sent to all shards. The shared key must be unique
